Timken Engineering User Manual

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TIMKEN ENGINEERING MANUAL

ENGINEERING MANUAL INDEX

TIMKEN OVERVIEW. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

SHELF LIFE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

WARNINGS/DISCLAIMERS ..................................8

BEARING SELECTION PROCESS ..............................9

Bearing Types ..........................................10

Cages .................................................28

Determination of Applied Loads and Bearing Analysis .......32

Bearing Reactions ......................................39

Bearing Ratings ........................................47

System Life and Weighted Average Load and Life ..........55

BEARING TOLERANCES, INCH AND METRIC SYSTEMS .........56

Metric System .........................................57

Inch System ...........................................68

MOUNTING DESIGNS, FITTING PRACTICE,

SETTING AND INSTALLATION ..............................74

Tapered Roller Bearings .................................77

Spherical and Cylindrical Roller Bearings ..................82

Angular Contact Ball Bearings ...........................95

Radial Ball Bearings ....................................99

Precision Bearings ....................................109

FITTING PRACTICE TABLES ...............................126

Spherical Roller Bearings. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

Cylindrical Roller Bearings ..............................128

Radial Ball, Spherical and Cylindrical Roller Bearings ......132

Angular Contact Ball Bearings ..........................146

Radial Ball Bearings ...................................147

Tapered Roller Bearings ................................154

Precision Tapered Roller Bearings .......................168

Thrust Bearings .......................................180

OPERATING TEMPERATURES ..............................184

Heat Generation and Dissipation ........................187

TORQUE .................................................188

SPEED RATINGS ..........................................193

CONVERSION TABLES ....................................196

LUBRICATION AND SEALS .................................199

Lubrication ...........................................200

Seals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209

TIMKEN ENGINEERING MANUAL

OVERVIEW

TIMKEN

GROW STRONGER WITH TIMKEN

Every day, people around the world count on the strength

of Timken. Our expertise in metallurgy, friction management

and mechanical power transmission helps them accelerate

improvements in productivity and uptime.

We supply products and services that can help keep your

operations moving forward, whether you need drive train

kits for commercial vehicles, durable housings for bearings

in dirty environments, couplings that avoid metal-to-metal

contact between motors and gearboxes, repair services for

bearings and gearboxes, roller chain for dry, abrasive and

high-moisture applications or other products and services for

your applications.

When you choose Timken, you receive more than high-quality

products and services: You gain a worldwide team of highly

trained and experienced Timken people committed to working

collaboratively with you to improve your business.

Globally, our 17,000 people provide reliable answers for a

wide range of operations in manufacturing, mining, medical

equipment, aerospace, transportation, oil and gas – and other

diverse industries.

2 TIMKEN ENGINEERING MANUAL

OVERVIEW

INCREASE YOUR EQUIPMENT UPTIME

In addition to high-quality bearings and mechanical power

transmission components, we provide valuable integrated

products and services. For example, we offer repair services

and equipment monitoring equipment that can alert you to

problems before they impact your uptime.

Additionally, we offer a broad selection of seals, premium

TIMKEN

lubricants, lubricators, couplings and chain to keep your

operations moving smoothly.

Our 12 technology and engineering centers in the United

States, Europe and Asia help pioneer tomorrow’s innovations

with extensive basic and applied scientiﬁc research programs.

Through internal development and strategic acquisition of

innovative companies, we continue to expand our portfolio

of highly engineered bearings, power transmission products

and advanced services.

TIMKEN ENGINEERING MANUAL

TIMKEN

INTRODUCTION

Timken is a leader in the advancement of bearing

technology. Expert craftsmanship, well-equipped

production facilities, and a continuing investment in

technology programs ensure that our products are

synonymous with quality and reliability. Today, our

plants manufacture several bearing types over a

broad range of sizes.

Anti-friction bearings inherently manage broad ranges

of speed and many combinations of radial and thrust

loads. Other important environmental conditions, such

as low and high temperature, dust and dirt, moisture,

and unusual mounting conditions, affect bearing

operation.

This engineering section is not intended to be

comprehensive, but does serve as a useful guide in

bearing selection.

Where more complex bearing applications are involved, your Timken engineer should be consulted. The following topics are covered within this manual:

Bearing design types.

•

Cage design types.

•

Life analysis procedure.

•

Bearing tolerances.

•

Fitting practice and mounting recommendations.

•

Operating temperatures.

•

Speed ratings.

•

Lubrication recommendations.

•

Seal design options.

•

4 TIMKEN ENGINEERING MANUAL

HOW TO USE THIS CATALOG

We designed this catalog to help you ﬁnd the Timken® spherical roller bearing solid-block housed units best suited to your speciﬁcations.

Timken offers an extensive range of bearings and accessories in both imperial and metric sizes. For your convenience, size ranges are indicated in millimeters and inches. Contact your Timken engineer to learn more about our complete line for the special needs of your application.

This publication contains dimensions, tolerances and load ratings, as well as engineering sections describing ﬁtting practices for shafts and housings, internal clearances, materials and other bearing features. It provides valuable assistance in the initial consideration of the type and characteristics of the bearings that may best suit your particular needs.

TIMKEN

ISO and ANSI/ABMA, as used in this publication, refer to the International Organization for Standardization and the American National Standards Institute/American Bearing Manufacturers Association.

TIMKEN ENGINEERING MANUAL

TIMKEN

SHELF LIFE AND STORAGE OF GREASE-LUBRICATED BEARINGS AND COMPONENTS

To help you get the most value from our products, Timken provides guidelines for the shelf life of grease-lubricated ball and roller bearings, components and assemblies. Shelf life information is based on Timken and industry test data and experience.

SHELF LIFE

Shelf life should be distinguished from lubricated bearing/ component design life as follows:

Shelf life of the grease-lubricated bearing/component

•

represents the period of time prior to use or installation.

The shelf life is a portion of the anticipated aggregate design

•

life. It is impossible to accurately predict design life due to variations in lubricant bleed rates, oil migration, operating conditions, installation conditions, temperature, humidity and extended storage.

Shelf life values, available from Timken, represent a

•

maximum limit and assume adherence to the storage and handling guidelines suggested in this catalog or by a Timken associate. Deviations from the Timken storage and handling guidelines may reduce shelf life. Any speciﬁcation or operating practice that deﬁnes a shorter shelf life should be used.

European REACH Compliance

Timken lubricants, greases and similar products sold in standalone containers or delivery systems are subject to the European REACH (Registration, Evaluation, Authorization and Restriction of CHemicals) directive. For import into the European Union, Timken can sell and provide only those lubricants and greases that are registered with ECHA (European CHemical Agency). For further information, please contact your Timken engineer.

Timken cannot anticipate the performance of the grease lubricant after the bearing or component is installed or placed in service.

TIMKEN IS NOT RESPONSIBLE FOR THE SHELF LIFE OF ANY BEARING/COMPONENT LUBRICATED BY ANOTHER PARTY.

6 TIMKEN ENGINEERING MANUAL

TIMKEN ENGINEERING MANUAL

SHELF LIFE AND STORAGE OF GREASE-LUBRICATED BEARINGS AND COMPONENTS

STORAGE

Timken suggests the following storage guidelines for our ﬁnished products (bearings, components and assemblies, referred to as “products”):

Unless directed otherwise by Timken, products should be

•

kept in their original packaging until they are ready to be placed into service.

Do not remove or alter any labels or stencil markings on the

•

packaging.

Products should be stored in such a way that the packaging

•

is not pierced, crushed or otherwise damaged.

After a product is removed from its packaging, it should be

•

placed into service as soon as possible.

When removing a product that is not individually packaged

•

from a bulk pack container, the container should be resealed immediately after the product is removed.

Do not use product that has exceeded its shelf life.

•

Contact your local Timken engineer for further information on shelf life limits.

The storage area temperature should be maintained

•

between 0° C (32° F) and 40° C (104° F); temperature ﬂuctuations should be minimized.

The relative humidity should be maintained below 60 percent

•

and the surfaces should be dry.

The storage area should be kept free from airborne

•

contaminants such as, but not limited to, dust, dirt, harmful vapors, etc.

The storage area should be isolated from undue vibration.

•

Extreme conditions of any kind should be avoided.

•

Due to the fact that Timken is not familiar with your particular storage conditions, we strongly suggest following these guidelines. However, you may be required by circumstances or applicable government requirements to adhere to stricter storage requirements.

TIMKEN

Most bearing components typically ship protected with a corrosion-preventive compound that is not a lubricant. These components may be used in oil-lubricated applications without removal of the corrosion-preventive compound. When using some specialized grease lubrications, we advise you to remove the corrosion-preventive compound before packing the bearing components with suitable grease.

We pre-pack most housed unit types in this catalog with general-purpose grease suitable for their normal applications. It may be necessary for you to frequently replenish the grease for optimum performance.

Be careful in selecting lubrication, however, since different lubricants are often incompatible. You may order housed units pre-lubricated with a speciﬁed lubrication.

When you receive a bearing or housed unit shipment, do not remove products from their packaging until they are ready for mounting so they do not become corroded or contaminated.

Store bearings and housed units in an appropriate atmosphere so they remain protected for the intended period.

TIMKEN ENGINEERING MANUAL

TIMKEN

WARNINGS/DISCLAIMERS

WARNING

Failure to observe the following warnings could

create a risk of death or serious injury.

Proper maintenance and handling practices are critical.

Always follow installation instructions and

maintain proper lubrication.

Never spin a bearing with compressed air.

The rollers may be forcefully expelled.

DISCLAIMER

This catalog is provided solely to give you analysis tools and data to assist you in your product selection. Product performance is affected by many factors beyond the control of Timken.

Therefore, the suitability and feasibility of all product selection must be validated by you.

Timken products are sold subject to Timken's terms and conditions of sale, which include its limited warranty and remedy, which terms may be found at www.timken.com/ termsandconditionsofsale. Please consult with your Timken sales engineer for more information and assistance.

Warnings for this product line are found in this catalog

and posted on www.timken.com/warnings

CAUTION

Failure to observe the following warnings could

create a risk of death or serious injury.

Remove oil or rust inhibitor from parts before heating,

to avoid ﬁre and fumes.

NOTE

Mixing greases can result in improper bearing lubrication.

Always follow the speciﬁc lubrication instructions of your

equipment supplier.

NOTE

Product performance is affected by many factors beyond the control of Timken. Therefore, the suitability and feasibility of all designs and product selection should be validated by you. This catalog is provided solely to give you, a customer of Timken or its parent or afﬁliates, analysis tools and data to assist you in your design. No warranty, expressed or implied, including any warranty of ﬁtness for a particular purpose, is made by Timken. Timken products and services are sold subject to a Limited Warranty.

You can see your Timken engineer for more information.

Every reasonable effort has been made to ensure the accuracy of the information in this writing, but no liability is accepted for errors, omissions or for any other reason.

COMPLIANCE

To view the complete engineering catalog, please visit www.timken.com. To order the catalog, please contact your Timken sales engineer and request a copy of the Timken Engineering Manual (order number 10424).

European REACH compliance Timken-branded lubricants, greases and similar products sold in stand-alone containers or delivery systems are subject to the European REACH (Registration, Evaluation, Authorization and Restriction of CHemicals) directive. For import into the European Union, Timken can sell and provide only those lubricants and greases that are registered with ECHA (European CHemical Agency). For further information, please contact your Timken sales engineer.

The Timken Company products shown in this catalog may be directly, or indirectly subject to a number of regulatory standards and directives originating from authorities in the USA, European Union, and around the world, including: REACH (EC 1907/2006, RoHS (2011/65/EU), ATEX (94/9/EC), 'CE' MARKING (93/68/EEC), CONFLICT MINERALS (Section 1502 of the Dodd-Frank Wall Street Reform and Consumer Protection Act).

For any questions or concerns regarding the compliancy or applicability of Timken products to these, or other unspecified standards, please contact your Timken sales engineer or customer services representative.

NOTE

Never attempt a press ﬁt on a shaft by applying pressure

to the outer ring or a press ﬁt in a housing by applying

pressure to the inner ring.

8 TIMKEN ENGINEERING MANUAL

Updates are made periodically to this catalog. Visit www.timken.com for the most recent version of the Timken Spherical Roller Bearing Solid-Block Housed Units Catalog.

BEARING SELECTION PROCESS

The ﬁrst step in bearing selection is to identify the best bearing type for the application. Each bearing type has advantages and disadvantages based on its internal design. Table 1, on page 10, ranks the different bearing types on various performance characteristics.

The next step is to assess the bearing size constraints including the bore, outside diameter (O.D.) and width. This is done by deﬁning the minimum shaft diameter, maximum housing diameter and available width for the bearing in the application. At this point, bearings may be selected from the manual that ﬁt within the deﬁned size constraints. Several bearings with different load-carrying capacities may be available that ﬁt within the envelope.

The third step is to evaluate the known environmental conditions and application requirements. Environmental conditions include factors such as ambient temperature, applied load, bearing speed and cleanliness of the environment immediately surrounding the bearing. Application requirements such as bearing ﬁts, bearing setting, lubricant type, cage type and ﬂange arrangements are determined based on the speed, temperature, mounting conditions and loading conditions within the application.

BEARING SELECTION PROCESS

Lastly, bearing life calculations are performed that take into account all of the environmental and application conditions. If more than one bearing has been evaluated up to this point, selection is based on the bearing that provides the best overall performance for the application. A detailed explanation of this analysis procedure is included in the following sections. For assistance, contact your Timken engineer for a comprehensive computer analysis of your bearing application.

To view more Timken catalogs, go

to www.timken.com/catalogs

for interactive versions, or to

download a catalog app for your

smart phone or mobile device

scan the QR code or go to

timkencatalogs.com.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES

Cylindrical roller bearingTapered roller bearing Thrust tapered roller bearing Thrust cylindrical roller bearing

Spherical roller bearing

Thrust spherical roller bearing

Radial ball bearing Thrust ball bearing Angular contact ball bearing

TABLE 1. RELATIVE OPERATING CHARACTERISTICS OF VARIOUS BEARING TYPES

Characteristic

Pure radial load Good Unsuitable Excellent Unsuitable Good Unsuitable Good Poor Fair

Pure axial load Good Excellent Unsuitable Good Fair Excellent Fair Excellent Good

Combined load Excellent Poor Fair Unsuitable Good Fair Good Poor Excellent

Moment load Excellent Poor Unsuitable Unsuitable Unsuitable Unsuitable Fair Poor Good

High stiffness Excellent Excellent Good Excellent Good Good Fair Good Good

Low friction Good Good Excellent Poor Fair Fair Excellent Good Good

Misalignment Poor Poor Poor Unsuitable Excellent Excellent Good Poor Poor

Locating position

(ﬁxed)

Non-locating

position (ﬂoating)

Speed Good Good Excellent Poor Fair Fair Excellent Excellent Excellent

Tapered Roller

Bearing

Excellent Good Fair Fair Good Good Good Excellent Good

Good Unsuitable Excellent Unsuitable Good Unsuitable Good Unsuitable Good

Thrust Tapered

Roller Bearing

Cylindrical Roller

Bearing

Thrust Cylindrical

Roller Bearing

Spherical Roller

Bearing

Thrust Spherical

Roller Bearing

Radial

Ball Bearing

Thrust Ball

Bearing

Angular Contact

Ball Bearing

10 TIMKEN ENGINEERING MANUAL

RADIAL BALL BEARINGS

Although radial ball bearings are designed primarily to support a radial load, they perform relatively well under thrust or combined radial and thrust load conditions.

Deep-groove ball bearings, commonly called Conrad or nonfilling-slot bearings, are assembled by displacing the inner ring relative to the outer ring and inserting balls into the space between the rings. By this method, only slightly more than half the annular space between the inner and outer rings can be ﬁlled with balls. Thus, capacity is limited.

To increase capacity, a ﬁlling slot or notch can be cut into the inner ring, permitting the insertion of balls. Once the balls have been inserted, the slot is ﬁlled by an insert. The increased number of balls increases radial load capacity, but thrust load capacity is sacriﬁced because of the ﬁlling slot.

The non-ﬁlling-slot or Conrad bearing is designated by the sufﬁx K and the ﬁlling slot bearing is designated by the sufﬁx W.

BEARING SELECTION PROCESS

BEARING TYPES • RADIAL BALL BEARINGS

BALL BEARINGS WITH SNAP RINGS (WIRELOC)

Single-row radial ball bearings, including those with seals or shields and open and shielded double-row types, are available with snap rings. The snap ring protrudes from a groove in the outer ring and acts as a shoulder to maintain bearing position. It is designed for mounting in through-bored housings. This feature is designated by adding the sufﬁx G to the standard bearing number. Single-shielded or sealed bearings with snap rings can be supplied with the snap ring on the same side or opposite the shield or seal position.

These bearings are advantageous in automobile transmission design and in all applications where compactness is essential, or where it is difﬁcult and costly to machine housing shoulders. The snap ring provides an adequate shoulder for the bearings without a sacriﬁce in bearing capacity. The thrust capacity of the snap ring in shear exceeds the thrust capacity of the bearing.

Typical designs illustrating how mounting simpliﬁcation can be accomplished through the use of snap ring bearings are shown below.

Sufﬁx K Sufﬁx W Conrad Filling Slot

Fixed mounting Floating mounting

Fig. 1. Typical mountings for radial ball bearings.

Fig. 2. Typical mountings for snap ring bearings.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • ANGULAR CONTACT BALL BEARINGS

ANGULAR CONTACT BALL BEARINGS

SINGLE-ROW

Single-row, angular contact ball bearings are designed for combination loading with high thrust capacity in one direction, and are suggested for applications where the magnitude of the thrust component is high enough to preclude the use of radialtype ball bearings. They are dimensionally interchangeable with single-row radial bearings of corresponding sizes.

The angular contact ball bearing has a relatively large contact angle, high ring depths, and a maximum complement of balls assembled through a counterbore in the outer ring. These features provide bearings with signiﬁcantly more thrust capacity than radial bearings of the same size.

Angular contact bearings are used in such applications as gear reducers, pumps, worm drives, vertical shafts and machine tool spindles, where they are frequently mounted in various singlerow arrangements.

DOUBLE-ROW

Double-row, angular contact ball bearings are used effectively where heavy radial, thrust or combined loads demand axial rigidity of the shaft. This type is similar to a duplex pair of singlerow bearings by virtue of its two rows of balls and angular-contact construction, which provide greater axial and radial rigidity than can be obtained by using a single-row radial bearing.

With the exception of small sizes, double-row ball bearings are made in the ﬁlling slot construction, and therefore, do not have as much thrust capacity as equivalent size single-row, angular contact bearings mounted in duplex pairs. Fixed and ﬂoating mountings of double-row bearings are shown. Smaller sizes are supplied with polymer retainers.

Fixed mounting Floating mounting

Fig. 4. Typical mountings for double-row, angular contact ball bearings.

Fig. 3. Typical mounting for single-row, angular contact ball bearings.

12 TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • PRECISION BEARINGS

PRECISION BEARINGS

(1)

MINIATURE AND THIN-SECTION BALL BEARINGS

Timken produces precision ball bearings and assemblies in miniature, instrument and thin-section series. All are manufactured with quality steel, tolerances and features that meet demanding application challenges. These precision bearings and assemblies are found in surgical and diagnostic imaging devices, precision pumps, measurement and material handling equipment, as well as guidance, weapons and space applications. Standard sizes range from 1 mm to 279.40 mm bore (0.0250 in. to 11.000 in. bore).

Radial ball bearings

These Conrad bearings are available in ISO P5/ABEC 5 to ISO P4/ABEC 7 precision levels as a standard catalog offering. The deep-groove construction allows for handling of radial, thrust or combination loads. These are offered primarily with 440C stainless-steel rings and balls with one-piece fully machined snap-in phenolic cages. In addition to 52100, other material and cage options are available, as well as shields and seals, and ceramic or titanium carbidecoated balls. Flanges are offered on miniature product. Typical applications include guidance systems, medical (surgical instruments and devices) and robotic joints.

Fig. 5. Radial ball bearing.

Angular contact ball bearings

Angular contact ball bearings offer maximum ball complement with a onepiece precision-machined retainer. The increased ball complement, combined with a relatively high contact angle, maximizes axial stiffness. Angular contact ball bearings are manufactured to the same tolerances and standards as the radial ball bearings. Rings and balls are normally 440C stainless steel, but other material options are offered. Steel and ceramic balls are available as standard. Typical applications use preloaded pairs for maximum stiffness, high speeds and precise positioning. These include surgical handpieces, control moment gyros and other high-speed or highstiffness applications.

Fig. 6. Angular contact ball bearing.

Fractured ring ball bearings

These bearings have outer rings that are radially fractured in one location. This permits the ring to be opened for complete ﬂexibility in the choice of ball complement and cage in a deep-groove radial bearing. High-strength stainless-steel holding bands are pressed on the ground shoulders to retain tight abutment and alignment of the fractured surface during handling and normal operation. Full complement and retainer conﬁgurations are available.

Typical applications have a limited radial cross section and a limited axial width. These applications require a bearing with maximum radial capacity, as well as axial capacity in both directions.

Fig. 7. Fractured ring ball bearing.

Pivot ball bearings

Designed for space constrained environments where low torque is required, pivot bearings use the mating shaft for the inner raceway. These bearings achieve maximum power density with a full complement of larger balls, no cage or inner ring. Shields are available for the standard line. Typical applications are in guidance systems, such as commercial gyroscopes.

Fig. 8. Pivot ball bearing.

Thrust ball bearings

These bearings are designed for applications where high axial load, low speed and relatively high torque are allowable. The standard offering has all stainless steel components for use where inert materials are required. Stainless steel allows operation as a fuel control governor.

Fig. 9. Thrust ball bearing.

(1)

For additional information, refer to the Timken Super Precision Bearings for

Machine Tool Applications Catalog (order no. 5918) on www.timken.com.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • PRECISION BEARINGS

PRECISION BEARINGS – continued

TAPERED ROLLER BEARINGS

Timken’s high-precision tapered roller bearings consist of carefully matched components that offer an added degree of ﬁne-tuning in the bearing setting and adjustment procedure to maximize customer machine productivity. Timken manufactures high-speed designs with a variable preload capability for optimum performance. Timken also manufacturers Precision Plus bearings – having an overall radial runout less than a single micron.

TS and TSF single-row bearings

These bearings are similar in design to the types described on page 16. They are only produced in high-precision quality, to be used in machine tool spindles, printing press cylinders and other applications where accuracy of rotation is required.

TSHR - Hydra-Rib™ bearing with preload adjustment device

For many applications, notably in the machine tool industry, bearings are required to run at high speeds with a controlled preload setting. The Hydra-Rib™ bearing has a floating outer ring rib controlled by hydraulic or pneumatic pressure, which ensures that the required bearing preload is maintained irrespective of the differential expansions or changes in loading taking place within the system.

Fig. 10. Hydra-Rib™ bearing.

TXR - crossed roller bearing

A crossed roller bearing is two sets of bearing rings and rollers brought together at right angles with alternate rollers facing opposite directions. TXR bearings have a section height not much greater than that of a TS bearing. The steep angle, tapered geometry of the bearing causes the load-carrying center of each of the rings to be projected along the axis, resulting in a total effective bearing spread many times greater than the width of the bearing itself. This type of bearing offers a high resistance to overturning moments.

The normal design of the bearing is type TXRDO, which has a double outer ring and two inner rings, with rollers spaced by polymer cages. Crossed roller bearings are manufactured in precision classes.

Fig. 11. TXR crossed roller bearing.

TXR

SUPER PRECISION BALL BEARINGS

The Timken line of super precision machine tool ball bearings is designed to meet ISO and ABEC tolerance levels. However, Timken manufactures all super precision ball bearings to surpass ISO/ABMA criteria to ensure that the end users receive only the highest quality product to maximize machine performance. Spindle bearings are the most popular type of super precision ball bearing used within the machine tool industry. These angular contact bearings are used primarily in precision, high-speed machine tool spindles. Timken manufactures super precision machine tool bearings in four metric ISO dimensional series. In addition, because of specialized variations of bearing design and geometry, Timken offers a total of seven angular contact bearing types within these four basic series:

ISO 19 (9300WI, 9300HX series).

•

ISO 10 (9100WI, 9100HX, 99100WN series).

•

ISO 02 (200WI series).

•

ISO 03 (300WI series).

•

Multiple internal geometries are available to optimize either loadcarrying capacity or speed capability with part number sufﬁxes designated as: WI, WN, HX or K. WI-type bearings are designed to maximize capacity of the various bearing cross sections and are used in low to moderate speeds. The HX is Timken’s proven highspeed design. It has a signiﬁcant advantage at higher speeds, generating less heat and less centrifugal loading forces. The WN-type is generally a compromise between the WI and HX as it offers higher speed capability than the WI, but lower capacity, higher stiffness and lower speed capability than the HX design.

Most of the bearing types are available in either 15 degree (2MM) or 25 degree (3MM) contact angles. In addition, Timken now stocks more ceramic ball sizes than ever for the highest speed requirements. The K-type deep-groove (Conrad) super precision radial ball bearing is generally used in applications where capacity and stiffness do not require sets containing multiple bearings. By virtue of the single-row, radial deep-groove construction, and super precision level tolerances, these are capable of carrying thrust loads in either direction. Also, they

Fig. 12. Super precision ball bearing.

14 TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • PRECISION BEARINGS • BALL BEARINGS WITH LOCKING DEVICES

have a relatively high-speed capability – especially if a light axial preload is applied. Timken offers deep-groove super precision ball bearings in the following ISO dimensional series:

ISO 10 (9100K series).

•

ISO 02 (200K series).

•

ISO 03 (300K series).

•

For additional information, refer to the Timken Super Precision Bearings for Machine Tool Applications Catalog (order number

5918) on www.timken.com. Or, contact your Timken engineer.

BALL BEARINGS WITH LOCKING DEVICES

By virtue of their independent locking devices, these bearings are suitable for mounting on straight shafting (no shoulders, etc.). They are often supplied with spherical outer rings for selfalignment at mounting. Mounted alignment is usually required because these bearings are generally assembled into pillow blocks or ﬂanged cartridges, or other housings bolted to pedestals or frames independent of each other.

Easiest of all to install, wide inner ring ball bearings with selflocking collars are available in various sizes. These bearings, shown with various seal and inner ring width variations, serve many purposes in farm and industrial applications.

SETSCREW SERIES BEARINGS

The GYA-RRB and the GY-KRRB series are extended inner ring and wide inner ring type bearings with specially designed setscrews to lock on the shaft. These bearings can be purchased so that they can be relubricated. Positive contact land-riding R-Seals provide protection against harmful contaminants and retain lubricant. Extended inner ring bearings are used when space is at a premium and overturning loads are not a problem. The wide inner ring setscrew series is available when additional surface contact on the shaft is a requirement for added stability.

Fig. 14. YA-RR series.

SELF-LOCKING (ECCENTRIC) COLLAR

Timken invented the eccentric self-locking collar to facilitate mounting of wide inner ring bearings. The self-locking collar eliminates the need for locknuts, lock washers, shoulders, sleeves and adapters.

The locking collar has a counterbored recess eccentric with the collar bore. This eccentric recess engages or mates with an eccentric cam end of the bearing inner ring when the bearing is assembled on the shaft.

The collar is engaged on the inner ring cam of the bearing. This assembly grips the shaft tightly with a positive binding action that increases with use. No adjustments are necessary. The collar setscrew provides supplementary locking.

RA-RR series Shroud-seal KRRB series extended inner ring wide inner ring with locking collar with locking collar

CONCENTRIC COLLAR

Using the concentric collar, the bearing is locked to the shaft by two setscrews, 120 degrees apart, tightened in the collar and passing through drilled holes in the inner ring. These units are suited for applications where space is limited and reversing shaft rotation is encountered.

Fig. 15. GC-KRRB series.

Fig. 13. Self-locking (eccentric) collar.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • TAPERED ROLLER BEARINGS

TAPERED ROLLER BEARINGS

SINGLE-ROW BEARINGS

TS - Single-row

This is the basic and the most widely used type of tapered roller bearing. It consists of the inner ring assembly and the outer ring. It is usually ﬁtted as one of an opposing pair. During equipment assembly, single-row bearings can be “set” to the required clearance (endplay) or preload condition to optimize performance.

TSF - Single-row, with ﬂanged outer ring

The TSF type is a variation on the basic single-row bearing. TSF bearings have a ﬂanged outer ring to facilitate axial location and accurately aligned seats in a through-bored housing.

Fig. 16. Single-row TS bearing.

Fig. 17. Single-row TSF bearing with ﬂanged outer ring.

DOUBLE-ROW BEARINGS

TDO - Double outer ring

This has a one-piece (double) outer ring and two single inner-rings. It is usually supplied complete with a inner-ring spacer as a pre-set assembly. This configuration gives a wide effective bearing spread and is frequently chosen for applications where overturning moments are a significant load component. TDO bearings can be used in ﬁxed (locating) positions or allowed to ﬂoat in the housing bore, for example, to compensate for shaft expansion. TDOCD outer rings also are available in most sizes. These outer rings have holes in the O.D. that permit the use of pins to prevent outer ring rotation in the housing.

Fig. 18. Double-row TDO bearing.

TDI - Double inner ring TDIT - Double inner ring with tapered bore

Both comprise a one-piece (double) inner ring and two single outer rings. They are usually supplied complete with an outerring spacer as a pre-set assembly. TDI and TDIT bearings can be used at ﬁxed (locating) positions on rotating shaft applications. For rotating housing applications, the double inner ring of type TDI can be used to ﬂoat on the stationary shaft. Type TDIT has a tapered bore to facilitate removal when an interference ﬁt is essential, yet regular removal is required.

16 TIMKEN ENGINEERING MANUAL

TDI

Fig. 19. Double-row, double-inner-ring bearings.

TDIT

BEARING SELECTION PROCESS

BEARING TYPES • TAPERED ROLLER BEARINGS

TNA - Non-adjustable TNASW - Non-adjustable with lubricant slots TNASWE - Non-adjustable with lubricant slots and extended back face rib

These three bearing types are similar to the TDO with a one-piece (double) outer ring and two single inner rings. The inner ring front faces are extended so they abut, eliminating the need for a separate inner-ring spacer. Supplied with a built-in clearance to give a standard setting range, these bearings provide a solution for many ﬁxed or ﬂoating bearing applications where optimum simplicity of assembly is required.

Types TNASW and TNASWE are variations having chamfers and slots on the front face of the inner ring to provide lubrication through the shaft. Type TNASWE have extended back face ribs on the inner rings which are ground on the O.D. to allow for the use of a seal or stamped closure. These designs are typically used on stationary shaft applications.

SPACER ASSEMBLIES

Any two single-row bearings (type TS) can be supplied as a double-row, pre-set, ready-to-ﬁt assembly by the addition of spacers, machined to pre-determined dimensions and tolerances.

Spacer assemblies are provided in two types: "2S" and "SR". This concept can be applied to produce custom-made double-row bearings to suit speciﬁc applications. In addition to providing a bearing that automatically gives a pre-determined setting at assembly without the need for a manual setting, it is possible to modify the assembly width to suit an application, simply by varying the spacer widths.

Fig. 21. Spacer assemblies.

TNA TNASW TNASWE

Fig. 20. Double-row, non-adjustable bearings.

2S - Two single-row assembly

Often referred to as snap-ring assemblies, type 2S consist of two basic single-row bearings (type TS). They are supplied complete with inner-ring and outer-ring spacers to give a predetermined bearing setting when assembled. Type 2S have a speciﬁed setting range to suit the duty of the application. They have an inner-ring spacer and a snap-ring, which also serves as the outer-ring spacer, to give axial location in a through-bored housing.

SR - SET-RIGHT™ assembly

Type SR are made to a standard setting range, based on Timken’s SET-RIGHT™ automated setting technique suitable for most industrial applications. They have two spacers and an optional snap-ring that may be used for axial location. Because both types are made up of popular sizes of single-row bearings, they provide a low-cost option for many applications.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • TAPERED ROLLER BEARINGS

TAPERED ROLLER BEARINGS – continued

There are three basic mounting arrangements for spacer assemblies.

Type 2TS-IM (indirect mounting)

•

These consist of two single-row bearings with an inner-ring and outer-ring spacer. In some applications, the outer-ring spacer is replaced by a shoulder in the bearing housing.

Type 2TS-DM (direct mounting)

•

These consist of two single-row bearings, with inner rings abutting and an outer-ring spacer. They are generally used at ﬁxed (locating) positions on rotating shaft applications.

Type 2TS-TM (tandem mounting)

•

Where combined radial and thrust load capacity is required, but the thrust component is beyond the capacity of a single bearing (within a given maximum O.D.), two single-row bearings can be mounted in tandem. Appropriate inner-ring and outer-ring spacers are supplied. Consult your Timken engineer for the most effective and economical solution.

2TS-IM

2TS-DM

Fig. 22. Basic spacer assemblies.

2TS-™

18 TIMKEN ENGINEERING MANUAL

PACKAGED BEARINGS

BEARING SELECTION PROCESS

BEARING TYPES • TAPERED ROLLER BEARINGS

PINION PAC

Fig. 23. Packaged bearings.

Pinion Pac

™

bearing

UNIPAC

™

UNIPAC-PLUS

™

The Pinion Pac™ bearing is a ready-to-install, pre-set and sealed package consisting of two rows of tapered roller bearings mounted in a carrier. It is custom designed for the ﬁnal drive pinions of heavy commercial vehicles. The package gives the differential pinion builder considerable improvements in reliability, ease of assembly and supply logistics.

™

UNIPAC

bearing

The UNIPAC-PLUS™ bearing is a ready-to-install, pre-set, pre-lubricated and sealed double-row assembly with a ﬂanged outer ring. Originally designed for the high-volume needs of passenger car wheels, the UNIPAC bearing now has wider application in wheel hubs of heavy vehicles as well as in industrial equipment.

The UNIPAC bearing provides improvements in reliability, ease of assembly and supply logistics.

™

bearing

™

The AP™ bearing is a self-contained assembly, made in a wide range of sizes. It consists of two single inner rings, a counterbored double outer ring, a backing ring, two radial seals, an end cap and cap screws. The AP bearing is supplied as a pre-set, prelubricated and sealed package. It was originally designed for railroad journals, but also is used in many industrial applications.

™

bearing

Similar in concept to AP bearings, the SP™ bearing is designed for rail journal bearing applications. The SP bearing type differs from the AP bearing in that SP bearings are more compact in size and are manufactured to metric boundary dimensions.

™

UNIPAC-PLUS

bearing

The UNIPAC-PLUS™ bearing is a ready-to-install, pre-set, sealed double-row assembly with a ﬂanged outer ring. It also is lubricated for the reasonable life of the bearing. It is designed for wheel applications subjected to moderate to heavy loading. The UNIPAC-PLUS bearing provides advantages of improved reliability, reduced weight and easier assembly.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • TAPERED ROLLER BEARINGS

HIGH-SPEED BEARINGS

TSMA - Single-row with axial oil TSMR - Single-row with radial oil

Some applications require extreme high-speed capability where special lubrication methods must be provided.

The TSMA and TSMR are single-row bearings with provisions for lubrication of critical roller-rib contact area to ensure adequate lubrication at high speeds. The TSMA concept works by capturing oil in a manifold (attached to the inner ring), which is then directed to the rib-roller contact through holes drilled axially through the large inner ring rib. The TSMR functions in a similar manner with the difference being that holes are drilled radially from the inner ring bore to the large rib face. Oil is captured in a circumferential groove in the inner ring bore. It is directed to the rib-roller contact area through radial holes.

Fig. 24. TSMA bearing.

OTHER DOUBLE-ROW BEARINGS

Type TDIE - Extended double inner ring Type TDIA - Extended single inner ring

These double-row bearings are designed for applications where it is required to lock the loose-ﬁtted inner ring to a shaft, with provision also for effective closure or sealing. Typical applications include pillow blocks, disc-harrow and similar agricultural machinery shafts and line shafts.

Type TDIE is available in two forms – cylindrical bore with the inner ring extended at both ends and provisions for setscrews and locking collars at each end, or with an inherently self-locking square bore – ideal for farm machinery applications.

Type TDIA is similar to type TDIE with a cylindrical bore. There is a provision for a locking collar at one end only. The compact conﬁguration is suited to pillow blocks and similar applications.

On all types, the hardened and ground O.D. of the inner ring extension provides an excellent surface for effective closure or sealing.

Type TNASWH - Non-adjustable, heavy-duty, double outer ring Type TNASWHF - Non-adjustable, heavy-duty, with ﬂanged double outer ring

These are double-row bearing assemblies with two inner rings and a one-piece outer ring, similar to type TNASWE listed in this manual on page 17.

The outer rings have a heavy wall section (type TNASWH), allowing the bearings to be used directly as steady rest rollers, in sheet and strip levellers or, with a ﬂange (type TNASWHF), as a complete wheel assembly for use on rails.

The outer ring is extended at both ends and counterbored to accept stamped closures. Contacting seals are available for certain sizes. These bearings are typically supplied as a unit assembly and are pre-lubricated.

TDIE TDIE (square bore)

Fig. 25. Other double-row bearings.

20 TIMKEN ENGINEERING MANUAL

TDIA

TNASWH

TNASWHF

BEARING SELECTION PROCESS

BEARING TYPES • TAPERED ROLLER BEARINGS

FOUR-ROW BEARINGS

Four-row bearings combine the inherent high-load, radial/thrust capacity and direct/indirect mounting variations of tapered roller bearings into assemblies of maximum load rating in a minimum space. Their main application is on the roll necks of rolling mill equipment.

All four-row bearings are supplied as pre-set matched assemblies, with all components numbered to ensure correct installation sequence.

Type TQO - Quad taper Type TQOW - Quad taper with lubrication slots

These pairs of directly mounted bearings consist of two double inner rings, two single and one double outer ring, with an innerring spacer and two outer-ring spacers. These types are used on roll necks of low- and medium-speed rolling mills, applied to the necks with a loose ﬁt. When the ﬁllet and/or ﬁller rings do not have lubrication slots, they are provided in the faces of the bearing inner rings (type TQOW). Slots in the inner-ring spacer permit lubricant to ﬂow from the bearing chamber to the roll neck. The inner-ring spacers also are hardened to minimize face wear.

Type TQITS Type TQITSE

The main feature of these bearings is a tapered bore – the taper being matched and continuous through the inner rings. This permits an interference ﬁt on the backup rolls of high-speed mills, where a loose inner ring ﬁt of a straight bore type TQO bearing could result in excessive neck wear.

These four-row bearings consist of two pairs of indirectly mounted bearings: two single and one double inner ring, four single outer rings and three outer-ring spacers. The adjacent faces of the inner-rings are extended so that they abut, eliminating the need for inner-ring spacers. The indirect mounting of the bearing pairs increase the overall effective spread of the bearing, to give optimum stability and roll rigidity.

Type TQITSE is the same as TQITS, but has an extension to the large bore inner ring adjacent to the roll body. This not only provides a hardened, concentric and smooth surface for radial lip seals, but also improves roll neck rigidity by eliminating a ﬁllet ring. This allows the centerline of the bearing to move closer to the roll body. It also permits shorter and less costly rolls.

Fig. 26. Four-row bearing assemblies.

TQO/ TQOW

Sealed roll neck

The sealed roll neck bearing is similar to the TQO. A specially designed sealing arrangement is incorporated in the bearing to endure highly contaminated environments. The special seal design is built into the bearing to prevent ingress of contamination from outside the bearing envelope and extend the useful bearing life.

Fig. 27. Sealed roll neck bearing.

TQITS TQITSE

Fig. 28. Four-row bearings with tapered bore.

SEALED BEARINGS

TSL

Timken offers a wide range of sealed bearings such as the DUO-FACE shown in ﬁg 29. The TSL incorporates a DUOFACE PLUS seal, making it an economical choice for grease-lubricated applications at moderate speeds. See the SEALS section in the back of this manual for additional seal designs.

PLUS seal

Fig. 29. TSL sealed bearing.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • THRUST BEARINGS

THRUST BEARINGS

Standard types of thrust bearings manufactured by Timken are included in this section. Each type is designed to take thrust loads, but four types (TVL, DTVL, TTHD and TSR) accommodate radial loads as well. All types reﬂect advanced design concepts, with large rolling elements for maximum capacity. In roller thrust bearings, controlled-contour rollers are used to ensure uniform, full-length contact between rollers and raceways with resultant high capacity. Thrust bearings should operate under continuous load for satisfactory performance.

Type TVB – Grooved-ring thrust ball bearing

Type TVL – Angular contact thrust ball bearing

Type DTVL – Two direction angular contact thrust ball bearing

Type TP – Thrust cylindrical roller bearing

Type TPS – Self-aligning thrust cylindrical roller bearing

Type TTHD – Thrust tapered roller bearing

Type TSR – Thrust spherical roller bearing

Type TTHDFL – V-ﬂat thrust tapered roller bearing

Type TTVS – Self-aligning V-ﬂat thrust tapered roller bearing

Type TTSP – Steering pivot thrust cylindrical roller bearing

ring is shaft-mounted. The stationary ring should be housed with sufﬁcient O.D. clearance to allow the bearing to assume its proper operating position. In most sizes, both rings have the same bore and O.D. The housing must be designed to clear the O.D. of the rotating ring, and it is necessary to step the shaft to clear the bore of the stationary ring.

Type TVL is a separable angular contact ball bearing primarily designed for unidirectional thrust loads. The angular contact design, however, will accommodate combined radial and thrust loads since the loads are transmitted angularly through the balls.

The bearing has two hardened and ground steel rings with ball grooves and a one-piece brass cage that spaces the ball complement. Although not strictly an angular ball bearing, the larger ring is still called the outer ring, and the smaller the inner ring. Timken standard tolerances for type TVL bearings are equivalent to ABEC 1 where applicable, but higher grades of precision are available.

Usually the inner ring is the rotating member and is shaft mounted. The outer ring is normally stationary and should be mounted with O.D. clearance to allow the bearing to assume its proper operating position. If combined loads exist, the outer ring must be radially located in the housing.

THRUST BALL BEARINGS

Thrust ball bearings are used for lighter loads and higher speeds than thrust roller bearings. Types TVB, TVL and DTVL are shown in ﬁg. 30.

Type TVB thrust ball bearing is separable and consists of two hardened and ground steel rings with grooved raceways, and a cage that separates and retains precision-ground and lapped balls. The standard cage material is brass, but this may be varied according to the requirements of the application. Timken tolerances for type TVB bearings are equivalent to ABEC 1 where applicable, but higher grades of precision are available.

Type TVB bearings provide axial rigidity in one direction and their use to support radial loads is not suggested. Usually the rotating

Fig. 30. Thrust ball bearing types.

standard

Type TVL bearings should always be operated under thrust load. Normally, this presents no problem as the bearing is usually applied on vertical shafts in oil ﬁeld rotary tables and machine tool indexing tables. If constant thrust load is not present, it should be imposed by springs or other built-in devices.

Low friction, cool running and quiet operation are advantages of TVL bearings, which may be operated at relatively high speeds. TVL bearings also are less sensitive to misalignment than other types of rigid thrust bearings.

DTVL is similar in design to TVL except the DTVL has an additional ring and ball complement permitting it to carry moderate thrust in one direction and light thrust in the other direction.

DTVLTVLTVB

22 TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • THRUST BEARINGS

THRUST CYLINDRICAL ROLLER BEARINGS

Thrust cylindrical roller bearings withstand heavy loads at relatively moderate speeds. Standard thrust bearings can be operated at bearing O.D. peripheral speeds of 3000 fpm (15 m/s). Special design features can be incorporated into the bearing and mounting to attain higher operating speeds.

Because loads are usually high, extreme-pressure (EP) lubricants should be used with cylindrical roller thrust bearings. Preferably, the lubricant should be introduced at the bearing bore and distributed by centrifugal force.

All types of thrust roller bearings are made to Timken Standard Tolerances. Higher precision may be obtained when required.

Type TP thrust cylindrical roller bearings have two hardened and ground steel rings, with a cage retaining one or more controlled-contour rollers in each pocket. When two or more rollers are used in a pocket, they are of different lengths and are placed in staggered position in adjacent cage pockets to create overlapping roller paths. This prevents wearing grooves in the raceways and helps prolong bearing life.

Because of the simplicity of their design, type TP bearings are economical. Shaft and housing seats must be square to the axis of rotation to prevent initial misalignment problems.

THRUST SPHERICAL ROLLER BEARINGS

Type TSR

The TSR thrust spherical roller bearing design achieves a high thrust capacity with low friction and continuous roller alignment. The bearings can accommodate pure thrust loads as well as combined radial and thrust loads. Typical applications are air regenerators, centrifugal pumps and deep well pumps. Maximum axial misalignment between inner and outer ring is ±2.5 degrees.

Fig. 32. Thrust spherical roller bearing, type TSR.

THRUST TAPERED ROLLER BEARINGS

Type TTHD

Type TTHD thrust tapered roller bearings have an identical pair of hardened and ground steel rings with conical raceways and a complement of controlled-contour tapered rollers equally spaced by a cage. The raceways of both rings and the tapered rollers have a common vertex at the bearing center. This assures true rolling motion.

TPS

Fig. 31. Thrust cylindrical roller bearings.

Type TPS bearings are the same as type TP bearings except one ring is spherically ground to seat against an aligning ring, thus making the bearing adaptable to initial misalignment. Its use is not suggested for operating conditions where alignment is continuously changing (dynamic misalignment).

TTHD bearings are well-suited for applications such as crane hooks, where extremely high thrust loads and heavy shock must

be resisted and some measure of radial location obtained.

For very low-speed, heavily loaded applications, these bearings are supplied with a full complement of rollers for maximum capacity. For application review of the full complement type TTHD bearing, consult your Timken engineer.

Fig. 33. Thrust tapered roller bearing, type TTHD.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • THRUST BEARINGS

THRUST BEARINGS – continued

TTC cageless TTSP steering pivot

There are two basic types of Timken® tapered roller thrust bearings designed for applications where the only load component is thrust, TTC and TTSP. The TTC bearing uses a full complement of tapered rollers without a cage and is used when the speeds are slow. The TTSP bearing uses a cage and is wellsuited for the oscillating motion of steering pivot positions.

Type TTHDFL Type TTVS Type TTHDSX Type TTHDSV

V-ﬂat tapered roller bearings (TTHDFL and TTVS) combine the best features of thrust tapered and cylindrical roller bearings, offering the highest possible capacity of any thrust bearing of its size. V-ﬂat design includes one ﬂat ring and the second with a tapered raceway matching the rollers. The design was originally developed to be screwed down in metal rolling mill applications where the thrust loads commonly exceed one million pounds. These bearings have exceptional dynamic capacity within a given envelope and provide superior static capacity. They are used inheavily loaded extruders, cone crushers and other applications where a wide range of operating conditions are found.

TTSPTTC

TTVSTTHDFL

TTHDFL

Most sizes utilize cages with hardened pins through the center of the rollers, allowing closer spacing of the rollers to maximize capacity. Smaller sizes have cast-brass cages, carefully machined to permit full ﬂow of lubricant.

Self-aligning V-ﬂat bearings (TTVS) employ the same basic roller and raceway design, except the lower ring is in two pieces, with the contacting faces spherically ground permitting self-alignment under conditions of initial misalignment. TTVS bearings should not be used if dynamic misalignment (changing under load) is expected.

TTHDSV

Fig. 34. Thrust tapered roller bearings.

TTHDSX

24 TIMKEN ENGINEERING MANUAL

RADIAL SPHERICAL ROLLER BEARINGS

BEARING SELECTION PROCESS

BEARING TYPES • RADIAL SPHERICAL ROLLER BEARINGS

The principle styles of radial spherical roller bearings that Timken offers are:

≤400 mm outer diameter: EJ, EM and EMB.

•

>400 mm outer diameter: YM, YMB, YMD and YP.

•

The newly redesigned Timken higher load ratings, increased thermal speed ratings and reduced operating temperatures compared to the previous offering.

In addition to these improvements, cage designs vary between the different styles as noted below. See the cage section for more details.

Style Cage Design

EJ Land-riding steel cage; one per row EM / YM Roller-riding one-piece brass cage EMB/YMB Land-riding one-piece brass cage YMD Land-riding two-piece brass cage YP Steel pin-type cage

EM/YM and

EMB/YMB

Fig. 35. Radial spherical roller bearings.

Most Timken spherical roller bearings are available with a cylindrical bore as well as a tapered bore. Tapered bore bearing part numbers are designated with a K sufﬁx.

EJ, EM and EMB bearings offer

YMDEJ

OPTIONAL FEATURES AVAILABLE WITH TIMKEN SPHERICAL ROLLER BEARINGS

W33 lubrication groove and oil holes

A lubrication groove and three oil holes are provided in the bearing outer ring as standard. This is designated by the W33 sufﬁx. It eliminates the expense of machining a channel in the housing bore for introducing lubricant to the bearing. This design feature allows the lubricant to ﬂow between the roller paths, through a single lubrication ﬁtting. The lubricant moves laterally outward from the center of the bearing, reaching all contact surfaces and ﬂushing the bearing. To order, add the sufﬁx W33 to the bearing number (e.g. 22216EMW33).

Bearings for vibratory applications

Timken offers specific spherical roller bearing designs for vibratory applications. They are designated by the W800 modiﬁcation code and made to a C4 clearance. Specify W800 when ordering. This design provides:

A lubrication groove on the outer ring with three lubrication

•

holes to facilitate bearing lubrication.

Extra-close running accuracy (P5) with high and low points

•

marked on the bearing.

Reduced bore and outside diameter tolerances.

•

Radial internal clearance is made in upper two-thirds of

•

C4 clearance range.

These bearings are available with either a cylindrical or tapered bore.

A taper of 1:12 is standard except for 240, 241 and 242 series, which have a taper of 1:30.

SERIES 239 230 240 231 241 222 232 213 223 233

Fig. 36. Radial spherical roller bearing series.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • RADIAL CYLINDRICAL ROLLER BEARINGS

RADIAL CYLINDRICAL ROLLER BEARINGS

STANDARD STYLES

Timken® cylindrical roller bearings consist of an inner and outer ring, a roller-retaining cage, and a complement of controlledcontour cylindrical rollers. Depending on the type of bearing, either the inner or the outer ring has two roller-guiding ribs. The other ring is separable from the assembly and has one rib or none. The ring with two ribs axially locates the position of the roller assembly. The ground diameters of these ribs may be used to support the roller cage. One of the ribs may be used to carry light thrust loads when an opposing rib is provided.

The decision as to which ring should be double ribbed is normally determined by considering assembly and mounting procedures in the application.

Type NU has double-ribbed outer and straight inner rings. Type N has double-ribbed inner and straight outer rings. The use of either type at one position on a shaft is ideal for accommodating shaft expansion or contraction. The relative axial displacement of one ring to the other occurs with minimum friction while the bearing is rotating. These bearings may be used in two positions for shaft support if other means of axial location are provided.

Type NJ has double-ribbed outer and single-ribbed inner rings. Type NF has double-ribbed inner and single-ribbed outer rings. Both types can support heavy radial loads, as well as light unidirectional thrust loads. The thrust load is transmitted between the diagonally opposed rib faces in a sliding action. When limiting thrust conditions are approached, lubrication can become critical. Your Timken engineer should be consulted for assistance in such applications. When thrust loads are very light, these bearings may be used in an opposed mounting to locate the shaft. In such cases, shaft endplay should be adjusted at time of assembly.

Type NUP has double-ribbed outer and single-ribbed inner ring with a loose rib that allows the bearing to provide axial location

in both directions. Type NP has a double-ribbed inner ring and a single-ribbed outer ring with a loose rib. Both types can carry heavy radial loads and light thrust loads in both directions. Factors governing the thrust capacity are the same as for types NJ and NF bearings.

A type NUP or NP bearing may be used in conjunction with type N or NU bearings for applications where axial shaft expansion is anticipated. In such cases, the N or NU bearing accommodates the shaft expansion. The NUP or NP bearing is considered the ﬁxed bearing because the ribs restrict the axial movement of the rolling element. The ﬁxed bearing is usually placed nearest the drive end of the shaft to minimize alignment variations in the drive. Shaft endplay, or ﬂoat, is determined by the axial clearance in the ﬁxed bearing.

Types NU, N, NJ, NF, NUP and NP conform to ISO and DIN standards for loose rib rings (thrust collars) and typical industry diameters over or under roller.

The cylindrical roller bearing part numbers are in accordance with ISO 15. They are composed of four digits, the ﬁrst two digits identify the dimensional series and the last two digits of the part number are the bore size divided by 5. In the dimensional series, the ﬁrst digit is the width series and the second is the diameter (outer) series. The width series increase width in the sequence 8 0 1 2 3 4 5 6 7. The diameter series increase radial section in the sequence 7 8 9 0 1 2 3 4.

Types having an R preﬁx are similar in construction to their N counterparts. However, they were designed to conform to ABMA standards.

Inch-size bearings are identiﬁed by the letter I in the part number. RIU, for example, indicates an inch bearing while RU indicates the equivalent style in metric dimensions.

NU, RIU, RU N, RIN, RN NJ, RIJ, RJ NF, RIF, RF NUP, RIT, RT NP, RIP, RP

Fig. 37. Radial cylindrical roller bearings.

26 TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING TYPES • RADIAL CYLINDRICAL ROLLER BEARINGS

EMA SERIES

The Timken® single-row EMA series cylindrical roller bearings incorporate a unique cage design, proprietary internal geometry and special surface textures. These features help to improve bearing performance and can help to improve uptime and reduce maintenance costs.

The cage is a one-piece brass design with full-milled pockets. It is a land-riding cage which, unlike traditional roller-riding cages, minimizes drag on the roller elements. This reduces heat generation and improves bearing life. The high cage rigidity allows for more rollers than possible with other brass cage conﬁgurations.

Proprietary proﬁles on the rings and/or rollers increase the ability to handle heavier loads than competing designs.

Engineered processes for rings and rollers provide enhanced surface textures, resulting in lower friction, lower operating temperatures and longer bearing life.

EMA series bearings are available in types N, NU, NJ and NUP.

FULL-COMPLEMENT (NCF)

The full-complement (NCF) single-row bearings include integral ﬂanges on the inner and outer rings. These bearings also can manage axial loads in one direction and permit small axial displacements.

5200 METRIC SERIES

This series features enhanced radial load ratings due to its internal design proportions. In this series, the outer ring is double-ribbed and the inner ring is full-width with a cylindrical O.D. The bearing also can be furnished without an inner ring for applications where radial space is limited. When so used, the shaft journal must be hardened to HRC 58 minimum, and the surface ﬁnished to 15 RMS maximum. The W designation in the sufﬁx indicates the outer ring is provided. The inner ring also can be furnished separately. The A preﬁx indicates that the inner ring is furnished either separately or as part of the assembly.

The bearing is usually provided with a rugged stamped-steel cage (S designation) and is land-riding on the outer ring ribs. The cage features depressed bars, which not only space rollers evenly, but retain them as a complete assembly with the outer ring. Cages of machined brass (M designation) are available for applications where reversing loads or high speeds might indicate their need. Outer rings are made from bearing quality alloy steel. The inner rings are deep-case hardened to accommodate the hoop stresses resulting from heavy press ﬁts.

The standard bearing is produced with radial internal clearances designated as R6. Other internal clearances can be supplied upon request. Proper roller guidance is assured by integral ribs and roller end clearance control.

A-52xx-WS A-52xx-WM

52xx-WS A-52xx

Fig. 38. 5200 metric series bearings.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

CAGES • TAPERED ROLLER BEARING CAGES

CAGES

Cages (also referred to as rolling element retainers) serve several purposes in the proper operation of a rolling element bearing. Cages separate the rolling elements and prevent rolling element on rolling element contact and wear. Cages align the rolling elements on the inner ring to prevent rolling element sliding, skidding, and skewing to facilitate true rolling motion. For handling purposes, cages retain the rolling elements on the inner ring assembly to allow for bearing installation. In some instances, cages also improve ﬂow of the lubricant to the bearing raceway or rib contacting surfaces.

The following sections discuss the common types of cages used for each major bearing design type (tapered, cylindrical, spherical, and ball bearing). The basic design geometry, material, and manufacture are discussed for each cage type.

TAPERED ROLLER BEARING CAGES

STAMPED-STEEL CAGES

The most common type of cage used for tapered roller bearings is the stamped-steel cage. These cages are mass produced from low-carbon sheet steel using a series of cutting, forming and punching operations. These cages can be used in high temperature and harsh lubricant environments.

POLYMER CAGES

Cages for tapered roller bearings made of polymer material are used primarily for pre-greased and sealed package designs. The most common polymer materials used are Nylon thermoplastics with glass reinforcement. Polymer cages can be mass produced in large quantities and offer more design ﬂexibility than stampedsteel types. Polymer cages are lightweight and easy to assemble. In some instances, increased bearing rating can be achieved by allowing one or two extra rollers in the bearing complement. Care should be exercised when using aggressive lubricants with EP (extreme-pressure) additives in combination with elevated temperatures greater than 107° C (225° F).

MACHINED CAGES

Machined cages for tapered roller bearings are robust in design and are suited for high-speed and high-load applications. Machined cages use alloy steels and are produced through milling and broaching operations. Assembly does not require a close-in operation and rollers can be retained using nibs or staking. Oil holes also can be easily added for extra lubrication for demanding applications. Some designs are silver plated for special applications.

Fig. 39. Stamped-steel cage.

PIN-TYPE CAGES

Tapered roller bearing pin-type cages retain the rolling elements by the use of a pin located through an axial hole in the center of the roller. Pin-type cages for tapered roller bearings consist of two rings with roller pins attached by screw threads at one end and welding at the other end. These types of cages are primarily used for larger tapered roller bearing designs (greater than 400 mm [15.7480 in.] O.D.). Pin-type cages are machined out of steel and typically allow for an increased number of rolling elements. Pin-type cages are restricted to low-speed applications (less than 20 m/sec [4000 ft/min] rib speed).

TIMKEN ENGINEERING MANUAL

SPHERICAL ROLLER BEARING CAGES

BEARING SELECTION PROCESS

CAGES • SPHERICAL ROLLER BEARING CAGES

STAMPED-STEEL CAGES

The redesigned Timken® EJ bearings incorporate a unique stamped-steel cage design.

The EJ design includes two independent cages, one for each row of rollers, which are assembled into an individual bearing. This feature serves to prevent cage bending when the operating environment is favorable for this to occur.

This cage is guided on the inner ring and runs above pitch. Each cage is surface hardened (nitrided) to provide improved wear resistance as well as additional strength to allow the bearing to operate in even the most severe environment. Face slots have been designed for improved lubrication ﬂow. This can result in a lower operating temperature and longer bearing life.

Fig. 40. EJ bearing.

Fig. 41. EJ cage.

PIN-TYPE CAGES

Large diameter spherical roller bearings can be supplied with these cages. Pin-type cages, one for each row of rollers, consist of two rings and a series of pins running through the center of the rolling element. The design of pin-type cages permits an increased roller complement, giving the bearing enhanced loadcarrying ability. Consult your Timken engineer for suggestions on the application of this cage.

MACHINED-BRASS CAGE

EM, EMB, YM, YMB and YMD bearing cages are precisionmachined from brass as shown in figs. 44-46. Their rugged construction provides an advantage in more severe applications. The open-end, ﬁnger-type design permits lubricant to reach all surfaces easily, ensuring ample lubrication and a cooler running bearing.

EM/YM YMD

Fig. 43. Machined cages.

EMB/YMB

EM, EMB, YM and YMB are all one-piece designs that are differentiated by their means of guidance within the bearing. With EM and YM designs, the cage mass is low and the rollers are used for guidance, while EMB and YMB cage designs typically have more mass and guide on the inner ring.

YMD cages are similar to YMB, except they have a two-piece design. Two independent cages, one for each row of rollers, are assembled into an individual bearing. This allows each row of rollers to rotate independently when required by the application, and prevents bending of the cage ﬁngers.

Fig. 42. Pin-type cage.

Fig. 44. One-piece, machined-brass, roller-riding, ﬁnger-type cage.

Fig. 45. One-piece, machined-brass, land-riding, ﬁnger-type cage.

TIMKEN ENGINEERING MANUAL

Fig. 46. Split, machined-brass, land-riding, ﬁnger-type cage.

BEARING SELECTION PROCESS

CAGES • CYLINDRICAL ROLLER BEARING CAGES

CYLINDRICAL ROLLER BEARING CAGES

STAMPED-STEEL CAGES

Stamped-steel cages for cylindrical roller bearings consist of low-carbon steel and are manufactured using a series of cutting, forming, and punching operations. These cages are made in a variety of different designs and are suitable for most general purpose cylindrical roller bearing applications. One speciﬁc type is the S-type design for the 5200 series cylindrical roller bearing, which is a land-riding cage piloted on the outer ring ribs. This design has depressed cage bridges which evenly space the rolling elements and retain them on the outer ring. Stampedsteel cages are easily mass produced and can be used in hightemperature and harsh-lubricant environments.

Fig. 47. S-type cage.

MACHINED CAGES

Machined cages are an option for smaller cylindrical bearing sizes, and are typically made from brass. Machined cage designs for cylindrical roller bearings offer increased strength for more demanding applications.

PIN-TYPE CAGES

Pin-type cages for cylindrical roller bearings consist of two rings and a series of pins running through the center of the rolling elements. These cages are used for large diameter cylindrical roller bearings where machined brass cages are not available. With this design, additional rollers can typically be added, resulting in increased load capacity.

Fig. 48. Pin-type cage.

Designs can be one-piece or two-piece cages. One-piece designs can be either a ﬁnger-type as shown in ﬁg. 49 or a standard cage conﬁguration having fully milled pockets. The one-piece ﬁngertype and the two-piece design with cage ring (ﬁg. 50) are more common in standard cylindrical roller bearings. They also are roller-guided designs.

The one-piece version with fully milled roller pockets (ﬁg. 51) is our premium cage. This cage is used with our EMA series bearings. Unlike traditional roller-riding cages, it is a land-riding cage which minimizes drag on the roller elements. This reduces heat generation, resulting in improved bearing life. Compared to a two-piece design, this one-piece cage also reduces heat and wear by enhancing lubrication ﬂow.

Fig. 49. One-piece ﬁnger-type cage.

Fig. 50. Two-piece brass cage.

Fig. 51. One-piece premium cage.

TIMKEN ENGINEERING MANUAL

BALL BEARING CAGES

BEARING SELECTION PROCESS

CAGES • BALL BEARING CAGES

PRESSED-STEEL WELDED CAGES

This cage type consists of two formed cage halves welded together. This type of cage is standard for most radial nonﬁlling-slot ball bearings and provides high strength and rigidity as well as good uniformity of ball to pocket clearance. It is suitable for very high-temperature applications, but does not accommodate application misalignment.

Fig. 52. Pressed-steel welded cage.

MOLDED-NYLON FINGER-TYPE CAGES

These types of cages consist of a one-

piece molded design. Rolling elements simply snap into place. These cages are molded of Nylon 66 which is heat stabilized and moisture conditioned. This cage type is used in the majority of wide inner ring (WIR) ball bearings. The polymer can withstand continuous

Fig. 53. Molded-nylon cage.

lubricating material with good resistance to abrasion, wear, most solvents, oils, and greases. This cage type can accommodate application misalignment.

operating temperatures up to 120° C (250° F) with spikes up to 150° C (300° F) and provides a non-corrosive, self-

MACHINED PHENOLIC-TYPE CAGES

Cages of this type are a one-piece design and are usually ring piloted. The cage is light weight, has oil-absorbing capability, and is suitable for high-speed applications. Cages of this type can be precisely machined, which reduces inertial ball and cage impact forces at high speeds. It does not provide for retention of the balls for handling purposes.

BRASS- AND STEEL-TYPE CAGES

Ball bearing cages made of brass or steel are designed for heavily loaded applications. Cage design variations include one-piece machined-steel or machined-brass and two-piece riveted cast brass. Most designs are ring piloted. Cages of this type also can be silver plated for applications requiring high reliability. The silver plating provides lubrication at the ball-cage interface during start-up to prevent skidding of the balls.

Fig. 55. Cast-brass cage.

Fig. 56. Machined-brass cage.

Care also needs to be exercised when using aggressive lubrications with extreme-pressure (EP) additives in combination with elevated temperatures greater than 107° C (225° F).

MOLDED REINFORCED NYLON-TYPE CAGES

These types of cages are one-piece outer-ring-piloted or ball guided. Cages of this type are molded out of Nylon 66 with 30 percent glass ﬁber added for moisture dimensional stability. The polymer can withstand continuous operating temperatures up to 120° C (250° F) with spikes up to 150° C (300° F) and provides a non-corrosive, selflubricating material with good resistance to abrasion, wear, most solvents, oils, and greases.

Care also needs to be exercised when using aggressive lubrications with extreme-pressure (EP) additives in combination with elevated temperatures greater than 107° C (225° F).

Fig. 54. Reinforced nylon cage.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

DETERMINATION OF APPLIED LOADS AND BEARING ANALYSIS

SUMMARY OF SYMBOLS USED TO DETERMINE APPLIED LOADS AND BEARING ANALYSIS

Symbol Description Units (Metric/Inch System)

a Axial Distance from Inner Ring Backface to

Effective Load Center mm, in.

Reliability Life Factor unitless

Material Life Factor unitless

Operating Condition Life Factor unitless

Debris Life Factor unitless

Load Zone Life Factor unitless

Lubrication Life Factor unitless

Low-Load Life Factor unitless

Effective Bearing Spread mm, in.

A, B, … Bearing Position (used as subscripts) unitless B Outer Ring Width mm, in. B

Inner Ring Width mm, in.

b Tooth Length mm, in. c

, c2 Linear Distance (positive or negative). mm, in.

C Basic Dynamic Radial Load Rating of a Double-Row N, lbf

Bearing for an L

Basic Dynamic Thrust Load Rating of a Single-Row

a90

Bearing for an L 3000 Hours at 500 RPM N, lbf

Basic Static Radial Load Rating N, lbf

Basic Static Axial Load Rating N, lbf

Basic Dynamic Radial Load Rating of a Single-Row

90(2)

Basic Dynamic Axial Load Rating N, lbf

Geometry Factor (used in a3l equation) unitless

Load Factor (used in a3l equation) unitless

Load Zone Factor (used in a3l equation) unitless

Speed Factor (used in a3l equation) unitless

Viscosity Factor (used in a3l equation) unitless

Grease Lubrication Factor (used in a3l equation) unitless

Bearing for an L

Basic Dynamic Radial Load Rating of a Double-Row

Bearing for an L

of One Million Revolutions

of 90 Million Revolutions or

of 90 Million Revolutions N, lbf

Cp Speciﬁc Heat of Lubricant J/(Kg - °C), BTU/(lbf - °F) C

Basic Thrust Dynamic Load Rating N, lbf

d Bearing Bore Diameter mm, in. d Ball Diameter mm, in. d

Spherical Diameter mm, in.

Shaft Shoulder Diameter mm, in.

Mean Inner Ring Diameter mm, in.

dc Distance Between Gear Centers mm, in. dm Mean Bearing Diameter mm, in. d

Shaft Inside Diameter mm, in.

D Bearing Outside Diameter mm, in. D

Tapered Roller Bearing Outer Ring

Mean Raceway Diameter mm, in. Dh Housing Outside Diameter mm, in. Dm Mean Diameter or Effective Working Diameter

of a Sprocket, Pulley, Wheel or Tire mm, in. Dm Tapered Roller Mean Large Rib Diameter mm, in.

Symbol Description Units (Metric/Inch System)

Mean or Effective Working Diameter of the Gear mm, in.

Effective Working Diameter of the Pinion mm, in.

Effective Working Diameter of the Worm mm, in.

Pitch Diameter of the Gear mm, in.

Pitch Diameter of the Pinion mm, in.

Pitch Diameter of the Worm mm, in.

e Life Exponent unitless e Limiting Value of Fa/Fr for the Applicability of

Different Values of Factors X and Y unitless

E Free Endplay mm, in.

f Lubricant Flow Rate L/min, U.S. pt/min

Viscous Dependent Torque Coefﬁcient unitless

Load Dependent Torque Coefﬁcient unitless

Belt or Chain Pull N, lbf

Speed Factor unitless

Combined Load Factor unitless

F General Term for Force N, lbf F

, F2, …, Fn Magnitudes of Applied Force During a Loading Cycle N, lbf

Applied Thrust (Axial) Load N, lbf

Induced Thrust (Axial) Load Due to Radial Loading N, lbf

Induced Thrust (Axial) Load Due to Centrifugal Loading N, lbf

Thrust Force on Gear N, lbf

Thrust Force on Pinion N, lbf

Thrust Force on Worm N, lbf

Allowable Axial Load N, lbf

Belt or Chain Pull N, lbf

Load Term for Torque Equation N, lbf

Fc Centrifugal Force N, lbf F

Applied Radial Load N, lbf

Resultant Horizontal Force N, lbf

Resultant Separating Force N, lbf

Resultant Vertical Force N, lbf

Separating Force on Gear N, lbf

Separating Force on Pinion N, lbf

Separating Force on Worm N, lbf

Tangential Force N, lbf

Tractive Effort on Vehicle Wheels N, lbf

Tangential Force on Gear N, lbf

Tangential Force on Pinion N, lbf

Tangential Force on Worm N, lbf

Force of Unbalance N, lbf

Weighted Average Load N, lbf

G Gear (used as subscript) unitless G

Geometry Factor from Bearing Data Tables unitless

H Power kW, hp H

Housing Shoulder Inner Diameter mm, in.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

DETERMINATION OF APPLIED LOADS AND BEARING ANALYSIS

Symbol Description Units (Metric/Inch System)

HFs Static Load Rating Adjustment Factor for

Raceway Hardness unitless i Number of Rows of Rollers in a Bearing unitless i

Number of Bearing Rows Taking Load unitless

k Centrifugal Force Constant lbf/RPM k1 Bearing Torque Constant unitless k

, k5, k6 Dimensional Factor to Calculate Heat Generation unitless

K Tapered Roller Bearing K-factor; ratio of

basic dynamic radial load rating to basic dynamic

thrust rating in a single-row bearing unitless K Ball Bearing Constant Based on Geometry K

, K2 Super Precision K-Factors unitless

Radial Runout of Outer Ring Assembly mm, in.

Outer Ring Contour Radius Expressed

Inner Ring Contour Radius Expressed

as a Decimal Fraction of the Ball Diameter decimal fraction

as a Decimal Fraction of the Ball Diameter decimal fraction Kia Radial Runout of Inner Ring Assembly mm, in. K

K-factor for Bearing #n unitless

Relative Thrust Load Factor – Ball Bearings unitless

Lead – Axial Advance of a Helix for One Complete

Revolution mm, in. L Distance Between Bearing Geometric Center Lines mm, in. L

Bearing Life revolutions or hours

Life Factor unitless

m Gearing Ratio unitless M Bearing Operating Torque N-m, N-mm, lb.-in. M

Moment N-m, N-mm, lb.-in.

n Bearing Operating Speed or General Term

for Speed rot/min, RPM n

, n2,…, nn Rotation Speeds During a Loading Cycle rot/min, RPM

Reference Speed rot/min, RPM

Gear Operating Speed rot/min, RPM

Pinion Operating Speed rot/min, RPM

Worm Operating Speed rot/min, RPM

Number of Rotations of the Ball and Cage Assembly unitless

Number of Rotations of the Inner Ring unitless

Number of Teeth in the Gear unitless

Number of Teeth in the Pinion unitless

Number of Teeth in the Sprocket unitless

Speed Factor unitless

P Pinion (used as subscript) unitless P

Static Equivalent Load N, lbf

Static Equivalent Thrust (Axial) N, lbf

Static Equivalent Radial Load N, lbf

Dynamic Equivalent Axial Load N, lbf

Dynamic Equivalent Radial Load N, lbf

Equivalent Dynamic Load N, lbf

Q Generated Heat or Heat Dissipation Rate W, BTU/min Q

Generated Heat W, BTU/min

gen

Heat Dissipated by a Circulating Oil System W, BTU/min

oil

r Radius to Center of Mass mm, in. R Percent Reliability, Used in the Calculation

of the a

Factor unitless

Symbol Description Units (Metric/Inch System)

RIC Radial Internal Clearance mm, in. S Shaft Diameter mm, in. s Shaft (used as subscript) unitless S

Inner Ring Reference Face Runout mm, in.

Outside Cylindrical Surface Runout mm, in.

Axial Runout of Outer Ring Assembly mm, in.

Axial Runout of Inner Ring Assembly mm, in.

, t2, …, tN Fractions of Time During a Loading Cycle unitless

T Applied Thrust (Axial) Load N, lbf T

Equivalent Thrust Load N, lbf

v Vertical (used as subscript) unitless V Linear Velocity or Speed km/h, mph V

Inner Ring Width Variation mm, in.

Outer Ring Width Variation mm, in.

Vr Rubbing, Surface or Tapered Roller Bearing

Rib Velocity m/s, fpm W Worm (used as subscript) unitless X Dynamic Radial Load Factor unitless X

Static Radial Load Factor unitless

Y, Y

, Y2, ... Dynamic Thrust (Axial) Load Factor unitless

Static Thrust (Axial) Load Factor unitless

Z Number of Rolling Elements unitless

Coefﬁcient of Linear Expansion mm/mm/°C, in./in./°F

Tapered Roller Bearing Half Included

Outer Ring Raceway Angle deg. a Ball Bearing Nominal Contact Angle deg. ΔT Temperature Difference Between Shaft/Inner Ring/

Rollers and Housing/Outer Ring °C, °F Δ

Inner Ring Width Deviation mm, in.

Outer Ring Width Deviation mm, in.

Deviation of Mean Bore Diameter in a Single Plane mm, in.

dmp

Deviation of Mean Outside Diameter in a Single Plane mm, in.

Dmp

ds Interference Fit of Inner Ring on Shaft mm, in. dh Interference Fit of Outer Ring in Housing mm, in.

η Efﬁciency, Decimal Fraction

, q2, q3 Gear Mesh Angles Relative to the Reference Plane deg., rad

qi, qo Oil Inlet or Outlet Temperature °C, °F l Worm Gear Lead Angle deg. m Coefﬁcient of Friction unitless m Lubricant Dynamic Viscosity cP

v Lubricant Kinematic Viscosity cSt

Approximate Maximum Contact Stress MPa, psi

Normal Tooth Pressure Angle for the Gear deg.

Normal Tooth Pressure Angle for the Pinion deg.

Helix (Helical) or Spiral Angle for the Gear deg.

Helix (Helical) or Spiral Angle for the Pinion deg.

r Lubricant Density kg/m

ΥG Bevel Gearing – Gear Pitch Angle deg.

Hypoid Gearing – Gear Root Angle deg.

Bevel Gearing – Pinion Pitch Angle deg.

Hypoid Gearing – Pinion Face Angle deg.

, lb./ft

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

DETERMINATION OF APPLIED LOADS AND BEARING ANALYSIS • GEARING

GEARING

The following equations are used to determine the forces developed by machine elements commonly encountered in bearing applications.

SPUR GEARING

Tangential force

x 10

) H

(metric system)

(inch system)

FtG =

(1.91

DpG n

(1.26

DpG n

Separating force

FsG = FtG tan

ΦG

Fig. 57. Spur gearing.

SINGLE HELICAL GEARING

STRAIGHT BEVEL AND ZEROL GEARING WITH ZERO DEGREES SPIRAL

In straight bevel and zerol gearing, the gear forces tend to push the pinion and gear out of mesh, such that the directions of the thrust and separating forces are always the same regardless of direction of rotation (ﬁg. 59). In calculating the tangential force (F

or FtG) for bevel gearing, the pinion or gear mean diameter

(Dm

or DmG) is used instead of the pitch diameter (DpP or DpG).

The mean diameter is calculated as follows:

G = DpG -

In straight bevel and zerol gearing:

= F

b sin

ΥG or DmP

= DpP - b sin

Fig. 59. Straight bevel and zerol gears.

ΥP

Tangential force

(1.91

FtG =

x 10

DpG n

(1.26

x 10

DpG n

Thrust force

FaG = FtG tan Ψ

Separating force

tan Φ

FsG = cos Ψ

) H

(metric system)

(inch system)

Fig. 58. Helical gearing.

PINION

Tangential force

FtP =

(1.91

DmP n

= DmP n

(1.26

x 10

Thrust force

FaP = FtP tan

ΦP

Separating force

FsP = FtP tan

ΦP

) H

sin

cos

ΥP

(metric system)

(inch system)

TIMKEN ENGINEERING MANUAL

STRAIGHT BEVEL GEAR

Tangential force

x 10

) H

FtG = DmG n

DmG n

(1.91

(1.26

Thrust force

(metric system)

(inch system)

BEARING SELECTION PROCESS

DETERMINATION OF APPLIED LOADS AND BEARING ANALYSIS • GEARING

Fig. 60. Straight bevel gearing.

FaG = FtG tan

ΦG

sin

ΥG

Separating force

FsG = FtG tan

ΦG

cos

ΥG

SPIRAL BEVEL AND HYPOID GEARING

In spiral bevel and hypoid gearing, the directions of the thrust and separating forces depend upon spiral angle, hand of spiral, direction of rotation, and whether the gear is driving or driven (see ﬁg. 61). The hand of the spiral is determined by noting whether the tooth curvature on the near face of the gear (ﬁg. 62) inclines to the left or right from the shaft axis. Direction of rotation is determined by viewing toward the gear or pinion apex.

In spiral bevel gearing:

In hypoid gearing:

F cos Ψ

= F

cos ΨP

Fig. 61. Spiral bevel and hypoid gears.

Hypoid pinion effective working diameter:

Dm N

= Dm

( )(

cos Ψ

)

Tangential force

x 10

) H

(metric system)

(inch system)

FtG = DmG n

DmG n

Hypoid gear effective working diameter:

(1.91

(1.26

= DpG - b sin Υ

Fig. 62. Spiral bevel and hypoid gearing.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

DETERMINATION OF APPLIED LOADS AND BEARING ANALYSIS • GEARING

TABLE 2. SPIRAL BEVEL AND HYPOID BEARING EQUATIONS

Driving Member Rotation Thrust Force Separating Force

Driving member Driving member

Right-hand spiral

clockwise

Left-hand spiral

counterclockwise

Right-hand spiral

counterclockwise

Left-hand spiral

clockwise

FtP

FaP =

cos Ψ

FtG

FaG = cos Ψ

FtP

FaP = cos Ψ

FtG

FaG = cos Ψ

(tan Φ

sin Υ

– sin Ψ

+ sin Ψ

– sin Ψ

cos ΥP)

cos ΥG)

cos ΥP)

cos ΥG)

sin Υ

Driven member Driven member

(tan Φ

Driving member Driving member

(tan Φ

Driven member Driven member

(tan Φ

FtP

FsP = cos Ψ

FtG

FsG = cos Ψ

FtP

FsP = cos Ψ

FtG

FsG = cos Ψ

STRAIGHT WORM GEARING

Worm

(tan Φ

cos ΥP + sin Ψ

(tan Φ

cos Υ

– sin Ψ

cos Υ

+ sin Ψ

(tan Φ

– sin Ψ

sin ΥP)

sin ΥG)

sin ΥP)

sin ΥG)

Tangential force

(1.91

x 10

DPW n

(1.26

x 10

DpW n

Thrust force

x 10

(1.91

DpG n

(1.26

x 10

DpG n

F tan

Separating force

cos Φ sin

) H

) H η

sin Φ

λ +

(metric system)

(inch system)

(metric system)

(inch system)

μ cos

Fig. 63. Straight worm gearing.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

DETERMINATION OF APPLIED LOADS AND BEARING ANALYSIS • GEARING

Worm Gear

Tangential force

x 10

(1.91

x 10

(1.26

x 10

-1

(

-1

(

W nW

-14

W nW

) H η

) H

sin Φ

μ cos

λ +

μ tan

) V

(metric system)

(inch system)

(metric system)

(inch system)

)

0.146

- 0.103

0.09

(meters per second)

0.235

- 0.103

0.09

(feet per minute)

(1.91

F DpG n

= DpG n

F tan

Thrust force

F DpW n

DpW n

Separating force

Fs cos Φ sin

Where:

m Dp

π Dp

and

η = cos Φ + μ cot

Metric system

μ V

Vr = (1.91 x 104) cos

Inch system

μ V

Vr =

3.82 cos

(1)

Approximate coefﬁcient of friction for the 0.015 to 15 m/s (3 to 3000 ft/min)

rubbing velocity range.

(1.26

= tan

cos Φ –

(1)

= (5.34 x 10 -7) V

(1)

= (7 x 10

DOUBLE ENVELOPING WORM GEARING

Worm

Tangential force

(1.91

F DmW n

= DmW n

Thrust force

Separating force

Fs cos

= 0.98 F

(1.26

0.98 F

x 10

) H

(metric system)

x 10

) H

(inch system)

Use this value for FtG for bearing loading calculations on worm gear

shaft. For torque calculations, use the following FtG equations.

tan Φ

Worm Gear

Tangential force

x 10

tan Φ

-1

(

) H m η

(metric system)

) H m η

(inch system)

) H η

(metric system)

) H η

(inch system)

) H

(metric system)

(inch system)

) (

= tan

-1

(1.91

F DpG n

= DpG n

F DpG n

= DpG n

Thrust force

F DmW n

= DmW n

Separating force

Fs cos

Where:

η = efﬁciency (refer to manufacturer’s catalog) Dm

Lead angle at center of worm:

m Dp

(1.26

(1.91

(1.26

(1.91

(1.26

0.98 F

= 2dc -0.98 Dp

= tan

Use this value for calculating torque in subsequent gears and shafts. For bearing loading calculations, use the equation for F

aW.

)

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

DETERMINATION OF APPLIED LOADS AND BEARING ANALYSIS

SHOCK LOADS

Belt and chain drive factors

Due to the variations of belt tightness as set by various operators, an exact equation relating total belt pull to tension F side and tension F

on the slack side (ﬁg. 64) is difﬁcult to establish.

The following equation and table 3 may be used to estimate the total pull from various types of belt and pulley, and chain and sprocket designs:

x 10

) H B

(metric system)

(1.91

Dm n

(1.26

105) H B

(inch system)

Dm n

Standard roller chain sprocket mean diameter.

sin

180

( )

Dm =

Where:

P = chain pitch

= Tension, slack side

on the tight

It is difﬁcult to determine the exact effect that shock loading has on bearing life. The magnitude of the shock load depends on the masses of the colliding bodies, their velocities and deformations at impact.

The effect on the bearing depends on how much of the shock is absorbed between the point of impact and the bearing, as well as whether the shock load is great enough to cause bearing damage. It also is dependent on frequency and duration of shock loads.

As a minimum, a suddenly applied load is equivalent to twice its static value. It may be considerably more than this, depending on the velocity of impact.

Shock involves a number of variables that generally are not known or easily determined. Therefore, it is good practice to rely on experience. Timken has years of experience with many types of equipment under the most severe loading conditions. Your Timken engineer should be consulted on any application involving unusual loading or service requirements.

CENTRIFUGAL FORCE

Centrifugal force resulting from imbalance in a rotating member:

r n2

8.94 x 10

r n

3.52 x 10

metric system)

(

(inch system)

= Tension, tight side

Fig. 64. Belt or chain drive.

TABLE 3. BELT OR CHAIN PULL FACTOR

BASED ON 180 DEGREES ANGLE OF WRAP

Type

Chains, single .................................. 1.00

Chains, double ................................. 1.25

“V” belts............................................. 1.50

TRACTIVE EFFORT AND WHEEL SPEED

Tractive effort is the tangential force between the driving wheels and the road necessary to propel a vehicle at a given speed against the combined grade, air and rolling resistance. The relationships of tractive effort, power, wheel speed and vehicle

speed are:

H =

and

n =

Fte V 3600

375

5300V

336V

TIMKEN ENGINEERING MANUAL

BEARING REACTIONS

Effective bearing

spread

Effective bearing

spread

Effective bearing

spread

Effective bearing

spread

Effective bearing

spread

For a shaft on two supports, bearing radial loads are determined by:

Deﬁning the bearing effective spread.

•

Resolving forces applied to the shaft into horizontal and ver-

•

tical components, relative to a convenient reference plane.

Summing moments about the effective center of each of

•

the bearing supports, and solving for the radial and axial reactions at each support.

EFFECTIVE SPREAD

TAPERED ROLLER OR ANGULAR CONTACT BALL BEARINGS

When a load is applied to a tapered roller or angular contact ball bearing, the internal forces at each rolling element-to-outer raceway contact act normal to the raceway. These forces have radial and axial components. With the exception of the special case of pure axial loads, the inner ring and the shaft will experience moments imposed by the asymmetrical axial components of the forces on the rolling elements. The effective center for tapered roller bearings is deﬁned as the point at which the lines of force normal to the outer ring raceway intersect the bearing axis. As an approximation, it also applies to angular contact ball bearings. The effective spread is then deﬁned as the distance between the bearing effective centers for a two-bearing system. It can be demonstrated mathematically that, if the shaft is modeled as being supported at its effective bearing center rather than at its geometric bearing center, the bearing moment may be ignored when calculating radial loads on the bearing.

Only externally applied loads need to be considered, and moments are taken about the effective centers of the bearings to determine loads or reactions.

BEARING SELECTION PROCESS

BEARING REACTIONS • EFFECTIVE SPREAD

Fig. 65 shows single-row bearings in a direct and indirect mounting conﬁguration. The choice of whether to use direct or indirect mounting depends upon the application.

SPHERICAL ROLLER BEARINGS

The effective center for each row of spherical rollers intersects the shaft axis at the bearing geometric center as shown in ﬁg.

66. As the distance between effective centers for each row of a bearing is zero (i.e. zero moment arm), a pure couple cannot be generated internal to the bearing. Therefore, when a shaft and housing are misaligned, the inner and outer rings of the bearing rotate up to a few degrees relative to each other, without creating internal forces. This self-aligning capability in turn prevents an external moment load from being supported by the bearing. Therefore, spherical roller bearings can only accommodate external shaft and housing loads through radial and axial reaction forces.

Effective bearing spread

Float position Fixed position

Fig. 66. Spherical roller bearing.

Effective bearing

spread

Indirect Mounting – Tapered Roller Bearings Back-to-Back/DB – Angular Contact Ball Bearings

Effective bearing

spread

Effective bearing

spread

Fig. 65. Choice of mounting conﬁguration for single-row bearings, showing position of effective load-carrying centers.

Effective bearing

spread

Direct Mounting – Tapered Roller Bearings Face-to-Face/DF – Angular Contact Ball Bearings

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING REACTIONS • FORCE RESOLUTION

FORCE RESOLUTION

SHAFTS ON TWO SUPPORTS

Simple beam equations are used to translate the externally applied forces on a shaft into bearing reactions acting at the bearing effective centers.

The following equations are for the case of a shaft on two supports with gear forces F (thrust), an external radial load F, and an external moment M The loads are applied at arbitrary angles (θ to the reference plane indicated in ﬁg. 67. Using the principle of superposition, the equations for vertical and horizontal reactions (F

and Frh) can be expanded to include any number of gears,

external forces or moments. For the bearing reaction calculations, the gear forces should include the sign (+/-) generated from the respective gear force equation.

2 1 3

Reference

Plane of Moment

θ θ

Plane of

(tangential), Fs (separating), and Fa

, θ2, and θ3) relative

Bearing A

Bearing B

Care should be used when doing this to ensure proper supporting degrees of freedom are used. That is, tapered roller bearings and ball bearings support radial loads, moment loads and thrust loads in both directions. Spherical roller bearings will not support a moment load, but will support radial and thrust loads in both directions. Cylindrical roller bearings support radial and moment loading, but can only support slight thrust loads depending upon

thrust ﬂange conﬁguration.

SHAFT ON THREE OR MORE SUPPORTS

The equations of static equilibrium are insufﬁcient to solve bearing reactions on a shaft having more than two supports. Such cases can be solved using computer programs if adequate information is available. In such problems, the deﬂections of the shaft, bearings and housings affect the distribution of loads. Any variance in these parameters can signiﬁcantly affect bearing reactions.

Fig. 67. Bearing radial reactions.

Vertical reaction component at bearing position B:

c1 (FsG cos θ1 + FtG sin θ1) +

(

Horizontal reaction component at bearing position B:

ae 2

c1 (FsG sin θ1 - FtG cos θ1) +

(

(DpG - b sin γG) FaG sin θ1 +c2 F sin θ2 + M sin θ

Vertical reaction component at bearing position A: F

= FsG cos θ1 + FtG sin θ1 + F cos θ2 - F

Horizontal reaction component at bearing position A: F

Resultant radial reaction: FrA = [(F

Resultant axial reaction: F

= FsG sin θ1 - FtG cos θ1 + F sin θ2 - F

= F

)2 + (F

)

(ﬁxed position) FaB = O (ﬂoat position)

- b sin γG) FaG cos θ1 +c2 F cos θ2 + M cos θ

1/2

FrB = [(F

]

)2 + (F

1/2

)

]

(

TIMKEN ENGINEERING MANUAL

BEARING REACTIONS • DYNAMIC EQUIVALENT RADIAL BEARING LOADS (Pr)

DYNAMIC EQUIVALENT RADIAL BEARING LOADS (Pr)

To calculate the L10 life, it is necessary to calculate a dynamic equivalent radial load, designated by P radial load is deﬁned as a single radial load that, if applied to the bearing, will result in the same life as the combined loading under which the bearing operates. For all bearing types, the equation takes the following form:

= XFr + YF

SPHERICAL ROLLER BEARINGS

For spherical roller bearings, the values for Pr can be determined using the equations below. Calculate the ratio of the axial load to the radial load. Compare this ratio to the e value for the bearing.

In equation form,

= F

+ YF

= 0.67F

Values for e and Y are available in the Spherical Roller Bearing Catalog available on www.timken.com.

+ YF

for Fa / F

CYLINDRICAL ROLLER BEARINGS

For cylindrical roller bearings with purely radial applied load:

= Fr

The maximum dynamic radial load that may be applied to a cylindrical roller bearing should be < C/3.

If, in addition to the radial load, an axial load Fa acts on the bearing, this axial load is taken into consideration when calculating the life of a bearing (with F

TABLE 4. CYLINDRICAL ROLLER BEARING

DYNAMIC EQUIVALENT RADIAL VALUES

Dimension Series Load Ratio

10.. 2..E, 3..E

22..E, 23..E

< Faz; Faz is the allowable axial load).

Fa/Fr < 0.11

Fa/Fr > 0.11

Fa/Fr < 0.17

Fa/Fr > 0.17

. The dynamic equivalent

e, and

> e.

Equivalent Load

P = 0.93 Fr + 0.69 F

P = 0.93 Fr + 0.45 F

Dynamic

P = F

BEARING SELECTION PROCESS

RADIAL AND ANGULAR CONTACT BALL BEARINGS

For ball bearings, the dynamic equivalent radial load equations can be found in table 5. The required Y factors are found in table 6 on page 42.

TABLE 5. DYNAMIC EQUIVALENT RADIAL LOAD EQUATIONS

RADIAL AND ANGULAR CONTACT BEARINGS

Bearing

Description (ref.)

Bearing Type and or Series

RADIAL TYPE BALL BEARINGS Use Larger Of Resulting Pr Value

M9300K,MM9300K M9100K,MM9100K

M200K,MM200K M300K,MM300K

Small inch and metric

9300,9100,200,300

and derivatives

XLS large inch

W and GW Tri-Ply

Wide inner ring ball

bearing housed units

ANGULAR CONTACT BALL BEARINGS Use Larger Of Resulting Pr Value

7200K, 7200W

7300W, 7400W

5200K-5300W

5311W-5318W

5218W, 5220W, 5407W

5221W, 5214W

5200, 5200W

(see 20° exceptions)

5300, 5300W

(see 20° exceptions)

5400, 5400W

(see 20° exceptions)

7200WN 7300WN 7400WN

2M9300WI

2MM9100WI

2M200WI, 2MM200WI

2MM300WI

2MM9100WO

3M9300WI

3M9100WI, 3MM9100WI

3M200WI, 3MM200WI

3MM300WI

(1)

If Pr > Co or Pr > 1/2 CE consult with your Timken engineer on life calculations.

FOR BALL BEARINGS

Contact

Angle

0°

20°

30°

40°

15°

25°

Single-Row

and Tandem

Mountings

= F

iBC

Pr = Fr

Pr = 0.56Fr + Y1F

Pr = Fr

Pr = 0.56Fr + Y1F

Pr = Fr

Pr = 0.56Fr + Y1F

= Fr

Pr = 0.43Fr + F

Pr = Fr

Pr = 0.39Fr +0.76F

Pr = F

Pr = 0.35Fr +0.57F

Pr = Fr

Pr = 0.44Fr +Y2F

Pr = Fr

Pr = 0.44Fr + Y3F

Pr = Fr

Pr = 0.41Fr +0.87F

and Preload Pair

Pr = Fr + 1.20Y1Fa

Pr = 0.78Fr + 1.625Y1F

Pr = Fr + 1.09F

Pr = 0.70Fr + 1.63F

Pr = Fr + 0.78F

Pr = 0.63Fr + 1.24F

Pr = Fr + 0.55F

Pr = 0.57Fr + 0.93F

Pr = Fr + 1.124Y2F

Pr = 0.72Fr + 1.625Y2F

Pr = Fr + 1.124Y3F

Pr = 0.72Fr + 1.625Y3F

Pr = Fr + 0.92F

Pr = 0.67Fr + 1.41F

Double-Row

Mountings

KT = F

(1)

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING REACTIONS • DYNAMIC EQUIVALENT RADIAL BEARING LOADS (Pr)

FOR BALL BEARING DYNAMIC EQUIVALENT RADIAL LOADS

TABLE 6. REQUIRED Y FACTORS

0.015 2.30 1.47 1.60

0.020 2.22 1.44 1.59

0.025 2.10 1.41 1.57

0.030 2.00 1.39 1.56

0.040 1.86 1.35 1.55

0.050 1.76 1.32 1.53

0.060 1.68 1.29 1.51

0.080 1.57 1.25 1.49

0.100 1.48 1.21 1.47

0.120 1.42 1.19 1.45

0.150 1.34 1.14 1.42

0.200 1.25 1.09 1.39

0.250 1.18 1.05 1.35

0.300 1.13 1.02 1.33

0.400 1.05 1.00 1.29

0.500 1.00 1.00 1.25

0.600 — — 1.22

0.800 — — 1.17

1.000 — — 1.13

1.200 — — 1.10

TAPERED ROLLER BEARINGS

Tapered roller bearings are designed to carry radial loads, thrust loads or any combination of the two. Because of the tapered design of the raceways, a radial load will induce a thrust reaction within the bearing, which must be opposed by an equal or greater thrust load to keep the inner ring and outer ring from separating. The induced thrust adds to or subtracts from any externally applied thrust loads, depending upon the direction of the applied thrust load. As a result, the seated bearing sees the induced thrust of the opposing bearing plus the external thrust. The unseated bearing sees only its own induced thrust.

The ratio of the radial to the thrust load and the bearing included outer ring angle determine the load zone in a given bearing. The number of rollers in contact as a result of this ratio deﬁnes the load zone. If all the rollers are in contact, the load zone is referred to as being 360 degrees.

When only radial load is applied to a tapered roller bearing, for convenience it is assumed in using the traditional calculation method that half the rollers support the load – the load zone is 180 degrees. In this case, induced bearing thrust is:

0.47 F

a(180)

The basic dynamic radial load rating, C90, is assumed to be the radial load-carrying capacity with a 180-degree load zone in the bearing. When the thrust load on a bearing exceeds the induced thrust, F

, a dynamic equivalent radial load must be used to

a(180)

calculate bearing life.

TIMKEN ENGINEERING MANUAL

The equations in tables 7 and 8 provide approximations of the dynamic equivalent radial load assuming a 180-degree load zone in one bearing and 180 degrees or more in the opposite bearing.

BEARING REACTIONS • DYNAMIC EQUIVALENT RADIAL BEARING LOADS (Pr)

Bearing A

Bearing B

Bearing A

Bearing B

Single-row mounting

To use this table for a single-row mounting, determine if bearings are direct or indirect mounted and to which bearing, A or B, thrust F

is applied. Once the appropriate design is established, follow

across the page opposite that design, and check to determine which thrust load and dynamic equivalent radial load equations apply.

TABLE 7. DYNAMIC EQUIVALENT RADIAL LOAD EQUATIONS, SINGLE-ROW TAPERED ROLLER BEARING MOUNTING

Design Thrust Condition Axial Load

BEARING SELECTION PROCESS

Dynamic Equivalent

Radial Load

Bearing A

Bearing B

Design Thrust Condition Axial Load

Bearing B

Dynamic Equivalent

Radial Load

(1)

If PA < FrA, use PA = FrA or if PB < FrB, use PB = F

rB.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

rAB

Bearing A

Bearing B

Fixed Bearing

Floating Bearing

Bearing C

rAB

Bearing A

Bearing B

rAB

Bearing B

Fixed Bearing

Floating Bearing

Bearing C

Bearing A

rAB

Bearing A

Bearing B

Fixed Bearing

Floating Bearing

Bearing C

rAB

Bearing A

Bearing B

rAB

Bearing B

Fixed Bearing

Floating Bearing

Bearing C

Bearing A

BEARING REACTIONS • DYNAMIC EQUIVALENT RADIAL BEARING LOADS (Pr)

Double-row mounting, ﬁxed or ﬂoating, similar bearing series

For double-row tapered roller bearings, the following table can be used. In this table, only bearing A has an applied thrust load. If bearing B has the applied thrust load, the A’s in the equations should be replaced by B’s and vice versa.

TABLE 8. DYNAMIC EQUIVALENT RADIAL LOAD EQUATIONS, DOUBLE-ROW TAPERED ROLLER BEARING MOUNTING

Design – Similar Bearing Series Thrust Condition

Bearing A

rAB

Fixed Bearing

rAB

Fixed Bearing

Bearing B

Bearing C

Floating Bearing

Bearing C

Floating Bearing

≤

0.6 F

For double-row similar bearing series with no external thrust, F

=0, the dynamic equivalent radial load, Pr, equals F

Since F

or FrC is the radial load on the double-row assembly,

rAB

the double-row basic dynamic radial load rating, C used to calculate bearing life.

Dynamic Equivalent

Radial Load

rAB

A =

B =

A =

B =

0.5 F

0.4 F

+ 0.83 K

rAB

- 0.83 K

rAB

+ K

rAB

A Fae

rAB

, is to be

90(2)

or FrC.

NOTE: F

Design – Dissimilar Bearing Series Thrust Condition

Bearing A

rAB

Bearing A

Bearing B

Fixed Bearing

is the radial load on the double-row assembly. The single-row basic dynamic radial load rating, C90, is to be applied when calculating life based on the above equations.

rAB

Floating Bearing

Bearing C

0.6 F

≤

0.6 F

rAB

B =

KA + KB

Dynamic Equivalent

KA + KB

0.4 F

A =

B =

Radial Load

+ 1.67 KB Fae)

rAB

- 1.67 KA Fae)

rAB

+ K

rAB

A Fae

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING REACTIONS • DYNAMIC EQUIVALENT THRUST BEARING LOADS (Pa) • STATIC RADIAL AND AXIAL EQUIVALENT LOADS

DYNAMIC EQUIVALENT THRUST BEARING LOADS (Pa)

For thrust ball, thrust spherical and thrust tapered roller bearings, the existence of radial loads introduces complex load calculations that must be carefully considered. If the radial load is zero, the equivalent dynamic thrust load (P the applied thrust load (F

). If any radial load is expected in the

) will be equal to

application, consult your Timken engineer for advice on bearing selection.

THRUST ANGULAR CONTACT BALL BEARINGS

For thrust angular contact ball bearings, the dynamic equivalent thrust load is determined by:

= Xr F + YF

The minimum permissible thrust load to radial load ratios (Fa/Fr), X factors and Y factors are listed in the bearing dimension tables in the Thrust Bearing Catalog available on www.timken.com.

THRUST SPHERICAL ROLLER BEARINGS

Thrust spherical roller bearing dynamic loads are determined by:

Pa = 1.2Fr + F

Radial load (Fr) of a thrust spherical roller bearing is proportional to the applied axial load (F roller angle induces a thrust load (F is applied. This thrust load must be resisted by another thrust bearing on the shaft or by an axial load greater than F

) such that Fr 0.55 Fa. The steep

= 1.2Fr) when a radial load

For all bearings, the maximum contact stress can be approximated using the static equivalent load and the static rating.

For roller bearings:

= 4000

= 580

( )

1/2

( )

For ball bearings:

1/2

MPa

ksi

= 4200

= 607

( )

1/3

( )

1/3

MPa

ksi

SPHERICAL ROLLER, RADIAL BALL AND ANGULAR CONTACT BALL BEARINGS

The load factors Xo and Yo, listed in table 9, are used with the following equation to estimate the static radial equivalent load.

= Xo Fr + Yo F

THRUST BALL BEARINGS

Similar to radial ball bearings, thrust ball bearings use the same equation for equivalent static and dynamic loading.

= Xo Fr + Yo F

The X and Y factors are listed in the Thrust Bearing Catalog available on www.timken.com along with the minimum required thrust load-to-radial load ratio for maintaining proper operation.

THRUST SPHERICAL ROLLER BEARINGS

STATIC RADIAL AND AXIAL EQUIVALENT LOADS

To compare the load on a non-rotating bearing with the basic static capacity, it is necessary to determine the static equivalent load. The static equivalent load is deﬁned as the pure radial or thrust load, whichever is appropriate, that produces the same contact pressure in the center of the most heavily stressed rolling element as the actual combined load. The static equivalent radial and/or axial loading is dependent on the bearing type selected. For bearings designed to accommodate only radial or thrust loading, the static equivalent load is equivalent to the applied load.

The following equation is used for thrust spherical roller bearings:

= Fa + 2.7 F

Thrust spherical roller bearings require a minimum thrust load for proper operation. P

should not be greater than 0.5 Coa. If

conditions exceed this, consult your Timken engineer.

TABLE 9. VALUES OF XO AND YO

FOR STATICALLY STRESSED RADIAL BEARINGS

Bearing Type

Radial Ball 0.6 0.5 0.6 0.5 Angular Contact Ball 15 0.5 0.47 1 0.94

Spherical Roller 0.5 0.22 cota 1 0.44 cota

Contact

Angle

(a)

20 0.5 0.42 1 0.84 25 0.5 0.38 1 0.76 30 0.5 0.33 1 0.66 35 0.5 0.29 1 0.58 40 0.5 0.26 1

Single-Row Double-Row

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING REACTIONS • STATIC RADIAL AND AXIAL EQUIVALENT LOADS • MINIMUM BEARING LOAD

TAPERED ROLLER BEARINGS

To determine the static equivalent radial load for a single-row mounting, first determine the thrust load, (F

), then use the

equations in this section, depending on the appropriate thrust load condition.

The bearing data tables do not include static ratings for doublerow bearings. The double-row static radial rating can be estimated as:

o(2)

= 2C

TABLE 10. STATIC EQUIVALENT LOAD EQUATIONS, SINGLE-ROW TAPERED ROLLER BEARING

Design Thrust Condition Axial Load

Bearing A

Design (external axial load, Fae, onto bearing A)

Use the values of PO calculated for comparison with the static rating (CO), even if PO is less than the radial applied Fr.

Bearing B

0.47 F

Bearing B

0.47 F

≤

A KB

rA >

A KB

0.47 F

+ F

0.47 F

Static Equivalent

Radial Load

= F

+ F

- F

for FaA < 0.6 FrA / K P

= 1.6 FrA - 1.269 KA F

for FaA > 0.6 FrA / K P

= 0.5 FrA + 0.564 KA F

for FaB > 0.6 FrB / K

= 0.5 FrB + 0.564 KB F

for FaB < 0.6 FrB / K P

= 1.6 FrB - 1.269 KB F

= F

MINIMUM BEARING LOAD

Slippage can occur if loads are too light and, if accompanied by inadequate lubrication, may cause damage to the bearings. The minimum load for radial cylindrical and spherical roller bearings is P

= 0.04 C.

Centrifugal force in thrust spherical roller bearings tends to propel the rollers outward. The bearing geometry converts this force to another induced thrust component, which must be overcome by an axial load. This induced thrust (F

= k n2 x 10

TIMKEN ENGINEERING MANUAL

-5

(pounds force per RPM)

) is given by:

The minimum required working thrust load on a thrust spherical roller bearing (F

a min

= 1.2 F

) is then computed by:

a min

r + Fac

1000

(lbf)

In addition to meeting the above calculated value, the minimum required working thrust load (F than 0.1 percent of the static thrust load rating (C

) should be equal to or greater

a min

BEARING SELECTION PROCESS

BEARING RATINGS • DYNAMIC LOAD RATING • STATIC LOAD RATING

BEARING RATINGS

There are two fundamental load ratings for bearings, a dynamic load rating and a static load rating. The dynamic load rating is used to estimate the life of a rotating bearing. Static load ratings are used to determine the maximum permissible load that can be applied to a non-rotating bearing.

DYNAMIC LOAD RATING

Published dynamic load ratings for Timken bearings are typically based on a rated life of one million revolutions. This rating, designated as C, is deﬁned as the radial load under which a population of bearings will achieve an L revolutions. For Timken tapered roller bearings, the dynamic load rating is more commonly based on a rated life of 90 million revolutions, with the designation of C load under which a population of bearings will achieve an L of 90 million revolutions. For tapered roller bearings, the dynamic thrust rating also is published and is designated as C rating is the thrust load under which a population of bearings will achieve an L

The dynamic load rating of a bearing is a function of the internal bearing geometry, which includes raceway angles, contact length between rolling elements and raceways, and the number and size of rolling elements. It also is a function of material cleanliness.

life of 90 million revolutions.

life of one million

. This rating is the radial

. The C

a90

life

a90

STATIC LOAD RATING

The basic static radial load rating and thrust load rating for Timken bearings are based on a maximum contact stress within a non-rotating bearing of 4000 MPa (580 ksi) for roller bearings and 4200 MPa (609 ksi) for ball bearings, at the center of contact on the most heavily loaded rolling element.

The 4000 MPa (580 ksi) or 4200 MPa (609 ksi) stress levels may cause visible light Brinell marks on the bearing raceways. This degree of marking will not have a measurable effect on fatigue life when the bearing is subsequently rotating under a lower application load. If sound, vibration or torque are critical, or if a pronounced shock load is present, a lower load limit should be applied. For more information on selecting a bearing for static load conditions, consult your Timken engineer.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING RATINGS • BEARING LIFE • RATING LIFE • BEARING LIFE EQUATIONS

BEARING LIFE

Many different performance criteria exist that dictate how a bearing should be selected. These include bearing fatigue life, rotational precision, power requirements, temperature limits, speed capabilities, sound, etc. This section deals primarily with bearing life as related to material-associated fatigue. Bearing life is deﬁned as the length of time, or number of revolutions, until a fatigue spall of 6 mm is a statistical phenomenon, the life of an individual bearing is impossible to predetermine precisely. Bearings that may appear to be identical can exhibit considerable life scatter when tested under identical conditions. Thus it is necessary to base life predictions on a statistical evaluation of a large number of bearings operating under similar conditions. The Weibull distribution function is the accepted standard for predicting the life of a population of bearings at any given reliability level.

(0.01 in.2) develops. Since fatigue

RATING LIFE

Rating life, (L10), is the life that 90 percent of a group of apparently identical bearings will complete or exceed before a fatigue spall develops. The L for a single bearing under a certain load.

life also is associated with 90 percent reliability

BEARING LIFE EQUATIONS

Traditionally, the L10 life has been calculated as follows for bearings under radial or combined loading, where the dynamic equivalent radial load, P load rating is based on one million cycles:

L10 =

For thrust bearings, the above equations change to the following.

L10 =

( )

( ) ( )

( )

( ) ( )

has been determined and the dynamic

(1x106)

1x106

60n

(1x106)

1x106

60n

revolutions

hours

revolutions

hours

Tapered roller bearings often use a dynamic load rating based on 90 million cycles, as opposed to one million cycles, changing the equations as follows:

10/3

L10 =

and

L10 =

The traditional form of the equations based on dynamic load ratings of one million cycles is most common and will, therefore, be used throughout the rest of this section. The dynamic equivalent load equations and the life adjustment factors deﬁned in subsequent sections are applicable to all forms of the life equation.

With increased emphasis on the relationship between the reference conditions and the actual environment in which the bearing operates in the machine, the traditional life equations have been expanded to include certain additional variables that affect bearing performance. The approach whereby these factors are considered in the bearing analysis and selection has been termed Bearing Systems Analysis (BSA).

The ABMA expanded bearing life equation is:

The Timken expanded bearing life equation is:

L P

Where:

e = 3 for ball bearings = roller bearings

( )

10/3

( )

10/3

a90

( )

10/3

a90

( )

= a1a2a3L

= a1a2a3da3ka3la3ma

/3 for tapered, cylindrical and spherical

(90x106)

90x106

( )

60n

(90x106) revolutions

90x106

60n

( )

revolutions

hours

(1x10

) revolutions

e = 3 for ball bearings

/3 for tapered, cylindrical and spherical

roller bearings

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING RATINGS • BEARING LIFE EQUATIONS

RELIABILITY LIFE FACTOR (a1)

Reliability, in the context of bearing life for a group of apparently identical bearings operating under the same conditions, is the percentage of the group that is expected to attain or exceed a speciﬁed life. The reliability of an individual bearing is the probability that the bearing will attain or exceed a speciﬁed life.

The reliability life adjustment factor is:

2/3

100

= 4.26 ln

ln = natural logarithm (base e)

To adjust the calculated L10 life for reliability, multiply by the a

factor. If 90 (90 percent reliability) is substituted for R in the

above equation, a

0.25. The following table lists the reliability factor for commonly used reliability values.

TABLE 11. RELIABILITY FACTORS

R (percent) L

90 L10 1.00

95 L 96 L 97 L 98 L 99 L

99.5 L

99.9 L

Note that the equation for reliability adjustment assumes there is a short minimum life below which the probability of bearing damage is minimal (e.g., zero probability of bearing damage producing a short life). Extensive bearing fatigue life testing has shown the minimum life, below which the probability of bearing damage is negligible, to be larger than predicted using the above adjustment factor. For a more accurate prediction of bearing lives at high levels of reliability, consult your Timken engineer.

( )

= 1. For R = 99 (99 percent reliability), a1 =

+ 0.05

0.64

0.55

0.47

0.37

0.25

0.175

0.5

0.093

0.1

that contact stresses are approximately less than 2400 MPa (350 ksi), and adequate lubrication is provided. It is important to note that improvements in material cannot offset poor lubrication in an operating bearing system. Consult your Timken engineer for applicability of the material factor.

DEBRIS LIFE FACTOR (a3d)

Debris within a lubrication system reduces the life of a roller bearing by creating indentations on the contacting surfaces, leading to stress risers. The Timken life rating equations were developed based on test data obtained with 40 μm oil ﬁltration, and measured ISO cleanliness levels of approximately 15/12, which is typical of cleanliness levels found in normal industrial machinery. When more or less debris is present within the system, the fatigue life predictions can be adjusted according to the measured or expected ISO lubricant cleanliness level to more accurately reﬂect the expected bearing performance.

A more accurate option for predicting bearing life in a debris environment is to perform a Debris Signature Analysis™. The Debris Signature Analysis is a process for determining the effects of the actual debris present in your system on the bearing performance. The typical way in which this occurs is through measurements of dented/bruised surfaces on actual bearings run in a given application. This type of analysis can be beneﬁcial because different types of debris cause differing levels of performance degradation. Soft, ductile particles can cause differing levels of performance degradation than hard, brittle particles. Hard, ductile particles are typically most detrimental to bearing life. Brittle particles can break down, thus not affecting performance to as large of a degree as hard ductile particles. For more information on Debris Signature Analysis or the availability of debris-resistant bearings for your application, consult your Timken engineer.

MATERIAL LIFE FACTOR (a2)

The life adjustment factor for bearing material, a2, for standard Timken bearings manufactured from bearing quality steel is 1.0. Bearings also are manufactured from premium steels, containing fewer and smaller inclusion impurities than standard steels and providing the beneﬁt of extending bearing fatigue life (e.g., DuraSpexx requires that fatigue life is limited by nonmetallic inclusions,

bearing). Application of the material life factor

Fig. 68. Surface map of a bearing raceway with debris denting.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING RATINGS • BEARING LIFE EQUATIONS

LOAD ZONE LIFE FACTOR (a3k)

Bearing fatigue life is a function of the stresses between rolling elements and raceways as well as the number of stress cycles the bearing surfaces experience per revolution. Stresses are inﬂuenced by the magnitude of the applied load, the internal bearing geometry and the number of rolling elements supporting the load. The number of stress cycles is a function of the number of rollers supporting the load, which, in turn, is inﬂuenced by the number of rollers per row, the bearing geometry, applied load and bearing setting.

The arc deﬁned by the rollers supporting the load is called the bearing load zone. The load zone is significantly influenced by bearing setting or internal clearance, either radial or axial depending on the bearing type. Neglecting preload, less clearance in a bearing results in a larger load zone and subsequently longer bearing life.

The dynamic equivalent load (P load (F

) to approximate the combined load zone effect on L

If a more accurate assessment of the load zone adjusted life is necessary (e.g., including the effects of internal clearance or ﬁtting practice), consult your Timken engineer.

) is used instead of the applied

10a

LUBRICATION LIFE FACTOR (a3l)

The inﬂuence of lubrication ﬁlm on bearing performance is related to the reduction or prevention of asperity (metal-metal) contact between the bearing surfaces. Extensive testing has been done at The Timken Technology Center to quantify the effects of the lubrication-related parameters on bearing life. It has been found that the roller and raceway surface ﬁnish, relative to lubricant ﬁlm thickness, has the most notable effect on improving bearing performance. Factors such as bearing geometry, material, loads and load zones also play an important role in bearing performance.

The following equation provides a method to calculate the lubrication factor for a more accurate prediction of the inﬂuence of lubrication on bearing life (L

= Cg Cl Cj Cs Cv C

The a3l maximum is 2.88 for all bearings. The a3l minimum is 0.200 for case-carburized bearings and 0.126 for through-hardened

bearings.

A lubricant contamination factor is not included in the lubrication factor because Timken endurance tests are typically run with a 40 μm ﬁlter to provide a realistic level of lubricant cleanness for most applications.

10a

Fig. 69. Bearing load zones and roller-raceway contact loading.

Geometry factor (Cg)

Cg is given for most part numbers that are available in the bearing catalogs on www.timken.com. The geometry factor also includes the material effects and load zone considerations for non-tapered roller bearings, as these also are inherent to the bearing design. However, it should be noted that the primary effect of the load zone is on roller load distributions and contact stresses within the bearing, which are not quantiﬁed within the lubrication factor. Refer to the previous section Load Zone Life Factor (a information.

The geometry factor (C

) is not applicable to our DuraSpexx™

product. For more information on our DuraSpexx product, consult your Timken engineer.

) for more

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING RATINGS • BEARING LIFE EQUATIONS

Load factor (C

)

The Cl factor can be obtained from ﬁg. 70. Note that the factor is different based on the type of bearing utilized. P

is the equivalent

load applied to the bearing in Newtons and is determined in the Dynamic Equivalent Bearing Loads (P

) section.

1.0

0.9

0.8

0.7

0.6

0.5

0.4

0.3

Ball Bearings Roller Bearings

0.2

0.1

0.0 1 10 100 1000 10000 100000 1000000 10000000

Pr (Newtons)

Fig. 70. Load factor (Cl) vs. dynamic equivalent bearing load (Pr).

Load zone factor (Cj)

For all non-tapered roller bearings, the load zone factor is one (1). For tapered roller bearings, the load zone factor can be taken from ﬁg. 71.

0.9

0.8

0.7

0.6

0.5 0 0.5 1 1.5 2 2.5

Fa K

0.747

Fig. 71. Load zone factor (Cj) for tapered roller bearings.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING RATINGS • BEARING LIFE EQUATIONS

Speed factor (Cs)

Cs can be determined from ﬁg. 72, where rev/min (RPM) is the rotational speed of the inner ring relative to the outer ring.

Fig. 72. Speed factor (Cs) vs.

rotational speed.

Viscosity factor (Cv)

The lubricant kinematic viscosity (centistokes [cSt]) is taken at the operating temperature of the bearing. The operating viscosity can be estimated by ﬁg. 73. The viscosity factor (C determined from ﬁgs. 73 and 74 shown here.

) can then be

1000

Ball Bearings Roller Bearings

100

1 1 0 100 1000 10000

Rotational Speed (RPM)

10000

1000

100

ISO VG

680 460 320 220 150 100

68 46 32

Fig. 73. Temperature vs.

kinematic viscosity.

Kinematic Viscosity (cSt)

0 50 100 150 200

1000

Temperature (˚C)

Ball Bearings Roller Bearings

100

Fig. 74. Viscosity factor (C

) vs.

kinematic viscosity.

1 1 0 100 1000 10000

Kinematic Viscosity (cSt)

TIMKEN ENGINEERING MANUAL

GREASE LUBRICATION FACTOR (Cgr)

Over time, grease degradation causes a reduction in lubricant ﬁlm thickness. Consequently, a reduction factor (C used to adjust for this effect.

) should be

BEARING SELECTION PROCESS

BEARING RATINGS • BEARING LIFE EQUATIONS

= 0.79

LOW-LOAD LIFE FACTOR (a3p)

Bearing life tests show greatly extended bearing fatigue life performance is achievable when the bearing contact stresses are low and the lubricant ﬁlm is sufﬁcient to fully separate the micro-scale textures of the contacting surfaces. Mating the test data with sophisticated computer programs for predicting bearing performance, Timken engineers developed a low-load factor to predict the life increase expected when operating under low-bearing loads. Fig. 75 shows the low-load factor (a function of the lubricant life factor (a

) and the ratio of bearing

dynamic rating to the bearing equivalent load.

6.5

C/P

=13.48

C/P

5.5 5

4.5 4

3.5 3

2.5 2

1.5 1

0.5

0 0.5 1 1.5 2 2.5 3

C/P

=9.63 C/P

=7.7 C/P

C/P

=6.74

) as a

=5.78

C/P

=3.5

C/P

=5.12

=4.81

=4.24

=3.85

=3.08

Fig. 75. Low-load life adjustment factor.

TIMKEN ENGINEERING MANUAL

BEARING SELECTION PROCESS

BEARING RATINGS • BEARING LIFE EQUATIONS

MISALIGNMENT LIFE FACTOR (a3m)

Accurate alignment of the shaft relative to the housing is critical for bearing performance. As misalignment increases under moderate to heavy loads, high contact stresses can be generated at the edges of contact between the raceway and rolling element. Special proﬁling of the raceway or rolling element can in most cases offset the effects of misalignment as shown in ﬁg. 76. This ﬁgure shows the roller-to-inner ring contact stress of a tapered roller bearing under a misaligned condition with and without special proﬁling. The proﬁling signiﬁcantly reduces the edge stress, resulting in improved bearing performance. The misalignment factor takes into account the effects of proﬁling on bearing life.

For tapered roller bearings, the base or reference condition upon which the bearing rating is generated includes a misalignment of

0.0005 radians. Above this misalignment value, reduction in life can be expected and will be reﬂected in the misalignment factor.

For cylindrical roller bearings, the misalignment factor is also a measure of the effect of bearing axial load on life. Axial loading of the bearing causes a moment to be generated about the roller center, thus shifting the roller-raceway contact stresses toward the end of the roller, similar to bearing misalignment.

Maximum recommended misalignment values for cylindrical roller bearings having proﬁled rollers are listed in the following table.

TABLE 12. CYLINDRICAL ROLLER BEARING

MAXIMUM MISALIGNMENT RECOMMENDATIONS

Maximum Recommended Misalignment

Load as %C

mrad Degrees

<20 1.2 0.07

20-35 0.5 0.03

>35 Check with your Timken engineer.

Inner Raceway Contact Stress with Misalignment

700

600

500

400

300

Stress (ksi)

200

100

700

600

500

400

300

Stress (ksi)

200

100

A. Raceway length

No special profile

B. Raceway length

Special profile

Fig. 76. Tapered roller bearing contact stress under misaligned condition.

The misalignment factor for spherical roller bearings is 1.0 due to the self-aligning capabilities of a spherical roller bearing. The allowable misalignment of a spherical roller bearing is between

0.5 and 1.25 degrees, depending on the bearing series as noted in table 13. Life will be reduced if these limits are exceeded.

Performance of all Timken bearings under various levels of misalignment and radial and axial load can be predicted using sophisticated computer programs. Using these programs, Timken engineers can design special bearing-contact proﬁles to accommodate the conditions of radial load, axial load and/or bearing misalignment in your application. Consult your Timken engineer for more information.

TIMKEN ENGINEERING MANUAL

TABLE 13. SPHERICAL ROLLER BEARING

MAXIMUM MISALIGNMENT RECOMMENDATIONS

Bearing Series Maximum Misalignment (Degrees)

238 ±0.5

222, 230, 231, 239, 249 ±0.75

223, 240 ±1 232, 241 ±1.25

BEARING SELECTION PROCESS

SYSTEM LIFE AND WEIGHTED AVERAGE LOAD AND LIFE • SYSTEM LIFE • WEIGHTED AVERAGE LOAD AND LIFE EQUATIONS

SYSTEM LIFE AND WEIGHTED AVERAGE LOAD AND LIFE

SYSTEM LIFE

System reliability is the probability that all of the given bearings in a system will attain or exceed some required life. System reliability is the product of the individual bearing reliabilities in the system:

In the application, the L10 system life for a number of bearings each having different L

= RA RB RC…. R

(system)

10(system)

= [(1/L

life is:

3/2

)

10A

+ (1/L

10B

3/2

)

+ ….(1/L

10n

3/2]-2/3

)

WEIGHTED AVERAGE LOAD AND LIFE EQUATIONS

In many applications, bearings are subjected to various conditions of loading, and bearing selection is often made on the basis of maximum load and speed. However, under these conditions, a more meaningful analysis may be made by examining the loading cycle to determine the weighted average load.

Bearing selection based on weighted average loading will take into account variations in speed, load, and proportion of time during which the variable loads and speeds occur. However, it is still necessary to consider extreme loading conditions to evaluate bearing contact stresses and alignment.

WEIGHTED AVERAGE LOAD

Variable speed, load and proportion time:

= [(n1 t1 F

10/3

+ ….nn tn F

Uniformly increasing load, constant speed:

= [(3/13) (F

max

13/3

- F

Use of the weighted average load in the bearing life equation does not take into account the effects of different speeds on the lubrication factor a

. For load cycles with varying speeds, it is

recommended that life calculations be made for each condition and that the life for each condition be plugged into the weighted average life equation.

min

13/3

10/3

) / (F

) / na]

max

- F

0.3

)]

min

WEIGHTED AVERAGE LIFE

= 1/{[t1 / (Ln)1]+ [t2 / (Ln)2]+… [tn / (Ln)

nwt

TIMKEN ENGINEERING MANUAL

]

}

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

Ball and roller bearings are manufactured to a number of speciﬁcations, with each having classes that deﬁne tolerances on dimensions such as bore, O.D., width and runout. In addition, bearings are produced in both inch and metric systems with the boundary dimension tolerances being different for these two systems. The major difference between the two systems is that inch bearings have historically been manufactured to positive bore and O.D. tolerances, whereas metric bearings have been manufactured to corresponding standard negative tolerances.

The following table summarizes the different speciﬁcations and classes for ball, tapered roller, cylindrical roller and spherical

TABLE 14. BEARING SPECIFICATIONS AND CLASSES

System Speciﬁcation Bearing Type Standard Bearing Class Precision Bearing Class

Metric Timken Tapered Roller Bearings K N C B A AA

ISO/DIN All Bearing Types P0 P6 P5 P4 P2 -

ABMA Cylindrical, Spherical Roller Bearings RBEC 1 RBEC 3 RBEC 5 RBEC 7 RBEC 9 -

Ball Bearings ABEC 1 ABEC 3 ABEC 5 ABEC 7 ABEC 9 -

Tapered Roller Bearings K N C B A -

Inch Timken Tapered Roller Bearings 4 2 3 0 00 000

ABMA Tapered Roller Bearings 4 2 3 0 00 -

roller bearings. For the purposes of this manual, ISO speciﬁcations are shown for ball, cylindrical roller and spherical roller bearings. Timken speciﬁcations are shown for tapered roller bearings.

Boundary dimension tolerances for ball and roller bearing usage are listed in the following tables. These tolerances are provided for use in selecting bearings for general applications in conjunction with the bearing mounting and ﬁtting practices offered in later sections.

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

METRIC SYSTEM

RADIAL BALL, SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

METRIC SYSTEM

Standard Timken® radial ball, radial spherical roller and radial cylindrical roller bearings maintain normal tolerances according to the current ISO 492 standard. Tables 15 and 16 list the critical tolerances for these bearing types. For applications where running tolerance is critical, P6 or P5 tolerances are recommended.

The term deviation is deﬁned as the difference between a single ring dimension and the nominal dimension. For metric tolerances, the nominal dimension is at a +0 mm (0 in.) tolerance. The deviation is the tolerance range for the listed parameter. Variation is deﬁned as the difference between the largest and smallest measurements of a given parameter for an individual ring.

TABLE 15. RADIAL BALL, SPHERICAL AND CYLINDRICAL ROLLER BEARING TOLERANCES – INNER RING (Metric)

in.

Face

Runout

with Bore

Bearing Bore

Over Incl. P0 P6 P5 P0 P6 P5 P0 P6 P5 P5 P5 P0, P6 P5

in.

2.5000 10.000 -0.008 -0.007 -0.005 0.015 0.015 0.005 0.010 0.006 0.004 0.007 0.007 -0.120 -0.040

0.0984 0.3937 -0.0003 -0.0003 -0.0002 0.0006 0.0006 0.0002 0.0004 0.0002 0.0002 0.0003 0.0003 -0.0047 -0.0157

10.000 18.000 -0.008 -0.007 -0.005 0.020 0.020 0.005 0.010 0.007 0.004 0.007 0.007 -0.120 -0.080

0.3937 0.7087 -0.0003 -0.0003 -0.0002 0.0008 0.0008 0.0002 0.0004 0.0003 0.0002 0.0003 0.0003 -0.0047 -0.0031

18.000 30.000 -0.010 -0.008 -0.006 0.020 0.020 0.005 0.013 0.008 0.004 0.008 0.008 -0.120 -0.120

0.7087 1.1811 -0.0004 -0.0003 -0.0002 0.0008 0.0008 0.0002 0.0005 0.0003 0.0002 0.0003 0.0003 -0.0047 -0.0047

30.000 50.000 -0.012 -0.010 -0.008 0.020 0.020 0.005 0.015 0.010 0.005 0.008 0.008 -0.120 -0.120

1.1811 1.9685 -0.0005 -0.0004 -0.0003 0.0008 0.0008 0.0002 0.0006 0.0004 0.0002 0.0003 0.0003 -0.0047 -0.0047

50.000 80.000 -0.015 -0.012 -0.009 0.025 0.025 0.006 0.020 0.010 0.005 0.008 0.008 -0.150 -0.150

1.9685 3.1496 -0.0006 -0.0005 -0.0004 0.0010 0.0010 0.0002 0.0008 0.0004 0.0002 0.0003 0.0003 -0.0059 -0.0059

80.000 120.000 -0.020 -0.015 -0.010 0.025 0.025 0.007 0.025 0.013 0.006 0.009 0.009 -0.200 -0.200

3.1496 4.7244 -0.0008 -0.0006 -0.0004 0.0010 0.0010 0.0003 0.0010 0.0005 0.0002 0.0004 0.0004 -0.0079 -0.0079

120.000 150.000 -0.025 -0.018 -0.013 0.030 0.030 0.008 0.030 0.018 0.008 0.010 0.010 -0.250 -0.250

4.7244 5.9055 -0.0010 -0.0007 -0.0005 0.0012 0.0012 0.0003 0.0012 0.0007 0.0003 0.0004 0.0004 -0.0098 -0.0098

150.000 180.000 -0.025 -0.018 -0.013 0.030 0.030 0.008 0.030 0.018 0.008 0.010 0.010 -0.250 -0.250

5.9055 7.0866 -0.0010 -0.0007 -0.0005 0.0012 0.0012 0.0003 0.0012 0.0007 0.0003 0.0004 0.0004 -0.0098 -0.0098

180.000 250.000 -0.030 -0.022 -0.015 0.030 0.030 0.010 0.040 0.020 0.010 0.011 0.013 -0.300 -0.300

7.0866 9.8425 -0.0012 -0.0009 -0.0006 0.0012 0.0012 0.0004 0.0016 0.0008 0.0004 0.0004 0.0005 -0.0018 -0.0018

250.000 315.000 -0.035 -0.025 -0.018 0.035 0.035 0.013 0.050 0.025 0.013 0.013 0.015 -0.350 -0.350

9.8425 12.4016 -0.0014 -0.0010 -0.0007 0.0014 0.0014 0.0005 0.0020 0.0010 0.0005 0.0005 0.0006 -0.0138 -0.0138

315.000 400.000 -0.040 -0.030 -0.023 0.040 0.040 0.015 0.060 0.030 0.015 0.015 0.020 -0.400 -0.400

12.4016 15.7480 -0.0016

400.000 500.000 -0.045 -0.035 – 0.050 0.045 – 0.065 0.035 – – – -0.450 –

15.7480 19.6850 -0.0018 -0.0014 – 0.0020 0.0018 – 0.0026 0.0014 – – – -0.0177 –

500.000 630.000 -0.050 -0.040 – 0.060 0.050 – 0.070 0.040 – – – -0.500 –

19.6850 24.8031 -0.0020 -0.0016 – 0.0024 0.0020 – 0.0028 0.0016 – – – -0.0197 –

630.000 800.000 -0.075 – – 0.070 – – 0.080 – – – – -0.750 –

24.8031 31.4961 -0.0030 – – 0.0028 – – 0.0031 – – – – -0.0295 –

(1)

Tolerance range is from +0 to value listed.

in.

Bore Deviation

in.

(1)

dmp

in.

-0.0012 -0.0009 0.0016 0.0016 0.0006 0.0024 0.0012 0.0006 0.0006 0.0008 -0.0157 -0.0157

in.

Width Variation

in.

Radial Runout

in.

Axial

Runout

in.

Width Deviation

Inner & Outer Rings

in.

and Δ

in.

(1)

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

METRIC SYSTEM

TABLE 16. RADIAL BALL, SPHERICAL AND CYLINDRICAL ROLLER BEARING TOLERANCES – OUTER RING (Metric)

Axial

Runout

in.

Bearing O.D.

Outside Deviation

Dmp

(1)

Width Variation

Radial Runout

Over Incl. P0 P6 P5 P0 P6 P0 P6 P5 P5 P5

in.

0.000 18.000 -0.008 -0.007 -0.005 0.015 0.005 0.015 0.008 0.005 0.008 0.008

0.0000 0.7087 -0.0003 -0.0003 -0.0002 0.0006 0.0002 0.0006 0.0003 0.0002 0.0003 0.0003

18.000 30.000 -0.009 -0.008 -0.006 0.020 0.005 0.015 0.009 0.006 0.008 0.008

0.7087 1.1811 -0.0004 -0.0003 -0.00024 0.0008 0.0002 0.0006 0.0004 0.00024 0.0003 0.0003

30.000 50.000 -0.011 -0.009 -0.007 0.020 0.005 0.020 0.010 0.007 0.008 0.008

1.1811 1.9685 -0.0004 -0.0004 -0.0003 0.0008 0.0002 0.0008 0.0004 0.0003 0.0003 0.0003

50.000 80.000 -0.013 -0.011 -0.009 0.025 0.006 0.025 0.013 0.008 0.010 0.008

1.9685 3.1496 -0.0005 -0.0004 -0.0004 0.0010 0.00024 0.0010 0.0005 0.0003 0.0004 0.0003

80.000 120.000 -0.015 -0.013 -0.010 0.025 0.008 0.035 0.018 0.010 0.011 0.009

3.1496 4.7244 -0.0006 -0.0005 -0.0004 0.0010 0.0003 0.0014 0.0007 0.0004 0.0004 0.0004

120.000 150.000 -0.018 -0.015 -0.011 0.030 0.008 0.040 0.020 0.011 0.013 0.010

4.7244 5.9055 -0.0007 -0.0006 -0.0004 0.0012 0.0003 0.0016 0.0008 0.0004 0.0005 0.0004

150.000 180.000 -0.025 -0.018 -0.013 0.030 0.008 0.045 0.023 0.013 0.014 0.010

5.9055 7.0866 -0.0010 -0.0007 -0.0005 0.0012 0.0003 0.0018 0.0009 0.0005 0.0006 0.0004

180.000 250.000 -0.030 -0.020 -0.015 0.030 0.010 0.050 0.025 0.015 0.015 0.011

7.0866 9.8425 -0.0012 -0.0008 -0.0006 0.0012 0.0004 0.0020 0.0010 0.0006 0.0006 0.0004

250.000 315.000 -0.035 -0.025 -0.018 0.035 0.011 0.060 0.030 0.018 0.018 0.013

9.8425 12.4016 -0.0014 -0.0010 -0.0007 0.0014 0.0004 0.0024 0.0012 0.0007 0.0007 0.0005

315.000 400.000 -0.040 -0.028 -0.020 0.040 0.013 0.070 0.035 0.020 0.020 0.013

12.4016 15.7480 -0.0016 -0.0011 -0.0008 0.0016 0.0005 0.0028 0.0014 0.0008 0.0008 0.0005

400.000 500.000 -0.045 -0.033 -0.023 0.045 0.015 0.080 0.040 0.023 0.023 0.015

15.7480 19.6850 -0.0018 -0.0013 -0.0009 0.0018 0.0006 0.0031 0.0016 0.0009 0.0009 0.0006

500.000 630.000 -0.050 -0.038 -0.028 0.050 0.018 0.100 0.050 0.025 0.025 0.018

19.6850 24.8031 -0.0020 -0.0015 -0.0011 0.0020 0.0007 0.0039 0.0020 0.0010 0.0010 0.0007

630.000 800.000 -0.075 -0.045 -0.035 – 0.020 0.120 0.060 0.030 0.030 0.020

24.8031 31.4961 -0.0030 -0.0018 -0.0014 – 0.0008 0.0047 0.0024 0.0012 0.0012 0.0008

800.000 1000.000 -0.100 -0.060 – – – 0.140 0.075 – – –

31.4961 39.3701 -0.0040 -0.0024 – – – 0.0055 0.0030 – – –

1000.000

1250.000 -0.125 – – – – 0.160 – – – –

39.3701 49.2126 -0.0050 – – – – 0.0063 – – – –

(1)

Tolerance range is from +0 to value listed.

Outside

Diameter

Runout

With Face

in.

TABLE 17. THRUST BALL BEARING TOLERANCES – TYPE TVB

Bore O.D. Height

Bearing Bore Tolerance

Over Incl. Over Incl. Over Incl. Max. Min.

in.

0.000 171.450 +0.127 0.000 134.938 -0.051 0.000 46.038 +0.127 -0.127

0.0000 6.7500 +0.0050 0.0000 5.3125 -0.0020 0.0000 1.8125 +0.0050 -0.0050

171.450 508.000 +0.178 134.938 441.325 -0.076 46.038 304.800 +0.254 -0.254

6.7500 20.0000 +0.0070 5.3125 17.3750 -0.0030 1.8125 12.0000 +0.0100 -0.0100

– – – 441.325 1000.000 -0.102 304.800 508.000 +0.381 -0.381

– – – 17.3750 39.3701 -0.0040 12.0000 20.0000 +0.0150 -0.0150

(1)

The tolerances in this table conform to ABMA Standard 21.2.

in.

(1)

Bearing O.D. Tolerance

in.

(1)

Bearing Bore Tolerance

in.

58 TIMKEN ENGINEERING MANUAL

in.

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

METRIC SYSTEM

TABLE 18. THRUST BALL BEARING TOLERANCES – TYPES TVL & DTVL

Bore O.D. Height

Bearing Bore Tolerance

Over Incl. Over Incl. Over Incl. Max.

in.

0.000 504.825 -0.076 0.000 584.000 -0.076

0.0000 19.8750 -0.0030 0.0000 23.0000 -0.0030 ±0.0150

504.825 1524.000 -0.127 584.000 1778.000 -0.127 –

19.8750 60.0000 -0.0050 23.0000 70.0000 -0.0050 –

(1)

The tolerances in this table conform to ABMA Standard 21.2.

Inner Ring Outer Ring

Bore Tolerance O.D. Tolerance Bore Diameter Tolerance

Over Incl. Over Incl. Over Incl. Max. Min.

in.

80.000 120.000 -0.020 0.025 120.000 150.000 -0.020 0.041 80.000 120.000 +0.094 -0.254

3.1496 4.7244 -0.0008 0.0010 4.7244 5.9055 -0.0080 0.0016 3.1496 4.7244 +0.0037 -0.0100

120.000 180.000 -0.025 0.030 150.000 180.000 -0.025 0.046 120.000 180.000 +0.109 -0.300

4.7244 7.0866 -0.0010 0.0012 5.9055 7.0866 -0.0010 0.0018 4.7244 7.0866 +0.0043 -0.0118

180.000 250.000 -0.030 0.041 180.000 250.000 -0.030 0.051 180.000 250.000 +0.130 -0.366

7.0866 9.8425 -0.0012 0.0016 7.0866 9.8425 -0.0012 0.0020 7.0866 9.8425 +0.0051 -0.0144

250.000 315.000 -0.036 0.051 250.000 315.000 -0.036 0.061 250.000 315.000 +0.155 -0.434

9.8425 12.4016 -0.0014 0.0020 9.8425 12.4016 -0.0014 0.0024 9.8425 12.4016 +0.0061 -0.0171

315.000 400.000 -0.041 0.061 315.000 400.000 -0.041 0.071 315.000 400.000 +0.170 -0.480

12.4016 15.7480 -0.0016 0.0024 12.4016 15.7480 -0.0016 0.0028 12.4016 15.7480 +0.0067 -0.0189

400.000 500.000 -0.046 0.066 400.000 500.000 -0.046 0.081 400.000 500.000 +0.185 -0.526

15.7480 19.6850 -0.0018 0.0026 15.7480 19.6850 -0.0018 0.0032 15.7480 19.6850 +0.0073 -0.0207

500.000 630.000 -0.051 0.071 500.000 630.000 -0.051 0.102 500.000

19.6850 24.8031 -0.0020 0.0028 19.6850 24.8031 -0.0020 0.0040 19.6850 +0.0080 -0.0230

630.000 800.000 -0.076 0.081 630.000 800.000 -0.076 0.119 – – – –

24.8031 31.4961 -0.0030 0.0032 24.8031 31.4961 -0.0030 0.0047 – – – –

800.000 1000.000 -0.102 0.089 800.000 1000.000 -0.102 0.140 – – – –

31.4961 39.3701 -0.0040 0.0035 31.4961 39.3701 -0.0040 0.0055 – – – –

1000.000 1250.000 -0.127 0.102 1000.000 1250.000 -0.127 0.163 – – – –

39.3701 49.2126 -0.0050 0.0040 39.3701 49.2126 -0.0050 0.0064 – – – –

– – – 1250.000 1600.000 -0.165 0.193 – – – – – – – – 49.2126 62.9921 -0.0065 0.0076 – – – – –

– – – 1600.000 2000.000 -0.203 0.229 – – – – – – – – 62.9921 78.7402 -0.0080 0.009 – – – – –

in.

Bore

in.

(1)

Bearing O.D. Tolerance

in.

(1)

Bearing Bore Tolerance

in.

±0.381

All Sizes

TABLE 19. THRUST SPHERICAL ROLLER BEARING TOLERANCES

(1)

Radial

Runout

in.

O.D.

(1)

Radial

Runout

in.

and up

Height

in.

+0.203 -0.584

in.

(1)

Tolerance range is from +0 to value listed.

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

METRIC SYSTEM

TAPERED ROLLER BEARING

Metric system bearings (ISO and J Preﬁx Parts)

Timken manufactures metric system bearings to six tolerance classes. Classes K and N are often referred to as standard classes. Class N has more closely controlled width tolerances than K. Classes C, B, A and AA are precision classes. These

TABLE 20. TAPERED ROLLER BEARING TOLERANCES – INNER RING BORE (Metric)

Bearing

Types

TSF

(1)

SR assemblies are manufactured to tolerance class N only.

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

10.000 18.000 0.000 -0.012 0.000 -0.012 0.000 -0.007 0.000 -0.005 0.000 -0.005 0.000 -0.005

0.3937 0.7087 0.0000 -0.00047 0.0000 -0.00047 0.0000 -0.0002 0.0000 -0.0001 0.0000 -0.0001 0.0000 -0.0001

18.000 30.000 0.000 -0.012 0.000 -0.012 0.000 -0.008 0.000 -0.006 0.000 -0.006 0.000 -0.006

0.7087 1.1811 0.0000 -0.0005 0.0000 -0.0005 0.0000 -0.0003 0.0000 -0.0002 0.0000 -0.0002 0.0000 -0.0002

30.000 50.000 0.000 -0.012 0.000 -0.012 0.000 -0.010 0.000 -0.008 0.000 -0.008 0.000 -0.008

1.1811 1.9685 0.0000 -0.0005 0.0000 -0.0005 0.0000 -0.0004 0.0000 -0.0003 0.0000 -0.0003 0.0000 -0.0003

50.000 80.000 0.000 -0.015 0.000 -0.015 0.000 -0.012 0.000 -0.009 0.000 -0.008 0.000 -0.008

1.9685 3.1496 0.0000 -0.0006 0.0000 -0.0006 0.0000 -0.0005 0.0000 -0.0004 0.0000 -0.0003 0.0000 -0.0003

80.000 120.000 0.000 -0.020 0.000 -0.020 0.000 -0.015 0.000 -0.010 0.000 -0.008 0.000 -0.008

3.1496 4.7244 0.0000 -0.00079 0.0000 -0.00079 0.0000 -0.0006 0.0000 -0.0004 0.0000 -0.0003 0.0000 -0.0003

120.000 180.000 0.000 -0.025 0.000 -0.025 0.000 -0.018 0.000 -0.013 0.000 -0.008 0.000 -0.008

4.7244 7.0886 0.0000 -0.00098 0.0000 -0.00098 0.0000 -0.0007 0.0000 -0.0005 0.0000 -0.0003 0.0000 -0.0003

180.000 250.000 0.000 -0.030 0.000 -0.030 0.000 -0.022 0.000 -0.015 0.000 -0.008 0.000 -0.008

7.0866 9.8425 0.0000 -0.0012 0.0000 -0.0012 0.0000 -0.0009 0.0000 -0.0006 0.0000 -0.0003 0.0000 -0.0003

250.000 265.000 0.000 -0.035 0.000 -0.035 0.000 -0.022 0.000 -0.015 0.000 -0.008 0.000 -0.008

9.8425 10.4331 0.0000 -0.0014 0.0000 -0.0014 0.0000 -0.0009 0.0000 -0.0006 0.0000 -0.0003 0.0000 -0.0003

265.000 315.000 0.000 -0.035 0.000 -0.035 0.000 -0.022 0.000 -0.015 0.000 -0.008 0.000 -0.008

10.4331 12.4016 0.0000 -0.0014 0.0000 -0.0014 0.0000 -0.0009 0.0000 -0.0006 0.0000 -0.0003 0.0000 -0.0003

315.000 400.000 0.000 -0.040 0.000 -0.040 0.000 -0.025 – – – – – –

12.4016 15.7480 0.0000 -0.0016 0.0000 -0.0016 0.0000 -0.0010 – – – – – –

400.000 500.000 0.000 -0.045 0.000 -0.045 0.000 -0.025 – – – – – –

15.7480 19.6850 0.0000 -0.0018 0.0000 -0.0018 0.0000 -0.0010 – – – – – –

500.000 630.000 0.000 -0.050 0.000 -0.050 0.000 -0.030 – – – – – –

19.6850 24.8031 0.0000 -0.0020 0.0000 -0.0020 0.0000 -0.0012 – – – – – –

630.000 800.000 0.000

24.8031 31.4961 0.0000 -0.0031 – – 0.0000 -0.0014 – – – – – –

800.000 1000.000 0.000 -0.100 – – 0.000 -0.050 – – – – – –

31.4961 39.3701 0.0000 -0.0040 – – 0.0000 -0.0020 – – – – – –

1000.000 1200.000 0.000 -0.130 – – 0.000 -0.060 – – – – – –

39.3701 47.2441 0.0000 -0.0051 – – 0.0000 -0.0024 – – – – – –

1200.000 1600.000 0.000 -0.150 – – 0.000 -0.080 – – – – – –

47.2441 62.9921 0.0000 -0.0065 – – 0.0000 -0.0031 – – – – – –

1600.000 2000.000 0.000 -0.200 – – – – – – – – – –

62.9921 78.7402 0.0000 -0.0079 – – – – – – – – – –

2000.000 – 0.000 -0.250 – – – – – – – – – –

78.7402 – 0.0000 -0.0098 – – – – – – – – – –

in.

Standard Bearing Class Precision Bearing Class

K N C B A AA

in.mmin.mmin.mmin.mmin.mmin.

-0.080 – – 0.000 -0.040 – – – – – –

tolerances lie within those currently speciﬁed in ISO 492 with the exception of a small number of dimensions indicated in the tables. The differences normally have an insigniﬁcant effect on the mounting and performance of tapered roller bearings.

in.mmin.mmin.mmin.mmin.mmin.

60 TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

TABLE 21. TAPERED ROLLER BEARING TOLERANCES – OUTER RING OUTSIDE DIAMETER (Metric)

Bearing

Type

TSF

(1)

SR assemblies are manufactured to tolerance class N only.

O.D.

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

10.000 18.000 0.000 - - - - - - 0.000 -0.008 0.000 -0.008

0.3937 0.7087 0.0000 - - - - - - 0.0000 -0.0003 0.0000 -0.0003

18.000 30.000 0.000 -0.012 0.000 -0.012 0.000 -0.008 0.000 -0.0006 0.000 -0.008 0.000 -0.008

0.7087 1.1811 0.0000 -0.00047 0.0000 -0.00047 0.0000 -0.0003 0.0000 -0.0002 0.0000 -0.0003 0.0000 -0.0003

30.000 50.000 0.000 -0.014 0.000 -0.014 0.000 -0.009 0.000 -0.007 0.000 -0.008 0.000 -0.008

1.1811 1.9685 0.0000 -0.0005 0.0000 -0.0005 0.0000 -0.0004 0.0000 -0.0003 0.0000 -0.0003 0.0000 -0.0003

50.000 80.000 0.000 -0.016 0.000 -0.016 0.000 -0.011 0.000 -0.009 0.000 -0.008 0.000 -0.008

1.9685 3.1496 0.0000 -0.0006 0.0000 -0.0006 0.0000 -0.0004 0.0000 -0.0004 0.0000 -0.0003 0.0000 -0.0003

80.000 120.000 0.000 -0.018 0.000 -0.018 0.000 -0.013 0.000 -0.010 0.000 -0.008 0.000 -0.008

3.1496 4.7244 0.0000 -0.0007 0.0000 -0.0007 0.0000 -0.0005 0.0000 -0.0004 0.0000 -0.0003 0.0000 -0.0003

120.000 150.000 0.000 -0.020 0.000 -0.020 0.000 -0.015 0.000 -0.011 0.000 -0.008 0.000 -0.008

4.7244 5.9055 0.0000 -0.00079 0.0000 -0.00079 0.0000 -0.0006 0.0000 -0.0004 0.0000 -0.0003 0.0000 -0.0003

150.000 180.000 0.000 -0.025 0.000 -0.025 0.000 -0.018 0.000 -0.013 0.000 -0.008 0.000 -0.008

5.9055 7.0866 0.0000 -0.00098 0.0000 -0.00098 0.0000 -0.0007 0.0000 -0.0005 0.0000 -0.0003 0.0000 -0.0003

180.000 250.000 0.000 -0.030 0.000 -0.030 0.000 -0.020 0.000 -0.015 0.000 -0.008 0.000 -0.008

7.0866 9.8425 0.0000 -0.0012 0.0000 -0.0012 0.0000 -0.0008 0.0000 -0.0006 0.0000 -0.0003 0.0000 -0.0003

250.000 265.000 0.000 -0.035 0.000 -0.035 0.000 -0.025 0.000 -0.018 0.000 -0.008 0.000 -0.008

9.8425 10.4331 0.0000 -0.0014 0.0000 -0.0014 0.0000 -0.0010 0.0000 -0.0007 0.0000 -0.0003 0.0000 -0.0003

265.000 315.000 0.000 -0.035 0.000 -0.035 0.000 -0.025 0.000 -0.018 0.000 -0.008 0.000 -0.008

10.4331 12.4016 0.0000 -0.0014 0.0000 -0.0014 0.0000 -0.0010 0.0000 -0.0007 0.0000 -0.0003 0.0000 -0.0003

315.000 400.000 0.000 -0.040 0.000 -0.040 0.000 -0.028 0.000 -0.020 – – – –

12.4016 15.7480 0.0000 -0.0016 0.0000 -0.0016 0.0000 -0.0011 0.0000 -0.0008 – – – –

400.000 500.000 0.000 -0.045 0.000 -0.045 0.000 -0.030 – – – – – –

15.7480 19.6850 0.0000 -0.0018 0.0000 -0.0018 0.0000 -0.0012 – – – – – –

500.000 630.000 0.000 -0.050 0.000

19.6850 24.8031 0.0000 -0.0020 0.0000 -0.0020 0.0000 -0.0014 – – – – – –

630.000 800.000 0.000 -0.075 – – 0.000 -0.040 – – – – – –

24.8031 31.4961 0.0000 -0.0030 – – 0.0000 *0.0016 – – – – – –

800.000 1000.000 0.000 -0.100 – – 0.000 -0.050 – – – – – –

31.4961 39.3701 0.0000 -0.0040 – – 0.0000 -0.0020 – – – – – –

1000.000 1200.000 0.000 -0.130 – – 0.000 -0.060 – – – – – –

39.3701 47.2441 0.0000 -0.0051 – – 0.0000 -0.0024 – – – – – –

1200.000 1600.000 0.000 -0.165 – – 0.000 -0.080 – – – – – –

47.2441 62.9921 0.0000 -0.0065 – – 0.0000 -0.0031 – – – – – –

1600.000 2000.000 0.000 -0.200 – – – – – – – – – –

62.9921 78.7402 0.0000 -0.0079 – – – – – – – – – –

2000.000 – 0.000 -0.250 – – – – – – – – – –

78.7402 – 0.0000 -0.0098 – – – – – – – – – –

in.

Standard Bearing Class Precision Bearing Class

K N C B A AA

in.

in.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.

-0.050 0.000 -0.035 – – – – – –

METRIC SYSTEM

in.mmin.

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

METRIC SYSTEM

TABLE 22. TAPERED ROLLER BEARING TOLERANCES – INNER RING WIDTH (Metric)

Bearing

Types

TSF

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

10.000 50.000 0.000 -0.100 0.000 -0.050 0.000 -0.200 0.000 -0.200 0.000 -0.200 0.000 -0.200

0.3937 1.9685 0.0000 -0.0040 0.0000 -0.0020 0.0000 -0.0079 0.0000 -0.0079 0.0000 -0.0079 0.0000 -0.0079

50.000 120.000 0.000 -0.150 0.000 -0.050 0.000 -0.300 0.000 -0.300 0.000 -0.300 0.000 -0.300

1.9685 4.7244 0.0000 -0.0059 0.0000 -0.0020 0.0000 -0.0118 0.0000 -0.0118 0.0000 -0.0118 0.0000 -0.0118

120.000 180.000 0.000 -0.200 0.000 -0.050 0.000 -0.300 0.000 -0.300 0.000 -0.300 0.000 -0.300

4.7244 7.0866 0.0000 -0.0079 0.0000 -0.0020 0.0000 -0.0118 0.0000 -0.0118 0.0000 -0.0118 0.0000 -0.0118

180.000 250.000 0.000 -0.200 0.000 -0.050 0.000 -0.350 0.000 -0.350 0.000 -0.350 0.000 -0.350

7.0866 9.8425 0.0000 -0.0079 0.0000 -0.0020 0.0000 -0.0138 0.0000 -0.0138 0.0000 -0.0138 0.0000 -0.0138

250.000 265.000 0.000 -0.200 0.000 -0.050 0.000 -0.350 0.000 -0.350 0.000 -0.350 0.000 -0.350

9.8425 10.4331 0.0000 -0.0079 0.0000 -0.0020 0.0000 -0.0138 0.0000 -0.0138 0.0000 -0.0138 0.0000 -0.0138

265.000 315.000 0.000 -0.200 0.000 -0.050 0.000 -0.350 0.000 -0.350 0.000 -0.350 0.000 -0.350

10.4331 12.4016 0.0000 -0.0079 0.0000 -0.0020 0.0000 -0.0138 0.0000 -0.0138 0.0000 -0.0138 0.0000 -0.0138

315.000 500.000 0.000 -0.250 0.000 -0.050 0.000 -0.350 – – – – – –

12.4016 19.6850 0.0000 -0.0098 0.0000 -0.0020 0.0000 -0.0138 – – – – – –

500.000 630.000 0.000 -0.250 0.000 -0.350 0.000 -0.350 – – – – – –

19.6850 24.8031 0.0000 -0.0098 0.0000 -0.0138 0.0000 -0.0138 – – – – – –

630.000 1200.000 0.000 -0.300 – – 0.000 -0.350 – – – – – –

24.8031 47.2441 0.0000 -0.0118 – – 0.0000 -0.0138 – – – – – –

1200.000 1600.000 0.000 -0.350 – – 0.000 -0.350 – – – – – –

47.2441 62.9921 0.0000 -0.0138 – – 0.0000 -0.0138 – – – – – –

1600.000 – 0.000 -0.350 – – – – – – – – – –

62.9921 – 0.0000 -0.0138 – – – – – – – – – –

in.

Standard Bearing Class Precision Bearing Class

K N C B A AA

in.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.

62 TIMKEN ENGINEERING MANUAL

TABLE 23. TAPERED ROLLER BEARING TOLERANCES – INNER RING STAND (Metric)

Bearing

Types

TSF

(1)

These sizes manufactured as matched assemblies only.

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

10.000 80.000 +0.100 0.000 +0.050 0.000 +0.100 -0.100

0.3937 3.1496 +0.0039 0.0000 +0.0020 0.0000 +0.0039 -0.0039

80.000 120.000 +0.100 -0.100 +0.050 0.000 +0.100 -0.100

3.1496 4.7244 +0.0039 -0.0039 +0.0020 0.0000 +0.0039 -0.0039

120.000 180.000 +0.150 -0.150 +0.050 0.000 +0.100 -0.100

4.7244 7.0866 +0.0059 -0.0059 +0.0020 0.0000 +0.0039 -0.0039

180.000 250.000 +0.150 -0.150 +0.050 0.000 +0.100 -0.150

7.0866 9.8425 +0.0059 -0.0059 +0.0020 0.0000 +0.0039 -0.0059

250.000 265.000 +0.150 -0.150 +0.100 0.000 +0.100 -0.150

9.8425 10.4331 +0.0059 -0.0059 +0.0039 0.0000 +0.0039 -0.0059

265.000 315.000 +0.150 -0.150 +0.100 0.000 +0.100 -0.150 – – – –

10.4331 12.4016 +0.0059 -0.0059 +0.0039 0.0000 +0.0039 -0.0059 – – – –

315.000 400.000 +0.200 -0.200 +0.100 0.000 +0.150 -0.150 – – – – – –

12.4016 15.7480 +0.0079 -0.0079 +0.0039 0.0000 +0.0059 -0.0059 – – – – – –

400.000 –

15.7480 – – – – – – –

in.

Standard Bearing Class Precision Bearing Class

K N C B A AA

in.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.

(1) (1) (1) (1) (1) (1)

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

METRIC SYSTEM

Inner Ring Stand. Inner ring stand is a measure of the variation in inner ring raceway

(1) (1) (1) (1)

(1) (1)

– – – – – –

size, taper and roller diameter. This is checked by measuring the axial location of the reference surface of a master outer ring or other type gauge with respect to the reference inner ring face.

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

METRIC SYSTEM

TABLE 24. TAPERED ROLLER BEARING TOLERANCES – OUTER RING WIDTH (Metric)

Bearing

Types

TSF

(1)

These differ slightly from tolerances in ISO 492. These differences normally have an insignificant effect on the mounting and performance

of tapered roller bearings. The 30000 series ISO bearings also are available with the above parameter according to ISO 492.

Bore

Over Incl. Max. Min.

10.000 80.000 0.000 -0.150 0.000 -0.100 0.000 -0.150 0.000 -0.150 0.000 -0.150 0.000 -0.150

0.3937 3.1496 0.0000 -0.0059 0.0000 -0.0040 0.0000 -0.0059 0.0000 -0.0059 0.0000 -0.0059 0.0000 -0.0059

80.000 150.000 0.000 -0.200 0.000 -0.100 0.000 -0.200 0.000 -0.200 0.000 -0.200 0.000 -0.200

3.1496 5.9055 0.0000 -0.0079 0.0000 -0.0040 0.0000 -0.0079 0.0000 -0.0079 0.0000 -0.0079 0.0000 -0.0079

150.000 180.000 0.000 -0.200 0.000 -0.100 0.000 -0.250 0.000 -0.250 0.000 -0.250 0.000 -0.250

5.9055 7.0866 0.0000 -0.0079 0.0000 -0.0040 0.0000 -0.0098 0.0000 -0.0098 0.0000 -0.0098 0.0000 -0.0098

180.000 250.000 0.000 -0.250 0.000 -0.100 0.000 -0.250 0.000 -0.250 0.000 -0.250 0.000 -0.250

7.0866 9.8425 0.0000 -0.0098 0.0000 -0.0040 0.0000 -0.0098 0.0000 -0.0098 0.0000 -0.0098 0.0000 -0.0098

250.000 265.000 0.000 -0.250 0.000 -0.100 0.000 -0.300 0.000 -0.300 0.000 -0.300 0.000 -0.300

9.8425 10.4331 0.0000 -0.0098 0.0000 -0.0040 0.0000 -0.0118 0.0000 -0.0118 0.0000 -0.0118 0.0000 -0.0118

265.000 315.000 0.000 -0.250 0.000 -0.100 0.000 -0.300 0.000 -0.300 0.000 -0.300 0.000 -0.300

10.4331 12.4016 0.0000 -0.0098 0.0000 -0.0040 0.0000 -0.0118 0.0000 -0.0118 0.0000 -0.0118 0.0000 -0.0118

315.000 400.000 0.000 -0.250 0.000 -0.100 0.000 -0.300 0.000 -0.300 – – – –

12.4016 15.7480 0.0000 -0.0098 0.0000 -0.0040 0.0000 -0.0118 0.0000 -0.0118 – – – –

400.000 500.000 0.000 -0.300 0.000 -0.100 0.000 -0.350 – – – – – –

15.7480 19.6850 0.0000 -0.0118 0.0000 -0.0040 0.0000 -0.0138 – – – – – –

500.000 800.000 0.000 -0.300 0.000 -0.100 0.000 -0.350 – – – – – –

19.6850 31.4961 0.0000 -0.0118 0.0000 -0.0040 0.0000 -0.0138 – – – – – –

800.000 1200.000 0.000 -0.350 – – 0.000 -0.400 – – – – – –

31.4961 47.2441 0.0000 -0.0138 – – 0.0000 -0.0157 – – – – – –

1200.000 1600.000 0.000 -0.400 – – 0.000 -0.400 – – – – – –

47.2441 62.9921 0.0000 -0.0157 – – 0.0000 -0.0157 – – – – – –

1600.000 – 0.000 -0.400 – – – – – – – – – –

62.9921 – 0.0000 -0.0157 – – – – – – – – – –

in.

Standard Bearing Class Precision Bearing Class

K N C B A AA

(1)

Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

in.mmin.

in.mmin.mmin.mmin.

in.mmin.

in.mmin.mmin.mmin.

64 TIMKEN ENGINEERING MANUAL

TABLE 25. TAPERED ROLLER BEARING TOLERANCES – OUTER RING STAND (Metric)

Bearing

Types

(1)

TSF

(1)

Stand for flanged outer ring is measured from flange backface (seating face).

(2)

These sizes manufactured as matched assemblies only.

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

10.000 18.000 +0.100 0.000 +0.050 0.000 +0.100 -0.100

0.3937 0.7087 +0.0039 0.0000 +0.0020 0.0000 +0.0039 -0.0039

18.000 80.000 +0.100 0.000 +0.050 0.000 +0.100 -0.100

0.7087 3.1496 +0.0039 0.0000 +0.0020 0.0000 +0.0039 -0.0039

80.000 120.000 +0.100 -0.100 +0.050 0.000 +0.100 -0.100

3.1496 4.7244 +0.0039 -0.0039 +0.0020 0.0000 +0.0039 -0.0039

120.000 265.000 +0.200 -0.100 +0.100 0.000 +0.100 -0.150

4.7244 10.4331 +0.0079 -0.0039 +0.0039 0.0000 +0.0039 -0.0059

265.000 315.000 +0.200 -0.100 +0.100 0.000 +0.100 -0.150

10.4331 12.4016 +0.0079 -0.0039 +0.0039 0.0000 +0.0039 -0.0059

315.000 400.000 +0.200 -0.200 +0.100 0.000 +0.100 -0.150 – – – –

12.4016 15.7480 +0.0079 -0.0079 +0.0039 0.0000 +0.0039 -0.0059 – – – –

315.000 400.000 +0.200 -0.200 +0.100 0.000 +0.150 -0.150 – – – – – –

12.4016 15.7480 +0.0079 -0.0079 +0.0040 0.0000 +0.0059 -0.0059 – – – – – –

400.000 –

15.7480 – – – – – – –

in.

Standard Bearing Class Precision Bearing Class

K N C B A AA

in.mmin.mmin.mmin.

(2) (2) (2) (2) (2) (2)

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

in.mmin.mmin.mmin.mmin.mmin.

(2) (2) (2) (2)

(2) (2)

– – – – – –

in.mmin.

Outer Ring Stand. Outer ring stand is a measure of the variation in outer ring I.D. size and taper. This is checked by measuring the axial location of the reference surface of a master plug or other type gauge with respect to the reference face of the outer ring.

METRIC SYSTEM

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

METRIC SYSTEM

TABLE 26. TAPERED ROLLER BEARING TOLERANCES – OVERALL BEARING WIDTH (Metric)

Bearing

Types

(1)

TSF

(2)

(1)

For bearing type TSF, the tolerance applies to the dimension T1. Refer to the Tapered Roller Bearing Catalog available on www.timken.com.

(2)

SR assemblies are manufactured to tolerance class N only.

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

10.000 80.000 +0.200 0.000 +0.100 0.000 +0.200 -0.200 +0.200 -0.200 +0.200 -0.200 +0.200 -0.200

0.3937 3.1496 +0.0078 0.0000 +0.0039 0.0000 +0.0078 -0.0078 +0.0078 -0.0078 +0.0078 -0.0078 +0.0078 -0.0078

80.000 120.000 +0.200 -0.200 +0.100 0.000 +0.200 -0.200 +0.200 -0.200 +0.200 -0.200 +0.200 -0.200

3.1496 4.7244 +0.0078 -0.0078 +0.0039 0.0000 +0.0078 -0.0078 +0.0078 -0.0078 +0.0078 -0.0078 +0.0078 -0.0078

120.000 180.000 +0.350 -0.250 +0.150 0.000 +0.350 -0.250 +0.200 -0.250 +0.200 -0.250 +0.200 -0.250

4.7244 7.0866 +0.0137 -0.0098 +0.0059 0.0000 +0.0137 -0.0098 +0.0078 -0.0098 +0.0078 -0.0098 +0.0078 -0.0098

180.000 250.000 +0.350 -0.250 +0.150 0.000 +0.350 -0.250 +0.200 -0.300 +0.200 -0.300 +0.200 -0.300

7.0866 9.8425 +0.0137 -0.0098 +0.0059 0.0000 +0.0137 -0.0098 +0.0078 -0.0118 +0.0078 -0.0118 +0.0078 -0.0118

250.000 265.000 +0.350 -0.250 +0.200 0.000 +0.350 -0.300 +0.200 -0.300 +0.200 -0.300 +0.200 -0.300

9.8425 10.4331 +0.0137 -0.0098 +0.0078 0.0000 +0.0137 -0.0118 +0.0078 -0.0118 +0.0078 -0.0118 +0.0078 -0.0118

265.000 315.000 +0.350 -0.250 +0.200 0.000 +0.350 -0.300 +0.200 -0.300 +0.200 -0.300 +0.200 -0.300

10.4331 12.4016 +0.0137 -0.0098 +0.0078 0.0000 +0.0137 -0.0118 +0.0078 -0.0118 +0.0078 -0.0118 +0.0078 -0.0118

315.000 500.000 +0.400 -0.400 +0.200 0.000 +0.350 -0.300 – – – – – –

12.4016 19.6850 +0.0157 -0.0157 +0.0078 0.0000 +0.0137 -0.0118 – – – – – –

500.000 800.000 +0.400 -0.400 – – +0.350 -0.400 – – – – – –

19.6850 31.4961 +0.0157 -0.0157 – – +0.0137 -0.0157 – – – – – –

800.000 1000.000 +0.450 -0.450 – – +0.350 -0.400 – – – – – –

31.4961 39.3701 +0.0177 -0.0177 – – +0.0137 -0.0157 – – – – – –

1000.000 1200.000 +0.450 -0.450 – – +0.350 -0.450 – – – – – –

39.3701 47.2441 +0.0177 -0.0177 – – +0.0137 -0.0177 – – – – – –

1200.000 1600.000 +0.450 -0.450 – – +0.350 -0.500 – – – – – –

47.2441 62.9921 +0.0177 -0.0177 – – +0.0137 -0.0196 – – – – – –

1600.000 +0.450 -0.450 – – – – – – – – – –

62.9921 +0.0177 -0.0177 – – – – – – – – – –

180.000 250.000 0.000 -0.200 0.000 -0.050 0.000 -0.350 0.000 -0.350 0.000 -0.350 0.000 -0.350

7.0866 9.8425 0.0000 -0.0079 0.0000 -0.0020 0.0000 -0.0138 0.0000 -0.0138 0.0000 -0.0138 0.0000 -0.0138

in.

Standard Bearing Class Precision Bearing Class

K N C B A AA

in.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.

66 TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

TABLE 27. TAPERED ROLLER BEARING TOLERANCES – RADIAL RUNOUT (Metric)

Bearing

Types

TSF

(1)

SR assemblies are manufactured to tolerance class N only.

Bore

Over Incl.

10.000 18.000 – – – – 0.002 0.001

0.3937 0.7087 – – – – 0.00008 0.00004

18.000 30.000 0.018 0.018 0.005 0.003 0.002 0.001

0.7087 1.1811 0.0007 0.0007 0.0002 0.0001 0.00008 0.00004

30.000 50.000 0.020 0.020 0.006 0.003 0.002 0.001

1.1811 1.9685 0.0008 0.0008 0.0002 0.0001 0.00008 0.00004

50.000 80.000 0.025 0.025 0.006 0.004 0.002 0.001

1.9685 3.1496 0.0010 0.0010 0.0002 0.0002 0.00008 0.00004

80.000 120.000 0.035 0.035 0.006 0.004 0.002 0.001

3.1496 4.7244 0.0014 0.0014 0.0002 0.0002 0.00008 0.00004

120.000 150.000 0.040 0.040 0.007 0.004 0.002 0.001

4.7244 5.9055 0.0016 0.0016 0.0003 0.0002 0.00008 0.00004

150.000 180.000 0.045 0.045 0.008 0.004 0.002 0.001

5.9055 7.0866 0.0018 0.0018 0.0003 0.0002 0.00008 0.00004

180.000 250.000 0.050 0.050 0.010 0.005 0.002 0.001

7.0866 9.8425 0.0020 0.0020 0.0004 0.0002 0.00008 0.00004

250.000 265.000 0.060 0.060 0.011 0.005 0.002 0.001

9.8425 10.4331 0.0024 0.0024 0.0004 0.0002 0.00008 0.00004

265.000 315.000 0.060 0.060 0.011 0.005 0.002 0.001

10.4331 12.4016 0.0024 0.0024 0.0004 0.0002 0.00008 0.00004

315.000 400.000 0.070 0.070 0.013 0.005 – –

12.4016 15.7480 0.0028 0.0028 0.0005 0.0002 – –

400.000 500.000 0.080 0.080 – – – –

15.7480 19.6850 0.0031 0.0031 – – – –

500.000 630.000 0.100 – – – – –

19.6850 24.8031 0.0039 – – – – –

630.000 800.000 0.120 – – – – –

24.8031 31.4961 0.0047 – – – – –

800.000 1000.000 0.140 – – – – –

31.4961 39.3701 0.0055 – – – – –

1000.000 1200.000 0.160 – – – – –

39.3701 47.2441 0.0063 – – – – –

1200.000 1600.000 0.180 – – – – –

47.2441 62.9921 0.0071 – – – – –

1600.000 2000.000 0.200 – – – – –

62.9921 78.7402 0.0079 – – – – –

2000.000 – 0.200 – – – – –

78.7402 – 0.0079 – – – – –

in.

Standard Bearing Class Precision Bearing Class

K N C B A AA

in.

METRIC SYSTEM

in.

Runout. Runout is a measure of rotational accuracy expressed by Total Indicator Reading (T.I.R.). Total displacement is measured by an instrument sensing against a moving surface, or moved with respect to a ﬁxed surface. A radial runout measurement includes both roundness errors and the centering error of the surface that the instrument head senses against.

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

INCH SYSTEM

TAPERED ROLLER BEARINGS

Inch system bearings are manufactured to a number of tolerance classes. Classes 4 and 2 are often referred to as standard classes. Classes 3, 0, 00 and 000 are precision classes. Inch system bearings conform to ABMA standard 19.2.

TABLE 28. TAPERED ROLLER BEARING TOLERANCES – INNER RING BORE (Inch)

Bearing

Types

TSF

(1)

TSL

TDI

TDIT

TDO

TNA

(1)

For TSL bearings these are the normal tolerances of the inner ring bore. However, bore size can be slightly reduced at large end due to tight ﬁt

assembly of the seal on the rib. This should not have any effect on the performance of the bearing.

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

0.000 76.200 +0.013 0.000 +0.013 0.000 +0.013 0.000 +0.013 0.000 +0.008 0.000 +0.008 0.000

0.0000 3.0000 +0.0005 0.0000 +0.0005 0.0000 +0.0005 0.0000 +0.0005 0.0000 +0.0003 0.0000 +0.0003 0.0000

76.200 304.800 +0.025 0.000 +0.025 0.000 +0.013 0.000 +0.013 0.000 +0.008 0.000 +0.008 0.000

3.0000 12.0000 +0.0010 0.0000 +0.0010 0.0000 +0.0005 0.0000 +0.0005 0.0000 +0.0003 0.0000 +0.0003 0.0000

304.800 609.600 – – +0.051 0.000 +0.025 0.000 – – – – – –

12.0000 24.0000 – – +0.0020 0.0000 +0.0010 0.0000 – – – – – –

609.600 914.400 +0.076 0.000 – – +0.038 0.000 – – – – – –

24.0000 36.0000 +0.0030 0.0000 – – +0.0015 0.0000 – – – – – –

914.400 1219.200 +0.102 0.000 – – +0.051 0.000 – – – – – –

36.0000 48.0000 +0.0040 0.0000 – – +0.0020 0.0000 – – – – – –

1219.200 – +0.127 0.000 – – +0.076 0.000 – – – – – –

48.0000 – +0.0050 0.0000 – – +0.0030 0.0000 – – – – – –

in.

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

in.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.

TABLE 29. TAPERED ROLLER BEARING TOLERANCES – OUTER RING OUTSIDE DIAMETER (Inch)

Bearing

Types

TS TSF TSL

TDI TDIT TDO TNA

TNASW

TNASWE

O.D.

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

0.000 304.800 +0.025 0.000 +0.025 0.000 +0.013 0.000 +0.013 0.000 +0.008 0.000 +0.008 0.000

0.0000 12.0000 +0.0010 0.0000 +0.0010 0.0000 +0.0005 0.0000 +0.0005 0.0000 +0.0003 0.0000 +0.0003 0.0000

304.800 609.600 +0.051 0.000 +0.051 0.000 +0.025 0.000 – – – – – –

12.0000 24.0000 +0.0020 0.0000 +0.0020 0.0000 +0.0010 0.0000 – – – – – –

609.600 914.400 +0.076 0.000 +0.076 0.000 +0.038 0.000 – – – – – –

24.0000 36.0000 +0.0030 0.0000 +0.0030 0.0000 +0.0015 0.0000 – – – – – –

914.400 1219.200 +0.102 0.000 – – +0.051 0.000 – – – – – –

36.0000 48.0000 +0.0040 0.0000 – – +0.0020 0.0000 – – – – – –

1219.200 – +0.127 0.000 – – +0.076 0.000 – – – – – –

48.0000 – +0.0050 0.0000 – – +0.0030 0.0000 – – – – – –

in.

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

in.mmin.mmin.mmin.mmin.mmin.

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

TABLE 30. TAPERED ROLLER BEARING TOLERANCES – OUTER RING FLANGE (Inch)

Bearing

Types

TSF

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

0.000 304.800 +0.051 0.000 +0.052 0.000 +0.051 0.000 +0.051 0.000 +0.051 0.000 +0.051 0.000

0.0000 12.0000 +0.0020 0.0000 +0.0020 0.0000 +0.0020 0.0000 +0.0020 0.0000 +0.0020 0.0000 +0.0020 0.0000

304.800 609.600 +0.076 0.000 +0.076 0.000 +0.076 0.000 +0.051 0.000 +0.051 0.000 +0.051 0.000

12.0000 24.0000 +0.0030 0.0000 +0.0030 0.0000 +0.0030 0.0000 +0.0020 0.0000 +0.0020 0.0000 +0.0020 0.0000

609.600 914.400 +0.102 0.000 +0.102 0.000 +0.102 0.000 – – – – – –

24.0000 36.0000 +0.0040 0.0000 +0.0040 0.0000 +0.0040 0.0000 – – – – – –

914.400 – +0.127 0.000 – – +0.127 0.000 – – – – – –

36.0000 – +0.0050 0.0000 – – +0.0050 0.0000 – – – – – –

in.

TABLE 31. TAPERED ROLLER BEARING TOLERANCES – INNER RING WIDTH (Inch)

Bearing

Types

TS TSF TSL

TDI TDIT TDO

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

in.

All Sizes

in.

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

in.mmin.mmin.mmin.

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

in.mmin.mmin.mmin.

+0.076 -0.254 +0.076 -0.254 +0.076 -0.254 +0.076 -0.254 +0.076 -0.254 +0.076 -0.254

+0.0030 -0.0100 +0.0030 -0.0100 +0.0030 -0.0100 +0.0030 -0.0100 +0.0030 -0.0100 +0.0030 -0.0100

in.mmin.mmin.mmin.mmin.mmin.mmin.mmin.

INCH SYSTEM

Bearing

Types

All

Types

TABLE 32. TAPERED ROLLER BEARING TOLERANCES – OUTER RING WIDTH (Inch)

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

in.

All Sizes

in.

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

in.mmin.mmin.mmin.

+0.051 -0.254 +0.051 -0.254 +0.051 -0.254 +0.051 -0.254 +0.051 -0.254 +0.051 -0.254

+0.0020 -0.0100 +0.0020 -0.0100 +0.0020 -0.0100 +0.0020 -0.0100 +0.0020 -0.0100 +0.0020 -0.0100

in.mmin.mmin.mmin.mmin.mmin.mmin.mmin.

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

INCH SYSTEM

TABLE 33. TAPERED ROLLER BEARING TOLERANCES – INNER RING STAND (Inch)

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

(2) (2) (2) (2) (2) (2)

Inner Ring Stand. Inner ring stand is a measure of the variation in inner ring raceway size, taper and roller diameter. This is checked by measuring the axial location of the reference surface of a master outer ring or other type gauge with respect to the reference inner ring face.

Bearing

Types

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

in.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.mmin.

0.000 101.600 +0.102 0.000 +0.102 0.000 +0.102 -0.102

0.0000 4.0000 +0.0040 0.0000 +0.0040 0.0000 +0.0040 -0.0040

101.600 266.700 +0.152 -0.152 +0.102 0.000 +0.102 +0.102

4.0000 10.5000 +0.0060 -0.0060 +0.0040 0.0000 +0.0040 -0.0040

TSF TSL

266.700 304.800 +0.152 -0.152 +0.102 0.000 +0.102 -0.102 – – – –

10.5000 12.0000 +0.0060 -0.0060 +0.0040 0.0000 +0.0040 -0.0040 – – – –

(1)

TDI

(1)

304.800 406.400 – – +0.178 -0.178 +0.178 -0.178 – – – – – –

TDIT

12.0000 16.0000 – – +0.0070 -0.0070 +0.0070 -0.0070 – – – – – –

TDO

406.400 –

16.0000 – – – – – – –

(1)

For class 2, TDI and TDIT bearings with an inner ring bore of 101.600 to 304.800 mm (4.0000 to 12.0000 in.), the inner ring stand is ±0.102 mm

(±0.0040 in.).

(2)

These sizes manufactured as matched assemblies only.

(2) (2) (2) (2)

(2) (2)

– – – – – –

TABLE 34. TAPERED ROLLER BEARING TOLERANCES – OUTER RING STAND (Inch)

Bearing

Types

Bore

Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

in.mmin.mmin.mmin.

0.000 101.600 +0.102 0.000 +0.102 0.000 +0.102 -0.102

0.0000 4.0000 +0.0040 0.0000 +0.0040 0.0000 +0.0040 -0.0040

101.600 266.700 +0.203 -0.102 +0.102 0.000 +0.102 -0.102

4.0000 10.5000 +0.0080 -0.0040 +0.0040 0.0000 +0.0040 -0.0040

(1)

TSF

266.700 304.800 +0.203 -0.102 +0.102 0.000 +0.102 -0.102 – – – –

TSL

10.5000 12.0000 +0.0080 -0.0040 +0.0040 0.0000 +0.0040 -0.0040 – – – –

TDI

304.800 406.400 +0.203 -0.203 +0.203 -0.203 +0.203 -0.203 – – – – – –

TDIT

12.0000 16.0000 +0.0080 -0.0080 +0.0080 -0.0080 +0.0080 -0.0080 – – – – – –

406.400 –

16.0000 – – – – – – –

(1)

Stand for ﬂanged outer ring is measured from ﬂange backface (seating face).

(2)

These sizes manufactured as matched assemblies only.

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

in.mmin.mmin.mmin.

in.mmin.mmin.mmin.mmin.mmin.

(2) (2) (2) (2)

(2) (2)

(2) (2) (2) (2) (2) (2)

– – – – – –

TIMKEN ENGINEERING MANUAL

Bearing

Types

TS TSF TSL

TDI TDIT TDO TNA

TNASW

TNASWE

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

TABLE 35. TAPERED ROLLER BEARING TOLERANCES – RADIAL RUNOUT (Inch)

Bore

Over Incl.

in.

0.000 266.700 0.051 0.038 0.008 0.004 0.002 0.001

0.0000 10.5000 0.0020 0.0015 0.0003 0.00015 0.000075 0.000040

266.700 304.800 0.051 0.038 0.008 0.004 0.002 0.001

10.5000 12.0000 0.0020 0.0015 0.0003 0.00015 0.000075 0.000040

304.800 609.600 0.051 0.038 0.018 – – –

12.0000 24.0000 0.0020 0.0015 0.0007 – – –

609.600 914.400 0.076 0.051 0.051 – – –

24.0000 36.0000 0.0030 0.0020 0.0020 – – –

914.400 – 0.076 – 0.076 – – –

36.0000 – 0.0030 – 0.0030 – – –

in.

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

in.

METRIC SYSTEM

INCH SYSTEM

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

INCH SYSTEM

TABLE 36. TAPERED ROLLER BEARING TOLERANCES – OVERALL BEARING WIDTH (Inch)

Bearing

Types

(1)

TSF

TSL

TNA

TNASW

TNASWE

TDI TDIT TDO

(1)

For bearing type TSF, the tolerance applies to the dimension T1. Refer to the Tapered Roller Bearing Catalog available on www.timken.com.

Bore O.D.

Over Incl. Over Incl. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min.

in.

0.000 101.600 – – +0.203 0.000 +0.203 0.000 +0.203 -0.203 +0.203 -0.203 +0.203 -0.203 +0.203 -0.203

0.0000 4.0000 – – +0.0080 0.0000 +0.0080 0.0000 +0.0080 -0.0080 +0.0080 -0.0080 +0.0080 -0.0080 +0.0080 -0.0080

101.600 304.800 – – +0.356 -0.254 +0.203 0.000 +0.203 -0.203 +0.203 -0.203 +0.203 -0.203 +0.203 -0.203

4.0000 12.0000 – – +0.0140 -0.0100 +0.0080 0.0000 +0.0080 -0.0080 +0.0080 -0.0080 +0.0080 -0.0080 +0.0080 -0.0080

304.800 609.600 0.000 508.000 – – +0.381 -0.381 +0.203 -0.203 – – – – – –

12.0000 24.0000 0.0000 20.0000 – – +0.0150 -0.0150 +0.0080 -0.0080 – – – – – –

304.800 609.600 508.000 – – – +0.381 -0.381 +0.381 -0.381 – – – – – –

12.0000 24.0000 20.0000 – – – +0.0150 -0.0150 +0.0150 -0.0150 – – – – – –

609.600 – – – +0.381 -0.381 – – +0.381 -0.381 – – – – – –

24.0000 – – – +0.0150 -0.0150 – – +0.0150 -0.0150 – – – – – –

0.000 127.000 – – – – +0.254 0.000 +0.254 0.000 – – – – – –

0.0000 5.0000 – – – – +0.0100 0.0000 +0.0100 0.0000 – – – – – –

127.000 – – – – – +0.762 0.000 +0.762 0.000 – – – – – –

5.0000 – – – – – +0.0300 0.0000 +0.0300 0.0000 – – – – – –

0.000 101.600 – – +0.406 0.000 +0.406 0.000 +0.406 -0.406 +0.406 -0.406 +0.406 -0.406 +0.406 -0.406

0.0000 4.0000 – – +0.0160 0.0000 +0.0160 0.0000 +0.0160 -0.0160 +0.0160 -0.0160 +0.0160 -0.0160 +0.0160 -0.0160

101.600 304.800 – – +0.711 -0.508 +0.406 -0.203 +0.406 -0.406 +0.406 -0.406 +0.406 -0.406 +0.406 -0.406

4.0000 12.0000 – – +0.0280 -0.0200 +0.0160 -0.0080 +0.0160 -0.0160 +0.0160 -0.0160 +0.0160 -0.0160 +0.0160 -0.0160

304.800 609.600 0.000 508.000 – – +0.762 -0.762 +0.406 -0.406 – – – – – –

12.0000 24.0000 0.0000 20.0000 – – +0.0300 -0.0300 +0.0160 -0.0160 – – – – – –

304.800 609.600 508.000

12.0000 24.0000 20.0000 – – – +0.0300 -0.0300 +0.0300 -0.0300 – – – – – –

609.600 – – – +0.762 -0.762 – – +0.762 -0.762 – – – – – –

24.0000 – – – +0.0300 -0.0300 – – +0.0300 -0.0300 – – – – – –

0.000 101.600

0.0000 4.0000

in.

– – – –

in.

– – – +0.762 -0.762 +0.762 -0.762 – – – – – –

in.

Standard Bearing Class Precision Bearing Class

4 2 3 0 00 000

in.

+0.457 -0.051 +0.457 -0.051

+0.0180 -0.0020 +0.0180 -0.0020

in.

– – – – – – – – – – – – – – – –

in.

TIMKEN ENGINEERING MANUAL

BEARING TOLERANCES, METRIC AND INCH SYSTEMS

INCH SYSTEM

TABLE 37. THRUST TAPERED ROLLER BEARING TOLERANCES – BORE (Inch)

TTHD, TTHDFL, TTVS

Bore Bearing Class Bore Deviation

Range

Over Incl. Over Incl. Max. Min. Over Incl. Over Incl.

TTHD, TTHDFL, TTVS TTC, TTSP

in.

0.000 304.800 +0.025 0.000 +0.013 0.000 0.000 25.400 +0.076 -0.076

0.0000 12.0000 +0.0010 0.0000 +0.0005 0.0000 0.0000 1.0000 +0.0030 -0.0030

304.800 609.600 +0.051 0.000 +0.025 0.000 25.400 76.200 +0.102 -0.102

12.0000 24.0000 0.0020 0.0000 +0.0010 0.0000 1.0000 3.0000 +0.0040 -0.0040

609.600 914.400 +0.076 0.000 +0.038 0.000 76.200 – +0.127 -0.127

24.0000 36.0000 +0.0030 0.0000 +0.0015 0.0000 3.0000 – +0.0050 -0.0050

914.400 1219.200 +0.102 0.000 +0.051 0.000

36.0000 48.0000 +0.0040 0.0000 0.0020 0.0000

1219.200 – +0.127 0.000 +0.076 0.000

48.0000 – +0.0050 0.0000 +0.030 0.0000

in.

Precision

in.

Precision

in.

TTC, TTSP – CLASS 4

Range

in.

Precision

in.

TABLE 38. THRUST TAPERED ROLLER BEARING TOLERANCES – OUTSIDE DIAMETER (Inch)

TTHD, TTHDFL, TTVS TTC, TTSP – CLASS 4

Outside Diameter Bearing Class Outside Diameter Deviation

Range

Over Incl. Over Incl. Max. Min. Over Incl. Over Incl.

TTHD, TTHDFL, TTVS TTC, TTSP

in.

0.000 304.800 +0.025 0.000 +0.013 0.000 0.000 127.000 +0.254 0.000

0.0000 12.0000 +0.0010 0.0000 +0.0005 0.0000 0.0000 5.0000 +0.0100 0.0000

304.800 609.600 +0.051 0.000 +0.025 0.000 127.000 203.200 +0.381 0.000

12.0000 24.0000 0.0020 0.0000 +0.0010 0.0000 5.0000 8.0000 +0.0150 0.0000

609.600 914.400 +0.076 0.000 +0.038 0.000 203.200 – +0508 0.000

24.0000 36.0000 +0.0030 0.0000 +0.0015 0.0000 8.0000 – +0.200 0.0000

in.

Precision

in.

Precision

in.

Precision

in.

Range

in.

TABLE 39. THRUST TAPERED ROLLER BEARING TOLERANCES – WIDTH (Inch)

TTHD, TTHDFL, TTVS TTC, TTSP – CLASS 4

Width Bearing Class Width Deviation

Range

Over Incl. Over Incl. Max. Min. Over Incl. Over Incl.

TTHD, TTHDFL, TTVS TTC, TTSP

in.

All Sizes

Precision

in.

+0.381 -0.381 +0.203 -0.203 0.000 76.200 +0.254 -0.254

+0.0150 -0.0150 +0.0080 -0.0080 0.0000 3.0000 +0.0100 -0.0100

in.

Precision

in.

Range

in.

76.200 127.000 +0.381 -0.381

3.0000 5.0000 +0.0150 -0.0150

127.000 – +0508 -0.508

5.0000 – +0.200 -0.0200

in.

Precision

in.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

MOUNTING

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

To achieve expected bearing performance, it is critical that proper mounting design, ﬁtting practices, settings and installation procedures are followed. While there are differences between tapered roller, cylindrical roller, spherical roller, radial ball and angular contact ball bearings relative to these practices, there are many similarities that apply to all. These similarities are summarized in the sections below, followed by a summary of practices speciﬁc to each bearing type.

MOUNTING

All bearing types are typically mounted onto a shaft and into a housing wherein the shaft and housing have shoulders to back the rings. The purpose of the shoulder is to positively establish the axial location and alignment of the bearing under all operating conditions. Various types of backing shoulder designs can be used as shown in ﬁg. 77. The conventional method uses a shoulder machined on a shaft or in the housing. In some applications, snap rings are used as the shoulder. For either solid shoulder or snap ring designs, spacers can be used between the bearing raceway and shoulder if necessary. It is essential that a shoulder be square with the bearing ring and of sufﬁcient diameter to provide adequate backing of the bearing raceway. It also must

be of sufﬁcient section to resist axial movement under loading, and must be wear resistant at the interface with the bearing.

It is highly recommended that roller bearing shaft seats be ground to a surface ﬁnish of 1.6 μm (65 μin) Ra maximum. Ball bearing seats should be 0.8 μm (32 μin) for shafts under 2 inches and 1.6 μm (65 μin) for all other sizes.

When shaft seats are turned, a tighter heavy-duty ﬁt should be used. The shaft diameter should be turned to a ﬁnish of 3.2 μm (125 μin) Ra maximum.

Housing bores should be ﬁnished to 3.2 μm (125 μin) Ra maximum.

Spacer Snap ring

TIMKEN ENGINEERING MANUAL

Conventional

Fig. 77. Backing designs.

WARNING

Failure to observe the following warnings could

create a risk of death or serious injury.

Proper maintenance and handling practices are critical.

Always follow installation instructions and

maintain proper lubrication.

Never spin a bearing with compressed air.

The rollers may be forcefully expelled.

Split spacerSpacer Snap ring

FITTING PRACTICE

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

FITTING PRACTICE

As a general guideline, bearing rings mounted on a rotating member should have an interference ﬁt. Loose ﬁts may permit the ring to creep or turn and wear the mating surface and backing shoulder. This wear can result in excessive bearing looseness and damage to the bearing, shaft or housing.

The choice of ﬁtting practices will mainly depend upon the following parameters:

Precision class of the bearing.

•

Rotating or stationary ring.

•

Type of layout (single- or double-row bearings).

•

Type and direction of load (continuous/alternate rotating).

•

Particular running conditions like shocks, vibrations, over-

•

loading or high speed.

Capability for machining the seats (grinding, turning or

•

boring).

Shaft and housing section and material.

•

Mounting and setting conditions.

•

Fig. 78 is a graphical representation of roller bearing shaft and housing ﬁt selection that conforms to accepted industry standards and practices. The bars designated g6, h6, etc., represent shaft/ housing diameter and tolerance ranges to achieve various loose and interference ﬁts required for various load and ring rotation conditions.

Tight Fit Range

Shaft

O.D.

Tolerance

Range

Housing

Bore

Tolerance

Range

Fig. 78. Shaft and housing ﬁt selection.

Tight Fit Range

Loose Fit Range

Nominal Bearing Bore

Bore Tolerance

Loose Fit Range

Nominal Bearing O.D.

O.D. Tolerance

P6 P7

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SETTING • INSTALLATION

SETTING

In the manufacture of rolling element bearings, it is standard practice to assemble rings and rolling elements with a speciﬁed internal clearance.

Internal clearance is often utilized to compensate for the effects of interference ﬁts and thermal expansion of bearings, shafts and housings. For some bearing types, it also can provide a desired contact angle in the bearing after mounting.

Internal clearance can be measured by either gauging radially or axially. Radial clearance is accepted as the typical setting characteristic to measure for most bearing types because it is more directly related to bearing ﬁts. This is commonly referred to as radial internal clearance (RIC). Tapered roller bearings and angular contact bearings are the exception as setting in these bearings is usually measured in the axial direction.

Correct bearing mounting and ﬁtting practices are key components of proper bearing setting.

INSTALLATION

Proper bearing installation, including cleanliness of the components, as well as use of proper tools, is critical to bearing performance.

Cleanliness of the bearing and mating components is essential for a bearing to achieve maximum service life. Burrs, foreign material and any raised portions of the components mating with the bearing can cause misalignment. Care should be taken to avoid these conditions. Shafts and housings, including lubrication holes, should be thoroughly cleaned before bearing installation. If blind holes are present, insert a magnetic rod to remove metal chips that might have accumulated during manufacture. An air hose may be used on shafts and housings, but should not be used on bearings. Bearings in their shipping containers are typically coated with a rust-inhibitive oil. This oil is compatible with most lubricants and does not need to be removed prior to installation.

Adequate tools must be used to properly ﬁt the inner rings onto the shaft and outer rings into the housing to avoid damage. Direct shock on the rings must be avoided.

Most applications require a tight interference ﬁt of one or both rings. It is acceptable to heat or cool rings to ease assembly. Standard bearings should not be heated above 120° C (250° F) or cooled below -55° C (-65° F). Precision bearings should not be heated above 65° C (150° F) or cooled below

-30° C (-20° F).

An alternate method of mounting, generally used on smaller sizes, is to press the bearing onto the shaft or into the housing using an arbor press.

For more information on these installation procedures, please contact your Timken engineer.

Speciﬁc mounting design, ﬁtting practice, setting and installation recommendations are summarized in the following pages for tapered roller, cylindrical roller, spherical roller, radial ball and angular contact ball bearings.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

TAPERED ROLLER BEARINGS

MOUNTING

Tapered roller bearings are designed to take both radial and thrust loading. Under radial loads, a force is generated in the axial direction that must be counteracted. As a result, tapered roller bearings are normally adjusted against a second bearing. They can be mounted in either a direct or indirect mounting arrangement shown in ﬁg. 79. For applications where a direct mounting arrangement is used and the outer ring is used to adjust the bearing setting, the outer ring is usually set in position by an outer-ring follower or mounted in an outer-ring carrier. See ﬁg. 80.

Effective bearing

spread

Indirect mounting

FITTING PRACTICE

General industrial application fitting practice standards for inner rings and outer rings are shown in the tables starting on page 154. These tables apply to solid or heavy-sectioned steel shafts, heavy-sectioned ferrous housings and normal operating conditions. To use the tables, it is necessary to determine if the member is rotating or stationary, the magnitude, direction and type of loading, and the shaft ﬁnish.

Outer-ring

follower

Fig. 80. Bearing setting devices - direct mounting.

Outer-ring

carrier

Effective bearing

spread

Direct mounting

Fig. 79. Comparison of mounting stability between indirect and direct mountings.

For indirect mountings, bearing setting is typically achieved by clamping against one of the inner rings. Various designs, including locknuts, stakenuts and end plates as shown in ﬁg. 81 can be used. For applications requiring precision-class bearings, a special precision nut can be used.

Backing shoulder diameters are listed for tapered roller bearings in the Tapered Roller Bearing Catalog on www.timken.com.

Locknuts Locknut with

tongued washer

End plateStakenut

Fig. 81. Bearing setting devices – indirect mounting.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

TAPERED ROLLER BEARINGS

Certain table ﬁts may not be adequate for light shaft and housing sections, shafts other than steel, nonferrous housings, critical operation conditions such as high speed, unusual thermal or loading conditions or a combination thereof. Also, assembly procedures and the means and ease of obtaining the bearing setting may require special ﬁts. In these cases, experience should be used as a guideline or your Timken engineer should be consulted for review and suggestions.

Rotating inner rings generally should be applied with an interference ﬁt. In special cases, loose ﬁts may be considered if it has been determined by test or experience they will perform satisfactorily. The term “rotating inner ring” describes a condition in which the inner ring rotates relative to the load. This may occur with a rotating inner ring under a stationary load or a stationary inner ring with a rotating load. Loose ﬁts will permit the inner rings to creep and wear the shaft and the backing shoulder. This may result in excessive bearing looseness and possible bearing and shaft damage.

Stationary inner ring ﬁtting practice depends on the application. Under conditions of high speed, heavy loads or shock, interference ﬁts using heavy-duty ﬁtting practices should be used. With inner rings mounted on unground shafts subjected to moderate loads (no shock) and moderate speeds, a metal-to-metal or near zero average ﬁt is used. In sheave and wheel applications using unground shafts, or in cases using ground shafts with moderate loads (no shock), a minimum ﬁt near zero to a maximum looseness that varies with the inner ring bore size is suggested. In stationary inner ring applications requiring hardened and ground spindles, a slightly looser ﬁt may be satisfactory. Special ﬁts also may be necessary on installations such as multiple sheave crane blocks.

Rotating outer ring applications where the outer ring rotates relative to the load should always use an interference ﬁt.

Stationary, non-adjustable and fixed single-row outer ring applications should be applied with a tight ﬁt wherever practical. Generally, adjustable ﬁts may be used where the bearing setup is obtained by sliding the outer ring axially in the housing bore. However, in certain heavy-duty, high-load applications, tight ﬁts are necessary to prevent pounding and plastic deformation of the housing. Tightly ﬁtted outer rings mounted in carriers can be used. Tight ﬁts should always be used when the load rotates relative to the outer ring.

To permit through-boring when the outside diameters of singlerow bearings mounted at each end of a shaft are equal, and one is adjustable and the other ﬁxed, it is suggested that the same adjustable ﬁt be used at both ends. However, tight ﬁts should be used if outer rings are backed against snap rings to prevent excessive dishing of snap rings, groove wear and possible loss of ring retention. Only outer rings with a maximum housing ﬁllet radius requirement of 1.3 mm (0.05 in.) or less should be considered for a snap ring backing.

Double-row stationary double outer rings are generally mounted with loose ﬁts to permit assembly and disassembly. The loose fit also permits float when a floating bearing is mounted in conjunction with an axially ﬁxed bearing on the other end of the shaft.

Fitting practice tables 70-81 on pages 138-163, have been prepared for both metric and inch dimensions.

For the inch system bearings, classes 4 and 2 (standard) and classes 3, 0, and 00 (precision) have been included.

The metric system bearings that have been included are: classes K and N (metric system standard bearings) and classes C, B, and A (metric system precision bearings).

Precision-class bearings should be mounted on shafts and in housings which are similarly ﬁnished to at least the same

78 TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

TAPERED ROLLER BEARINGS

precision limits as the bearing bore and O.D. High-quality surface ﬁnishes also should be provided. Recommended surface ﬁnishes are shown on page 119 for tapered roller bearings and pages 121-122 for ball bearings.

Effects of tight ﬁts on bearing setting/width

Interference ﬁts of the inner ring cause inner ring expansion and interference ﬁts of the outer ring cause outer ring contraction. As the inner ring diameters increase and the outer ring diameters decrease, internal clearance within the bearing is reduced and bearing width is increased. The change in clearance or setting is approximately equal to the change in width.

For matched assemblies where the setting is pre-set from the factory and SET-RIGHT assemblies, the effects of ﬁt must be taken into account to provide the desired mounted setting.

Double-row and four-row bearings that are provided with spacers are examples of matched assemblies. These bearings are pre-set to a speciﬁc bench endplay or axial clearance prior to installation into the application. Mounting the bearing with a tight ﬁt will reduce this bench endplay. In order to meet the desired mounted setting, the bench endplay must be compensated for the ﬁt effect.

stretch the outer ring seat, resulting in less change in bearing setting and overall width. The effects can be calculated according to the following formulas.

Inner ring setting reduction/width increase:

0.39

= 0.5

Outer ring setting reduction/width increase:

= 0.5

For shaft or housing material other than steel, consult your Timken engineer.

( )

{

Do D

{

[

(

[

( )

)

( )( )

]

}

]

}

SET-RIGHT assemblies rely on the control of bearing, shaft and housing tolerances to known distributions, resulting in a statistical mounted bearing setting range. This mounted setting takes into account any reductions in setting due to tight ﬁts.

Bearing width increase can affect setting in applications such as outer-ring-adjusted, direct-mounting designs. In this case, a shim is inserted between the outer ring and a backing plate. Tight ﬁts will affect calculation of the shim thickness. In other applications where axial tolerance summation calculations are made, tight ﬁt effects must be taken into consideration.

For solid steel shafts and heavy-section steel housings, the change in setting is calculated as follows:

Inner ring setting reduction/width increase:

K d

Outer ring setting reduction/width increase:

0.39 D

Interference ﬁts on thin-walled shafts and light-section steel housings have a tendency to collapse the inner ring seat and

= 0.5

(

0.39 d

( )

)

K D

( )

Fig. 82.

DoDdod

Parameters for

calculation of ﬁt effect on setting.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

TAPERED ROLLER BEARINGS

SETTING

Setting is deﬁned as the axial clearance between roller and raceway. Establishing the setting at the time of assembly is an inherent advantage of tapered roller bearings. They can be set to provide optimum performance in almost any application. Fig. 83 gives an example of the relationship between fatigue life and bearing setting. Unlike some types of anti-friction bearings, tapered roller bearings do not rely strictly on housing or shaft ﬁts to obtain a certain bearing setting. One ring can be moved axially relative to the other to obtain the desired bearing setting.

100

Rated life (percent)

-0.15 -0.10 -0.05 0.000 0.05 0.10 0.15 mm

-0.006 -0.0040 -0.0020 0.00 0.0020 0.0040 0.0060 in

Fig. 83. Typical life vs. setting curve.

At assembly, the conditions of bearing setting are deﬁned as:

Endplay (EP) – An axial clear-

•

ance between rollers and raceways producing a measurable axial shaft movement when a small axial force is applied – ﬁrst in one direction then in the other, while oscillating or rotating the shaft. See ﬁg. 84.

Preload (PL) – An axial interference

•

between rollers and raceways such that there is no measurable axial shaft movement when a small axial force is applied – in both directions – while oscillating or rotating the shaft.

Line-to-line – A zero setting

•

condition: the transitional point between endplay and preload.

Preload Endplay

Axial clearance

360 180 135 100

216

Load zone (degrees)

Fig. 84. Internal clearance – endplay.

Axial Endplay

Bearing setting obtained during initial assembly and adjustment is the cold or ambient bearing setting, and is established before the equipment is subjected to service.

Bearing setting during operation is known as the operating bearing setting, and is a result of changes in the ambient bearing setting due to thermal expansion and deﬂections encountered during service.

The ambient bearing setting necessary to produce the optimum operating bearing setting varies with the application. Application experience or testing generally determines optimum settings. Frequently, however, the exact relationship of ambient to operating bearing setting is unknown and an educated estimate has to be made. To determine a suggested ambient bearing setting for a speciﬁc application, contact your Timken engineer.

Generally, the ideal operating bearing setting is near zero to maximize bearing life (ﬁg. 83). Most bearings are set with endplay at assembly to reach the desired near-zero setting at operating temperature.

There is an ideal bearing setting value for every application. To achieve this condition, the bearing setting must take into account deﬂection under load (radial + axial) as well as thermal expansions and material used.

1. Standard mounting

Operating setting = mounted setting ± temperature effect + deﬂection

2. Pre-set assemblies

Mounted EP or PL = bench EP or bench PL – effect of ﬁts

Operating setting = mounted EP or PL (MEP or MPL) + deﬂection ± temperature effect

The temperature and ﬁt effects will depend upon the type of mounting, bearing geometry and size, shaft and housing sizes, and material as deﬁned in the following sections. Dimensional parameters affecting bearing setting are noted in ﬁg. 85.

80 TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

TAPERED ROLLER BEARINGS

Fit effect

Solid shaft/heavy section housing

Setting Reduction/Width Increase for Single Inner Ring

= 0.5

0.39 d

Hollow shaft/thin-wall section

Shaft Reduction/Width Increase for Single Inner Ring

= 0.5

0.39 do

Shaft Reduction/Width Increase for Single Outer Ring

= 0.5

0.39 D

(1)

These equations apply only to ferrous shaft and housing.

(1)

K d

( )( )

Setting Reduction/Width Increase for Single Outer Ring

= 0.5

0.39 D

K D

( )( )

K d

( )( )

K D

( )( )

1 -

[

1 - d

1 - D

[

1 - D

( )

[

Fig. 85. Dimensional parameters affecting ﬁt and

temperature effects on setting.

DoDd

Setting methods

Upper and lower limits of bearing setting values are determined by consideration of the following factors:

Application type.

•

Duty cycle/loading.

•

Operational features of adjacent mechanical drive

•

elements.

Temperature effect

Direct mounting - setting change due to temperature

0.39 2 0.39 2

Indirect mounting - setting change due to temperature

0.39 2 0.39 2

1 2

Direct mounting

aTΔT

( )( )

[

ΔT

( )( )

[

Fig. 86. Direct and indirect mounting.

( )( )

1 2

Indirect mounting

+ L

[

- L

[

Changes in bearing setting due to temperature differentials

•

and deﬂections.

Size of bearing and method of obtaining bearing setting.

•

Lubrication method.

•

Housing and shaft material.

•

The setting value to be applied during assembly will depend on any changes that may occur during operation. In the absence of experience with bearings of similar size and operating conditions, a bearing setting range suggestion should be obtained from your Timken engineer.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

MOUNTING

Spherical roller bearings can be mounted individually, but most often are mounted in combination with another spherical roller bearing or a cylindrical roller bearing.

With spherical roller bearings, typically one bearing is ﬁxed axially and the other is mounted with loose ﬁts and axial space. This allows movement or ﬂoat for environmental conditions such as uneven thermal growth between shaft and housing.

Cylindrical roller bearings can be mounted individually, but most often are mounted in combination with another cylindrical roller, a spherical roller or a tapered roller bearing.

Fig. 87 shows a typical gearbox application using two spherical roller bearings where one bearing is free to ﬂoat and the other bearing is ﬁxed axially.

Effective bearing

spread

Fig. 88 shows a pulverizer wheel assembly where a doublerow spherical roller bearing is mounted in combination with a cylindrical roller bearing. In this application, the cylindrical roller bearing allows the shaft to ﬂoat relative to the housing.

Fig. 89 shows a single-reduction gear reducer with herringbone gears. A tapered roller bearing is mounted in combination with a cylindrical roller bearing on the upper shaft, and two cylindrical roller bearings are mounted on the lower shaft.

FITTING PRACTICE

Tables 55 -67 on pages 120-131 list the recommended ﬁtting practices for spherical roller and cylindrical roller bearings. The tables assume:

The bearing is of normal precision.

•

The housing is thick and made from steel or cast iron.

•

The shaft is solid and made from steel.

•

The bearing seats are ground or accurately turned to less

•

than approximately 1.6 µm Ra ﬁnish.

The suggested ﬁt symbols are in accordance with ISO 286. For help with recommended ﬁtting practices, contact your Timken engineer.

Float position Fixed position

Fig. 87. Spherical roller bearing direct mounting.

As a general guideline, rotating inner rings should be applied with an interference ﬁt. Loose ﬁts may permit the inner rings to creep or turn and wear the shaft and the backing shoulder. This wear may result in excessive bearing looseness and possible bearing and shaft damage. Additionally, abrasive metal particles resulting from creep or turning may enter into the bearing and cause damage and vibration.

Fig. 88. Pulverizer wheel assembly. Fig. 89. Single-reduction gear reducer.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

Stationary inner-ring ﬁtting practice depends on the loading of the application. The load conditions and bearing envelope dimensions should be used to select the suggested shaft ﬁt from the tables.

Similarly, rotating outer-ring applications should use an interference ﬁt between the outer ring and housing.

Stationary outer rings are generally mounted with loose ﬁts to permit assembly and disassembly. The loose ﬁt also permits axial movement when a spherical bearing is mounted in the ﬂoat position.

Thin-walled housings, light-alloy housings or hollow shafts must use press ﬁts tighter than those required for thick-walled housings, steel, or cast iron housings or solid shafts. Tighter ﬁts also are required when mounting the bearing on relatively rough or unground surfaces.

Tapered bore designs

Typically, the tapered bore bearings are selected to simplify shaft mounting and dismounting. Since the spherical roller bearing is not separable, mounting can be simpliﬁed by use of an adapter sleeve with a cylindrical bore and tapered O.D. A tapered bore roller bearing also can be mounted directly onto a tapered shaft.

Fitting practice

An interference ﬁt between the inner ring and a solid steel

•

shaft will reduce the radial clearance within the bearing by approximately 80 percent of the ﬁt.

Interference ﬁts between the outer ring and steel or cast iron

•

housing will reduce radial clearance by approximately 60 percent.

Spherical roller bearings with a tapered bore require a

•

slightly greater interference ﬁt on the shaft than a cylindrical bore bearing.

NOTE

It is critical to select the RIC that allows for this reduction.

Thermal gradients

Thermal gradients within the bearing are primarily a func-

•

tion of the bearing rotational speed. As speed increases, thermal gradients increase, thermal growth occurs and the radial clearance is reduced.

As a rule of thumb, radial clearance should be increased for

•

speeds in excess of 70 percent of the speed rating.

For help selecting the correct radial internal clearance for your application, consult with your Timken engineer.

Fig. 90. Spherical roller bearing mounted with an adapter sleeve.

Bearings with a tapered bore typically require a tighter ﬁt on the shaft than bearings with a cylindrical bore. A locknut is typically used to drive the inner ring up a tapered shaft sleeve. The locknut position is then secured by use of a lockwasher or lockplate. Timken offers a wide range of accessories to ease the assembly of spherical roller bearings with a tapered bore (see page 89). For approximating the clearance loss for axial drive-up, an 85 percent radial loss approximation can be used. That is, the radial clearance loss per axial drive-up can roughly be approximated as 71 μm/mm for a 1:12 tapered bore and 28 μm/mm for a 1:30 tapered bore. Table 41 on page 85 shows the relationship between axial displacement of the inner ring and the reduction in RIC (radial internal clearance) for tapered bore applications.

SETTING

To achieve appropriate operation clearance, attention must be paid to the effects ﬁtting practice and thermal gradients have within the bearing.

Radial internal clearance tolerances are listed in tables 40 and 41 for spherical and cylindrical roller bearings, respectively.

Spherical and cylindrical roller bearings are ordered with a speciﬁed standard or non-standard radial internal clearance value. The standard radial internal clearances are designated as C2, C0 (normal), C3, C4 or C5 and are in accordance with ISO

5753. C2 represents the minimum clearance and C5 represents the maximum clearance. Non-standardized values also are available by special request.

The clearance required for a given application depends on the desired operating precision, the rotational speed of the bearing, and the ﬁtting practice used. Most applications use a normal or C3 clearance. Typically, larger clearance reduces the operating load zone of the bearing, increases the maximum roller load, and reduces the bearing’s expected life. However, a spherical or cylindrical roller bearing that has been put into a preload condition can experience premature bearing damage caused by excessive heat generation and/or material fatigue. As a general guideline, spherical and cylindrical roller bearings should not operate in a preloaded condition.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

TAPERED ROLLER BEARINGS

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

TABLE 40. RADIAL INTERNAL CLEARANCE LIMITS – SPHERICAL ROLLER BEARINGS – CYLINDRICAL BORE

Radial Internal Clearance Prior To Mounting

Bore

(Nominal)

C2 C3 C5

Over Incl. Min. Max. Min. Max. Min. Max.

in.

20 30 0.015 0.025 0.040 0.055 0.075 0.095

0.9449 1.1811 0.0006 0.0010 0.0016 0.0022 0.0030 0.0037

30 40 0.015 0.030 0.045 0.060 0.080 0.100

1.1811 1.5748 0.0006 0.0012 0.0018 0.0024 0.0031 0.0039

40 50 0.020 0.035 0.055 0.075 0.100 0.125

1.5748 1.9685 0.0008 0.0014 0.0022 0.0030 0.0039 0.0049

50 65 0.020 0.040 0.065 0.090 0.120 0.150

1.9685 2.5591 0.0008 0.0016 0.0026 0.0035 0.0047 0.0059

65 80 0.030 0.050 0.080 0.110 0.145 0.180

2.5591 3.1496 0.0012 0.0020 0.0031 0.0043 0.0057 0.0071

80 100 0.035 0.060 0.100 0.135 0.180 0.225

3.1496 3.9370 0.0014 0.0024 0.0039 0.0053 0.0071 0.0089

100 120 0.040 0.075 0.120 0.160 0.210 0.260

3.9370 4.7244 0.0016 0.0030 0.0047 0.0063 0.0083 0.0102

120 140 0.050 0.095 0.145 0.190 0.240 0.300

4.7244 5.5118 0.0020 0.0037 0.0057 0.0075 0.0094 0.0118

140 160 0.060 0.110 0.170 0.220 0.280 0.350

5.5118 6.2992 0.0024 0.0043 0.0067 0.0087 0.0110 0.0138

160 180 0.065 0.120 0.180 0.240 0.310 0.390

6.2992 7.0866 0.0026 0.0047 0.0071 0.0094 0.0122 0.0154

180 200 0.070 0.130 0.200 0.260 0.340 0.430

7.0866 7.8740 0.0028 0.0051 0.0079 0.0102 0.0134 0.0169

200 225 0.080 0.140 0.220 0.290 0.380 0.470

7.8740 8.8582 0.0031 0.0055 0.0087 0.0114 0.0150 0.0185

225 250 0.090 0.150 0.240 0.320 0.420 0.520

8.8582 9.8425 0.0035 0.0059 0.0094 0.0126 0.0165 0.0205

250 280 0.100 0.170 0.260 0.350 0.460 0.570

9.8425 11.0236 0.0039 0.0067 0.0102 0.0138 0.0181 0.0224

280 315 0.110 0.190 0.280 0.370 0.500 0.630

11.0236 12.4016 0.0043 0.0075 0.0110 0.0146 0.0197 0.0248

315 355 0.120 0.200 0.310 0.410 0.550 0.690

12.4016 13.9764 0.0047 0.0079 0.0122 0.0161 0.0217 0.0272

355 400 0.130 0.220 0.340 0.450 0.600 0.750

13.9764 15.7480 0.0051 0.0087 0.0134 0.0177 0.0236 0.0295

400 450 0.140 0.240 0.370 0.500 0.660 0.820

15.7480 17.7165 0.0055 0.0094 0.0146 0.0197 0.026 0.0323

450 500 0.140 0.260 0.410 0.550 0.720 0.900

17.7165 19.6850 0.0055 0.0102 0.0161 0.0217 0.0283 0.0354

500 560 0.150 0.280 0.440 0.600 0.780 1.000

19.6850 22.0472 0.0059 0.0110 0.0173 0.0236 0.0307 0.0394

560 630 0.170 0.310 0.480 0.650 0.850 1.100

22.0472 24.8031 0.0067 0.0122 0.0189 0.0256 0.0335 0.0433

in.

Normal

Min. Max. Min. Max.

in.

84 TIMKEN ENGINEERING MANUAL

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

Continued from previous page.

Over Incl. Min. Max. Min. Max. Min. Max.

630 710 0.190 0.350 0.530 0.700 0.920 1.190

24.8031 27.9528 0.0075 0.0138 0.0209 0.0276 0.0362 0.0469

710 800 0.210 0.390 0.580 0.770 1.010 1.300

27.9528 31.4961 0.0083 0.0154 0.0228 0.0303 0.0398 0.0512

800 900 0.230 0.430 0.650 0.860 1.120 1.440

31.4961 35.4331 0.0091 0.0169 0.0256 0.0339 0.0441 0.0567

900 1000 0.260 0.480 0.710 0.930 1.220 1.570

35.4331 39.3701 0.0102 0.0189 0.0280 0.0366 0.0480 0.0618

1000 1120 0.290 0.530 0.780 1.020 1.330 1.720

39.3701 44.0950 0.0114 0.0209 0.0307 0.0402 0.0524 0.0677

1120 1250 0.320 0.580 0.860 1.120 1.460 1.870

44.0950 49.2130 0.0126 0.0228 0.0339 0.0441 0.0575 0.0736

TABLE 40. RADIAL INTERNAL CLEARANCE LIMITS – SPHERICAL ROLLER BEARINGS – CYLINDRICAL BORE

Radial Internal Clearance Prior To Mounting

in.

Bore

(Nominal)

in.

Normal

Min. Max. Min. Max.

C2 C3 C5

in.

TABLE 41. SPHERICAL ROLLER BEARING ENDPLAY

E.P

––––

RIC

8.7

7.0

5.5

5.0

4.8

4.4

4.3

4.2

3.9

Spherical roller bearings

Series

39 30 22 31 40 32 23 41 33

in.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

TABLE 42. RADIAL INTERNAL CLEARANCE LIMITS – SPHERICAL ROLLER BEARINGS – TAPERED BORE

Radial Internal Clearance Prior To Mounting

Bore

(Nominal)

Over Incl. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. CO C3 C4

in.

20 30 0.020 0.030 0.040 0.055 0.075 0.095 0.015 0.020 0.230 0.300 – – 0.015 0.025 0.040

0.9449 1.1811 0.0008 0.0012 0.0016 0.0022 0.0030 0.0037 0.0006 0.0008 0.0091 0.0118 – – 0.0006 0.0010 0.0016

30 40 0.025 0.035 0.050 0.065 0.085 0.105 0.020 0.025 0.300 0.380 – – 0.015 0.025 0.040

1.1811 1.5748 0.0010 0.0014 0.0020 0.0026 0.0033 0.0041 0.0008 0.0010 0.0118 0.0150 – – 0.0006 0.0010 0.0016

40 50 0.030 0.045 0.060 0.080 0.100 0.130 0.025 0.030 0.380 0.460 – – 0.02 0.030 0.050

1.5748 1.9685 0.0012 0.0018 0.0024 0.0031 0.0039 0.0051 0.0010 0.0012 0.0150 0.0181 – – 0.0008 0.0012 0.0020

50 65 0.040 0.055 0.075 0.095 0.120 0.160 0.030 0.038 0.460 0.560 – – 0.025 0.040 0.060

1.9685 2.5591 0.0016 0.0022 0.0030 0.0037 0.0047 0.0063 0.0012 0.0015 0.0181 0.0220 – – 0.0010 0.0015 0.0025

65 80 0.050 0.070 0.0950 0.120 0.150 0.200 0.038 0.051 0.560 0.760 – – 0.025 0.045 0.075

2.5591 3.1496 0.0020 0.0028 0.0037 0.0047 0.0059 0.0079 0.0015 0.0020 0.0220 0.0299 – – 0.0010 0.0017 0.0030

80 100 0.055 0.080 0.110 0.140 0.180 0.230 0.046 0.064 0.680 0.970 – – 0.036 0.050 0.075

3.1496 3.9370 0.0022 0.0030 0.0043 0.0055 0.0071 0.0091 0.0018 0.0025 0.0268 0.0382 – – 0.0014 0.0020 0.0030

100 120 0.065 0.100 0.135 0.170 0.220 0.280 0.051 0.071 0.760 1.070 1.900 2.540 0.051 0.060 0.100

3.9370 4.7244 0.0026 0.0039 0.0053 0.0067 0.0087 0.0110 0.0020 0.0028 0.0299 0.0421 0.0748 0.1000 0.0020 0.0025 0.0040

120 140 0.080 0.120 0.160 0.200 0.260 0.330 0.064 0.089 0.890 1.270 2.290 3.050 0.056 0.075 0.115

4.7244 5.5118 0.0031 0.0047 0.0063 0.0079 0.0102 0.0130 0.0025 0.0035 0.0350 0.0500 0.0902 0.1201 0.0022 0.0030 0.0045

140 160 0.090 0.130 0.180 0.230 0.300 0.380 0.076 0.102 1.140 1.520 2.670 3.430 0.056 0.075 0.125

5.5118 6.2992 0.0035 0.0051 0.0071 0.0091 0.0118 0.0150 0.0030 0.0040 0.0449 0.0598 0.1051 0.1350 0.0022 0.0030 0.0050

160 180 0.100 0.140

6.2992 7.0866 0.0039 0.0055 0.0079 0.0102 0.0134 0.0169 0.0030 0.0045 0.0449 0.0650 0.1051 0.1598 0.0024 0.0035 0.0060

180 200 0.110 0.160 0.220 0.290 0.370 0.470 0.089 0.127 1.400 1.900 3.050 4.450 0.071 0.100 0.165

7.0866 7.8740 0.0043 0.0063 0.0087 0.0114 0.0146 0.0185 0.0035 0.0050 0.0551 0.0748 0.1201 0.1752 0.0028 0.0040 0.0065

200 225 0.120 0.180 0.250 0.320 0.410 0.520 0.102 0.140 1.520 2.030 3.560 4.830 0.076 0.115 0.180

7.8740 8.8582 0.0047 0.0071 0.0098 0.0126 0.0161 0.0205 0.0040 0.0055 0.0598 0.0799 0.1402 0.1902 0.0030 0.0045 0.0070

225 250 0.140 0.200 0.270 0.350 0.450 0.570 0.114 0.152 1.780 2.290 4.060 5.330 0.089 0.115 0.200

8.8582 9.8425 0.0055 0.0079 0.0106 0.0138 0.0177 0.0224 0.0045 0.0060 0.0701 0.0902 0.1598 0.2098 0.0035 0.0045 0.0080

250 280 0.150 0.220 0.300 0.390 0.490 0.620 0.114 0.165 1.780 2.540 4.060 5.840 0.102 0.140 0.230

9.8425 11.0236 0.0059 0.0087 0.0118 0.0154 0.0193 0.0244 0.0045 0.0065 0.0701 0.1000 0.1598 0.2299 0.0040 0.0055 0.0090

280 315 0.170 0.240 0.330 0.430 0.540 0.680 0.127 0.178 1.900 2.670 4.450 6.220 0.102 0.150 0.250

11.0236 12.4016 0.0067 0.0094 0.0130 0.0169 0.0213 0.0268 0.0050 0.0070 0.0748 0.1051 0.1752 0.2449 0.0040 0.0060 0.0100

315 355 0.190 0.270 0.360 0.470 0.590 0.740 0.140 0.190 2.030 2.790 4.830 6.600 0.114 0.165 0.280

12.4016 13.9764 0.0075 0.0106 0.0142 0.0185 0.0232 0.0291 0.0055 0.0075 0.0799 0.1098 0.1902 0.2598 0.0045 0.0065 0.0110

355 400 0.210 0.300 0.400 0.520 0.650 0.820 0.152 0.203 2.290 3.050 5.330 7.110 0.127 0.190 0.330

13.9764 15.7480 0.0083 0.0118 0.0157 0.0205 0.0256 0.0323 0.0060 0.0080 0.0902 0.1201 0.2098 0.2799 0.0050 0.0075 0.0130

in.

Normal

Min. Max. Min. Max.

C2 C3 C5 1:12 Taper 1:30 Taper

in.

0.200 0.260 0.340 0.430 0.076 0.114 1.140 1.650 2.670 4.060 0.061 0.090 0.150

in.

Suggested

Reduction

of RIC

Due to

Installation

in.

Axial Displacement

of Inner Ring for RIC Reduction –

Tapered Shaft

in.

(1)(2)

in.

Minimum Permissible

RIC After

Installation

in.

(1)

in.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

Continued from previous page.

Bore

(Nominal)

Over Incl. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max. CO C3 C4

in.

400 450 0.230 0.330 0.440 0.570 0.720 0.910 0.165 0.216 2.540 3.300 5.840 7.620 0.152 0.230 0.360

15.7480 17.7165 0.0091 0.0130 0.0173 0.0224 0.0283 0.0358 0.0065 0.0085 0.1000 0.1299 0.2299 0.3000 0.0060 0.0090 0.0140

450 500 0.260 0.370 0.490 0.630 0.790 1.000 0.178 0.229 2.670 3.430 6.220 8.000 0.165 0.270 0.410

17.7165 19.6850 0.0102 0.0146 0.0193 0.0248 0.0311 0.0394 0.0070 0.0090 0.1051 0.1350 0.2449 0.3150 0.0065 0.0105 0.0160

500 560 0.290 0.410 0.540 0.680 0.870 1.100 0.203 0.254 3.050 3.810 7.110 8.890 0.178 0.290 0.440

19.6850 22.0472 0.0114 0.0161 0.0213 0.0268 0.0343 0.0433 0.0080 0.0100 0.1201 0.1500 0.2799 0.3500 0.0070 0.0115 0.0175

560 630 0.320 0.460 0.600 0.760 0.980 1.230 0.229 0.279 3.430 4.190 8.000 9.780 0.203 0.320 0.510

22.0472 24.8031 0.0126 0.0181 0.0236 0.0299 0.0386 0.0484 0.0090 0.0110 0.1350 0.1650 0.3150 0.3850 0.0080 0.0125 0.0200

630 710 0.350 0.510 0.670 0.850 1.090 1.360 0.254 0.305 3.810 4.570 8.890 10.670 0.203 0.370 0.550

24.8031 27.9528 0.0138 0.0201 0.0264 0.0335 0.0429 0.0535 0.0100 0.0120 0.1500 0.1799 0.3500 0.4201 0.0080 0.0145 0.0215

710 800 0.390 0.570 0.750 0.960 1.220 1.500 0.279 0.356 4.190 5.330 9.780 12.450 0.229 0.390 0.610

27.9528 31.4961 0.0154 0.0224 0.0295 0.0378 0.0480 0.0591 0.0110 0.0140 0.1650 0.2098 0.3850 0.4902 0.0090 0.0155 0.0240

800 900 0.440 0.640 0.840 1.070 1.370 1.690 0.305 0.381 4.570 5.720 10.670 13.330 0.252 0.460 0.690

31.4961 35.4331 0.0173 0.0252 0.0331 0.0421 0.0539 0.0665 0.0120 0.0150 0.1799 0.2252 0.4201 0.5248 0.0100 0.0180 0.0270

900 1000 0.490 0.710 0.930 1.190 1.520 1.860 0.356 0.432 5.330 6.480 12.450 15.110 0.279 0.490 0.750

35.4331 39.3701 0.0193 0.0280 0.0366 0.0469 0.0598 0.0732 0.0140 0.0170 0.2100 0.2551 0.4902 0.5949 0.0110 0.0195 0.0300

1000 1120 0.530 0.770 1.030 1.300 1.670 2.050 0.400 0.480 6.100 7.240 14.220 16.890 0.280 0.550 0.810

39.3701 44.0950 0.0209 0.0303 0.0406 0.0512 0.0657 0.0807 0.0160 0.0190 0.2400 0.2850 0.5600 0.6650 0.0110 0.0215 0.0320

1120 1250 0.570 0.830

44.0950 49.2130 0.0224 0.0327 0.0441 0.0559 0.0720 0.0886 0.0170 0.0200 0.2550 0.3000 0.5950 0.7000 0.0130 0.0240 0.0360

Note: Axial displacement values apply to solid steel shafts or hollow shafts with bore diameter less than half the shaft diameter. For shaft materials other than steel, or for thin-walled shafts, please consult your Timken sales engineer.

(1)

This displacement is valid for assembly of tapered bore bearings and is measured starting from a line-to-line ﬁt of the bearing bore to the tapered shaft.

(2)

1:12 Taper used for 213, 222, 223, 230, 231, 232, 233, 238, 239 series. 1:30 Taper used for 240, 241, 242 series. For sleeve mounting, multiply axial displacement values by 1.1 for 1:12 Taper or by 1.05 for 1:30 Taper. For questions on tapered shaft data, consult your Timken sales engineer.

TABLE 5. RADIAL INTERNAL CLEARANCE LIMITS – SPHERICAL ROLLER BEARINGS – TAPERED BORE

in.

Radial Internal Clearance Prior To Mounting

Normal

Min. Max. Min. Max.

C2 C3 C5 1:12 Taper 1:30 Taper

in.

1.120 1.420 1.830 2.250 0.430 0.500 6.480 7.620 15.110 17.780 0.330 0.610 0.910

in.

Suggested

Reduction

of RIC

Due to

Installation

in.

Axial Displacement

of Inner Ring for RIC Reduction –

Tapered Shaft

in.

(1)(2)

in.

Minimum Permissible

RIC After

Installation

in.

(1)

in.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

TABLE 43. RADIAL INTERNAL CLEARANCE LIMITS – CYLINDRICAL ROLLER BEARINGS – CYLINDRICAL BORE

Bore – RIC

Bore (Nominal) C2 C0 C3 C4 C5

Over Incl. Min. Max. Min. Max. Min. Max. Min. Max. Min. Max.

in.

– 10 0.000 0.025 0.020 0.0045 0.035 0.060 0.050 0.075 – – – 0.3937 0.0000 0.0010 0.0008 0.0018 0.0014 0.0024 0.0020 0.0030 – –

10 24 0.000 0.025 0.020 0.0045 0.035 0.060 0.050 0.075 0.065 0.090

0.3937 0.9449 0.0000 0.0010 0.0008 0.0018 0.0014 0.0024 0.0020 0.0030 0.0026 0.0035

24 30 0.000 0.025 0.020 0.0045 0.035 0.060 0.050 0.075 0.070 0.095

0.9449 1.1811 0.0000 0.0010 0.0008 0.0018 0.0014 0.0024 0.0020 0.0030 0.0028 0.0037

30 40 0.005 0.030 0.025 0.050 0.0045 0.070 0.060 0.085 0.080 0.105

1.1811 1.5748 0.0002 0.0012 0.0010 0.0020 0.0018 0.0028 0.0024 0.0033 0.0031 0.0041

40 50 0.005 0.035 0.030 0.060 0.050 0.080 0.070 0.100 0.095 0.125

1.5748 1.9685 0.0002 0.0014 0.0012 0.0024 0.0020 0.0031 0.0028 0.0039 0.0037 0.0049

50 65 0.010 0.040 0.040 0.070 0.060 0.090 0.080 0.110 0.110 0.140

1.9685 2.5591 0.0004 0.0016 0.0016 0.0028 0.0024 0.0035 0.0031 0.0043 0.0043 0.0055

65 80 0.010 0.0045 0.040 0.075 0.065 0.100 0.090 0.125 0.130 0.165

2.5591 3.1496 0.0004 0.0018 0.0016 0.0030 0.0026 0.0039 0.0035 0.0049 0.0051 0.0065

80 100 0.015 0.050 0.050 0.085 0.075 0.110 0.105 0.140 0.155 0.190

3.1496 3.9370 0.0006 0.0020 0.0020 0.0033 0.0030 0.0043 0.0041 0.0055 0.0061 0.0075

100 120 0.015 0.055 0.050 0.090 0.085 0.125 0.125 0.165 0.180 0.220

3.9370 4.7244 0.0006 0.0022 0.0020 0.0035 0.0033 0.0049 0.0049 0.0065 0.0071 0.0087

120 140 0.015 0.060 0.060 0.105 0.100 0.145 0.145 0.190 0.200 0.245

4.7244 5.5118 0.0006 0.0024 0.0024 0.0041 0.0039 0.0057 0.0057 0.0075 0.0079 0.0096

140 160 0.020 0.070 0.070 0.120 0.115 0.165 0.165 0.215 0.225 0.275

5.5118 6.2992 0.0008 0.0028 0.0028 0.0047 0.0045 0.0065 0.0065 0.0085 0.0089 0.0108

160 180 0.025 0.075 0.075 0.125 0.120 0.170 0.170 0.220 0.250 0.300

6.2992 7.0866 0.0010 0.0030 0.0030 0.0049 0.0047 0.0067 0.0067 0.0087 0.0098 0.0118

180 200 0.035 0.090 0.090 0.145 0.140 0.195 0.195 0.250 0.275 0.330

7.0866 7.8740 0.0014 0.0035 0.0035 0.0057 0.0055 0.0077 0.0077 0.0098 0.0108 0.0130

200 225 0.045 0.105 0.105 0.165 0.160 0.220 0.220 0.280 0.305 0.365

7.8740 8.8583 0.0018 0.0041 0.0041 0.0065 0.0063 0.0087 0.0087 0.0110 0.0120 0.0144

225 250 0.045 0.110 0.110 0.175 0.170 0.235 0.235 0.300 0.330 0.395

8.8583 9.8425 0.0018 0.0043 0.0043 0.0069 0.0067 0.0093

250 280 0.055 0.125 0.125 0.195 0.190 0.260 0.260 0.330 0.370 0.440

9.8425 11.0236 0.0022 0.0049 0.0049 0.0077 0.0075 0.0102 0.0102 0.0130 0.0146 0.0173

280 315 0.055 0.130 0.130 0.205 0.200 0.275 0.275 0.350 0.410 0.485

11.0236 12.4016 0.0022 0.0051 0.0051 0.0081 0.0079 0.0108 0.0108 0.0138 0.0161 0.0191

315 355 0.065 0.145 0.145 0.225 0.225 0.305 0.305 0.385 0.455 0.535

12.4016 13.9764 0.0026 0.0057 0.0057 0.0089 0.0089 0.0120 0.0120 0.0152 0.0179 0.0211

355 400 0.100 0.190 0.190 0.280 0.280 0.370 0.370 0.460 0.510 0.600

13.9764 15.7480 0.0039 0.0075 0.0075 0.0110 0.0110 0.0146 0.0146 0.0181 0.0201 0.0236

400 450 0.110 0.210 0.210 0.310 0.310 0.410 0.410 0.510 0.565 0.665

15.7480 17.7165 0.0043 0.0083 0.0083 0.0122 0.0122 0.0161 0.0161 0.0201 0.0222 0.0262

450 500 0.110 0.220 0.220 0.330 0.330 0.440 0.440 0.550 0.625 0.735

17.7165 19.6850 0.0043 0.0087 0.0087 0.0130 0.0130 0.0173 0.0173 0.0217 0.0246 0.0289

500 560 0.120 0.240 0.240 0.360 0.360 0.480 0.480 0.600 0.690 0.810

19.6850 22.0472 0.0047 0.0095 0.0095 0.0142 0.0142 0.0189 0.0189 0.0236 0.0272 0.0319

560 630 0.140 0.260 0.260 0.380 0.380 0.500 0.500 0.620 0.780 0.900

22.0472 24.8031 0.0055 0.0102 0.0102 0.0150 0.0150 0.0197 0.0197 0.0244 0.0307 0.0354

630 710 0.145 0.285 0.285 0.425 0.425 0.565 0.565 0.705 0.865 1.005

24.8031 27.9528 0.0057 0.0112 0.0112 0.0167 0.0167 0.0222 0.0222 0.0278 0.0341 0.0396

710 800 0.150 0.310 0.310 0.470 0.470 0.630 0.630 0.790 0.975 1.135

27.9528 31.4961 0.0059 0.0122 0.0122 0.0185 0.0185 0.0248 0.0248 0.0311 0.0384 0.0447

800 900 0.180 0.350 0.350 0.520 0.520 0.690 0.690 0.860 1.095 1.265

31.4961 35.4331 0.0071 0.0138 0.0138 0.0205 0.0205 0.0272 0.0272 0.0339 0.0431 0.0498

900 1000 0.200 0.390 0.390 0.580 0.580 0.770 0.770 0.960 1.215 1.405

35.4331 39.3701 0.0079 0.0154 0.0154 0.0228 0.0228 0.0303 0.0303 0.0378 0.0478 0.0553

in.

0.0093 0.0118 0.0130 0.0156

in.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

EXAMPLE #1 – Calculating RIC Reduction Using a Spherical Roller Bearing with Tapered Bore

Step 1:

Place bearing in upright position and center the inner ring and rollers. Apply pressure to the inner ring and oscillate several times to properly seat the rollers.

Step 2:

Use a feeler gauge to measure the unmounted radial internal clearance (RIC) for both bearing rows.

- RIC must be checked at the unloaded roller.

- Feeler gauge must cover the length of the roller.

- Unmounted RIC is the thickest gauge that will slide through the gap between the roller and outer ring.

- Unmounted RIC is then the average reading for the two rows.

Fig. 91. Measure RIC

before installation.

Example: 22328KEJW33C3 140 mm bore (5.5118 in.) RIC measurement is 0.178 mm (0.0070 in.)

Step 3:

Use table 42 (page 86) to conﬁrm that the measured unmounted RIC value is within speciﬁcation.

Example: 22328KEJW33C3 140 mm bore (5.5118 in.) RIC range is 0.160 mm – 0.200 mm (0.0063 in. – 0.0079 in.), the

example’s measured RIC is 0.178 mm (0.007 in.) so it is within speciﬁed range.

Step 4:

Use table 42 (page 86) to determine the Suggested Reduction of RIC Due to Installation.

Example: 22328KEJW33C3 140 mm bore (5.5118 in.) Suggested Reduction of RIC Due to installation is

0.064 mm – 0.089 mm (0.0025 in. – 0.0035 in.).

Step 5:

Determine the maximum and minimum RIC after mounting.

MAX RIC = actual unmounted RIC – maximum suggested

reduction in RIC

MIN RIC = actual unmounted RIC – maximum suggested

reduction in RIC

Example: 22328KEJW33C3 140 mm bore (5.5118 in.)

Max Mounted RIC: 0.178 mm – 0.064 mm = 0.114 mm

(0.0070 in. – 0.0025 in. = 0.0045 in.)

Min Mounted RIC: 0.178 mm – 0.089 mm = 0.089 mm

(0.0070 in. – 0.0035 in. = 0.0035 in.)

Step 6:

Use table 42 (page 86) to determine Axial Displacement of Inner Ring for RIC Reduction.

Example: 22328KEJW33C3 140 mm bore (5.5118 in.) 22328KEJW33C3 is a 223 series which has a 1:12

tapered bore.

Axial Displacement of Inner Ring for RIC Reduction is

0.890 mm – 1.270 mm (0.035 in. – 0.050 in.).

Step 7:

Place bearing on tapered shaft (or tapered sleeve) until line-toline contact exists with the bearing bore.

Fig. 92. During mounting, the

RIC should be checked at

the unloaded roller.

Step 8:

Use a locknut (or hydraulic nut) to apply installation force and move the bearing up the shaft or tapered sleeve until the mounted RIC reaches the desired range established in Step 5. During mounting, RIC should be measured at unloaded roller.

Example: 22328KEJW33C3 140 mm bore (5.5118 in.) Mounted RIC range is 0.089 mm – 0.114 mm

(0.0035 in. – 0.0045 in.).

Step 9:

Use table 42 (page 86) to evaluate mounted RIC against Minimum Permissible RIC After Installation.

Example: 22328KEJW33C3 140 mm bore (5.5118 in.) The minimum permissible RIC after mounting would be

0.075 mm (0.0030 in.).

Step 7 (Alternative Procedure):

Use a locknut (or hydraulic nut) to apply installation force and move the bearing up the shaft or tapered sleeve until the axial displacement of the inner ring reaches the desired range. During mounting, the axial displacement of the inner ring should be measured.

Example: 22328KEJW33C3 140 mm bore (5.5118 in.) Axial Displacement of Inner Ring for RIC Reduction is

0.890 mm – 1.270 mm (0.035 in. – 0.050 in.).

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

TAPERED ROLLER BEARINGS

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

EXAMPLE #2 – Calculating RIC Reduction Using a Spherical Roller Bearing with Cylindrical Bore

Step 1:

Gather general information required for ﬁtting practice review.

- Bearing Bore and OD Dimensions/Tolerances

- Bearing operating conditions (Load/Speed)

Calculate bearing loading to bearing rating ratio by dividing the expected radial load by the basic dynamic radial load rating (BDLR) of the bearing.

Example: 22230EMW33

- Bore: 149.975 mm -150.00 mm (5.9045 in. – 5.9055 in.)

- OD: 269.965 mm – 270.00 mm (10.6285 in. – 10.6299 in.)

- BDLR: 1000 KN (225,000 lbf)

- Speed: 1,200 RPM; rotating shaft

- Radial Loading: 90 KN (20,250 lbf)

- Lubrication: grease

- Load/Bearing Rating Ratio: 90 KN/1000 KN (20,250 lbf/225,000 lbf) = 0.09 P= 0.09

Step 2:

Determine which shaft and housing ﬁts should be used.

- Using table 56 (page 126) determine the suggested ﬁts for the inner ring on the shaft.

- Using table 57 (page 127) determine the suggested ﬁts for the outer ring in the housing.

Example: 22230EMW33

Inner Ring/Shaft: 150 mm (5.9055 in.)

- Rotating inner ring

- Normal/light loads applied

- ISO ﬁt – p6 suggested

Outer Ring: 270 mm OD (10.6299 in.)

- Solid, one piece housing

- Normal/light loads applied

- ISO ﬁt – H8 suggested

Step 3:

Determine the shaft OD and housing bore dimensions/tolerances.

- Using tables 68 and 69 (pages 132-137) determine the suggested shaft diameter dimensions

- Using table 70 and 71 (pages 138-145) determine the suggested housing bore dimension

Example: 22230EMW33

Shaft dimensions: p6 ﬁt selected Shaft tolerance: +0.043 mm/+0.068 mm

(+0.0017 in./+0.0027 in.)

Shaft diameter: 150.043 mm – 150.068 mm

(5.9072 in. – 5.9082 in.)

Housing Dimensions: H8 ﬁt selected Housing tolerance: +0.000 mm/+0.081 mm

(+0.0000 in./+0.0032 in.)

Housing diameter: 270.000 mm – 270.081 mm

(10.6299 in. – 10.6331 in.)

Step 4:

Calculate the resultant ﬁts on the shaft and in the housing.

- Calculate the maximum and minimum interference ﬁt on the shaft.

- Calculate the maximum and minimum interference ﬁt in the housing.

- Note: Negative resultant ﬁts are tight ﬁt interference.

- Note: Positive resultant ﬁts are loose ﬁt interferences.

Example: 22230EMW33

Shaft Fit: Max interference = min bore – max shaft OD 149.975 mm –

150.068 mm = -0.093 mm (tight ﬁt) OR

5.9045 in. – 5.9082 in. = -0.0037 in. (tight ﬁt)

Min interference = max bore – min shaft OD 150.000 mm –

150.043 mm = -0.043 mm (tight ﬁt) OR

5.9055 in. – 5.9072 in. = -0.0017 in. (tight ﬁt)

Housing Fit: Max interference = min housing bore – max bearing OD

270.000 mm – 270.000 mm = 0.000 mm (loose) OR

10.6299 in. – 10.6299 in. = 0.0000 in. (loose)

Min interference = max housing bore – min bearing OD

270.081 mm – 269.965 mm = +0.116 mm (loose) OR

10.6331 in. – 10.6285 in. = +0.0046 in. (loose)

90 TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

Step 5:

Calculate the RIC reduction due to ﬁts.

- RIC reduction due to tight ﬁt on the shaft = approx. 80% of the ﬁt

- RIC reduction due to tight ﬁt on the housing = approx. 60% of the ﬁt

Example: 22230EMW33

RIC reduction due to tight ﬁt on shaft: Max RIC reduction: 0.80 x 0.093 mm = 0.074 mm

(0.80 x 0.0037 in. = 0.0030 in.)

Min RIC reduction: 0.080 x 0.043 mm = 0.034 mm

(0.80 x 0.0017 in. = 0.0014 in.)

RIC reduction is due to loose ﬁt in the housing. No reduction in RIC is due to loose ﬁt.

Step 6:

Use table 40 (page 84) to determine the unmounted RIC.

Example: 22230EMW33

RIC designation is C0 (normal)

Unmounted RIC: 0.110 mm – 0.170 mm (0.0043 in. – 0.0067 in.)

Step 7:

Calculate the mounted RIC.

- Calculate the max mounted RIC Max unmounted RIC – min RIC ﬁt reduction

- Calculate the min mounted RIC Min unmounted RIC – max RIC ﬁt reduction

Example: 22230EMW33

Max mounted RIC: 0.170 mm – 0.034 mm = 0.136 mm

(0.0067 in. – 0.0014 in. = 0.0053 in.)

Min mounted: RIC 0.110 mm – 0.074 mm = 0.036 mm

(0.0043 in. – 0.0030 in. = 0.0013 in.)

Step 8:

Use table 40 (page 84) to evaluate the mounted RIC.

Example: 22230EMW33 (which has a C0 RIC)

Min permissible RIC is 0.056 mm (0.0022 in.)

Since min mounted RIC is below min permissible level, C0 ﬁt selection needs to be reevaluated.

Step 9:

Review ﬁtting repeating steps 6-8 using C3 clearance levels.

Example: 22230EMW33C3

Unmounted RIC: 0.170 mm – 0.220 mm (0.0067 in. – 0.0087 in.) Mounted RIC: 0.096 mm – 0.186 mm (0.0037 in. – 0.0073 in.)

Mounted RIC is greater than min permissible, so C3 ﬁt appears to be acceptable.

Step 10:

Conﬁrm RIC designation selection against operating speeds. As a general rule of thumb, the RIC level is increased for

bearings operating at speeds that exceed 70% of thermal speed rating (page 56).

Example: 22230EMW33C3

From page 74 of the Spherical Roller Bearing Catalog (Order

No. 10446), thermal reference speed: 2,000 rpm 2,000 rpm x 0.7 = 1,400 rpm Current operating speed of application is 1,200 rpm.

Current C3 clearance designation appears to be acceptable.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS • INSTALLATION

INSTALLATION

When using a tight ﬁt inner ring, the method of assembly will depend on whether the bearing has a cylindrical or tapered bore.

CLEANLINESS

Choose a clean environment, free from dust and moisture.

•

The installer should make every effort to ensure cleanliness

•

by use of protective screens and clean cloths.

PLAN THE WORK

Know your plans in advance and have the necessary tools

•

at hand. This reduces the amount of time for the job and decreases the chance for dirt to get into the bearing.

INSPECTION AND PREPARATION

All component parts of the machine should be on hand and

•

thoroughly cleaned before proceeding. Housings should be cleaned, including blowing out the

•

oil holes. Do not use air hose on bearings.

•

If blind holes are used, insert a magnetic rod to remove

•

metal chips that might be lodged there during fabrication. Shaft shoulders and spacer rings contacting the bearing

•

should be square with the shaft axis. The shaft ﬁllet must be small enough to clear the radius of

•

the bearing. On original installations, all component parts should

•

be checked against the detail speciﬁcation prints for dimensional accuracy. Shaft and housing should be carefully checked for size and form (roundness, etc.).

SHAFT AND HOUSING FINISH

Shaft surfaces on which the bearing will be mounted must

•

be clean and free from nicks and burrs. For applications with stationary housing and rotating shaft,

•

it is suggested that the bearing seat on the shaft be ground to 1.6 µm (65 µin.) Ra maximum.

If it is impractical to use a ground ﬁnish, a machined ﬁnish

•

of 3.2 µm (125 µin.) Ra is acceptable in many cases, but the amount of interference ﬁt should be slightly increased.

Housing bores should be ﬁnished to 3.2 µm (125 µin)

•

Ra maximum.

Note: Do not remove the bearing from its wrapping until you are ready to mount it.

Bearing

Bearing held from bottom by screen

Oil

Bearing support block

Flame burner

INSTALLING CYLINDRICAL BORE BEARINGS

Heat expansion method

Most applications require a tight interference ﬁt on

•

the shaft. Mounting is simpliﬁed by heating the bearing to expand it

•

sufﬁciently to slide easily onto the shaft. Two methods of heating are commonly used:

•

- Tank of heated oil.

- Induction heating. The ﬁrst is accomplished by heating the bearing in a tank of

•

oil that has a high ﬂash point. The oil temperature should not be allowed to exceed 121° C

•

(250° F). A temperature of 93° C (200° F) is sufﬁcient for most applications.

The bearing should be heated for 20 or 30 minutes, or until it

•

is expanded sufﬁciently to slide onto the shaft easily. The induction heating process can be used for

•

mounting bearings. Induction heating is rapid. Care must be taken to prevent

•

bearing temperature from exceeding 93° C (200° F). Trial runs with the unit and bearing are usually necessary to

•

obtain proper timing. Thermal crayons melted at predetermined temperatures

•

can be used to check the bearing temperature. While the bearing is hot, it should be positioned squarely

•

against the shoulder. Lockwashers and locknuts or clamping plates are then

•

installed to hold the bearing against the shoulder of the shaft.

As the bearing cools, the locknut or clamping plate should

•

be tightened. In cases of outer ring rotation, where the outer ring is

•

a tight ﬁt in the housing, the housing member can be expanded by heating.

The oil bath is shown in ﬁg. 93. The bearing should not be in

•

direct contact with the heat source. The usual arrangement is to have a screen several inches

•

from the bottom of the tank. Small support blocks separate the bearing from the screen.

It is important to keep the bearing away from any

•

localized high-heat source that may raise its temperature excessively, resulting in ring hardness reduction.

Flame-type burners are commonly used. An automatic

•

device for temperature control is desirable. If safety regulations prevent the use of an open heated oil

•

bath, a mixture of 15 percent soluble-oil water may be used. This mixture may be heated to a maximum of 93° C (200° F) without being ﬂammable.

Fig. 93. Heat expansion method.

92 TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

ARBOR PRESS METHOD

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS • INSTALLATION

Arbor press method

An alternate method of mounting, generally used only on

•

smaller size bearings, is to press the bearing onto the shaft or into the housing. This can be done by using an arbor press and a mounting tube as shown in ﬁg. 94.

The tube should be made from soft steel with an inside

•

diameter slightly larger than the shaft. The O.D. of the tube should not exceed the shaft

•

backing diameter. The tube should be faced square at both ends. It should

•

be thoroughly clean inside and out, and long enough to clear the end of the shaft after the bearing is mounted.

If the outer ring is being

•

pressed into the housing, the O.D. of the mounting tube should be slightly smaller than the housing bore. The I.D. should not be less than the suggested housing backing diameter in the table of dimensions.

Coat the shaft with a light

•

machine oil to reduce the force needed for a press ﬁt.

Carefully place the bearing

•

on the shaft, making sure it is square with the shaft axis.

Apply steady pressure from

•

the arbor ram to drive the bearing ﬁrmly against the shoulder.

Never attempt a press ﬁt on a shaft by applying pressure to the outer ring or a press ﬁt in a housing by applying pressure to the inner ring.

Fig. 94. Arbor press method.

NOTE

Mounting tapered bore spherical roller bearings

Use a feeler gage with the thinnest blade of 0.038 mm

•

(0.0015 inch). Place the bearing in an upright position with the inner and

•

outer ring faces parallel. Place thumbs on the inner ring bore and oscillate the inner

•

ring the distance of two or three roller spacings. Position the individual roller assemblies so that a roller is at

•

the top of the inner ring on both sides of the bearing. With the roller in the correct position, insert a thin blade of

•

the feeler gage between the roller and the outer ring. Move the feeler gage carefully along the top roller between

•

the roller and outer ring raceway. Repeat this procedure using thicker feeler gage blades until one is found that will not go through.

The blade thickness that preceded the “no-go” blade is a

•

measure of RIC before installation. Start the mounting procedure by lubricating the tapered

•

shaft with a light coat of machine oil. Slide the bearing onto the shaft as far as it will go by hand.

•

As the locknut is tightened, the interference ﬁt builds up,

•

resulting in expansion of the inner ring. Periodically measure to keep track of the reduction in RIC.

•

Continue the procedure until the proper amount of

•

reduction is obtained. Do not exceed suggested amount of reduction.

As a ﬁnal check, make sure the remaining RIC equals or

•

exceeds the minimum mounted clearance shown in table 42. During mounting, the RIC should be checked at the

•

unloaded roller. If this is at the bottom, make sure that the roller is raised to seat ﬁrmly at the inboard position of the inner ring.

When the suggested amount of RIC reduction has been

•

accomplished, the bearing is properly ﬁtted. Complete the procedure by peening the lockwasher tang

•

into the locknut slot or securing the lockplate.

NOTE

Never use steam or hot water when cleaning the bearings because these methods can create rust or corrosion.

NOTE

Never expose any surface of a bearing to the ﬂame of a torch.

NOTE

Do not heat bearing beyond 149˚ C (300˚ F).

Fig. 95. Measure RIC before installation.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

Fig. 27:

ARBOR PRESS METHOD

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

TAPERED ROLLER BEARINGS

SPHERICAL AND CYLINDRICAL ROLLER BEARINGS

Mounting Cylindrical Bore Bearings -continued

Arbor press method

An alternate method of mounting, generally used only on

•

smaller size bearings, is to press the bearing onto the shaft or into the housing. This can be done by using an arbor press and a mounting tube as shown in ﬁg. 96.

The tube should be made from soft steel with an inside

•

diameter slightly larger than the shaft.

The O.D. of the tube should not exceed the shaft backing

•

diameter given in the Timken Spherical Roller Bearing Catalog (order no. 10446), found on www.timken.com.

The tube should be faced square at both ends. It should be

•

thoroughly clean inside and out, and long enough to clear the end of the shaft after the bearing is mounted.

Mounting tapered bore spherical roller bearings

Use a feeler gage with the thinnest blade of 0.038 mm

•

(0.0015 in.).

Place the bearing in an upright position with the inner and

•

outer ring faces parallel.

Place thumbs on the inner ring bore and oscillate the inner

•

ring the distance of two or three roller spacings.

Position the individual roller assemblies so that a roller is at

•

the top of the inner ring on both sides of the bearing.

With the roller in the correct position, insert a thin blade of

•

the feeler gage between the roller and the outer ring.

Move the feeler gage carefully along the top roller between

•

the roller and outer ring raceway. Repeat this procedure using thicker feeler gage blades until one is found that will not go through.

The blade thickness that preceded the “no-go” blade is a

•

measure of RIC before installation.

Start the mounting procedure by lubricating the tapered

•

shaft with a light coat of machine oil.

Slide the bearing onto the shaft as far as it will go by hand.

•

As the locknut is tightened, the interference ﬁt builds up,

•

resulting in expansion of the inner ring.

•

Fig. 96. Arbor press method.

If the outer ring is being pressed into the housing, the O.D. of the mounting tube should be slightly smaller than the housing bore. The I.D. should not be less than the suggested housing backing diameter in the table of dimensions available in the Timken Spherical Roller Bearing Catalog (order no. 10446), found on www.timken.com.

Coat the shaft with a light machine oil to reduce the force needed for a press ﬁt.

Carefully place the bearing on the shaft, making sure it is square with the shaft axis.

Apply steady pressure from the arbor ram to drive the bearing ﬁrmly against the shoulder.

NOTE

Never attempt a press ﬁt on a shaft by applying pressure

to the outer ring or a press ﬁt in a housing by applying

pressure to the inner ring.

Periodically measure to keep track of the reduction in RIC.

•

Continue the procedure until the proper amount of reduction

•

is obtained. Do not exceed suggested amount of reduction.

As a ﬁnal check, make sure the remaining RIC equals or

•

exceeds the minimum mounted clearance shown in table 42.

During mounting, the RIC should be checked at the unloaded

•

roller. If this is at the bottom, make sure that the roller is raised to seat ﬁrmly at the inboard position of the inner ring.

When the suggested amount of RIC reduction has been

•

accomplished, the bearing is properly ﬁtted.

Complete the procedure by peening the lockwasher tang

•

into the locknut slot or securing the lockplate.

Fig. 97. Measure of RIC before installation.

94 TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

ANGULAR CONTACT BALL BEARINGS

MOUNTING

Like tapered roller bearings, angular contact ball bearings are designed to take both radial and thrust loading. Forces are transmitted from the inner raceway to the outer raceway along a given contact angle, which is deﬁned as the angle between the line of action of forces and a radial plane; see ﬁg. 98. Forces along this contact angle can be resolved into radial and axial components. The axial force must be counteracted. As a result, most angular contact bearings are mounted in pairs and preloaded against each other to counteract the induced axial load from the opposing bearing and to stiffen the assembly in the axial direction.

Contact angle

Combined load

Axial or

thrust load

Radial

load

A duplex bearing is comprised of two single-row bearings that are manufactured speciﬁcally for use as a unit. It is analogous to a double-row bearing having the same bore and outside diameter but twice the single-row width. Duplex bearings may be mounted back-to-back, face-to-face or in tandem as shown in ﬁgs. 100-102. The tandem mounting arrangement is used to achieve greater thrust-carrying capacity.

Typical applications for duplex angular contact ball bearings include deep well pumps, marine propeller shafts, machine tool spindles, speed reducers and elevator worm drives.

Duplex bearings may be used with spacers to increase bearing spread, which in turn increases the resistance to moment loading and decreases shaft deﬂection. Shaft and housing spacers must be accurately ground to the desired widths to ensure that proper preload is maintained. In addition, attention should be given to shaft and housing ﬁts, squareness of shaft and housing shoulders and alignment of mating parts.

Fig. 98. Example of ball bearing loading.

In the case where an angular contact ball bearing is mounted alone, it requires adjustments and must be installed with care. As the bearing is relatively loose axially before mounting, it is important that the design incorporates some means to move the outer ring axially into its correct position relative to the inner ring. This adjustment should be made when the bearing is mounted. A common method is to place a preloaded spring or shims between either the inner raceway and shaft shoulder or outer raceway and housing such that the outer raceway is seated against the inner raceway.

Bearing

Fig. 99. Typical preload mountings.

Bearing

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

ANGULAR CONTACT BALL BEARINGS

Typical mountings of duplex bearings

Back-to-back mounting, DB or (O) (Contact angles diverging toward shaft centerline)

Before mounting, there is clearance between the two adjacent inner-ring faces. After mounting, these faces are clamped together to provide an internal preload on each bearing. This arrangement is well-suited for pulleys, sheaves and in other applications where there are overturning loads. It also is suited in all ﬂoating positions where thermal expansion of the shaft occurs. It provides axial and radial rigidity and equal thrust capacity in either direction when used in a ﬁxed location. Back-to-back is the most commonly used of all duplex arrangements.

Marked faces

of outer rings

together.

Clearance

between

inner-ring faces.

Inner-ring faces

clamped together.

These inner- and

outer-ring faces

are ﬂush.

Face-to-face mounting, DF or (X) (Contact angles converging toward shaft centerline)

Before mounting, there is clearance between the two adjacent outer-ring faces. After mounting, these faces are clamped together between the housing shoulder and cover-plate shoulder. This provides an internal preload on each bearing. This arrangement provides equal thrust capacity in either direction, as well as radial and axial rigidity.

Since the face-to-face mounting has inherent disadvantages of low resistance to moment loading and thermal instability, it should not be considered unless a signiﬁcantly more convenient method of assembly or disassembly occurs from its use.

Unmarked faces

of outer rings

together.

Clearance

between

outer-ring faces.

These inner- and

outer-ring faces

not ﬂush.

Inner- and

outer-ring faces

clamped together.

Faces ﬂush

on both sides.

Before mounting Mounted

Fig. 100. Back-to-back bearing assemblies before and after mounting.

Before mounting Mounted

Fig. 101. Face-to-face bearing assemblies before and after mounting.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

ANGULAR CONTACT BALL BEARINGS

Tandem mounting, DT

Before mounting, the inner-ring faces of each bearing are offset from the outer-ring faces. After mounting, when a thrust load is applied equal to that of twice the normal preload, the inner- and outer-ring faces are brought into alignment on both sides. This arrangement provides double thrust capacity in one direction only. More than two bearings can be used in tandem if additional thrust capacity is required.

One marked and

one unmarked

outer-ring face

together.

Under axial

Inner- and

outer-ring faces

not ﬂush

on either side.

Before mounting Mounted

load equivalent to

twice the normal

preload. Inner-

and outer-ring

faces are ﬂush

on both sides.

Fig. 102. Tandem bearing assemblies before and after mounting.

Other mountings

Flush-ground (DU) pairs may be mounted in combination with a single ﬂush-ground bearing as a triplex (TU) set shown below (ﬁg. 103). Also shown below is a quadruplex (QU) set where three bearings in tandem are mounted back-to-back with a single bearing. These arrangements provide high capacity in one direction and also a positively rigid mounting capable of carrying a moderate amount of reverse thrust.

TU QU

Fig. 103. Typical triplex and quadruplex bearing mountings.

TIMKEN ENGINEERING MANUAL

MOUNTING DESIGN, FITTING PRACTICE, SETTING AND INSTALLATION

ANGULAR CONTACT BALL BEARINGS

FITTING PRACTICE

Recommended shaft ﬁts are listed in table 72 on page 146 for 7000WN, 7200WU, 7300WN and 7400WN series.

This table is to be

used for applications where only one ring (either inner or outer) has an interference ﬁt. In cases where interference ﬁts are used for both rings, bearings with a special internal clearance may be required. Shaft diameter dimensions are for solid steel shafts. Consult your Timken engineer when special ﬁts are required or when using hollow shafts.

SETTING

Timken has established standard preload levels that are considered proper for most duplex bearing applications. Special preloads also can be provided to satisfy extreme requirements. For example, a heavily loaded, slow-speed rotating shaft may require heavier-than-normal preload in order to minimize deﬂection. Although heavy preload provides slightly greater rigidity, it reduces bearing life and increases power consumption; therefore, preload levels should be chosen with care.

The axial deﬂection of a bearing subject to thrust loading is based on Hertz’s theories for elastic bodies in contact. The general expression is:

1/3

= K

A typical axial deﬂection curve for an unpreloaded single-row angular contact bearing is shown as curve A in ﬁg. 104. This curve represents the deﬂection characteristics of bearing A being subjected to thrust load F to load F

by doubling the thrust load to F deﬂection of a ball bearing.

( )

. The amount of deﬂection due

is much greater than the increase in deﬂection caused

. This illustrates the non-linear

Curves C1 and C2 show the deﬂection of a double-row preloaded bearing as shown in ﬁg. 104. Curve C having a preload of F a preload of F

and curve C2 represents the bearing having

. Comparing curves C1 and C2 with curve A shows

represents the bearing

the deﬂection of the preloaded pair is much lower than that of the unpreloaded bearing.

Curves B mounted in ﬁg. 105, from the preloaded conditions F

and B2 show the axial deﬂection of bearing B as

or F

to a

non-preload condition.

Preloading can be accomplished by using springs or spacer width adjustment, but consult your Timken engineer for design review.

Deﬂection

Load, F

Fig. 104. Axial load-deﬂection curve of back-to-back mounted angular contact bearings. Curve A is for bearing A; B is for bearing B; and C1 and C2 are preload curves.

TIMKEN ENGINEERING MANUAL

Bearing

Fig. 105. Typical preload mountings.

Bearing

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Frequently Asked Questions

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