Timken Setting Techniques for Tapered Roller Bearings User Manual
Setting Techniques for Tapered Roller Bearings
TECHNIQUES FOR TAPERED ROLLER BEARINGS
1
Failure to observe the following warnings
could create a risk of death or serious injury.
Proper maintenance and handling procedures are critical. Always follow
installation instructions and maintain proper lubrication.
Never spin a bearing with compressed air. The rollers may be forcefully expelled.
Overheated bearings can ignite explosive atmospheres. Special care must
be taken to properly select, install, maintain, and lubricate bearings that are
used in or near atmospheres that may contain explosive levels of combustible
gases or accumulations of dust such as from grain, coal, or other combustible
materials. Consult your equipment designer or supplier for installation and
maintenance instructions.
Tensile stresses can be very high in tightly fitted bearing components.
Attempting to remove such components by cutting the cone (inner race) may
result in a sudden shattering of the component causing fragments of metal to
be forcefully expelled. Always use properly guarded presses or bearing pullers
to remove bearings from shafts, and always use suitable personal protective
equipment, including safety glasses.
CAUTION
Failure to follow these cautions could
create a risk of injury.
If hammer and bar are used for installation or removal of a part, use a mild steel bar
(e.g., 1010 or 1020 grade). Mild steel bars are less likely to cause release of
high-speed fragments from the hammer, bar or the part being removed.
Remove oil or rust inhibitor from parts before heating to avoid fire or fumes.
CAUTION
Failure to follow these cautions may
result in property damage.
Do not use damaged bearings.
Use of improper bearing fits may cause damage to equipment.
Please consult with your Timken engineer for more information and assistance.
NOTE
Do not use excessive force when mounting or dismounting the unit.
Follow all tolerance, fit, and torque recommendations.
Always follow the Original Equipment Manufacturer’s installation and maintenance guidelines.
Ensure proper alignment.
Do not heat components with an open flame.
Do not heat bearing beyond 300° F.
Unless directed otherwise by Timken, products should be kept in their original packaging until they are ready to be placed in service.
Components may become damaged and affect the performance and service life of bearing.
Do not attempt to disassemble unitized bearings.
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.
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TECHNIQUES FOR TAPERED ROLLER BEARINGS
DISCLAIMER
SETTING TECHNIQUES FOR
TAPERED ROLLER BEARINGS
Tapered Roller Bearing Setting Techniques .............................................. 4
Bearing Setting............................................................................................... 4
Manual Bearing Setting ................................................................................ 6
Preset Bearing Assemblies .......................................................................... 7
Automated Bearing Setting Techniques .................................................... 7
Set-Right .......................................................................................................... 8
Acro-Set ........................................................................................................ 11
Projecta-Set .................................................................................................. 13
Torque-Set ..................................................................................................... 14
Mounting Designs And Setting Devices .................................................. 16
Summary........................................................................................................ 18
TECHNIQUES FOR TAPERED ROLLER BEARINGS
3
BEARING SETTING
SETTING TECHNIQUES FOR
TAPERED ROLLER BEARINGS
TAPERED ROLLER BEARING
SETTING TECHNIQUES
Tapered roller bearings can be set at initial machine assembly
to any desired axial or radial clearance. This unique feature
enables a designer to control bearings to meet anticipated
application operating conditions, and thereby provide optimum
bearing and system performance.
Some advantages of tapered roller bearings pertaining to
setting include:
Longer bearing life, achieved by optimizing bearing settings
•
while meeting application performance requirements.
Increased mounting stiffness, achieved by properly set
•
tapered roller bearings resulting, for example, in better gear
contact and longer gear life.
Easier assembly because cone and cup are separable.
•
The bearings can be set at the time of machine assembly,
•
allowing wider shaft and housing tolerances.
The setting of tapered roller bearings can be readily
accomplished by a wide variety of viable methods. These
bearings can be set manually, supplied as preset assemblies,
or set by automated techniques. There are a number of
approaches, considerations and advantages of each with
special focus on five popular automated techniques (i.e. SET-
TM
RIGHT
CLAMP-SET
BEARING SETTING
With tapered roller bearings, the term “setting” simply
indicates the specific amount of end play (axial clearance)
or preload (axial interference) within a mounted bearing. The
flexibility to easily adjust and optimize setting at the time of
assembly is an inherent advantage of tapered roller bearings.
Unlike other types of anti-friction bearings, tapered roller
bearings do not require tight control of shaft or housing fits to
obtain setting. Because tapered roller bearings are mounted
in pairs (Figure 1), their setting is primarily dependent upon the
axial location of one bearing row relative to the opposite row.
, ACRO-SETTM, PROJECTA-SETTM, TORQUE-SETTM, and
TM
). SeeTable 1.
Figure 1. Simplified machine assembly showing a typical
tapered roller bearing (indirect) mounting
The three primary conditions of bearing setting are defined as:
End play — An axial clearance between rollers and races
•
producing a measurable axial shaft movement when a
small axial force is applied, first in one direction and then
in the other, while oscillating or rotating the shaft (the
reference bearing load zone less than 180 degrees).
Preload — An axial interference between rollers and races
•
such that there is no discernible axial shaft movement when
measured as described above. A rolling resistance to shaft
rotation results which may be measured (load zone greater
than 180 degrees).
Line-to-line — A zero setting condition, the transitional
•
point between end play and preload.
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 permits the determination of optimum settings.
Frequently, however, the exact relationship of ambient to
operating bearing settings is unknown and an educated
estimate has to be made. To determine a suggested ambient
bearing setting for a specific application, contact a Timken
sales engineer or representative.
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TECHNIQUES FOR TAPERED ROLLER BEARINGS
Requirements
Mounted bearing
setting range, in.
(Typical Min to Max)
TABLE 1 - COMPARISON OF TAPERED ROLLER BEARING SETTING METHODS
SETTING METHOD
Manual
0.004 -
0.010
Preset
assembly
0.006 -
0.012
Set-Right Acro-Set Projecta-Set Torque-Set Clamp-Set
0.008 -
0.014
(probable)
0.0 04 -
0.006
0.002 -
0.004
BEARING SETTING
0.005 -
0.007
0.003-
0.005
Mounted setting region
Loose fitted member
for adjustment?
Apply set-up load?
Special gauges,
fixtures; components?
Special bearing codes
or assemblies?
Pretesting needed to
develop method?
Typical production volume
Assembler skill
or training level
Shim pack applied?
End play
No No No Yes No No Yes
Yes No No Yes (constant)
No No No No
No
No No Yes (limited) Yes Yes
Low to
Moderate
High Low Low
Yes No No Yes Yes Yes
End play or
preload
Yes
“Matched”
assembly
Low to High
End play or
preload
Yes Codes &
spacers
Moderate
to High
End play or
preload
No No
Low to High
Low-Med
Chart reading
End play or
preload
Yes
Gauge spring
Yes
Special gauge
& LVDT*
Moderate
to High
Low
LVDT reading
End play or
preload
Yes Yes (constant)
Yes
Rolling torque
gauge
No No
Yes Yes
Low to High
Low-Med Chart/
gauge reading
End play
Yes
Compensating
ring
Low to High
Low
Yes
constant size
Shim gap measurement?
Possible use of wider
bearing system mounting
tolerances?
Bearing rotation
or oscillation?
Applicable for field service?
Readily applicable
to large, heavy units?
Note: All bearing setting methods above require proper backing and positive clamping of bearing components.
* Linear Variable Differential Transformer (LVDT)
Yes No No Yes
Yes
Yes No No Yes Yes Yes Ye s
Yes Yes Yes
No Yes Yes Yes No No No
No
Control fit
tolerances
No
Need tighter
tolerances
Yes Yes Yes Ye s
Yes (with
service
manual)
No
(LVDT)
No
No
(brg torque)
Yes
(with manual
and new brgs)
No
Yes
TECHNIQUES FOR TAPERED ROLLER BEARINGS
5
MANUAL BEARING SETTING
Generally, the ideal operating bearing setting is near- zero to
maximize bearing life. Most bearings are set with a cold setting
of end play at assembly. This comes as close as possible to the
desired near-zero setting when the unit reaches its stabilized
operating temperature.
Some applications are set with cold preload to increase
rigidity and axial positioning of highly stressed parts that
would otherwise be dramatically affected by excessive
deflection and misalignment.
Excessive operating preload must be avoided as bearing
fatigue life can be drastically reduced. Also, excessive
operating preload can lead to lubrication problems and
premature bearing damage due to high heat generation.
Load zone is a physical measure of the raceway loaded arc
and is a direct indication of how many rollers share the applied
load. For a single-row tapered roller bearing, maximum life
is obtained with a load zone of approximately 225 degrees.
Figure 2 shows the graphical representation of bearing L10 life
versus operating bearing setting for a typical (overhung) pinion
bearing mounting.
The ideal operating setting that will maximize bearing system
life is generally near-zero to slight preload.
Figure 3. Truck Nondriven Wheel
MANUAL BEARING SETTING
15000
10000
5000
LIFE – hours
0.41 mm
(.016”)
Environment
Adjusted Life of
Seated Bearing
Bearing
System Life
0.20 mm
(.008”)
Optimum
Setting
0
Environment
Adjusted Life of
Set-up Bearing
Non-Adjusted
System Life
0.20 mm
(.008”)
PRELOADENDPLAY
BEARING AXIAL SETTING
Figure 2. Calculated Bearing L10 Life vs. Operating Setting
Manual methods are frequently used to set bearings on a
variety of equipment with low to moderate volume production
requirements whereby a non- exact, primarily end play, setting
range variation is acceptable. No special tooling, gauges,
charts or fixtures are typically required, but assembler’s skill
and judgment are necessary. For example, in the case of a
conventional truck non-driven wheel with a single adjusting
nut design (Figure 3), manual setting involves tightening the
adjusting nut while rotating the wheel until a slight bind is felt.
Then the adjusting nut is backed off 1/6 to 1/4 turn to the nearest
locking hole or sufficiently to allow the wheel to rotate freely
with some minimal end play. The adjusting nut is then locked in
this position. Skill and judgment are required to determine when
the wheel binds slightly in rotation. The more complicated the
equipment and/or the larger and heavier it is, the greater degree
of skill and judgment required.
For certain complex designs, large equipment or high
production applications, manual setting may be too
troublesome, of inappropriate accuracy and reliability, or too
time consuming. The Timken Company has devised preset
bearing assemblies and automated setting techniques as
alternatives to manual setting.
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TECHNIQUES FOR TAPERED ROLLER BEARINGS
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