310-0510/-0610/-0710
Integrated Hydrostatic Transaxle
Service and Repair Manual
BLN-51260
July, 2011
Table of Contents
Section
Page
Foreword........................................................................................................................................ 1
Section 1 Description and Operation .......................................................................................... 2
Introduction ........................................................................................................................................................ 2
General Description............................................................................................................................................ 2
Hydraulic Schematic........................................................................................................................................... 3
External Features 310-0510 ............................................................................................................................... 4
Model Recognition ............................................................................................................................................. 5
Technical Specifications..................................................................................................................................... 6
Product Identification.......................................................................................................................................... 6
Section 2 Safety ............................................................................................................................ 7
Personal Safety.................................................................................................................................................. 7
Tool Safety......................................................................................................................................................... 7
Work Area Safety ............................................................................................................................................... 7
Servicing Safety ................................................................................................................................................. 7
Section 3 Troubleshooting ........................................................................................................... 8
Section 4 Service and Maintenance ............................................................................................ 9
External Maintenance......................................................................................................................................... 9
Service and Maintenance Procedures ................................................................................................................ 9
Fluids................................................................................................................................................................. 9
Fluid Change.................................................................................................................................................... 10
Purging Procedures.......................................................................................................................................... 11
Return to Neutral Setting .................................................................................................................................. 12
Brake Maintenance .......................................................................................................................................... 13
Friction Pack Adjustment.................................................................................................................................. 13
Section 5 Repair .......................................................................................................................... 14
How To Use This Section ................................................................................................................................. 14
General Instructions ......................................................................................................................................... 14
Transaxle Removal .......................................................................................................................................... 14
Limited Disassembly ........................................................................................................................................ 14
Tools and Torques ........................................................................................................................................... 15
Brake Assembly and Bypass Arm..................................................................................................................... 16
Control Arm and Friction Pack.......................................................................................................................... 17
Seal Kit Replacement ...................................................................................................................................... 18
Side Housing.................................................................................................................................................... 19
Axle Shaft, Differential and Reduction Gears .................................................................................................... 20
Motor Shaft and Bypass Rod............................................................................................................................ 21
Input Shaft ....................................................................................................................................................... 22
Hydraulic Components ................................................................................................................................ 23-26
Transaxle Installation ....................................................................................................................................... 27
Assembly After a Complete Teardown.............................................................................................................. 27
Sealant Application..................................................................................................................... 28
310-0610 & 310-0710 IHT ............................................................................................................ 29
Description....................................................................................................................................................... 29
Features........................................................................................................................................................... 29
Transaxle Removal .......................................................................................................................................... 29
Parts List................................................................................................................................. 30-35
Glossary of Terms.................................................................................................................. 36-37
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
troubleshooting the Hydro-Gear 310-0510
Integrated Hydrostatic Transaxle (IHT). Troubleshooting for the 310-0510 is further illustrated in video BLN-51368 (NTSC).
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!
Repair procedures require that the transaxle
unit be removed from the vehicle.
This is not a certification, test or study guide for
a certification test. If a technician is interested
in certification they should contact an agent
representing OPEESA (Outdoor Power Equipment and Engine Service Association) at (860)
767-1770 or their Hydro-Gear Distributor. Many
distributors will be hosting certification 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.
It is necessary, and good shop practice, that
your service area be equipped with the proper
tools and the mechanics be supplied with the
latest information available. All repair
procedures illustrated in this guide are
suggested, but preferred methods of repair.
310-0510 IHT
1
SECTION 1. DESCRIPTION AND OPERATION
INTRODUCTION
The purpose of this manual is to provide
information useful in servicing the Hydro-Gear®
Integrated Hydrostatic Transaxle (IHT). This
manual includes the IHT’s general description,
hydraulic schematic, technical specifications,
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.
GENERAL DESCRIPTION
The 310-0510 is a self contained unit designed
for the transfer and control of power. It provides
an infinitely 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 flow 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 310-0510 has a self contained fluid supply
and an internal filter. The fluid is forced through
the filter by a positive “head” on the fluid 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 makeup flow of the fluid to the low
pressure side of the loop.
A check ball lifting bypass is utilized in the 3100510 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.
The 310-0510 utilizes an in-line floating disc
brake controlled by a “cam” style actuating arm.
Figure 1. 310-0510 Hydraulic Schematic
2
310-0510 IHT
INPUT SHAFT
VARIABLE SWASH PLATE
CYLINDER BLOCK ASSEMBLY
CYLINDER BLOCK ASSEMBLY
10 CC VARIABLE
10 CC FIXED
DISPLACEMENT PUMP
FIXED DISPLACEMENT ANGLE
DISPLACEMENT MOTOR
CHECK VALVE
BYPASS ACTUATOR
CHECK VALVE
FILTER ASSEMBLY
RESERVOIR
DIFFERENTIAL ASSEMBLY
TRANSAXLE HOUSING
Figure 2. 310-0510 Hydraulic Flow Illustration
HYDRAULIC SCHEMATIC
Figure 2 provides an illustration of the hydraulic
oil circuit. The oil supply for the hydraulic
system of the 310-0510 IHT is also utilized for
lubricating the components of the final 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 flow is
controlled by the direction and amount that the
variable swashplate is angled. As the pump
pistons compress they force the oil to flow
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 fixed displacement angle it is forced to
turn with the flow 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 swashplate will reverse the direction of
oil flow.
During the operation of the transaxle, fluid 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” fluid 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 filter.
The motor cylinder block mounts onto a splined
motor shaft which drives the gear train.
The bypass feature in the 310-0510 has a
mechanical lever which lifts the check valve
balls off their seat. This allows oil flow from the
cylinder blocks to be discharged.
EXTERNAL FEATURES 310-0510
FAN
FRICTION
PACK
BELT KEEPER
CONTROL ARM
BRAKE ARM
BRAKE
DISC
ADJUSTING
PUCK
BYPASS ARM
Return to Neutral Option
Friction Pack Option
AXLE CLIP
FILL PORT
AXLE CLIP
EXPANSION
TANK
AXLE SHAFT
INPUT SHAFT
AXLE CLIP
AXLE CLIP
4
310-0510 IHT
MODEL RECOGNITION
618-0319
173839
310-0510 IHT
166768
104-1760
036932
618-0389A
5
TECHNICAL SPECIFICATIONS
Technical specifications for the 310-0510 IHT are listed in Table 1.
Table 1. 310-0510 Technical Specifications
Overall Transaxle Reduction
22.15:1
Axle Shaft Options
Type: Keyed / Double “D”
Diameter: 0.75 inch; 19.05 mm
Input Speeds
Maximum: 3000 RPM
Minimum: 1800 RPM
Brake Type
Disc
Maximum Tire Diameter
20 inch; 508 mm
Weight of Unit
30 lb; 14 kg
PRODUCT IDENTIFICATION
The model and configuration of the 310-0510 IHT can be determined from the label shown in
Figure 3.
H Y D R O - G E A R
SULLIVAN, IL.
U.S.A.
Model
Number
I IIII III IIII II II
166768
13054
314-0510
318-2400
I II IIII IIII III III I II IIII
0 319 T
Z1 401
Hydro-Gear
Ref. Number
Made in U.S.A.
Serial Number
Year Built
(unique number for that model - for that day)
Date
(Julian - day of year)
Type of Product and Build Information
Figure 3. 310-0510 Configuration Label
6
310-0510 IHT
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.
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 slipproof shoes.
Never use compressed air to clean debris from
yourself or your clothing.
TOOL SAFETY
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 310-0510
IHT, fully read and understand the safety
precautions described in this section.
PERSONAL SAFETY
Certain safety precautions must be observed
while servicing or repairing the 310-0510 IHT.
This section addresses some of these
precautions but must not be considered an allinclusive 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.
310-0510 IHT
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 floor should be clean and dry, and all extension 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. Proper brake maintenance is very important
should this condition develop.
Some cleaning solvents are flammable. Use
only approved cleaning materials. Do not use
explosive or flammable liquids to clean the
equipment.
To avoid possible fire do not use cleaning solvents in an area where a source of ignition may
be present.
Discard used cleaning material in the appropriate containers.
7
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!
Follow all safety procedures outlined in
the vehicle owner’s manual!
In many cases problems with the 310-0510 are
not 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 unit is malfunctioning. Table 2
below provides a troubleshooting check list to
help determine the cause of operational problems.
Table 2. 310-0510 Troubleshooting Checklist
Possible Cause
Corrective Action
UNIT OPERATES IN ONE DIRECTION ONLY
Control linkage bent or out of adjustment
Drive belt slipping or pulley damaged
Repair or replace linkage, Page 9
Repair or replace drive belt or pulley, Page 9
VEHICLE DOES NOT DRIVE/TRACK STRAIGHT
Vehicle tires improperly inflated
Control linkage bent, loose or out of adjustment
Bypass partially engaged
Refer to vehicle manufacturer suggested pressure
Repair, adjust or replace vehicle linkage
Adjust bypass linkage
UNIT IS NOISY
Oil level low or contaminated oil
Excessive loading
Brake setting incorrect
Loose parts
Bypass assembly sticking
Air trapped in hydraulic system
Fill to proper level or change oil, Page 10
Reduce vehicle loading, Page 9
Adjust brake to proper setting, Page 13
Repair or replace loose parts
Repair or replace valve or linkage
Purge hydraulic system, Page 11
UNIT HAS NO/LOW POWER
Engine speed low
Control linkage bent or out of adjustment
Brake setting incorrect
Drive belt slipping or pulley damaged
Oil level low or contaminated oil
Excessive loading
Bypass assembly sticking
Air trapped in hydraulic system
Adjust to correct setting
Repair or replace linkage, Page 9
Adjust brake to proper setting, Page 13
Repair or replace drive belt or pulley, Page 9
Fill to proper level or change oil, Page 10
Reduce vehicle loading, Page 9
Repair or replace valve or linkage
Purge hydraulic system, Page 11
UNIT OPERATING HOT
Debris buildup around transaxle
Brake setting incorrect
Cooling fan damaged
Oil level low or contaminated oil
Excessive loading
Air trapped in hydraulic system
Clean off debris, Page 9
Adjust brake to proper setting, Page 13
Repair or replace cooling fan
Fill to proper level or change oil, Page 10
Reduce vehicle loading, Page 9
Purge hydraulic system, Page 11
TRANSAXLE LEAKS OIL
Damaged seals, housing, or gaskets
Air trapped in hydraulic system
8
Replace damaged component
Purge hydraulic system, Page 11
310-0510 IHT
SECTION 4. SERVICE AND MAINTENANCE
NOTE: Any servicing dealer attempting
a warranty repair must have prior
approval before conducting maintenance
of a Hydro-Gear® product unless the
servicing dealer is a current Authorized
Hydro-Gear Service Center.
EXTERNAL MAINTENANCE
Regular external maintenance of the 310-0510
IHT should include the following:
1. Check the vehicle operator’s manual for
the recommended load ratings. Insure
the current application does not exceed
load rating.
mentioned in the repair section of this manual
must be performed after the unit has been
removed from the vehicle.
FLUIDS
The fluids 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 cSt (55 SUS) at 230°F (110° C) and an API
classification of SL is recommended. A 20W-50
engine oil has been selected for use by the factory and is recommended for normal operating
temperatures.
2. Check oil level in accordance with Figure 4
Page 10.
FLUID VOLUME AND LEVEL
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.
Certain situations may require additional fluid to
be added or even replaced. Refer to Page 4
and Figure 4 for the proper fill port location.
4. Inspect the transmission cooling fan for
broken or distorted blades and remove any
obstructions (grass clippings, leaves, dirt,
etc.).
5. Inspect the axle parking brake and vehicle
linkage to insure proper actuation and
adjustment of the parking brake.
Fluid volume information is provided in Table 3.
Fill the 310-0510 to the top of the oil fill port.
Recheck the fluid level once the unit has been
operated for approximately 1 minute.
Purging may be required. Refer to the purging
procedures on page 11.
6. Inspect the vehicle control linkage to the
directional control arm on transaxle. Also,
insure the control arm is securely fastened
to the trunnion arm of the transaxle.
7. Inspect the bypass mechanism on the
transaxle and vehicle linkage to insure it
actuates and releases fully.
SERVICE AND MAINTENANCE
PROCEDURES
All the service and maintenance procedures
presented on the following pages can be
performed while the 310-0510 is mounted on
the vehicle. Any repair procedures as
310-0510 IHT
9
FLUID CHANGE
FLUID CHANGE PROCEDURE
This transaxle is factory filled, 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.
seal. 8. Install the tank support bracket and self tapping bolt making sure not to cross thread the bolt. Torque the bolt to the lower value of the torque specifica on listed in Table 5. 1. Remove the transaxle from the vehicle. 9. Fill the transaxle at the oil fill port according to Figure 4. 2. Clean the expansion tank and oil fill port areas of any debris. 10. Install the oil fill port fi ng. EXPANSION TANK FUNCTION 3. Remove the oil fill port fi ng. 4. Posi on the transaxle so the oil will drain completely out of the housing. 5. A er all the oil is drained from the transaxle, remove the expansion tank by removing the self tapping bolt (10-32 x ½) that holds the tank support bracket. 6. Remove the tank and drain the oil from the tank. DO NOT remove the vent cap from the tank. DO NOT remove the tank hose or o-ring unless a replacement is needed. 7. Install the tank by first inser ng the hose into the opening in the expansion tank. Push the tank opening over the o-ring to ensure a proper The expansion tank allows the 310‐0510 to operate free of air entrainment and provides maximum lubrica on to the mechanical and hydraulic components in the transaxle. As the 310‐0510 transaxle is operated, oil in the transaxle housing heats up which causes the oil to expand. The oil flows through an internal hose to the bo om of the vented expansion tank. As the oil cools, the oil in the transaxle housing contracts, causing the oil level to go down in the housing. This creates a nega ve pressure in the housing causing the oil to be drawn back into the case. This keeps the transaxle housing full of oil at specified opera ng temperatures. Table 3. Fluid Volumes for the 310-0510 IHT
Fluid Description
Volume
20W-50 engine oil
79 fl. oz. (2336 ml.)
FILL PORT
OIL LEVEL
1¼" (31.75mm) Max. Depth
at 50°- 100° F (10°- 38° C)
Figure 4. 310-0510 Fluid Level and Fill Port
10
310-0510 IHT
PURGING PROCEDURES
Due to the effects air has on efficiency in
hydrostatic drive applications, it is critical that it
be 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 inefficiency because its compression 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.
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 to 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
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.
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, fill to the specifications outlined on page
10, Figure 4.
310-0510 IHT
11
RETURN TO NEUTRAL SETTING (FOOT CONTROL)
WARNING
WARNING
POTENTIAL FOR SERIOUS INJURY
Certain procedures require the vehicle
engine to be operated and the vehicle
to be raised off the ground. To prevent
possible injury to the servicing technician and/or bystanders, insure the
vehicle is properly secured.
The return to neutral mechanism on the transmission is designed to set the directional control into a neutral position when the operator
removes their foot from the foot control. Follow
the procedures below to properly adjust the
return to neutral mechanism on the transaxle:
1. Confirm 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 tire from the axle hub to access
the linkage control and the transaxle
return arm.
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
full engine speed.
Do not attempt any adjustments with the
engine running. Use extreme caution while
inspecting all vehicle linkage!
Follow all safety procedures outlined in the
vehicle owner’s manual.
4. Check for axle rotation. If the axles do not
rotate, go to Step 5. If the axles rotate, go to
Step 6.
5. Stop the vehicle’s engine. Reattach and adjust the OEM linkage according to the OEM
manual. Recheck according to Step 3 and
4. Stop the vehicle engine. Refer to Figure
5.
6. Note the axle directional movement. Stop
the vehicle engine. Loosen the adjusting
puck screw until the puck can be rotated.
Rotate the adjusting puck the opposite direction of the wheel rotation in 5 degree increments. Tighten the adjusting puck screw.
Refer to Table 5. Required Torque Values,
Page 15. 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.
Control Arm
Brake Arm
ROTATION B
ROTATION A
Bypass Arm
Adjusting Puck
Figure 5. Return to Neutral, Foot Control
12
310-0510 IHT
BRAKE MAINTENANCE
BRAKE SETTING
BRAKE CHECKING
1. Remove the brake arm bias spring, and
then the cotter pin securing the brake castle
nut.
When checking the brake puck/rotor gap, the
gap should be 0.010-0.030 inches (0.2540.762 mm).
2. Insert a 0.015" feeler gage between the
brake disc and top brake puck, and then set
the brake by finger tightening or loosening
the castle nut.
FRICTION PACK ADJUSTMENT
3. Install a new cotter pin to secure the castle
nut, and then install the brake arm bias
spring.
Adjustment for the amount of drag or holding
force can be made by turning the friction pack
nut in or out.
The friction pack dampens or holds the operator control lever in its desired position.
Adjustments should be made in no more than
1/4 turn increments.
BRAKE ARM
BIAS SPRING
Over-tightening will result in difficulty or inability
of the operator to move the control lever.
CASTLE NUT
BRAKE DISC
Note: The factory setting for the friction pack is
tightening of the friction pack nut to 100 in-lbs
(11 Nm) torque. The friction pack nut is then
backed off per the vehicle manufacturer’s specifications.
FRICTION PACK NUT
CONTROL ARM
COTTER PIN
BRAKE ARM
BIAS SPRING
BRAKE DISC
TOP BRAKE PUCK
Figure 7. Friction Pack
CASTLE NUT
Figure 6. Brake Components
310-0510 IHT
13
SECTION 5. REPAIR
HOW TO USE THIS SECTION
Each subassembly illustrated in this section is
illustrated by an exploded view showing the
parts involved. The item reference numbers
in each illustration are for assembly
instructions only. See pages 31 and 33 for
part names and descriptions. A complete exploded view and item list of the transaxle is provided at the end of this section.
Many of the parts and subassemblies of this
transaxle can be removed and serviced independently of other components. Where some
components and assemblies must be removed
before a given assembly can be serviced, that
information is given at the beginning of the
disassembly instructions.
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.
IMPORTANT: When internal repair is performed on the 310-0510 IHT, the filter assembly must be replaced.
TRANSAXLE REMOVAL
It is necessary to remove the 310-0510 from
the vehicle before performing the repair
procedures presented in this section.
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.
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,
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 identified in the Items
Listing, found at the end of this manual. Use
only original Hydro-Gear® replacement parts
found listed in BLN-51427 (CD).
14
310-0510 IHT
TOOLS AND TORQUES
Table 4. Required Tools
Miscellaneous
310-0510 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
Sockets
1/2"- 3/8" Adapter
1/2" Deep
7/16" Deep
9/16" Deep
3/4" Deep
7/8"
10 mm
T-25 Torx Head
Table 5. Required Torque Values
Operation
Side Housing Screws
Housing Stud
Control Arm Screw
Check Plugs
Center Section Bolts
Brake Yoke Bolt
Brake Yoke Bolt
Friction Pack Mounting Stud
Friction Pack Nut
Expansion Tank Hose Fitting
Belt Keeper Screw
Bracket Support Bolt
Friction Pack Wedge Screw
Puck Inner Wedge Bolt
Adjusting Puck Screw
RTN Screw
Bracket Screw
Fan/Pulley-Input Shaft Nut
Fan/Pulley Screws
Fan/Pulley Nuts
Cruise Damper Bracket Nuts
Axle Hub Nut (310-0710)
Axle Hub Nut (310-0710)
310-0510 IHT
U.S. Torque
105-155 lb-in
230-310 lb-in
230-310 lb-in
280-400 lb-in
450-550 lb-in
80-120 lb-in
80-120 lb-in
50-120 lb-in
85-120 lb-in
96-120 lb-in
40-70 lb-in
42-65 lb-in
30-70 in-lb
42-65 lb-in
250-320 lb-in
180-240 lb-in
230-310 lb-in
540-660 lb-in
65-90 lb-in
35-50 lb-in
160-210 lb-in
240-260 lb-ft
180-200 lb-ft
Metric Torque
12-17 Nm
26-35 Nm
26-35 Nm
32-45 Nm
50-62 Nm
9-14 Nm
9-14 Nm
6-14 Nm
10-14 Nm
11-14 Nm
5-8 Nm
5-7 Nm
3.4-8 Nm
5-7 Nm
28-36 Nm
20-27 Nm
26-35 Nm
61-74 Nm
8-10 Nm
4-6 Nm
18-24 Nm
271-298 Nm
244-271 Nm
Item
7
8
16
23/75
44
63
64
76
80
84
88
88
88
88
95
97
110
121
122
124
132
152
152
Description
Screw ¼-20 x 1.25
Stud 5/16-24 Hex
Screw 5/16-24 x 0.75
Check Plug Assembly
Screw 3/8-24 x 2.5
HFHCS ¼-20 x 2
Bolt ¼-20 x 1
Stud 5/16-24
Lock Nut 5/16-24
Fitting 5/16 SAE 5/32 Tube
Screw, Self-Tapping 10-32 x .5
Bolt 10-32 x 0.5
Screw, Self Tapping 10-32 x .5
Bolt 10-32 x 0.5
Socket Hd CS 5/16-24 x 1.50
Screw, Countersunk 5/16-18 x 1
Screw, Torx Hd 5/16-18 x 1.50
Nut, Patch Lock
Screw, Hex Flange ¼-20 x .75
Nut, Hex ¼-20
Nut, Hex 5/16-18
Nut, Pin-Lock 3/4-16
Nut, Hex Lock 3/4-16
15
BRAKE ASSEMBLY AND BYPASS ARM
Refer to Figure 8.
INSPECTION
DISASSEMBLY
1. Inspect the brake arm bias spring (66),
castle nut (69), washer (73), brake arm (68),
actuating pins (62), spring (71), brake yoke
screws (63/64), brake yoke (58), pucks (60),
puck plate (61), bypass arm (49), spacer
(65) and brake rotor (59) for wear or damage.
1. Remove the brake arm bias spring (66).
Note the orientation of the spring for proper
reassembly.
2. Remove the cotter pin (70), castle nut (69),
washer (73), brake arm (68), spring (71)
and actuating pins (62). Note the orientation
of the brake arm for proper reassembly. Discard the cotter pin (70).
3. Remove the two brake yoke screws (63/64)
and spacer (65) from the side housing assembly (2). Note the orientation of the spacer(s) (65) on the brake yoke assembly to
ensure proper reassembly. Remove the
brake yoke assembly (58), puck plate (61)
and puck (60).
4. Remove the bypass arm retaining ring (50)
and bypass arm (49). Discard the retaining
ring.
5. Remove the brake rotor (59) and puck (60).
Note: The hub on the rotor faces away from
the transaxle.
ASSEMBLY
1. Install the brake puck (60) and brake rotor
(59).
2. Install the bypass arm (49) onto the bypass
rod. Secure the bypass arm with a new retaining ring (50).
3. Install the brake puck (60), puck plate (61),
brake yoke assembly (58), spacer(s) (65)
and brake yoke screws (63/64).
4. Insert the brake actuating pins (62) into the
brake yoke (58). Install the spring (71).
5. Assemble the brake arm (68), washer (73)
and castle nut (69). Adjust the brake gap.
Refer to page 13. Install the brake arm bias
spring (66).
49
50
70
60
62
66
68
2
64
60
73
59
69
58
63
71
65
61
Figure 8. Brake Assembly and Bypass Arm
16
310-0510 IHT
CONTROL ARM AND FRICTION PACK
Refer to Figure 9.
3. Inspect the inner wedge puck (90).
DISASSEMBLY
4. Inspect the friction pack stud (76) for wear
or damage.
1. Remove the brake assembly. See page 16.
2. Loosen and remove the friction pack lock
nut (80), flat washer (73), spring (78), spacer (79), washer clip (82) and puck (77). Discard the lock nut (80).
3. Remove the hex head screw (16) from the
directional control.
ASSEMBLY
1. Install the friction pack stud (76), if removed.
Torque according to specifications in Table
5.
4. Remove the flat washer (73) and control
arm (18).
2. If previously removed, install the friction
pack wedge (81) and self tapping bolt (88).
Refer to Table 5 for bolt torque specifications. Use the marks made during disassembly to reposition the wedge properly.
5. Remove the inner wedge puck (90).
3. Install the inner wedge puck (90).
6. Removal of the friction pack wedge (81)
should not be necessary. Note: If it is removed, mark the orientation of the wedge
for ease in reassembly.
4. Install the control arm (18).
7. If necessary, remove and replace the friction pack stud (76).
INSPECTION
1. Inspect the friction pack assembly components for wear or damage.
2. Inspect the control arm for wear or damage.
5. Install the flat washer (73) and control arm
screw (16). Note: Remember to apply
thread adhesive to the screw threads before
installation. Refer to Table 5 for screw
torque specifications.
6. Install the puck (77), washer clip (82), spacer (79), spring (78), flat washer (73) and a
new lock nut (80). Adjust the friction pack
according to instructions on page 13.
7. Install the brake assembly. See page 16.
90
77
79
18
76, 81, 88
82
78
80
73
16
73
Figure 9. Control Arm & Friction Pack
310-0510 IHT
17
SEAL KIT REPLACEMENT
Before disassembly, wipe the unit free of any
debris to avoid contamination.
Refer to Figure 10.
input shaft.
2. The seal (13) can be replaced by following
steps 2-6 of the procedure used to replace
the axle seals.
Axle Seal
Trunnion Seal
1. Remove the axle clips (93) from the axle
horns (for units with keyed axle shafts).
2. Remove the seal retaining rings (12).
3. Carefully pull the axle seals (34) out of the
housing bore with a “hook” type tool. Care
must be taken to avoid damage to the housing bore or to the shaft sealing areas.
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.
6. Slide the seal over the shaft and press it into the housing bore.
7. The seal should seat against the sleeve
bearing.
8. Install the seal retaining rings (12).
9. Install the axle clips (93), if applicable.
1. Remove the control arm and any attachments to the control arm. See page 17.
2. The seal (17) can be replaced by following
steps 3-6 of the procedure used to replace
the axle seals.
Brake Seal
1. Remove the brake assembly and any attachments to the brake assembly. See page
16.
2. The seal (74) can be replaced by following
steps 3-6 of the procedure used to replace
the axle seals. Install a new retaining ring
(74).
Bypass Seal
1. Remove the bypass arm and any attachments to the bypass arm. See page 16.
2. The seal (51) can be replaced by following
steps 3-6 of the procedure used to replace
the axle seals.
Input Seal
1. Remove the input pulley and fan from the
12
13
12
93
34
34
93
12
17
74
51
Figure 10. Seal Kit Replacement
18
310-0510 IHT
SIDE HOUSING
Refer to Figure 11.
ASSEMBLY
DISASSEMBLY
1. Apply a bead of sealant around the perimeter of the side housing face. See sealant
pattern on page 28.
1. Remove the brake assembly and bypass
arm. See page 16.
2. Remove the control arm and friction pack.
See page 17.
3. Remove the oil from the transaxle. See
page 10.
4. After all of the oil has been removed from
the transaxle, remove the housing screws
(7) and torque strap screw (8).
5. Pull away the side housing (2), leaving the
axle assembly (35, Page 32) in the main
housing (1). It may be necessary to use
screwdrivers at the pry points to break loose
the sealant (positions B-H and G-J, Fig. 11).
2. Install the axle and sleeve bearing (31).
Note the orientation of the locating tab on
the sleeve bearing. It is essential for this to
align with the side housing bore.
3. Install the locating pins (83), if not already
installed.
4. Install the side housing (2) while aligning
the bypass rod into its side housing bore.
Use care not to smear the sealant bead.
5. Install the torque strap screw (8). Tighten
the screw according to the specifications in
Table 5.
6. Remove all the seals in the side housing.
See page 18.
6. Install the side housing screws (7). Refer to
the screw tightening pattern in figure 11 and
torque specs in Table 5.
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.
7. Install the remaining seals. Refer to page
18. Remember to use a seal protector during installation.
INSPECTION
1. Inspect the bearing areas in the side housing.
9
5
1
4
8. Fill the transaxle with new oil. See page 10.
9. Install the control arm and friction pack. See
page 17.
10. Install the bypass arm and brake assembly.
See page 16.
83
8
31
12
13
31
15
14
10
11
6
2
3
1
7
Bolt Torque Sequence
83
7
2
8
Figure 11. Side Housing Assembly
310-0510 IHT
19
AXLE SHAFT, DIFFERENTIAL & REDUCTION GEARS
Refer to Figure 12.
3. Inspect the bull gear for wear or damage.
DISASSEMBLY
4. Inspect the reduction gears, shaft and
washers.
1. Remove the brake assembly and bypass
arm. See page 16.
5. Inspect the housing bores.
ASSEMBLY
2. Remove the control arm and friction pack.
See page 17.
1. Reassemble and install the reduction gears
(28 & 29), jack shaft pin (41) and washers
(72).
3. Remove the oil from the transaxle. See
page 10.
2. Install the bull gear (30).
4. Remove the side housing. See page 19.
3. Reassemble and install the center block
bearing (54) (earlier units), differential cross
shaft(s) (39) and miter gears (38).
5. Remove the axle assembly (36), sleeve
bearing (31) and washer (33).
6. Remove the center block bearing (54)
(earlier models), differential cross shaft(s)
(39) and miter gears (38).
4. Install the washer (33), sleeve bearing (31)
and axle assembly (36).
5. Install the side housing. See page 19.
7. Remove the bull gear (30).
8. Remove the reduction gears (28 & 29), jack
shaft pin (41) and washers (72).
6. Install the outer sleeve bearing (32), axle
seal (34) (see page 18) and retaining ring
(12).
INSPECTION
7. Install all remaining seals. See page 18.
1. Inspect the axle, sleeve bearing and washer
for wear or damage. Replace as necessary.
8. Fill the unit with oil. See page 10.
9. Install the control arm and friction pack. See
page 17.
2. Inspect the differential cross shaft, center
block bearing and miter gears for wear or
damage.
10. Install the brake assembly and bypass arm.
See page 16.
32
30
36
31
39
38
New Bull Gear/Differential Assembly
(This is a direct replacement for the
assembly illustrated to the right.)
34
33
39
31
12
28
33
41
72
72
32
30
29
38
36
34
54
Figure 12. Axle Shaft, Differential & Reduction Gears (earlier bull gear shown)
12
MOTOR SHAFT AND BYPASS ROD
2. Inspect the bypass rod (48) for wear or
damage.
Refer to Figure 13.
DISASSEMBLY
1. Remove the brake assembly and bypass
arm. See page 16.
2. Remove the control arm and friction pack.
See page 17.
3. Drain the oil from the transaxle. See page 10.
4. Remove the side housing. See page 19.
5. Remove the axle shaft, differential and reduction gears. See page 20.
6. Remove the flat washer (52), motor shaft
and pinnion gear (24 & 27), and the flat
washer (108).
ASSEMBLY
1. Insert the bypass rod’s (48) short end into
the housing while aligning the rod’s flat with
the bypass actuator. Confirm proper bypass
function.
2. Insert the motor shaft (24) with the pinnion
gear (27) and flat washers (52 &108) into
the center section (3).
3. Install the axle shaft, differential and reduction gears. Refer to page 20.
4. Install the side housing. Refer to page 19.
5. Install new seals. Refer to page 18.
7. Remove the bypass rod (48). Clean the
magnet (42) of any foreign material.
6. Fill the transaxle with oil. See page 10.
INSPECTION
7. Install the control arm and friction pack. See
page 17.
1. Inspect the motor shaft (24), pinnion gear
(27) and flat washers (52 & 108) for wear or
damage.
8. Install the brake assembly and bypass arm.
See page 16.
24
48
3
48
42
3
108
24
52
27
Figure 13. Motor Shaft & Bypass Rod Assemblies
310-0510 IHT
21
INPUT SHAFT
Refer to Figure 14.
ASSEMBLY
DISASSEMBLY
1. Install the block thrust washer (56) and
spring (55) onto the input shaft (9).
2. Ensure that the pump block is aligned concentrically with the center section running
face.
3. Insert the input shaft (9), with bearing (14)
and retaining ring (10), 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 fit into
place.
4. Install the washer (11), seal (13) and retaining ring (12).
5. Install the motor shaft & bypass rod. See
page 21.
6. Install the axle, differential & reduction
gears. Refer to page 20.
7. Install the side housing. Refer to page 19.
8. Install new seals in the side housing. See
page 18.
9. Fill the transaxle with oil. See page 10.
10. Install the control arm and friction pack.
See page 17.
11. Install the brake assembly and bypass arm.
See page 16.
1. Remove the brake assembly and bypass
arm. See page 16.
2. Remove the control arm and friction pack.
See page 17.
3. Drain the oil from the transaxle. See page
10.
4. Remove the side housing. See page 19.
5. Remove the seals in the side housing. See
page 18.
6. Remove the axle shaft, differential and reduction gears. Refer to page 20.
7. Remove the motor shaft and bypass rod.
See page 21.
8. Remove the retaining ring (12) and shaft
seal (13). Discard the seal.
9. Remove the washer (11), input shaft assembly (9,10 and 14), block thrust washer
(56) and block spring (55).
INSPECTION
1. Inspect the input shaft components for wear
or damage.
12
13
11
10
14
9
55
56
Figure 14. Input Shaft Assembly
22
310-0510 IHT
HYDRAULIC COMPONENTS
Refer to Figures 15-24.
DISASSEMBLY
12. Reassemble the pistons, springs and seats
into the cylinder block and set aside.
(Pump Block)
13. (See Fig. 18) Remove the thrust bearing
assembly (19) from the swashplate (4).
1. Remove the brake assembly and bypass
arm. See page 16.
(Center Section/Filter)
2. Remove the control arm and friction pack.
See page 17.
3. Drain the oil from the transaxle. See page
10.
4. Remove the side housing. See page 19.
5. Remove the seals in the side housing. See
page 18.
6. Remove the axle shaft, differential and reduction gears. Refer to page 20.
7. Remove the motor shaft and bypass rod.
See page 21.
8. Remove the input shaft. See page 22.
9. (See Fig. 15) Remove the swashplate (4)
and pump cylinder block (5) 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
(18, Page 32) may be loosely assembled at
this point to assist in swashplate removal.
While gently removing the swashplate and
block assembly, keep the block face flush
with the center section to minimize damage
to the running surface.
10. (See Fig. 16) Disassemble the pump cylinder block (5) from the swashplate (4).
11. (See Fig. 17) 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 (1), piston springs (2) and
piston seats (3) for excessive wear or damage. NOTE: Piston seats may be held in
place in the piston by residual oil.
310-0510 IHT
14. (See Fig. 19) Remove the center section
mounting screws (44). NOTE: The center
section is under motor block piston spring
pressure. These screws are factory installed to 700 in. lbs. (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.
15. Remove the center section and filter assembly (124, Fig. 20).
16. (See Fig. 21) Remove the filter (45) from
the filter base (46) by snipping the four
posts with side cutters or applicable tool.
NOTE: This filter cannot be reused.
17. Remove and inspect the deflector (107),
bypass actuator (47) and bypass spring
(43).
18. Note the location of both check plugs (23 &
75) before removal for correct placement
during reassembly. Remove and inspect
the check plug assemblies (23) for debris
or damage.
19. Remove the filter base (46) and discard it.
NOTE: The filter base is included in the filter kit to be installed during reassembly of
the unit.
(Motor Block)
20. (See Fig. 22) Remove the motor cylinder
block assembly (5) from the housing (1).
21. Disassemble the motor cylinder block assembly (5). 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 piston
23
HYDRAULIC COMPONENTS
seats for excessive wear or damage.
NOTE: Piston seats may be held in place
in the piston by residual oil.
22. Reassemble the pistons, springs and seats
into the cylinder block and set aside.
23. Remove the thrust bearing assembly (19)
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 fingernail 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.
(Center Section)
3. (See Fig. 21) Install the new filter base (46)
onto the center section (3).
4. Install the check plugs (23 & 75), in their
correct location, into the center section (3).
Tighten the check plugs according to Table
5.
5. Install the bypass spring (43) into the filter
base (46).
6. Install the deflector (107) into the underside
of the filter (45).
7. Install the bypass actuator (47) into the underside of the deflector (107).
8. Hold the stem of the bypass actuator (47)
from the top of the filter (45) to retain the
deflector (107) and bypass actuator (47) in
place when snapping the filter (45) onto the
filter base (46). NOTE: Filter installation is
best accomplished by using the spacer (65,
Page 32) as an assembly tool over each of
the (4) snaps while lightly tapping with a
rubber mallet. Excessive force will result in
damage to the plastic filter components.
5. Inspect the motor cylinder block running
surface for damage and wear.
9. (See Figures 13 & 23) Install the motor
shaft (24), pinion gear (27) and flat washers
(52 & 108) into the center section (3).
6. Inspect all bearing, bushing and wear areas
in the housing.
10. Assemble the motor block assembly (5)
onto the motor shaft (24).
ASSEMBLY
11. (See Fig. 23) Install the motor shaft, center
section and motor block assembly so that
the block pistons contact the thrust bearing
race. NOTE: Hold in place and insure all
pistons are still positioned correctly in the
cylinder bore by confirming spring bias
against the center section.
(Motor Block)
1. (See Fig. 22) Turn the housing (1) so the
axle horn is pointing down. This will assist in
the installation of the thrust bearing assembly (19) keeping it in the bearing cavity during installation of the center section assembly.
2. Insert the thrust bearing (19) in the housing
(1). NOTE: Place the thin race of the bearing towards the housing bearing cavity. The
thick race must face the pistons.
24
12. (See Fig. 19) After applying thread adhesive, insert the center section mounting
screws (44) while holding downward pressure on the center section assembly (3,
Fig. 23).
310-0510 IHT
HYDRAULIC COMPONENTS
13. Tighten the center section mounting
screws (44) to the proper torque. Refer to
Table 5.
(Swashplate/Pump Block)
14. (See Fig. 18) Install the pump thrust bearing (19) in the trunnion machined swashplate (4). NOTE: Place the thin race of the
bearing towards the swashplate. The thick
race must face the pistons.
4
15. (See Fig. 16) Place the pump block assembly (5), pistons down, on top of the
thrust bearing in the swashplate (4).
5
16. Coat the pump running surface with clean
motor oil.
Figure 15
17. Care must be taken to prevent the scaring
or scratching of the center section sealing
face during this step. Insert the short shaft
side of the swashplate/pump block assembly (Fig. 24) into the housing while simultaneously compressing the pistons in the
block. NOTE: To assist in the installation of
these components, insert the assembly until ¾ of the pump block is covered by the
center section. Then slightly angle the trunnion shaft end away while pressing the
short swashplate shaft into its pocket.
18. Install the input shaft. See page 22.
4
5
Figure 16
1
3
19. Install the bypass rod. See page 21.
2
20. Install the axle shaft, differential and reduction gears. Refer to page 20.
21. Install the side housing. See page 19.
22. Install the seals in the side housing. See
page 18.
Figure 17
23. Fill the transaxle with new oil. See page 10.
24. Install the control arm and friction pack.
See page 17.
4
25. Install the brake assembly and bypass arm.
See page 16.
19
Figure 18
310-0510 IHT
25
HYDRAULIC COMPONENTS
Axle Horn
44
1
19
44
5
Figure 19
Figure 22
124
5
3
Figure 20
24
Figure 23
Short Shaft
3
46
Post
Figure 24. Swashplate/Pump Block Assembly
23
75
43
47
107
45
Figure 21
26
310-0510 IHT
TRANSAXLE INSTALLATION
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.
ASSEMBLY AFTER
TEARDOWN
A COMPLETE
If the unit has been torn down completely, the
following summary identifies the assembly procedures 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 32.
1. Install the hydraulic components. See pages 23-26.
2. Install the input shaft. See page 22.
3. Install the bypass rod. See page 21.
4. Install the axle shaft, differential and reduction gears. See page 20.
5. Install the side housing. See page 19.
6. Install new seals in the side housing. Refer
to page 18.
7. Fill the transaxle with new oil. See page 10.
8. Install the control arm and friction pack.
See page 17.
9. Install the brake assembly and bypass arm.
See page 16.
10. Install the transaxle onto the vehicle.
11. Perform the purge procedures listed on
page 11.
12. Perform the return to neutral procedure on
page 12.
310-0510 IHT
27
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 sufficient. Use sparingly.
The illustration below indicates the correct
areas.
Sealant Path
28
310-0510 IHT
310-0710 INTEGRATED HYDROSTATIC TRANSAXLE
DESCRIPTION
TRANSAXLE REMOVAL
The 310-0710 transaxle is an upgraded
310-0510 unit with different axle shafts, pump
cylinder block assembly, center section and
seal kit. The 310-0710 will have, as standard,
black axle shafts. Flanged hubs will be an
available option.
It is necessary to remove the 310-0710 from
the vehicle before performing the repair procedures presented in the repair section. Use the
following procedure to prepare the unit for removal from the vehicle.
Except for flanged hub removal and assembly
described below, repair techniques for this
model are the same as described in the
preceding sections of this manual. Table 6
illustrates key feature differences between the
310-0510 and the 310-0710.
1. With the vehicle wheels on the ground,
loosen the nuts retaining the hubs on the
transaxle. Use an air impact wrench and
socket to loosen the nuts.
NOTE: If unit is equipped with a Pin-Loc locknut, a punch must be used to tap the pin-lock
off of the axle shaft before removing the nut.
Pin-Lock
2. Lift the vehicle wheels from the ground and
remove the nut completely.
3. Remove the wheel from the hub.
4. Using a wheel or gear puller, remove the
hub from the shaft. Always inspect the hub
for damage after removal.
FEATURE COMPARISIONS
Table 6. Transaxle Features
310-0510/-0610 Features
310-0710 Features

5 piston 10cc pump

7 piston 10cc pump

¾" axle shafts

1" axle shafts

Keyed and two flats axle end options

Splined axle ends

Seal Kit part no. 70463

Seal Kit part no. 70722

Optional flanged hub
Note that larger (1") axle shafts make it necessary to specify a seal kit and axle bushings different
from the 310-0510 unit. The center section, pump cylinder block assembly, and associated kits also differ from those on the 310-0510. Refer to the appropriate model schematic for specific
component part numbers.
310-0510 IHT
29
310-0710 EXPLODED VIEW
30
310-0510 IHT
310-0710 ITEMS LIST
No.
DESCRIPTION
No.
DESCRIPTION
1
Main Housing, Assembly, Black
Main Housing, Black
Bushing .865 x .985 x .790
Side Housing, Assembly, Black
Side Housing, Black
Bushing .865 x .985 x .790
Bushing .624 x .719 x .562
Center Section Assembly
Center Section Machined
Bushing .707 x .788 x .591
Swashplate, Trunnion Machined
Block - Assembly
Block - Cylinder
Piston
Spring Compression
Thrust - Washer
Sealant
Hex Flange Screw 1/4-20 x 1.25
Shaft, Input
Ring - Retaining
Washer, Flat 1.23 x 1.57 x .04
Ring - Retaining
Seal, Lip 17 x 40 x 7
Ball Bearing 17MM x 40MM x 12MM
Hex Flange Head Screw 5/16-24 x 0.94 w/patch
Lip Seal 18 X 32 X 7
Arm, Control
Bearing, 30X52X13 Thrust
Check Plug Assembly, .027, Washer, “A” Port
Shaft, Motor
Gear - Pinion, 13T
10T/48T Gear
Gear, 10T Jackshaft
60T Bull Gear
Sleeve Bushing (Inboard)
Sleeve Bushing (Outboard) 1.002 x 1.571 x .625
Washer, Flat .77 x 1.5 x .10
Lip Seal Axle Seal
Shaft, Black, Axle 1.00/.75 x 10.65 (Flange, R.H.)
Shaft, Black, Axle 1.00/.75 x 16.25 (Flange, R.H.)
Miter Gear, 12T (Splined)
Miter Gear 12T (0.5 ID)
Shaft
Ring, Spiral Retaining
Pin, Jackshaft
Magnet, Ring
Spring, Bypass
Bolt, Hex Flange 3/8-24 x 2.5
Filter
Base, Filter
Actuator, Bypass
Rod, Bypass Actuator
Arm, Bypass
Retaining Ring .250 External
Seal, Lip ..250 x .750 x .250 TC
Flat Washer, .63 x 1.0 x .05
Retaining Ring
Spring, Block
Washer, Thrust .59 x .79 x .04
20W-50 Oil
Brake Yoke Kit
Disk, Brake
Brake Puck
Puck Plate
Brake Actuating Pin
Bolt, Hex Head 1/4-20 x 2 w/patch
Spacer
Spring, Brake Arm Bias
Arm, Brake
Nut, Castle 5/16-24
Cotter Pin 3/32 X 3/4
71
72
73
74
75
94
95
96
97
98
99
100
101
102
103
107
108
109
110
114
117
119
120
121
122
124
Compression Spring Brake Anti-Drag
Washer, Flat .51 x 1.00 x .03
Washer, Flat .34 x .88 x .06
Oil Seal .625 X 1.0 X .25
Check Plug Assy, .027, Washer, “B” Port
Ball Bearing .62 I.D. x 1.38 x .44
Socket Head Cap Screw, 5/16-24 x 1-1/2
Spacer Locating
Screw, Countersunk 5/16-18 x 1.0
Arm, Return
Puck, Adjusting
Washer, .32 x 1.60 x .24
Spring, Extension
Spacer, .260 x .560 x .87
Bracket, Torque
Deflector
Washer, Motor Shaft .71 x 1.16 x .04
Plug, 9/16-18 (Metal)
Torx Head Screw 5/16-18 x 1.5
Spring Guide
Pin, Spring .304 x.75
Fan, 7.0 in. (10 Blade)
Pulley, 3.86 in.
Nut, Hex Lock 1/2-20 w/nylon insert
Washer, OD slotted .53 x 1.63 x .06
Center Section-Filter-Bypass Assy
Center Section Machined
Base Filter
Check Plug Assy.
Spring, Bypass
Actuator, Bypass
Deflector
Filter
Bushing, .707 X .788 X .591
Filter Assembly
Kit, Fan/Pulley
Kit, Seal & O-Ring
Seal, Lip 17 x 40 x 7
Seal, Lip 18 x 32 x 7
Seal, Lip 1.00 X 1.577 X .250
Seal, Lip .250 X .750 X .250
Seal, Lip .625 X 1.0 X .25
O-Ring .299 x .505 x .103
Assembly, Block 7 Piston
Block, Cylinder
Piston
Spring, Compression
Seat
Nut, Pin Lock 3/4-16
Assembly, Hub
Hub, 4 Stud Metric (Painted)
Stud, M12 x 1.5 (Rib Neck)
Plug, 9/16-18 (Magnetic)
Fitting, 90° 9/16 SAE Beaded
Kit, 60T Bull Gear Diff Pins
Gear, 60T
Pin, 0.5 OD
Bulletin, Bull Gear
2
3
4
5
6
7
9
10
11
12
13
14
16
17
18
19
23
24
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
55
56
57
58
59
60
61
62
63
65
66
68
69
70
310-0510 IHT
125
126
127
135
152
153
164
165
200
31
310-0610 EXPLODED VIEW
32
310-0510 IHT
310-0610 ITEMS LIST
No.
DESCRIPTION
No.
DESCRIPTION
1
Main Housing, Assembly
Main Housing
Bushing .865 x .985 x .790
Pin, Headless Standard
Side Housing, Assembly
Side Housing
Bushing .865 x .985 x .790
Bushing .624 x .719 x .562
Center Section Assembly
Center Section Machined (5 piston)
Bushing .707 x .788 x .591
Swashplate, Trunnion Machined
Block - Assembly
Block - Cylinder
Piston
Spring Compression
Thrust - Washer
Sealant
Screw, Hex Washer 1/4-20 x 1.25
Stud, 5/16-18 THD, 5/16-18 Strap
Shaft, Input
Ring - Retaining
Washer, Flat 1.23 x 1.57 x .04
Ring - Retaining
Seal, Lip 17 x 40 x 7
Ball Bearing 17MM x 40MM x 12MM
Bolt, Hex Flange 5/16-24 x 0.94 w/patch
Lip Seal 18 x 32 x 7
Arm, Control
Bearing, Thrust 30 x 52 x 13
Shock Valve Assembly, .027, Washer, “A” Port
Shaft, Motor
Gear - Pinion, 13T
10T/48T Gear
Gear, 10T Jackshaft
60T Bull Gear
Sleeve Bushing (Inboard)
Sleeve Bushing .752 x 1.571 x .625
Washer, Flat .77 x 1.5 x .10
Lip Seal .750 x 1.577 x .250
Shaft, Axle .75 x 11.39 (Key, R.H.)
Shaft, Axle .75 x 16.99 (Key, L.H.)
Miter Gear, 12T (Splined)
Miter Gear 12T (0.5 ID)
Shaft
Ring, Spiral Retaining
Pin, Jackshaft .50 x 2.43
Magnet, Ring
Spring, Bypass
Bolt, Hex Flange 3/8-24 x 2.5
Filter
Base, Filter
Actuator, Bypass
Rod, Bypass Actuator
Arm, Bypass
Retaining Ring .250 External
Seal, Lip ..250 x .750 x .250 TC
Flat Washer, .63 x 1.0 x .05
Retaining Ring
Spring, Block
Washer, Thrust .59 x .79 x .04
20W-50 Oil
Brake Yoke Kit
Yoke, Brake
Bolt, Sq. Hd. 5/16-24 Ribbed
Disk, Brake
Brake Puck
Puck Plate
Brake Actuating Pin
Bolt, Hex Head 1/4-20 x 2 w/patch
Bolt, Hex Head 1/4-20 x 1 w/patch
65
66
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
84
85
87
88
90
93
107
108
109
111
113
119
120
121
122
123
124
Spacer .26 x .57 x .87
Spring, Brake Arm Bias
Arm, Brake
Nut, Castle 5/16-24
Cotter Pin 3/32 X 3/4
Compression Spring Brake Anti-Drag
Washer, Flat .51 x 1.00 x .03
Washer, Flat .34 x .88 x .06
Kit, Motor Shaft Seal .625 X 1.0 X .25
Check Plug Assy, .027, Washer, “B” Port
Stud, 5/16-24 Friction Pack
Puck .330 x 1.50 x .0975
Spring, Helical Compression
Spacer, .32 x .59 x .50
Nut, Hex lock 5/16-24 w/nylon insert
Wedge, Friction Pack
Spacer, Friction Pack
Fitting, 5/16 SAE 5/32 Tube
Hose, Expansion Tank 7.56
Cap, Barbed Vent
Bolt, Self Tapping
Puck, Inner Wedge
Spring Clip, Housing Thrust (.75 In Axle)
Deflector
Washer, Motor Shaft .71 x 1.16 x .04
Plug, 9/16-18 (Metal)
O-Ring .299 x .505 x .103
Bracket, Expansion Tank
Kit, Fan, 7.0 in. (10 Blade)
Pulley, 3.86 in.
Nut, Hex Lock 1/2-20 w/nylon insert
Washer, OD slotted .53 x 1.63 x .06
Bracket, Belt Keeper, Angled
Center Section-Filter-Bypass Assy
Center Section Machined
Base Filter
Shock Valve Assy.
Check Plug Assy.
Spring, Bypass
Actuator, Bypass
Deflector
Filter
Bushing, .707 X .788 X .591
Filter Assembly
Kit, Fan/Pulley
Kit, Seal & O-Ring
Seal, Lip 17 x 40 x 7
Seal, Lip 18 x 32 x 7
Seal, Lip 1.00 X 1.577 X .250
Seal, Lip .250 X .750 X .250 TC
Seal, Lip .625 X 1.0 X .25
O-Ring .299 x .505 x .103
Kit, Expansion Tank
Kit, 60T Bull Gear Diff Pins
Gear, 60T
Pin, 0.5 OD
Bulletin, Bull Gear
2
3
4
5
6
7
8
9
10
11
12
13
14
16
17
18
19
23
24
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
55
56
57
58
59
60
61
62
63
64
310-0510 IHT
125
126
127
128
200
33
6—SEALANT
57—20W-50 OIL
127—SEAL & O-RING KIT
310-0510 EXPLODED VIEW
34
310-0510 IHT
310-0510 ITEMS LIST
No.
DESCRIPTION
No.
DESCRIPTION
1
Main Housing, Assembly
Main Housing, Machined
Bushing .865 x .985 x .790
Pin, Standard Headless
Side Housing, Assembly
Side Housing, Machined
Bushing .865 x .985 x .790
Bushing .624 x .719 x .562
Center Section Assembly
Center Section Machined (5 piston)
Bushing .707 x .788 x .591
Swashplate, Trunnion Machined
Block - Assembly
Block - Cylinder
Pistons
Springs, Compression
Thrust - Washer
Sealant (10.1 oz.)
Hex Flange Screw 1/4-20 x 1.25
Stud, 5/16-24 Hex Double End
Shaft, Input
Ring - Retaining
Washer, Flat 1.23 x 1.57 x .04
Ring - Retaining
Seal, Lip 17 x 40 x 7
Ball Bearing 17MM x 40MM x 12MM
Hex Flange Head Screw 5/16-24 x 0.94 w/patch
Lip Seal 18 x 32 x 7
Arm, Control
Bearing, 30 x 52 x 13 Thrust
Check Plug Assembly, .027 Bleed, Washer (“A” port)
Shaft, Motor
Gear - Pinion, 13T
10T/48T Gear
Gear, 10T Jackshaft
60T Bull Gear
Sleeve Bushing (Inboard)
Sleeve Bushing .75 x 1.575 x .625
Washer, .77 x 1-1/2 x .10 THK
Lip Seal Axle Seal
Shaft, Axle .75 x 11.39 (DD, R.H.)
Shaft, Axle .75 x 17.99 (DD, L.H.)
Miter Gear 12T (Splined)
Miter Gear 12T (0.5 ID)
Pin
Ring, Spiral Retaining
Pin, Jackshaft
Magnet, Ring
Spring, Bypass
Bolt, Hex Flange 3/8-24 x 2.5
Filter
Base, Filter
Actuator, Bypass
Rod, Bypass Actuator
Arm, Bypass
Retaining Ring .250 External
Seal, Lip .250 x .750 x .250TC
Flat Washer, 5/8 x 1.0 x .05
Retaining Ring
Spring - Helical Compression
Washer, Thrust .59 x .79 x .04
20W-50 Oil
Brake Yoke
Rotor, Brake
Brake Puck
Puck Plate
Brake Actuating Pin
Bolt, Hex Hd 1/4-20 x 2 w/patch
Spacer
Spring, Brake Arm Bias
Arm, Brake
69
70
71
72
73
74
75
84
85
87
88
94
95
96
97
98
99
100
101
102
103
107
108
109
110
111
113
114
124
Nut, Castle 5/16-24
Cotter Pin 3/32 x 3/4
Compression Spring, Brake, Anti-Drag
Washer, HT .51 x 1.0 x .03
Flat - Washer .34 x .88 x.06
Oil Seal .625 x 1.0 x .25
Check Plug Assembly, .027 Bleed, Washer (“B” port)
Fitting, 5/16 SAE 5/32 Tube
Hose, Expansion Tank
Cap - Vent
Bolt, Self Tapping 10-32 x 1/2
Bearing, Ball .62 x 1.38 x.44
Screw, Socket Hd Cap 5/16-24 x 1.5
Spacer, Locating
Screw, Countersunk 5/16-18 1.0
Arm, Return
Puck, Adjusting
Washer, Flat .32 x 1.60 x .24
Spring, Extension Double Loop
Spacer .26 x .56 x .87
Bracket, Torque
Deflector
Washer, Flat .71 x 1.16 x .04
Plug, 9/16-18 (Metal)
Screw, Torx Hd 5/16-18 x 1.5
O-Ring .299 x .505 x .103
Bracket, Support Expansion Tank
Spring Guide
Center Section-Filter-Bypass Assy
Center Section (5 piston)
Base Filter (w/poppet)
Check Plug Assy. .027 Bleed, Washer
Spring, Bypass .50 in
Actuator, Bypass
Deflector
Bottom, Filter
Bushing, .707 x .788 x .591
Filter Assembly
Bottom, Filter
Spring, Bypass .50 in
Actuator, Bypass
Deflector
Base, Filter w/poppet
Kit, Seal & O-Ring
Seal, Lip 17 x 40 x 7
Seal, Lip 18 x 32 x 7
Seal Lip .75 x 1.577 x .250
Seal, Lip .250 x .750 x .250 TC
Seal, Lip .625 x 1.0 x .25
O-Ring .299 x .505 x .103
Kit, Expansion Tank
Tank, Expansion Assembly
Cap, Expansion
Bolt, Self Tapping 10-32 x 1/2
Bracket, Expansion Tank
Kit, 60T Bull Gear Diff Pins
Gear, 60T
Pin, 0.5 OD
2
3
4
5
6
7
8
9
10
11
12
13
14
16
17
18
19
23
24
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
55
56
57
58
59
60
61
62
63
65
66
68
310-0510 IHT
125
127
128
200
35
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 fluid 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 fluid from the component housing to the
reservoir.
Cavitation: A concentrated gaseous condition within the fluid 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 fluid to the fluid power system (closed loop).
Charge Pressure: The pressure at which replenishing fluid is forced into a fluid 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 flow in one direction.
Closed Loop: A sealed and uninterrupted circulating path for fluid flow 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 mechanical 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 fluid power into mechanical force and motion
by transfer of flow under pressure.
Hydraulic Pump: A device which converts mechanical force and motion into hydraulic fluid power
by producing flow.
Hydrostatic Pump: See “Hydraulic Pump”
36
310-0510 IHT
GLOSSARY OF TERMS
Hydrostatic Transaxle: A multi-component assembly including a gear case and a hydrostatic
transmission.
Hydrostatic Transmission: The combination of a hydraulic pump and motor in one housing to
form a device for the control and transference of power.
Inlet Line: A supply line to the pump.
Integrated Hydrostatic Transaxle (IHT): 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 fluid flow and system pressure is below that
which is required to turn the output shaft of the motor.
Pressure Decay: A falling pressure.
Priming: The filling of the charge circuit and closed loop of the fluid power system during start up,
frequently achieved by pressurizing the fluid in the inlet line.
Purging: The act of replacing air with fluid in a fluid power system by forcing fluid into all of the
components and allowing the air a path of escape.
Rated Flow: The maximum flow that the power supply system is capable of maintaining at a specific 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 fluid
power system.
System Charge Check Valve: A valve controlling the replenishing flow of fluid from a charge circuit to the closed loop in a fluid power system.
System Pressure: The pressure which overcomes the total resistance in a system, including all
losses.
Valve: A device which controls fluid flow direction, pressure, or flow rate.
Variable Displacement Pump: A pump in which the displacement per cycle can be varied.
Volumetric Displacement: The volume for one revolution.
310-0510 IHT
37
© 2010 HYDRO-GEAR
Printed in U.S.A.
Rev. P5
38
310-0510 IHT