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EZT

Hydro Gear EZT Service Manual

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Page 1
EZT
®
Integrated Zero-Turn Transaxle
Service and Repair Manual
(ZC & ZD Models)
BLN-52622
December 2008
www.mymowerparts.com
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TABLE OF CONTENTS
Section Page
Foreword .............................................................................................................................. 1
Description and Operation ................................................................................................. 2
Introduction .................................................................................................................................................. 2
General Description ..................................................................................................................................... 2
Hydraulic Schematic .................................................................................................................................... 3
External Features -EZT® ......................................................................................................................... 4
Technical Specifi cations ............................................................................................................................... 5
Product Identifi cation ................................................................................................................................... 5
Safety .................................................................................................................................... 6
Personal Safety ............................................................................................................................................ 6
Tool Safety ................................................................................................................................................... 6
Work Area Safety ......................................................................................................................................... 6
Servicing Safety ........................................................................................................................................... 6
Troubleshooting .................................................................................................................. 7
Service and Maintenance.................................................................................................... 8
External Maintenance .................................................................................................................................. 8
Service and Maintenance Procedures ......................................................................................................... 8
Fluids ........................................................................................................................................................... 8
Fluid Volume and Level ................................................................................................................................ 8
Fluid Change Procedure .............................................................................................................................. 9
Purging Procedures ................................................................................................................................... 10
Return to Neutral Setting ............................................................................................................................11
Repair ................................................................................................................................. 12
How To Use This Section ........................................................................................................................... 12
General Instructions ................................................................................................................................... 12
Transaxle Removal .................................................................................................................................... 12
Limited Disassembly .................................................................................................................................. 12
Tools and Torques ...................................................................................................................................... 13
Control Arm and Bypass Arm ..................................................................................................................... 14
Seal Kit Replacement ................................................................................................................................ 15
Cog Brake Assembly .................................................................................................................................. 16
Disc Brake Assembly ................................................................................................................................. 17
Side Cover ................................................................................................................................................ 18
Axle Shaft, Reduction Gears and Expansion Plate .................................................................................... 19
Motor Shaft ................................................................................................................................................ 20
Input Shaft and Bypass Rod ...................................................................................................................... 21
Hydraulic Components .......................................................................................................................... 22-26
Transaxle Installation ................................................................................................................................. 26
Assembly After a Complete Teardown ....................................................................................................... 27
Sealant Application ........................................................................................................... 28
Parts List ...................................................................................................................... 30, 31
Glossary of Terms ....................................................................................................... 32, 33
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FOREWORD
Headquartered in Sullivan, Illinois, Hydro-Gear® is a world leader in the design, manufacture, and service of quality hydrostatic transaxles for the lawn and garden industry. The mission of our company is to be recognized by our custom­ers and the industry as a world-class supplier and the quality leader in everything we do.
This Service and Repair Manual is designed to provide information useful in servicing and
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troubleshooting the Hydro-Gear EZT grated Zero-Turn Transaxle.
Also included is a glossary of terms that are frequently used throughout the industry and in Hydro-Gear service publications. Understand­ing terminology is very important!
It is necessary, and a good shop practice, that your service area be equipped with the proper tools and the mechanics be supplied the latest information available. All repair procedures illustrated in this guide are suggested, but pre­ferred methods of repair.
Inte-
Repair procedures require that the transaxle unit be removed from the vehicle.
This is not a certifi cation, test or study guide for a certifi cation test. If a technician is interested in certifi cation, they should contact an agent representing OPEESA (Outdoor Power Equip­ment and Engine Service Association) at (860) 767-1770 or their Hydro-Gear Central Service Distributor. Many distributors will be hosting certifi cation testing. These study guides will cover most of the products and manufacturers in our industry.
For more information about Hydro-Gear or our products, please contact your Central Service Distributor, or call our Customer Service Depart­ment at (217) 728-2581.
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SECTION 1. DESCRIPTION AND OPERATION
INTRODUCTION
The purpose of this manual is to provide infor-
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mation useful in servicing the Hydro-Gear grated Zero-Turn Transaxle (EZT®). This man­ual includes the EZT’s general descriptions, hydraulic schematics, technical specifi cations, servicing and troubleshooting procedures.
The transaxle normally will not require servic­ing during the life of the vehicle in which it is installed. Should other servicing be required, the exterior of the transaxle will need to be thoroughly cleaned before beginning most procedures. Do not wash the transaxle while it is hot. Do not use a pressure washer to
clean the unit.
Inte-
GENERAL DESCRIPTION
The EZT is a self contained unit designed for the transfer and control of power. It provides an infi nitely variable speed range between zero and maximum in both forward and reverse modes of operation.
This transaxle uses a variable displacement pump with a maximum displacement of 10cc per revolution, and motor with a fixed dis­placement of 10cc per revolution. The vari­able displacement pump features a trunnion mounted swashplate with a direct-proportional displacement control. Reversing the direction
of the swashplate reverses the fl ow of oil from the pump and thus reverses the direction of the motor output rotation. The pump and motor are of the axial piston design and utilize spherical nosed pistons which are held against a thrust race by internal compression springs.
The EZT has a self contained fl uid supply and an internal fi lter. The fl uid is forced through the fi lter by a positive “head” on the fl uid in the housing/expansion tank with an assist by the negative pressure created in the pump pistons as they operate.
The check valves in the center section are used to control the make-up fl ow of the fl uid to the low pressure side of the loop.
A cam style, block lifting bypass is utilized in the EZT to permit moving the vehicle for a short distance at a maximum of 2 m.p.h. (3.2 Km/h) without starting the engine.
WARNING
Actuating the bypass will result in the loss of hydrostatic braking capacity. The machine must be stationary on a level surface and in neutral when actuating the bypass.
Figure 1. Hydraulic Schematic
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EZT® HYDRAULIC FLOW SCHEMATIC
Figure 2. Hydraulic Flow Illustration
HYDRAULIC SCHEMATIC
Figure 2 provides an illustration of the hydraulic oil circuit. The oil supply for the hydraulic sys­tem of the EZT® is also utilized for lubricating the components of the fi nal drive assembly.
The input shaft and pump cylinder block are turned in one direction only by the engine/ drive belt/pulley combination. Output of the oil fl ow is controlled by the direction and amount that the variable swashplate is angled. As the pump pistons compress they force the oil to fl ow through one of two passageways (forward or reverse) in the center section to the motor cylinder block and motor shaft. Since the mo­tor has a fi xed displacement angle it is forced to turn with the fl ow of oil. As the angle of the pump swashplate is increased the amount of oil being pumped will increase and cause a
higher speed output of the motor. Reversing the angle of the pump swashplate will reverse the direction of oil fl ow.
During the operation of the transaxle, fl uid is “lost” from the hydraulic loop through leak paths designed into the product for lubrication purposes (around pistons, under the rotating cylinder blocks, etc.). This “lost” fl uid returns to the transaxle housing, then is pulled back into one of the check valves depending upon the direction of vehicle operation. All of this oil must pass through an internal fi lter.
The motor cylinder block mounts onto a splined motor shaft which drives the gear train.
The bypass feature in the EZT has a mechanical lever which lifts the motor block off of the center section running surface. This allows oil fl ow from the cylinder blocks to be discharged.
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EXTERNAL FEATURES EZT
MAIN HOUSING
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AXLE SHAFT
BYPASS ARM
SIDE COVER
FILL PORT
BRAKE ARM
INPUT SHAFT
CONTROL ARM
COG BRAKE DISC
FAN
PULLEY
AXLE SHAFT
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TECHNICAL SPECIFICATIONS
Technical specifi cations for the EZT® are listed in Table 1.
Table 1. Technical Specifi cations
Input Speeds Weight of Unit
Maximum: 3000 RPM 29 lbs. (13 Kg) Minimum: 1800 RPM
Table 2. EZT Component Options
Component Component Options Axle Shaft Diameter and End Options: 1˝ Flange 1˝ DD Brake Location: Inboard Outboard Brake Type: Cog Disc Control Arm Location: Inboard Outboard Control Arrangements: Standard Control Arm RTN (scissor style) Overall Transaxle Reduction: 19.2:1 21.2:1
PRODUCT IDENTIFICATION
The model and confi guration of the EZT can be determined from the label shown in Figure 3.
Figure 3. Confi guration Label
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SECTION 2. SAFETY
This symbol points out important safety
instructions which, if not followed, could endan­ger the personal safety and/or property of your­self and others. Read and follow all instruc­tions in this manual before attempting main­tenance on your transaxle. When you see this symbol - HEED ITS WARNING.
WARNING
POTENTIAL FOR SERIOUS INJURY
Inattention to proper safety, operation, or maintenance procedures could result in personal injury, or damage to the equipment. Before servicing or repair­ing the EZT®, fully read and understand the safety precautions described in this section.
PERSONAL SAFETY
Certain safety precautions must be observed while servicing or repairing the EZT. This sec­tion addresses some of these precautions but must not be considered an all-inclusive source on safety information. This section is to be used in conjunction with all other safety material which may apply, such as:
1) Other manuals pertaining to this machine,
2) Local and shop safety rules and codes,
3) Governmental safety laws and regula­tions.
Be sure that you know and understand the equipment and the hazards associated with it. Do not place speed above safety.
Notify your supervisor whenever you feel there is any hazard involving the equipment or the performance of your job.
Never allow untrained or unauthorized person­nel to service or repair the equipment.
Wear appropriate clothing. Loose or hanging clothing or jewelry can be hazardous. Use the appropriate safety equipment, such as eye and hearing protection, and safety-toe and slip-proof shoes.
Never use compressed air to clean debris from yourself or your clothing.
TOOL SAFETY
Use the proper tools and equipment for the task.
Inspect each tool before use and replace any tool that may be damaged or defective.
WORK AREA SAFETY
Keep the work area neat and orderly. Be sure it is well lit, that extra tools are put away, trash and refuse are in the proper containers, and dirt or debris have been removed from the working areas of the machine.
The fl oor should be clean and dry, and all ex- tension cords or similar trip hazards should be removed.
SERVICING SAFETY
Certain procedures may require the vehicle to be disabled in order to prevent possible injury to the servicing technician and/or bystanders.
The loss of hydrostatic drive line power may result in the loss of hydrostatic braking capa­bility.
Some cleaning solvents are fl ammable. Use only approved cleaning materials: Do not use explosive or fl ammable liquids to clean the equipment.
To avoid possible fi re, do not use cleaning solvents in an area where a source of ignition may be present.
Discard used cleaning material in the appropri­ate containers.
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SECTION 3. TROUBLESHOOTING
WARNING
Do not attempt any servicing or ad­justments with the engine running. Use extreme caution while inspecting the drive belt assembly and all vehicle linkage!
related to a defective transaxle, but are caused by slipping drive belts, partially engaged bypass valves, and loose or damaged control linkages. Be sure to perform all operational checks and adjustments outlined in Section 4, Service and Maintenance, before assuming the pump is malfunctioning. Table 3 below provides a
In many cases, problems with the EZT® are not
Follow all safety procedures outlined in the vehicle owner’s manual.
Table 3. EZT Troubleshooting Checklist
troubleshooting checklist to help determine the cause of operational problems.
Possible Cause Corrective Action
UNIT OPERATES IN ONE DIRECTION ONLY
Control linkage bent or out of adjustment Repair or replace linkage, Page 8 Drive belt slipping or pulley damaged Repair or replace drive belt or pulley, Page 8
VEHICLE DOES NOT DRIVE/TRACK STRAIGHT
Vehicle tires improperly infl ated Refer to vehicle manufacturer suggested pressure Control linkage bent or out of adjustment Repair or replace linkage, Pages 8 and 11 Bypass assembly sticking Repair or replace bypass, Page 21
UNIT IS NOISY
Oil level low or contaminated oil Fill to proper level or change oil, Page 9 Excessive loading Reduce vehicle loading, Page 8
Loose parts Repair or replace loose parts Bypass assembly sticking Repair or replace linkage Air trapped in hydraulic system Purge hydraulic system, Page 10
UNIT HAS NO/LOW POWER
Engine speed low Adjust to correct setting Control linkage bent or out of adjustment Repair or replace linkage, Page 8
Drive belt slipping or pulley damaged Repair or replace drive belt or pulley, Page 8 Oil level low or contaminated oil Fill to proper level or change oil, Page 9 Excessive loading Reduce vehicle loading, Page 8 Bypass assembly sticking Repair or replace linkage Air trapped in hydraulic system Purge hydraulic system, Page 10
UNIT IS OPERATING HOT
Debris buildup around transaxle Clean off debris, Pages 2 and 8 Cooling fan damaged Repair or replace cooling fan
Oil level low or contaminated oil Fill to proper level or change oil, Page 9 Excessive loading Reduce vehicle loading, Page 8 Air trapped in hydraulic system Purge hydraulic system, Page 10
TRANSAXLE LEAKS OIL
Damaged seals, housing, or gaskets Replace damaged component Air trapped in hydraulic system Purge hydraulic system, Page 10
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SECTION 4. SERVICE AND MAINTENANCE
NOTE: Any servicing dealer attempting a warranty repair must have prior ap­proval before conducting maintenance
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of a Hydro-Gear servicing dealer is a current Authorized Hydro-Gear Service Center.
product unless the
EXTERNAL MAINTENANCE
Regular external maintenance of the EZT® should include the following:
1. Check the vehicle operator’s manual for the recommended load ratings. Insure that the current application does not exceed load rating.
2. Check oil level in accordance with Figure 4 Page 9.
3. Inspect the vehicle drive belt, idler pulley(s), and idler spring(s). Insure that no belt slip­page can occur. Slippage can cause low input speed to the transmission.
4. Inspect the vehicle control linkage to the directional control arm on the transaxle. Also insure that the control arm is securely fas­tened to the trunnion arm of the transaxle.
FLUIDS
The fl uids used in Hydro-Gear products have been carefully selected, and only equivalent, or better products should be substituted.
Typically, an engine oil with a minimum rating of 9.0 cSt (55 SUS) at 230° F (110° C) and an API classifi cation of SL is recommended. A 20W50 engine oil has been selected for use by the factory and is recommended for normal operating procedures.
FLUID VOLUME AND LEVEL
Fluid volume information is provided in Table
4.
Certain situations may require additional fl uid to be added or even replaced. Refer to Page 4 for the proper fi ll port location.
Fill the EZT so the oil level is .75”-1.50” (19-38 mm) below the oil fi ll port.
Recheck the fl uid level once the unit has been operated for approximately 1 minute.
Purging will be required. Refer to the purging procedures on Page 10.
5. Inspect the bypass mechanism on the trans­axle and the vehicle linkage to insure that both actuate and release fully.
SERVICE AND MAINTENANCE PROCEDURES
Some of the service procedures presented on the following pages can be performed while the EZT is mounted on the vehicle. Any repair procedures as mentioned in the repair section of this manual must be performed after the unit has been removed from the vehicle. The unit should be thoroughly cleaned before any service procedures are performed.
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FLUID CHANGE PROCEDURE
FLUID CHANGE
This transaxle is factory fi lled, sealed and does not require oil maintenance. However, in the event of oil contamination or degradation, oil addition or change may alleviate certain per­formance problems.
1. Remove the transaxle from the vehicle.
NOTE: If removing the wheel from the transaxle, do so by removing the four (4) lug nuts. Do not remove the axle/hub nut.
2. Clean the oil fi ll port area of any debris.
3. Remove the oil fi ll port fi tting.
Table 4. Fluid Volumes for the EZT
Fluid Description
4. Position the transaxle so the oil will drain completely out of the housing.
5. Fill the transaxle at the oil fi ll port according to Figure 4.
6. Install the oil fi ll port fi tting.
7. Purging will be required. Refer to the purging procedures on Page 10.
8. Recheck the fl uid level once the unit has been operated for approximately 1 min­ute.
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Volume
20W50 engine oil
OIL LEVEL
52.4 fl . oz. (1550 ml) to 55.8 fl . oz. (1650 ml)
TOP OF FILL PORT
0.75” - 1.50” (19-38mm) depth at 50°-100°F (10°-38°C)
Figure 4. Fluid Level and Fill Port
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PURGING PROCEDURES
Due to the effects air has on effi ciency in hy- drostatic drive applications, it is critical that it is purged from the system.
These purge procedures should be imple­mented any time a hydrostatic system has been opened to facilitate maintenance or any additional oil has been added to the system.
Air creates ineffi ciency because its compres- sion and expansion rate is higher than that of the oil approved for use in hydrostatic drive systems.
The resulting symptoms in hydrostatic systems may be:
1. Noisy operation.
2. Lack of power or drive after short term op­eration.
3. High operation temperature and excessive expansion of oil.
Before starting, make sure the transaxle/trans­mission is at the proper oil level. If it is not, fi ll to the specifi cations outlined on Page 9, Figure
4.
The following procedures should be performed with the vehicle drive wheels off the ground, then repeated under normal operating condi­tions.
1. With the bypass valve open and the engine running, slowly move the directional control in both forward and reverse directions (5 or 6 times), as air is purged from the unit, the oil level will drop.
2. With the bypass valve closed and the engine running, slowly move the directional control in both forward and reverse directions (5 to 6 times). Check the oil level, and add oil as required after stopping the engine.
3. It may be necessary to repeat Steps 1 and 2 until all the air is completely purged from the system. When the transaxle moves for­ward and reverse at normal speed purging is complete.
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RETURN TO NEUTRAL SETTING
WARNING
POTENTIAL FOR SERIOUS INJURY
Inattention to proper safety, operation, or maintenance procedures could result in personal injury, or damage to the equipment. Before servicing or repair­ing the EZT®, fully read and understand the safety precautions described in this section.
The return to neutral mechanism on the trans­mission is designed to set the directional con­trol into a neutral position when the operator releases the vehicle hand control. Follow the procedures below to properly adjust the return to neutral mechanism on the transaxle:
1. Confi rm the transaxle is in the operating mode (bypass disengaged). Raise the vehicle’s drive tires off the ground to allow free rota­tion.
NOTE: It may be necessary to remove the drive wheel from the axle hub to access the linkage control and the transaxle return arm. Remove the wheel by removing the four (4) lug nuts. Do not remove the axle/hub nut.
2. Remove the Original Equipment Manufactur­er’s (OEM’s) control linkage at the control arm. Refer to Figure 5.
3. Start the engine and increase the throttle to
AXLE
ROTATION
“B”
AXLE
ROTATION
“A”
WARNING
Do not attempt any servicing or ad­justments with the engine running. Use extreme caution while inspecting the drive belt assembly and all vehicle linkage!
Follow all safety procedures outlined in the vehicle owner’s manual.
full engine speed.
4. Check for axle rotation. If the axle does not
rotate, go to Step 5. If the axle rotates, go to Step 6.
5. Stop the vehicle’s engine. Reattach and
adjust the OEM linkage according to Step 3 and Step 4. Stop the vehicle engine. Refer to Figure 5.
6. Note the axle directional movement. Stop
the vehicle engine. Loosen the RTN adjust­ment screw until the control arm can be rotated. Rotate the control arm in the opposite direction of the wheel rotation in 5 degree increments. Tighten the RTN adjustment screw. Refer to table 6. Required Torque values, page 14. Recheck according to steps 3 and 4. Stop the vehicle engine. Reattach and adjust the OEM linkage according to the OEM manual. Recheck according to steps 3 and 4. Refer to Figure 5.
AXLE ROTATION “B”AXLE ROTATION “A”
15°
15°
RTN Adjustment Screw
Speed and Directional Control
Figure 5. Return to Neutral Setting
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SECTION 5. REPAIR
HOW TO USE THIS MANUAL
Each subassembly illustrated in this section is illustrated with an exploded view showing the parts involved. The item reference numbers
in each illustration are for assembly instruc­tions only. See page 31 for part names and
descriptions. A complete exploded view and item list of the transaxle is provided at the end of the repair section.
GENERAL INSTRUCTIONS
Cleanliness is a primary means of assuring satisfactory life on repaired units. Thoroughly clean all exposed surfaces prior to any type of maintenance. Cleaning of all parts by us­ing a solvent wash and air drying is usually adequate. As with any precision equipment, all parts must be kept free of foreign material and chemicals.
Protect all exposed sealing surfaces and open cavities from damage and foreign material. The external surfaces should be cleaned before beginning any repairs.
Upon removal, it is recommended that all seals, O-rings, and gaskets be replaced. During installation lightly lubricate all seals, O-rings and gaskets with a clean petroleum jelly prior to assembly. Also protect the inner diameter of seals by covering the shaft with a cellophane (plastic wrap, etc.) material.
Parts requiring replacement must be replaced from the appropriate kits identifi ed in the Items Listing, found at the end of this manual. Use
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only original Hydro-Gear found in BLN-51427 (CD).
IMPORTANT: When internal repair is per­formed on the EZT®, the fi lter assembly must be replaced.
replacement parts
TRANSAXLE REMOVAL
It is necessary to remove the EZT from the ve­hicle before performing the repair procedures presented in this section.
NOTE: If removing the wheel from the transaxle, do so by removing the four (4) lug nuts. Do not remove the axle/hub nut.
LIMITED DISASSEMBLY
The following procedures are presented in the order in which they must be performed to completely disassemble the unit. Do not disas­semble the unit any farther than is necessary to accomplish the required repairs. Each disas­sembly procedure is followed by a correspond­ing assembly procedure.
Reassembly is accomplished by performing the “Assembly” portions of the procedures. If the unit has been completely disassembled, a summary of the assembly procedures, in the order in which they should occur, is given on page 27.
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TOOLS AND TORQUES
Table 5. Required Tools
Miscellaneous
EZT® Service & Repair Manual Flat Blade Screw Driver (2) Torque Wrench Air Impact Wrench Rubber Mallet Breaker Bar Side Cutters/Snips
Pliers
Needle Nose Large External Snap Ring Small Internal Snap Ring
Table 6. Required Torque Values
Sockets
1/2”-3/8” Adapter 3/8” Deep 1/2” Deep 7/16” Deep 9/16” Deep 3/4” Deep 13/16” Deep 7/8” T-25 Torx Head T-40 Torx Head Apex AN-08
Operation Torque Item Description
Metal Plug 180-240 lb-in [20-27 Nm] 7 Plug 9/16-18 Side Housing Screws 105-155 lb-in [12-17 Nm] 9 Screw 1/4-20 x 1.25 Center Section Bolts 525-700 lb-in [60-80 Nm] 12 Screw 3/8-24 x 2.5 Control Arm Stop Stud 50-120 lb-in [6-18 Nm] 21 Stud 5/16-24 Control Arm Screw 230-310 lb-in [26-35 Nm] 25 Screw 5/16-24 x 1 Stop Stud Nut 85-120 lb-in [10-14 Nm] 26 Nut, Lock 5/16-24 UNF Check Plugs 280-400 lb-in [32-45 Nm] 56 Check Plug Assembly Expansion Plate Screws 25-50 lb-in [3-6 Nm] 65 Screw 10-32 x 0.50 Brake Assembly Screw 80-120 lb-in [9-14 Nm] 73 Screw 1/4-20 x 1 Hub Nut 200-220 lb-ft [271-298 Nm] 99 Nut, Hex 3/4-16 Lock Fan/Pulley Lock Nut 360-520 lb-in [41-59 Nm] 122 Lock Nut 1/2 x 20 Breather Fitting 180-240 lb-in [20-27 Nm] 126 Fitting 9/16 RTN Adjustment Screw 175-200 lb-in [19-22 Nm] 131 Screw 5/16-24 x 1 Disc Brake Screw 80-120 lb-in [9-14 Nm] 157 Screw 1/4-20 x 2
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CONTROL ARM AND BYPASS ARM
Refer to Figure 6.
Disassembly
1. Loosen and remove the lock nut (26) and fl at washer (24). Discard the lock nut (26) and fl at washer (24).
2. Remove the torx head screw (25) from the directional control.
3. Remove control arm (23) and pucks (22). Discard the pucks.
4. Remove the bypass arm retaining ring (18) and bypass arm (17). Discard the retaining ring.
5. If necessary, remove and replace the control arm stop stud (21).
Inspection
1. Inspect the control arm stop stud (21) for wear or damage.
Assembly
1. Install the bypass arm (17) onto the bypass rod. Secure the bypass arm with a new re­taining ring (18).
2. Replace the control arm stop stud (21) if removed. Torque according to specifi cations in Table 6 on page 13.
3. Install the control arm (23).
4. Install the control arm screw (25). Refer to Table 6 for screw torque specifi cations.
2. Inspect the control arm (23) for wear or damage.
3. Inspect the bypass arm (17) for wear or damage.
Figure 6. Control Arm and Bypass Arm
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SEAL KIT REPLACEMENT
Before disassembly, wipe the unit free of any debris to avoid contamination.
Refer to Figure 7.
Input Seal
1. Remove the input pulley from the input shaft.
2. Remove the seal retaining ring (34).
3. Carefully pull the input seal (33) out of the housing bore with a “hook” type tool. Care must be taken to avoid damage to the hous­ing bore or shaft sealing area.
4. Lubricate the new seal with petroleum jelly prior to installation.
5. Wrap the shaft keyway (splines) with cel­lophane to prevent damage to the seal lip during installation.
Trunnion Seal
1. Remove the control arm and any attach­ments to the control arm. See page 14.
2. The seal (20) can be replaced by following steps 3-6 of the procedure used to replace the input shaft.
Bypass Seal
1. Remove the bypass arm and any attach­ments to the bypass arm. See page 14.
2. Remove the seal retaining ring (16). Re­move the bypass rod, keeping the retaining ring (14) attached. Remove the bypass rod seal (13). Deburr the bypass rod.
3. Install the seal (13). Install the bypass rod with the retaining ring (14) attached. Install the seal retaining ring (16).
6. Slide the seal over the shaft and press it into the housing bore.
7. The seal should seat against the spacer.
8. Install the seal retaining ring (34) and make sure it is fully seated in its groove.
Output Seal
1. The seal (51) can be replaced by following steps 2-6 of the procedure used to replace the input seal.
2. Install the retaining ring (34) and make sure it is fully seated in its groove.
Motor Shaft Seal
1. Remove the brake assembly. See pages 16-17.
2. The seal (10) can be replaced by following steps 3-6 of the procedure used to replace the input shaft.
Figure 7. Seal Kit Replacement
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COG BRAKE ASSEMBLY
Refer to Figure 8.
Disassembly
1. Remove the control arm and bypass arm. See page 14.
2. Remove the oil from the transaxle. See page
9.
3. Remove the brake arm spring (75), if in­stalled. Remove the brake arm screw(s) (73), washer(s) (72), brake arm (74) and bushing(s) (71).
4. Remove the retaining ring (14) and cog brake disc (100).
5. Remove the motor shaft lip seal (10), if re­moving the side housing.
Inspection
1. Check the brake arm and cog brake disc for excessive wear or teeth damage. Replace if necessary.
2. Check for excessive looseness at the arm pivot point.
Assembly
1. Install the motor shaft lip seal (10), if re­moved. Refer to page 15. Remember to use a seal protector during installation.
2. Install the cog brake disc (100) and retaining ring (14).
3. Install the bushing(s) (71), brake arm (74), washer(s) (72) and brake arm screw(s) (73). Torque screws to 80-120 in-lbs (9-14 Nm).
4. Install the brake arm spring (75), if re­moved.
5. Fill the transaxle with new oil. See page 9.
6. Install the bypass arm and control arm. See page 14.
100
14
74
71
75
72
73
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72
73
Figure 8. Cog Brake Assembly
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DISC BRAKE ASSEMBLY
Refer to Figure 9.
Disassembly
1. Remove the control arm and bypass arm. See page 14.
2. Remove the oil from the transaxle. See page
9.
3. Remove the brake arm bias spring (75).
4. Remove the cotter pin (160), castle nut (159) and washer (158).
5. Remove the brake arm (74), compression spring (156) and two brake pins (155).
6. Remove the brake yoke assy screws (73 & 157), the spacer (154), brake yoke assy (153), puck plate (151), outer puck (150), rotor (100) and inner puck (150).
7. Remove the motor shaft lip seal (10), if re­moving the side housing.
Inspection
2. Check for excessive looseness at the arm pivot point.
Assembly
1. Install the motor shaft lip seal (10), if re­moved. Refer to page 15. Remember to use a seal protector during installation.
2. Install the inner puck (150), rotor (100), outer puck (150) and puck plate (151).
3. Install the brake yoke assy (153), brake pins (155), spacer (154) and the brake yoke assy screws (73 & 157).
4. Install the compression spring (156), the brake arm (74), the washer (158), the castle nut (159) and the cotter pin (160).
5. Install the brake arm bias spring (75).
7. Fill the transaxle with new oil. See page 9.
8. Install the bypass arm and control arm. See page 14.
1. Check the brake disc and pucks for exces­sive wear. Replace if necessary.
100
157
153
154
75
74
160
158
2X 155
156
159
10
151
2X 150
153
73
Figure 9. Disc Brake Assembly
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SIDE COVER
Refer to fi gure 10.
Disassembly
1. Remove the control arm and bypass arm. See page 14.
2. Remove the oil from the transaxle. See page
9.
3. Remove the brake assembly. See pages 16 and 17.
4. Remove the motor shaft lip seal. See page
15.
5. Remove the side housing screws (9) and belt defl ector (144), if installed.
6. Pull the side housing (68), leaving the axle (49) and bull gear (46) assembled in the main housing. It may be necessary to use pry tools at the pry points to break loose the sealant (positions 1-16 and 4-6, Figure
10).
Inspection
1. Inspect the bearing and bushing areas of the side cover.
Assembly
1. Apply a bead of sealant around the perim­eter of the side housing face. See sealant pattern on page 28.
2. Install the locating pins (8), if not already installed.
3. Install the side housing (2). Use care not to smear the sealant bead.
4. Install the side housing screws (9) and belt defl ector (144, if used). Refer to the screw tightening pattern in Figure 10 and torque specifi cation in Table 6 on page 13.
5. Install the remaining seals. Refer to page
15. Remember to use a seal protector dur­ing installation.
7. Clean off all the old sealant on the side and main housings. Take care not to damage the sealing surfaces. A wire brush and solvent is effective.
66
2X 8
16X 9
68
144
6. Install the brake assembly. See pages 16 and 17.
7. Fill the transaxle with new oil. See page 9.
8. Install the bypass arm and control arm. See page 14.
14
16
1
3
5
12
9
7
10
8
11
13
6
4
2
15
Figure 10. Side Cover
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AXLE SHAFT, REDUCTION GEARS AND EXPANSION PLATE
Refer to Figure 11.
Disassembly
1. Remove the bypass arm and control arm. See page 14.
2. Remove oil from the transaxle. See page
9.
3. Remove the side cover. See page 18.
4. Remove the spiral retaining ring (45), bull gear (46), inboard sleeve bearing (48) and washer (47).
5. Remove the reduction gears (42 &43), jack shaft pin (44) and washers (41).
6. Remove seal retaining ring (34), seal (51), axle (49) and bushing (50).
7. If necessary, remove the expansion plate assembly (53).
NOTE: Expansion plate removal will typically
destroy the plate. Clean all sealant from the expansion plate area.
Inspection
1. Inspect the bull gear for wear or damage.
2. Inspect the reduction gears, jack shaft pin and washers.
3. Inspect the axle shaft, bearing and bush­ing.
4. Inspect the expansion plate.
Assembly
1. Apply a small bead of sealant to the expan­sion plate area of the housing. See page 28. Install the expansion plate (53). Torque the screws according to Table 6.
2. Reassemble and install the reduction gears (42 & 43), jack shaft pin (44) and washers (41).
3. Install the bull gear (46), retaining ring (45), bearing (48) and washer (47) onto the axle (49).
4. Install the axle (49) and bushing (50) into the housing (1).
5. Install the axle seal (51) and retaining ring (34).
6. Install the side cover. See page 18.
7. Install all remaining seals. See page 15.
8. Fill the transaxle with oil. See page 9.
9. Install the bypass arm and control arm. See page 14.
Figure 11. Axle Shaft, Reduction Gears and Expansion Plate
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MOTOR SHAFT
Refer to Figure 12.
Disassembly
1. Remove the control arm and bypass arm. See page 14.
2. Drain the oil from the transaxle. See page
9.
3. Remove the side cover. See page 18.
4. Remove the reduction gears. See page
19.
5. Remove fl at washer (36), motor shaft and pinion gear (39 & 38) and fl at washer (40).
Inspection
1. Inspect the motor shaft (39), pinnion gear (38) and fl at washers (36 & 40) for wear or damage.
Assembly
1. Insert the motor shaft (39) with the pinnion gear (38) and fl at washers (36 & 40) into the center section (57).
2. Install the reduction gears. See page 19.
3. Install the side cover. Refer to page 18.
4. Install new seals. Refer to page 15.
5. Fill the transaxle with oil. See page 9.
6. Install the bypass arm and control arm. See page 14.
Figure 12. Motor Shaft
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INPUT SHAFT AND BYPASS ROD
Refer to Figure 13.
Disassembly
1. Remove the control arm and bypass arm. See page 14.
2. Drain the oil from the transaxle. See page
9.
3. Remove the side cover. See page 18.
4. Remove the reduction gears. See page
19.
5. Remove the motor shaft. See page 20.
6. Remove the retaining ring (34) and shaft seal (33). Discard the seal.
7. Remove the spacer (32) and input shaft assembly (29, 30 & 31).
installing the input shaft seal.
5. Deburr the end of the bypass rod. Install the bypass rod (15), retaining ring (14), seal (13) and retaining ring (16).
6. Install the motor shaft. See page 20.
7. Install the reduction gears. See page 19.
8. Install the side cover. See page 18.
9. Install new seals in the side housing. See page 15.
10. Fill the transaxle with oil. See page 9.
11. Install the bypass arm and control arm. See page 14.
8. Remove the compression spring (27) and washer (28).
9. Remove the rings (14 & 16), bypass rod (15) and seal (13).
Inspection
1. Inspect the input shaft components and bypass rod for wear or damage.
Assembly
1. Visually ensure that the pump block is aligned concentrically with the center sec­tion running face.
2. Install the compression spring (27) and washer (28).
3. Insert the input shaft (29), with bearing (30) and retaining ring (31), into the pump block assembly. NOTE: Do not force the shaft and bearing as damage may occur. If alignment is correct, the shaft assembly will fi t into place.
4. Install the washer (32), seal (33) and retain­ing ring (34). Use a seal protector when
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Figure 13. Input Shaft and Bypass Rod Assembly
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HYDRAULIC COMPONENTS
Refer to Figures 14-23.
Disassembly
1. Remove the bypass arm and control arm. See page 14.
2. Drain the oil from the transaxle. See page
9.
3. Remove the side cover. See page 18.
4. Remove the reduction gears. See page
19.
5. Remove the motor shaft. See page 20.
6. Remove the input shaft and bypass rod. See page 21.
7. (See Figure 14) Remove the swashplate (19) and pump cylinder block (4) as one assembly. NOTE: Removal will be aided by applying a small amount of pressure on the trunnion mounted swashplate towards the center section. Also note that the control arm (23, page 30) may be loosely assembled at this point to assist in swashplate removal. While gently removing the swashplate and block assembly, keep the block face fl ush with the center section to minimize damage to the running surface.
8. (See Figure 15) Disassemble the pump cyl- inder block (4) from the swashplate (19).
assembly (35) from the swashplate (19).
(Center Section/Filter)
12. (See Figure 18) Remove the center sec-
tion mounting screws (12). NOTE: The center section is under motor block piston spring pressure. These screws are factory installed to 700 lb-in (80 Nm) and use an anaerobic thread adhesive. A breaker bar will be required at this step. Clean the in­ternal threads of the mounting holes with compressed air.
13. Remove the center section and fi lter as- sembly (57, Figure 19). NOTE: Bypass plate (Figure 20) may slide out of the center section.
14. Remove the fi lter cover by pressing in and down on the fi lter cover tabs. Discard the cover.
15. Note the location of both check plugs (56) before removal for correct replacement during reassembly. Remove and inspect the check plug assemblies (56) for debris or damage.
16. Remove the fi lter base (61) and discard it. NOTE: The fi lter base is included in the fi lter kit to be installed during reassembly of the unit.
(Motor Block)
9. (See Figure 16) Check each piston for
proper operation by pressing the pistons in and releasing them in the block bore. Dis­assemble the pump cylinder block. Check for piston/block wear in the cylinder bore. Inspect the pistons (A), piston springs (C) and thrust washers (B) for excessive wear or damage. NOTE: Thrust washers may be held in place in the piston by residual oil.
10. Reassemble the pistons, springs and wash­ers into the cylinder block and set aside.
11. (See Figure 17) Remove the thrust bearing
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17. (See Figure 21) Remove the motor cylinder
block assembly (6) from the housing (1).
18. Disassemble the motor cylinder block as­sembly (4). Check each piston for proper operation by pressing the pistons in and releasing them in the block bore. Disas­semble the motor cylinder block. Check for piston/block wear in the cylinder bore. Inspect the pistons, piston springs and thrust washers for excessive wear or dam­age. NOTE: Thrust washers may be held in place in the piston by residual oil.
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19. Reassemble the pistons, springs and thrust washers into the cylinder block and set aside.
20. Remove the thrust bearing assembly (35) from the housing (1). Inspect the thrust bearing and thrust bearing cavity in the housing.
Inspection
1. Inspect the pump cylinder block running surface for wear or damage.
2. Inspect the swashplate and thrust bearing assemblies for wear or damage.
3. Inspect the center section block running surfaces. NOTE: These “sealing” surfaces should be smooth in appearance without scratches, scoring, nicks or abrasions. Drag a fi ngernail across the surface to detect uneven wear or scratches which may not be visible.
4. Inspect the threaded check plug ports of the center section for debris or damage.
5. Inspect the motor cylinder block running surface for damage and wear.
6. Inspect all bearing, bushing and wear areas in the housing.
HYDRAULIC COMPONENTS
(Center Section/Filter)
3. (See Figure 20) Install the new fi lter base
(61) onto the center section (57).
4. It will be necessary to clean the check plugs prior to re-assembly. Install the check plugs (56), in their correct location, into the center section (57). Tighten the check plugs ac­cording to Table 6.
5. Align the tabs on the fi lter cover with the slots in the fi lter base and carfully press the cover onto the base until the tabs snap into place. Insure the bypass plate (Figure 20) is located properly in the center section.
6. (See Figures 12 & 22) Install the motor shaft (39), pinion gear (38) and fl at washers (36 & 40) into the center section (57).
7. Assemble the motor block assembly (6) onto the motor shaft (39).
8. (See Figure 22) Install the motor shaft, center section and motor block assembly into the housing so that the motor block pistons contact the thrust bearing race. NOTE: Hold in place and insure all pistons are still positioned correctly in the cylinder bore by confi rming spring bias against the center section.
Assembly
(Motor Block)
1. (See Figure 21) Turn the housing (1) so
the motor thrust bearing cavity is facing up. This will assist in the installation of the motor thrust bearing assembly (35) keeping it in the bearing cavity during installation of the center section assembly (57, Figure 19).
2. Insert the thrust bearing (35) in the housing (1). NOTE: Place the thin race of the bear­ing towards the housing bearing cavity. The thick race must face the pistons.
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9. (See Figure 18) After applying thread ad-
hesive, insert the center section mounting screws (12) while holding downward pres­sure on the center section assembly (57, Figure 22).
10. Tighten the center section mounting screws (12) to the proper torque. Refer to Table
6. NOTE: The center section must be fully seated into the pilot bore before the screws are tightened. The center section will not self locate.
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(Swashplate/Pump Block)
11. (See Figure 17) Install the pump thrust
bearing (35) in the trunnion machined swashplate (19). NOTE: Place the thin race of the bearing towards the swashplate. The thick race must face the pistons.
12. (See Figure 15) Place the pump block
assembly (4), pistons down, on top of the thrust bearing in the swashplate (19).
13. Coat the pump running surface with clean motor oil.
14. Care must be taken to prevent the scaring
or scratching of the center section sealing face during this step. Insert the shaft of the
swashplate/pump block assembly (Figure
23) into the housing while simultaneously compressing the pistons in the block. NOTE: To assist in the installation of these components, insert the assembly until 3/4 of the pump block is covered by the center section. Then slightly press the shaft end toward the center section while pushing the shaft into its bore.
Figure 14.
19
35
15. Install the input shaft and bypass rod. See page 21.
16. Install the axle shaft, reduction gears and expansion plate, if removed. Refer to page
19.
17. Install the side cover and brake. See pages 16-18.
18. Fill the transaxle with new oil. See page
9.
19. Install the bypass arm and control arm. See page 14.
4
Figure 15.
A
B
C
Figure 16.
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Figure 17.
Figure 18.
Figure 20.
1
35
6
Figure 21.
Figure 19.
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TRANSAXLE INSTALLATION
6
19
1
4
38
57
39
Use the following procedure to complete the installation of the transaxle on the vehicle.
1. Install and secure the transaxle on the vehicle according to the instructions in the vehicle owner’s manual.
2. With the vehicle raised, install the wheels on the axles, and snug the wheel hard­ware.
3. Lower the vehicle wheels to the ground and torque the wheel hardware per the vehicle owner’s manual.
Figure 22.
Figure 23.
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ASSEMBLY AFTER A COMPLETE TEARDOWN
If the unit has been torn down completely, the following summary identifi es the assembly pro- cedures necessary to completely assemble the unit. Each assembly procedure is located by a page reference.
The part reference numbers provided in each assembly procedure are keyed to the individual exploded views, and are also keyed to the com­plete unit exploded view on page 30.
1. Install the hydraulic components. See pages 22-26.
2. Install the input shaft and bypass rod. See page 21.
3. Install the axle shaft, reduction gears and expansion plate. See page 19.
4. Install the cog brake and side cover. See page 16-18.
5. Fill the transaxle with new oil. See page 9.
6. Install the bypass arm and control arm. See page 14.
7. Install the transaxle onto the vehicle.
8. Perform the purge procedures listed on page 10.
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SEALANT APPLICATION
NOTE: Prior to applying the new sealant, the
old sealant must be removed from all sur­faces.
A small consistent bead of the sealant around the housing face will be suffi cient. Use spar- ingly.
The illustration below indicates the correct areas.
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NOTES
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159
158
160
74
75
157
156
154
73
2X 155
153
151
2X 150
100
55
DISC BRAKE
BRAKE KIT
W/ SPRING
OR
100
14*
144
36
55
71
71
75
74
72
72
72
73
73
73
71
55
55
74
70
71
72
74
73
73
74
71
55
BRAKE KIT
THROUGH HOLE
BRAKE KIT
CLEVIS PIN
BRAKE KIT
TOP MOUNT
OR
OR
OR
37*
38
39
40
64
62
63
3
56
60
61
57
35
6
4
35
19
2
16X 9
68
10*
41
44
43
42
3X 12
41
45*
46
47
48
67
2X 65
THICK RACE TOWARD
PISTONS
2X 8
1
20*
66
53
13*
29
28
27
7
30
31*
32
34*
33*
49
50
51*
34*
124
99
25
59
18*
17
16*
15
14*
127
138
128
126
139
54
54
54
122
122
122
123
123
120
120
120
121
119
121
121
3X 130
6X 131
3X 123
OR
OR
OR
200
200
200
26
26
24
24
24
135
134
141
23
131
140
5
22
22
21
21
23
23
25
25
EZT® EXPLODED VIEW
NOTES:
1. BRAKE AND CONTROL ARM CAN BE ON EITHER
SIDE.
2. LH SIDE SHOWN. RH SIDE IS A MIRROR IMAGE.
ITEMS NOT SHOWN
11 - OIL, 20W50
58 - SEALANT TUBE (10.3 oz)
52 - KIT, SEAL
145 - ASSEMBLY, HUB PULLER
Figure 24. EZT
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EZT® ITEMS LIST
No. DESCRIPTION
1 ASSEMBLY, MAIN HOUSING
BUSHING
2 ASSEMBLY, SIDE COVER
BUSHING 3 PLATE, BYPASS 4 ASSEMBLY, PUMP BLOCK
BLOCK, CYLINDER
PISTONS
SPRINGS, COMPRESSION
WASHERS, THRUST 5 SPACER 6 ASSEMBLY, MOTOR BLOCK 7 PLUG, 9/16-1 8 PIN, STAINLESS, HEADLESS 9 HFHCS 1/4-20 X 1.25 (SELF-TAPPING)
10 SEAL, LIP 12 BOLT, HEX FLANGE 3/8-24 X 2.5 13 SEAL, LIP 14 RING, RETAINING 15 ROD, BYPASS 16 RING, RETAINING 17 ARM, BYPASS 18 RING, RETAINING (PUSHNUT) 19 SWASHPLATE, TRUNNION, MACHINED 20 SEAL, LIP 21 STUD 22 WASHER 23 ARM, CONTROL 24 WASHER, FLAT 25 TWHCS 5/16-24 X 1.0 26 NUT, HEX LOCK 5/16-24 UNJF 27 SPRING-HELICAL COMPRESSION 28 WASHER 29 SHAFT, INPUT 30 BEARING, BALL 31 RING, RETAINING WIRE 32 SPACER 33 SEAL, LIP 34 RING, RETAINING 35 BEARING, THRUST 36 WASHER, FLAT 37 RING, RETAINING 38 GEAR, PINION, 13T 39 SHAFT, MOTOR 40 WASHER, MOTOR SHAFT 41 WASHER, HT 42 GEAR, 10T/48T 43 GEAR, 10T JACKSHAFT 44 PIN, JACKSHAFT 45 RING, SPIRAL RETAINING 46 GEAR, 52T BULL 47 WASHER 48 BEARING, SLEEVE (INBOARD) 49 AXLE 50 BUSHING 51 SEAL, LIP 52 KIT, SEAL 53 KIT, EXPANSION PLATE 54 KIT, FAN-PULLEY
No. DESCRIPTION
55 KIT, BRAKE ASSEMBLY 56 CHECK PLUGS 57 KIT, CENTER SECTION-FILTER 59 KIT, BYPASS ARM 60 ASSEMBLY, COVER 61 KIT, FILTER 62 FILTER, BASE 63 CENTER SECTION 64 MAGNET 65 SCREW, 10-32 X 1/2 (SELF-TAPPING) 66 HOUSING, MAIN 67 PLATE, EXPANSION 68 COVER, SIDE 70 PIN, CLEVIS 71 BUSHING 72 WASHER 73 SCREW 74 ARM, BRAKE 75 SPRING
99 NUT, HEX LOCK 100 ROTOR 119 HUB 120 FAN 121 PULLEY 122 NUT, HEX LOCKING 123 WASHER OR CAPSCREW 1/4-20 124 HUB KIT 126 FITTING 127 HOSE, EXPANSION TANK 128 CAP, BARBED VENT 130 NUT, HEX 1/4-20 131 SPACER OR CAPSCREW 5/16-20 X 1 134 WASHER 135 SPRING 138 KIT, BREATHER ASSEMBLY 139 KIT, BREATHER ASSEMBLY 140 ARM, NEUTRAL 141 RTN 144 DEFLECTOR, BELT 150 PUCK, BRAKE 151 PLATE, PUCK 153 ASSEMBLY, BRAKE YOKE 154 SPACER 155 PIN, BRAKE 156 SPRING, BRAKE COMPRESSION 157 CAPSCREW, 1/4-20 X 2.0 158 WASHER 159 NUT, CASTLE 5/16-24 160 PIN, COTTER 200 KIT, RTN
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GLOSSARY OF TERMS
Axial Piston: Type of design for hydraulic motors and pumps in which the pistons are arranged parallel with the spindle (input or output shaft).
Bantam Duty: A descriptive term relating to the product capacity (meaning: light duty).
Bypass Valve: A valve whose primary function is to open a path for the fl uid to bypass the motor
or pump. Also referred to occasionally as the freewheel valve or dump valve.
Case Drain Line (Return Line): A line returning fl uid from the component housing to the reser- voir.
Cavitation: A concentrated gaseous condition within the fl uid causing the rapid implosion of a gaseous bubble.
Center Section: A device which acts as the valve body and manifold of the transmission.
Charge Pump: A device which supplies replenishing fl uid to the fl uid power system (closed
loop).
Charge Pressure: The pressure at which replenishing fl uid is forced into a fl uid power system.
Charge Relief Valve: A pressure control valve whose primary function is to limit pressure in the
charge circuit.
Check Valve: A valve whose primary function is to restrict fl ow in one direction.
Closed Loop: A sealed and uninterrupted circulating path for fl uid fl ow from the pump to the
motor and back.
Decay Rate: The ratio of pressure decay over time.
End Cap: See “Center Section”
Entrained Air: A mechanically generated mixture of air bubbles having a tendency to separate
from the liquid phase.
Gerotor: A positive displacement pump frequently used as a charge pump.
Hydraulic Motor: A device which converts hydraulic fl uid power into mechanical force and mo-
tion by transfer of fl ow under pressure.
Hydraulic Pump: A device which converts mechanical force and motion into hydraulic fl uid power by producing fl ow.
Hydrostatic Pump: See “Hydraulic Pump”
Hydrostatic Transaxle: A multicomponent assembly including a gear case and a hydrostatic
transmission.
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Hydrostatic Transmission: The combination of a hydraulic pump and motor in one housing to form a device for the control and transfer of power.
Inlet Line: A supply line to the pump.
Integrated Zero-Turn Transaxle: The combination of a hydrostatic transmission and gear case
in one housing to form a complete transaxle.
Manifold: A conductor which provides multiple connection ports.
Neutral: Typically described as a condition in which fl uid fl ow and system pressure is below that
which is required to turn the output shaft of the motor.
Pressure Decay: A falling pressure.
Priming: The fi lling of the charge circuit and closed loop of the fl uid power system during start
up, frequently achieved by pressurizing the fl uid in the inlet line.
Purging: The act of replacing air with fl uid in a fl uid power system by forcing fl uid into all of the components and allowing the air a path of escape.
Rated Flow: The maximum fl ow that the power supply system is capable of maintaining at a specifi c operating pressure.
Scoring: Scratches in the direction of motion of mechanical parts caused by abrasive contami­nants.
Swash Plate: A mechanical device used to control the displacement of the pump pistons in a fl uid power system.
System Charge Check Valve: A valve controlling the replenishing fl ow of fl uid from a charge circuit to the closed loop in a fl uid power system.
System Pressure: The pressure which overcomes the total resistance in a system, including all effi ciency losses.
Valve: A device which controls fl uid fl ow direction, pressure, or fl ow rate.
Variable Displacement Pump: A pump in which the displacement per revolution can be var-
ied.
Volumetric Displacement: The volume for one revolution.
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© 2008 Hydro-Gear Printed in U.S.A. Rev. P4
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