Toro 74901, 74901CP, 74902TE, 74903, 74903CP Service Manual

HY13-1521-M2/US

Parker Product

Effective: January, 2010

UHT
Product Series
Service Procedure

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

WARNING

FAILURE OR IMPROPER SELECTION OR IMPROPER USE OF THE PRODUCTS AND/OR SYSTEMS
DESCRIBED HEREIN OR RELATED ITEMS CAN CAUSE DEATH, PERSONAL INJURY AND PROPERTY
DAMAGE.

This document and other information from Parker Hannifin Corporation, its subsidiaries and authorized
distributors provide product and/or system options for further investigation by users having technical expertise. It
is important that you analyze all aspects of your application and review the information concerning the product or
system in the current product catalog. Due to the variety of operating conditions and applications for these
products or systems, the user, through its own analysis and testing, is solely responsible for making the final
selection of the products and systems and assuring that all performance, safety and warning requirements of the
application are met.

The products described herein, including without limitation, product features, specifications, designs, availability
and pricing, are subject to change by Parker Hannifin Corporation and its subsidiaries at any time without notice.

© Copyright 2009, Parker Hannifin Corporation, All Rights Reserved

2

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Section 1 General Information

Definitions/Disclaimer 4
Introduction/Design Features 5
Troubleshooting Guide 6
Troubleshooting Checklist 7
Tools & Materials Required for Servicing 8
Flow Test Instructions 9-10
Exploded Views 11-20

Section 2 Reseal & Repair

Disassembly & Assembly - Fan Option 21
Disassembly 22-29
Assembly 30-38

Section 3 Maintenance

System Maintenance Tips 39
Hydraulic Fluids 39
Filtration 39
Oil Temperature 39

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Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

WARNING A warning describes hazards or unsafe practices which could result in severe
personal injury or death.

CAUTION

A caution describes hazards or unsafe practices which could result in personal injury or

product or property damage.

NOTE A note gives key information to make fo

llowing a procedure easier or quicker.

Disclaimer

This Service Manual has been prepared by Parker Hannifin Corporation for reference and u se by mechanics
who have been trained to repair and service hydraulic pumps on commercial and non-commercial equipment
applications. Parker Hannifin Corporation has exercised reasonable care and diligence to present accurate, clear
and complete information and instructions regarding the techniques and tools required for maintaining, repairing
and servicing the Parker UHT Series. Since this is a general Service Manual, the photographs and illustrations
may not look exactly like the UHT being serviced. The procedures, therefore, must be carefully read and
understood before servicing.

If inspection or testing reveals evidence of abnormal wear or damage to the UHT or if you encounter
circumstances not covered in the Manual, STOP - CONSULT THE EQUIPMENT MANUFACTURER’S SERVICE
MANUAL AND WARRANTY. DO NOT TRY TO REPAIR OR SERVICE A UHT Series WHICH HAS BEEN
DAMAGED OR INCLUDES ANY PART THAT SHOWS EXCESSIVE WEAR UNLESS THE DAMAGED AND
WORN PARTS ARE REPLACED WITH ORIGINAL PARKER REPLACEMENT AND SERVICE PARTS AND
THE UNIT IS RESTORED TO PARKER SPECIFICATIONS FOR THE UHT Series.

It is the responsibility of the mechanic performing the maintenance, repairs or service on a particular UHT Series
to (a) inspect the unit for abnormal wear and damage, (b) choose a repair procedure which will not endanger
his/her safety, the safety of others, the equipment or the safe operation of the UHT Series, and (c) fully inspect
and test the UHT Series and the hydraulic system to ensure that the repair or service of the UHT Series has
been properly performed and that the UHT Series and hydraulic system will function properly.

Conversions

Inches Mm Inches mm
.020 .511 1.060 26.92
.021 .531 1.295 32.89
.029 .741 1.297 32.94
.030 .760 1.396 35.46
.111 2.81 1.398 35.51
.119 3.02 1.620 41.15
.152 3.86 1.622 41.20
.160 4.06 1.983 50.37
.296 7.52 1.985 50.42
.304 7.72 2.120 53.85
.460 11.68 2.122 53.90
.470 11.94 2.233 56.72
.500 12.70 2.235 56.77
.585 14.86 2.483 63.07
.595 15.11 2.485 63.12
.660 16.76 2.500 63.5
.675 17.15 2.88 73.2

1.058 26.87

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Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Introduction

The three-column format used in this Service Manual will help make it easy for you to service a UHT. Column 1
illustrates the procedure with photographs, Column 2 gives a brief key for each step, and Column 3 explains in
detail the procedure you should follow. Pay special attention to the notes, cautions, and warnings.

This manual contains troubleshooting information and checklists. With them you can diagn ose a hydraulic
system problem without removing the entire assembly the checklists will help you to determine where the
problem may be.

Item numbers on the exploded view correspond with item numbers used throughout the Service Manual.
As you gain experience in servicing UHT Series, you may find that some information in this Service Manual

could be clearer and more complete. If so, let us know about it. Don’t try to second-guess the Service Manual; if
problems occur that you cannot solve, please contact your local OEM approved distributor. Servicing UHT Series
should be safe and productive.

DESIGN FEATURES
UHT

Large area cooling fins result in a cooler running system



Top housing and charge pump cover are sturdy, lightweight aluminum, excellent at



dispersing heat, resulting in an overall cooler system

Forged trunnion shaft increases shaft strength and lengthens pump life



Double caged thrust bearing improve lubrication and vibration absorption, thus



lengthening life of pump

Torqmotor

Roller vane to reduce friction and internal leakage and to maintain efficiency



A patented orbiting commutator system for less wear and longer life



A unique high-pressure shaft seal that eliminates the need for case drain



Manifold designed to improve operating efficiency



Roller vane and sealed commutation assure high volumetric efficiency and smooth low



speed operation

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Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Troubleshooting Guide

NOTE

Before troubleshooting any system problem, check
service literature published by the equipment and/or
component manufacturers. Follow their instructions, if
given, for checking any component other than the
transmission.

Preparation

Make your troubleshooting easier by preparing as
follows:

• work in a clean, well-lighted place

• have proper tools and materials nearby

• have an air pressure source.

WARNING

Since solvents are flammable, be extremely careful
when using any solvent. Even a small explosion could
cause injury or death.

WARNING

Wear eye protection and be sure to comply with
OSHA and other maximum air pressure
requirements.

Preliminary Checks

Hydraulic systems are often trouble-free. Hence, the
problem an operator complains of could be caused by
something other than the hydraulic components.

Thus, once you have determined that a problem
exists, start with the easy-to-check items, such as:

• Parts damaged from impact that were not properly
repaired, or that should have been replaced

• Improper replacement parts used in previous
servicing

• Mechanical linkage problems such as binding,
broken or loose parts, or slipping belts

Hydraulic Components

If you think the problem is caused by a hydraulic
component, start by checking the easy-to-reach
items.

Check all belts for cracks, hardening or other signs of
wear. Check all pulleys, fans and bolts to make sure
they are tightened to specified torque value. Look for
leaks, especially at coupling shaft, plugs and fittings.

Next, go to the reservoir and filters. Check fluid level
and look for air bubbles. Check external filter(s). A
filter with a maximum of 25 - 30 micron filtration is
recommended for the UHT system.

Visually check other components to see if they are
loosely mounted, show signs of leaks, or other
damage or wear.

Excessive heat in a hydraulic system can create
problems that can easily be overlooked. Every
system has its limitation for the maximum amount of
temperature. After the temperature is attained and
passed, the following can occur:

• oil seal leaks

• pump loss of efficiency (resulting in lower
transmission speeds)

• pump failure

• belts become hard and brittle

• pulley lose

A normal temperature range means an efficient
hydraulic system. Consult the manuals published by
equipment and/or component manufacturers for
maximum allowable temperatures and hydraulic tests
that may be necessary to run on the performance of
the hydraulic components. The UHT is not
recommended for hydraulic systems with maximum
temperatures above 280

o

F (137o C).

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Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Troubleshooting Checklist

Trouble Cause Remedy
Oil Leakage

Operates Hot

1. Fitting loose, worn or
damaged.

2. Oil seals deteriorated
by excess heat.

1. Debris buildup Remove debris

2. Cooling fan damaged Replace fan

Check & replace damaged fittings or
“O” rings. Torque to manufacturers
specifications.
Replace oil seals by disassembling
unit.

No/Low Power

3. Oil level low or

Fill or change filter

contaminated

4. Excessive loading Reduce vehicle load

5. Air trapped in system

Run vehicle slowly forward and then
reverse several times

6. Mowing conditions Heavy grass or embankments

1. Engine speed low Adjust setting

2. Oil level low or

Fill or change filter

contaminated

3. Bypass turned Turn to closed (horizontal) position

4. Excessive loading Reduce vehicle load

5. Air trapped in system Purge per instructions

6. Suspect internal Disassemble and inspect

7. Pulley or belt loose

Tighten to specifications

Noisy Unit

1. Excessive speed input Adjust input speed above 1800 rpm
and below 3600 rpm

2. Oil level low or

Fill or change filter

contaminated

3. Excessive loading Reduce vehicle load

4. Air trapped in system Run vehicle slowly forward and then
reverse several times

5. Bypass valve open

Turn to closed (horizontal) position

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Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Tools and Materials Required for Servicing

• Clean, petroleum-based solvent

• Emery paper

• Vise with soft jaws

• Air-pressure source

• Arbor press

• Flat screwdriver

• Grease pencil or paint pen

• Wheel puller

• 1/4" torque wrench : 155-190 in-lbs, 282-342 in-lbs, 90-110 in-lbs, 160-200 in-lbs

• Sockets: 3/8" drive ratchet, 5/16" hex, 1/4” hex, 3/8” hex, 10mm, 14mm, 16mm

• Allen wrenches: 5mm, 6mm, 1/4" and 3/8”

• Combination wrenches:

• Locking pliers

• Internal & external snap ring pliers

• Loctite ™ 242

• Grease – Mobil Mobilith SHC PM 460

• Oil – Recommended OEM Type Oil

• Four inch adjustable spanner wrench (Armstrong 34-157) or three inch fixed spanner (Armstrong 34-

124)

CAUTION

Mixing greases that have different bases can be detrimental to bearing and seal life.

8

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

UHT Flow Test Kit Instructions
SK000251

Parts List

Item Qty Part Number

1
2 1 411102 Needle Valve 525 in lbs.

3 2 414003 Gauge Fitting “T” 165-525 in lbs.
4 2 411103 3000 PSI Pressure Gauge 165 in lbs.
5 2 411104 Hose Assembly 525 in lbs.
6 2 414005 Reducer Fitting 525-950 in lbs.
7 1 411105 20 GPM Flow Meter 525 in lbs.
8 1 409350 Diagnostic Plug 525 in lbs.
9 1 SAE-J514-8-8-070120CF Straight Thread Fitting 525 in lbs.

- 1 SK000251 Service Bulletin N/A

1 414002 SAE Swivel Fitting 525 in lbs.

Description

Torque

Overview:

The Flow Test Kit allows the dealer to easily determine if UHT pump is faulty by isolating the
pump section from the wheel motor. The following information describes how to test the pump
by installing the Flow Test Kit and simulating a wheel motor load.

Procedure:

1. Raise the drive tires off the ground and block the remaining

tires to prevent movement of the vehicle during testing.

2. Remove wheel from the hub to gain access to motor.

3. Ensure the pump bypass lever is in the “Closed” position

(horizontal).

4. Isolate the pump from the wheel motor by removing the two
plugs from the top of the wheel motor assembly and installing
the Flow Test Kit. Install the Diagnostic Plug in port “A”, and the
Straight Thread Fitting in port “B”. Take precautions to ensure
no debris gets into the wheel motor system ports.

There is no need to determine the direction of flow with the
Parker flow tester. The flow meter may be connected in either
direction into the high pressure system lines.

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Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

WARNINGS

Portions of this procedure
require testing while the
vehicle is operated in an
elevated position.

Ensure vehicle is properly
secured to prevent injury
to the service technician
or bystanders.

Do not attempt any ad­justments with the engine
running. When working
around vehicle linkages,
use extreme caution.

High temperatures can be
generated.

Follow all safety proce­dures in the vehicle own­er’s manual.

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

CAUTION: All fittings and hoses must be securely attached. The test is
accomplished using the vehicle’s high pressure system lines. Failure to secure
connections could result in bodily injury.

5. Completely open the restriction valve.

6. Start the engine and, if required, engage the drive pulley.

7. Slowly bring engine up to maximum operating speed.

8. Move the vehicle’s directional control lever on the pump being tested all the way into the

forward position. Lock the control arm into position to prevent false readings.

9. Continue to operate without any load to allow the system oil temperature to rise.

NOTE: Raising the temperature of the oil will make a difference in your readings. To complete
the test accurately, the oil temperature should fall between 110˚ and 140˚ F.

10. Tighten the restriction valve until the difference between the pressure gauge readings is

300 psi (21 bar). Record the flow reading from the bi-directional flow meter.

11. Tighten the restriction valve until the difference between the pressure gauge readings is

1000 psi (69 bar) and record the flow reading again.

12. The maximum allowable flow rate change is shown below. If the difference exceeds this

level, the pump is unacceptable.

13. When testing is complete, re-install the motor port plugs. Torque to 35 to 50 ft-lb.

Displacement

Series

cc/rev

(nominal)

UHT 12 to 16 1.0

* Max. Allowable Flow Rate Change is equal to the flow rate at 300 psi minus the flow rate at 1000 psi.

Max. Allowable Flow Rate

Change* (gpm)

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Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

EXAMPLE:
First Reading 300 psi (21 bar) 5 gpm (19 l/min)

Second Reading 1000 psi (69 bar) - 3 gpm (11 l/min)
Difference 2 gpm (8 l/min)

By subtracting the second reading from the first, a
defective pump can be identified. In the example
above, 2 gpm indicates a defective pump.

11

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

12

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

13

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Note: When servicing UHT assemblies with a serial number code of 09256 or earlier, item 29 is not req uired.

When servicing UHT assemblies with a serial number code of 09257 or after, item 25 is not required. Though item 22 is
provided in the seal kit, it can be discarded if the endblock does not include a machined seal groove.

14

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

Service Manual
Series HB Hydrostatic Transmission

HY13-1521-M2/US

General Information

15

Parker Hannifin Corporation
Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

SK000243 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

22 4 032202-017

PACKING, PREFORMED, O-RING SEAL

23 4

032860-001

RETAINER, PACKING BACKUP

24 1

032203-114

PACKING, PREFORMED, O-RING SEAL

SK000244 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

27 1

478035

SEAL

28 1

032818

SEAL, SHAFT

31 1

406018

LUBRICANT PACK SK000245 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

22 1 032202-017

PACKING, PREFORMED, O-RING SEAL

23 4 032860-001

RETAINER, PACKING BACKUP

24 4 032203-114

PACKING, PREFORMED, O-RING SEAL

25 1

032203-249

PACKING, PREFORMED, O-RING SEAL

26 2 032206-018

PACKING, PREFORMED, O-RING SEAL

27 1 478035

SEAL, (DIRT & WATER)

28 1

032818

SEAL, SHAFT

29 6 032820

O-RING SEALS

30

1 032439

SEAL, COMMUTATOR

31 1

406018

LUBRICANT PACK SK000246- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

8 1 HP2013000-A1

SA, SWASH BLOCK

9 1 069010

WASHER, THRUST

10 1

063048

BEARING, THRUST

11 1

069011

WASHER, THRUST

SK000247 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

5

1 032090

SEAL, FAN DRIVE

6 1

478087

SEAL, TRUNNION ARM

7 1

401303

RING, RETAINING

12

1 034001

GASKET

13 2 032203-114

PACKING, PREFORMED, O-RING SEAL

14 1

032202-111

PACKING, PREFORMED, O-RING SEAL

15

1 032202-239

PACKING, PREFORMED, O-RING SEAL

16

** WASHER, SEAL (NOT REQUIRED) **

17 1

478086

SEAL, SHAFT

18 1

401114

RING, RETAINING

22 1 032202-017

PACKING, PREFORMED, O-RING SEAL

23

4 032860-001

RETAINER, PACKING BACKUP

24 4 032203-114

PACKING, PREFORMED, O-RING SEAL

SK000249 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

19 1 403855

PULLEY

20 1

028413

WASHER

21 1

025164

NUT SK000250- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

1 1

100000025-038

SCREW, HEX FLANGE UNRC

2 1

028020

WASHER, FAN DRIVE

3 1

420066

FAN, 8.3 INCH

4 1

100000032

SPACER, FAN

Service Manual
Series HB Hydrostatic Transmission

HY13-1521-M2/US

General Information

16

Parker Hannifin Corporation
Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

SK000257 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0240ZF080UHTA

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

25 1 032203-249

PACKING, PREFORMED, O-RING SEAL

1 SK000243

SERVICE KIT, SEALS

SK000258 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0240ZF081UHTA

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

25 1 032203-249

PACKING, PREFORMED, O-RING SEAL

1 SK000243

SERVICE KIT, SEALS

SK000259 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0280ZF080UHTB

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

25 1 032203-249

PACKING, PREFORMED, O-RING SEAL

1 SK000243

SERVICE KIT, SEALS

SK000260- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0280ZF081UHTB

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

25 1 032203-249

PACKING, PREFORMED, O-RING SEAL

1 SK000243

SERVICE KIT, SEALS

SK000261- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0240YF080UHTC

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

1 SK000243

SERVICE KIT, SEALS

SK000262 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0240YF081UHTC

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

1 SK000243

SERVICE KIT, SEALS

SK000263- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0280YF080UHTD

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

1 SK000243

SERVICE KIT, SEALS

SK000264 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0280YF081UHTD

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

1 SK000243

SERVICE KIT, SEALS

SK000265- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0240YF080UHTE

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

1 SK000243

SERVICE KIT, SEALS

SK000266 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

32 1 TL0240YF081UHTE

SA, MOTOR

33 2 036016-008

PLUG, HOLLOW HEX

1 SK000243

SERVICE KIT, SEALS

Service Manual
Series HB Hydrostatic Transmission

HY13-1521-M2/US

General Information

17

Parker Hannifin Corporation
Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

SK000267- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

34 1 HB011002

NOSE CUP, MACHINED

1 SK000243

SERVICE KIT, SEALS

SK000268 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

34 1 HB011003

NOSE CUP, MACHINED

25 1 032203-249

PACKING, PREFORMED, O-RING SEAL

1 SK000243

SERVICE KIT, SEALS

SK000271- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

35 1 HB012002-A1

SA, TOP HOUSING

12 1 034001

GASKET

SK000272 - PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

35 1 HB012003-A1

SA, TOP HOUSING

12 1 034001

GASKET

SK000273- PART LIST

ITEM

QTY

PART NUMBER

DESCRIPTION

36 1 478088

DUST CAP

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Before you disassemble the UHT or any of its components, read this entire manual. It provides important
information on parts and procedures you will need to know to service the UHT Unit.

The UHT will have a six cross member bolts and four frame mounting bolts.
Remove fan from shaft prior to servicing any portion of UHT unit to prevent from breaking.
Thoroughly clean off all outside dirt, especially from around fittings before disconnecting and removing the UHT

transmission. Remove rust or corrosion from the coupling shaft.
Remove shaft connections and immediately plug port holes and fluid lines.
Remove the UHT from the system, drain it of fluid and take it to a clean work surface.
Clean and dry the UHT before you start to disassemble it.
As you disassemble the UHT, clean all parts, except seals, in clean, OSHA approved solvent, and air blow them

dry.

WARNING
Solvents are flammable, be extremely careful when using them. Even a small explosion or fire could

cause injury or death.

WARNIN

Wear eye protection and be sure to comply with OSHA and other maximum air pressure requirements.

ARN

W

Never steam or high pressure wash hydraulic components. Do not force or abuse closely fitted parts.

Keep parts separate to avoid nicks and burrs.

rd all seals and seal rings as they are removed from the UHT Unit. Replace all seal rings and any damaged

Disca
or worn parts with genuine Parker Hannifin Corporation or OEM approved service parts.

G

G

IN

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Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Clean unit of grass and other
debris; let dry.

Remove unit from vehicle

Drain the oil from the unit

Remove the breather/dipstick
assembly.
Place an oil pan under the
unit for oil collection.
Remove the filter and
position the unit as
necessary to drain oil into the

Remove the fan and fan
spacer

Inspect drive fingers for
wear

Note: Some units may not

pan.
Remove the ¼-20UNC bolt

securing the fan to the shaft
using a 3/8” socket. Remove
the fan washer and fan.
Using a small pry bar or flat
head screwdriver, gently pry
the fan spacer from the taper
on the pump shaft.

have a fan. If fan is not
present, skip to next step.

Remove the pulley
Inspect the pulley for

damage or abnormal wear

While holding the pulley from
turning, remove the 5/8­18UNF nut. Remove the flat
pulley washer. Use puller
with ¼-20 bolts of
appropriate length threaded
into the face of pulley to
remove from shaft.

Remove the motor bolts

Using a ¾” socket remove
the (4) ½-20 bolts securing
the motor and parking brake
cable anchor. The lower two
bolts are 2 ¼ “long and the
two top bolts are 6 ½” long.

19

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Remove the complete drive
motor

Remove the motor from the
nosecup by tapping cast iron
housing with a soft-face
mallet and gently prying on
the flange surface of the
motor taking care not to
damage the aluminum
nosecup.

Remove the nosecup

Remove the nosecup from
the endblock by removing the
two (2) ½-20 x 2 ¾” long
socket head caps screws
with a 5/16” allen head
socket.

Remove the transfer tubes

Remove the transfer tubes
by gently pulling the tubes
out of the endblock. It may
be necessary to rotate the
tubes while pulling.

Remove the charge pump

Using snap ring pliers
remove the charge pump
cover snap ring.

cover seal snap ring

20

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Disassemble the pump
section

Note: Two left bolts
measure 1 ¾” long the
other four are 2 ¾” long.

Using a 9/16” socket remove
the (6) 3/8-16UNC bolts
securing the top housing to
the endblock. Note two (2) of
the bolts are shorter than the
other four (4) that secures
the charge pump cover to
endblock and top housing.

Disassemble the pump
section

Note: Before completely
removing the top housing,
lay pump section on its side
so that pistons do not fall out
of the bores.

Disassemble the pump
section

Remove the top housing
from the endblock assembly.

Note that the swash block
and trunnion arm will remain
in the top housing when it is
removed from the end block
assembly.

Remove the swash block
assembly

Remove the swash block
assembly from the top
housing by lifting it out.

21

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Remove bearing cage and
thrust washers

Note: Washers should be
re-installed in the same
orientation/position they
were found – Do not Flip

Remove the trunnion arm
and control block

Caution:
Do not remove the two

cradle bushings!

Remove the bearing cage
and thrust washers from the
swash block by lifting them
out. Check both washers and
bearing for excess wear or
pitting damage.

Remove the trunnion arm
and the control block by
sliding the trunnion arm
toward the center of the top
housing and removing it from
the bore.

The bushings can have light
wear pattern but no other
damage. Both bushings must
be tight and seated flat
against radius.

Trunnion arm seal

Inspect trunnion arm seal for
any damage or leakage at or
around trunnion arm seal.

If replacing the trunnion seal
remove retainer clip then
trunnion arm seal with a flat
head screw driver.

22

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Remove the cylinder block

Remove spring retainer

Remove the cylinder block
assembly

Inspect pistons, bores and
both running surfaces

Remove the snap ring from
the pump shaft with external
snap ring pliers. Use care
not to over-stretch snap ring.
Take special notice not to
scratch sealing zone on shaft
while removing and replacing
snap ring.

Remove the spring retainer
and the cylinder block spring
from the shaft.

Remove the cylinder block
from the pump shaft by
sliding the cylinder block off
the splines on the pump
shaft. It may be necessary
to rotate the cylinder block
by hand while lifting.

Check for excessive wear

Check surface of rotating
group and sides of pistons
for excessive wear, indicated
by scoring. Remove pistons
and check bores and springs
for signs of scoring. Check
top of OD of pistons for
pitting or scratch marks.
Parts must be replaced if the
scoring is deep enough to

23

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

catch a fingernail.

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Remove the charge pump
cover and shaft bearing
sub-assembly from end
block

Remove charge pump seal

Remove shaft bearing sub­assembly from charge
pump cover

Remove the charge pump
cover assembly and shaft
bearing sub-assembly by
sliding the pump shaft
through the central hole in
the end block.

Push out charge pump seal
with shaft.

Pull shaft bearing sub­assembly from charge pump
cover.

Pump shaft and bearing
sub-assembly

Inspect shaft and bearing
assembly for any heavy
scoring or damage around
seal area. Do not attempt to
remove bearing from shaft
this is a sub-assembly.

24

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Remove charge pump
rotor and stator

Remove two dowel pins

Remove the charge pump
pressure relief valve

Remove charge pump rotor,
stator and o-ring. Inspect for
scoring or any damage to
rotor and stator. Inspect the
O-ring, it should be flexible
and conform to the o-ring
groove in the charge pump
cover.

Remove the dowel pins by
sliding the pins out of the
bores in the end block.

Remove with ¼” allen head
socket or appropriate hex
wrench as necessary.

Orifice Plug

Do not remove the orifice
plug! Make sure the orifice is
free from debris by blowing
low pressure shop air
through orifice to ensure
clean passage.

25

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Remove the bypass valve
snap ring

Remove the bypass valve

Remove the shock / check
valves

Remove the snap ring
securing the bypass valve in
the bore with internal snap
ring pliers.

Remove the bypass valve
from the bore by pulling the
valve directly out of the bore
in the end block.

Remove shock valve with
3/8” allen head socket
16cc – 280 will have 241
number on the outside of
shock valve.
12cc – 240 will have 275
number on the outside of
shock valve.

Shock Valves

16cc – 280 will have 241
number on the outside of
shock valve.
12cc – 240 will have 275
number on the outside of
shock valve.

26

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Check Valves

Remove check valve with
5/16” allen head socket .
Check valves will not have
any numbers on the outside.
Please refer to picture to
determine if you have either
check or shock valves.

27

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

End block assembly

Key factor in the successful
repair is cleanliness. Prior to
assembly make sure all
exposed surfaces are
thoroughly clean and free of
foreign material and
chemicals. Replace all seals,
o-rings, oils and gaskets with
original OEM parts.

Orifice plug is clean

Do not remove the orifice
plug! Make sure the orifice is
free from debris by blowing
low pressure shop air through
orifice to ensure clean
passage.

Install the shock /
check valves

16cc – 280 will have 241
number on the outside of
shock valve
12cc – 240 will have 275
number on the outside of
shock valve

Engage threads manually
hand start several threads to
prevent cross threading.
Torque shock valve to
specifications 480 - 540 in.
lbs.
Torque check valves to 252 –
288 in lbs.

Lube the bypass valve O-ring
and position in bypass port.

Install the bypass valve

28

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Install bypass valves

Install the bypass valve
retaining ring, pliers
required

Install the bypass valve
snap ring

Install the bypass valve. Push
valve directly in the bore of
the end block as far as it will
go.

Install the snap ring securing
the bypass valve in the bore.
Place retaining ring on bypass
valve shaft and position into
the groove on the inside of
the bypass valve port.

Use the tip on the pliers to
make sure the retaining ring is
seated in the groove around
the entire circumference of
hole.

Install two dowel pins

Install the dowel pins by
sliding the pins into the bores
in the end block.

29

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Install ¼ SAE hex plug
into port on side of end
block

Torque to
specifications

Install charge relief
cartridge

Install O-ring

Install the ¼ SAE hex plug.
Hand start several threads to
prevent cross threading.

Torque ¼ SAE hex plug on
side of end block 252 – 288 in
lbs.

Install the charge relief
cartridge hand start several
threads to prevent cross
threading. Using a ¼ “ allen
head socket torque to 252 –
288 in lbs.
*If a hex type valve is present,
use an 11/16“hex socket to
apply torque.

Lube case drain O-ring and
install in end block.

Note: Certain models may or
may not have this o ring.
If your end block has this O­ring replace if end block does
not have this o ring then it will
not be required.

30

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Polish I.D. with emery
cloth paper

Replacement Trunnion
seal

Remove any burrs with emery
cloth paper from the I.D. of
trunnion seal area. Clean
area with a lint free cloth after
polishing I.D.

With the flat side of seal
facing up push seal in flush to
top housing.

Place socket on top of
seal

Tap seal into place

Place 11/16 deep well socket
over seal.

Gently tap socket with rubber
hammer driving seal into
place.

31

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Install retainer clip

eat retainer clip

S

isual check

V

Place retainer clip with the
tongs pointed away from seal.

ently tap socket with rubber

G
hammer driving retainer clip.

See that the seal retainer is

ush with the top of the

fl
housing.

octite ™ 242

L

hreadlocker

T

Apply Loctite ™ 242
Threadlocker to the O.D. of
seal bore

Use of Loc

liminates the need for a snap

e

tite ™ 242

ring.

32

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Apply Loctite ™ 242
Threadlocker to the
O.D. of the fan seal

Press fan seal into top
housing bore
Look for rubber
scraped off by snap
ring groove replace
seal if it has been
damaged

Top housing in now
complete sub assembly

Note: Loctite ™ 242 should
not contact rubber I.D. on
seal.

Place a rubber hammer on
top of seal. Use second
rubber hammer drive seal into
cavity flush. Place a 5/8
socket over seal using rubber
hammer drive seal either
below snap ring groove in
bore or .200” deep.

Note: By adding Loctite to the
O.D. of fan seal the snap ring
will not be required.

Install trunnion arm

Install control block

Lubricate trunnion arm shaft
and insert into and through
the trunnion arm seal.

Install control block onto
trunnion arm inside of top
housing.

33

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Apply Oil

Install swash block

Apply Oil into swash
block

Apply OEM recommended oil
to cradle bushings.

Install swash block
subassembly onto cradle
bearing in top housing. Verify
that swash block moves freely
back and forth on bushing
without binding or dragging

Apply OEM recommended oil
prior to installing thin washer
into swash block

Install thrust washer

Install thrust bearing

Install thin (.143”) thrust
washer into swash block.

Install thrust bearing on top of
thrust washer.

34

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Install top washer

Apply Oil to top washer

Install charge pump
shaft and bearing
assembly into charge
pump cover.

Install thick (.261”) thrust
washer into swash block.

Apply OEM recommended oil
to top of thrust washer.

Place charge pump cover
face down with the extended
shaft through hole in table.
Be careful as you insert shaft
assembly into charge pump
cover not to damage I.D. of
cover.

fter bearing

A
installation en

sure
there is room for the
seal.

ote: Flat washer not

N

ush shaft and bearing

P
assembly to the bottom o
cover.

ote: Flat washer not

N
required if present.

f the

used after mid 2009 in
production.

35

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Install charge pump
seal

stall snap ring

In

stall charge pump O-

In

ng

ri

Place seal over output shaft
requires pushing down on
seal below snap ring groove
of cover. Ade of a socket that
fits flush to the face of seal
lightly tap until seal is below
snap ring groove.

se internal snap ring pliers

U
and insert snap ring into
groove of charge pump co

ver.

Lightly oil O-ring, flip charge

ump cover over and install

p
O-ring into charge pump
cover groove.

Install charge pump
stator and rotor

Lightly oil both parts, place
the stator into charge pump

over followed by the rotor c

inside of stator.

36

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Install charge pump
shaft into end block

emporarily bolt charge

T
pump cover to end
block

Rotating group

ssembly

a

With the end block sitting on
edge insert the charge pump
shaft until face of charge
pump cover mates to end
block.

se two charge pump cover

U
bolts, flat washers and nuts,
finger tighten to temporarily
hold the charge pump cover
to end block.

Install rotating group
over the charge pump

haft

s

Flip end block over with
charge pump shaft up.

ightly oil face of end block

L
place rotating group over
shaft resting on face of e

nd

block.

37

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Central spring and
bushing

Place central spring and
bushing onto pump shaft on
top of barrel.

Install snap ring onto
shaft

Using internal snap ring
pliers, put retaining snap ring
over pump shaft and place on
top of the central spring
bushing.

Place 16mm socket
over shaft

Place a 16mm deep well
socket 3 ½” long over shaft
resting on the snap ring.

Compress snap ring

By pushing down on socket
compress the central spring
until snap ring locks into snap
ring groove of shaft.

38

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Remove two nuts and
washers

Install face gasket

Install all six bolts

Remove the two nuts and
washers.

Install gasket onto sealing
surface of top of end block.

Install the two hex bolts that
are (1.75”) long in the end
block install the other four hex
head bolts that are (2.75”)
long through charge pump
cover and through end block.

Carefully position top
housing to end block

Take special care not to allow
the swash block or the
internal bearing and washers
to fall out of position.

39

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Carefully assembly top
housing to end block

Slip pump shaft through the
center hole of swash block

Hand tighten bolts

While holding the top housing
level to end block hand start
each of the six bolts with
socket to secure both the top
housing and end block
together.

Torque all six hex head
bolts

Going diagonal from each bolt
torque to 300 – 336 in lbs.

Install filter

Torque filter

Lightly oil filter O- ring and
insert into end block hand
start until snug.

Torque filter to 108 – 114 in
lbs.

40

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Install both pipe tubes
Inspect interface for

slivers of backup ring
replace if sheared

Install O-Ring if hole is
present

stall nose cup

In

Oil all O-rings on both ends of
pipe tubes. First slightly rotate
pipe into end block tube
holes. With the palm of your
hand slightly compress tubes
down pass O-rings.

Oil O-ring and place into
position.

osition nose cup over both

P
tube pipes.

stall both allen head

In
screws

Install motor O-ring

Note:
When servicing UHT assembli

erial number code of

with a s
09257 or earlier, this O-ring (item

25) is not required.

and start each one of the

H
two allen head screws that
measure 2.750” long, torque
to 540 – 708 in lbs.

Slip O-ring over the end cover
of motor down to the O.D. of
motor housing base. Then
install motor into nose cup.

es

Press down on motor
mounting flange to seat the
pipes in the ports until
ends of the pipes rest on the
oil port shoulders.

oil

the

41

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Oil nose cup ID

Note: If assembly does
not have motor o-ring
skip this process.

Install wheel motor into
nose cup

Install pump pulley

Use OEM recommended oil to
lube the ID of the nose cup
where the motor O-ring will be
located.

Position the motor tube holes
of the wheel motor casting
over the two oil pipes. Press
down on motor mounting
flange to seat the oil pipes in
the ports until the ends of the
pipes rest on the oil port
shoulders.

Place pulley onto pump shaft
as shown.

Washer

Lock nut

Place washer on top of pulley.

Use Loctite ™ 242 on threads
of nut. Hand start the lock nut
onto shaft.

42

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Torque nut

Install brake cable
bracket nearest to “A”
port as shown.

Position brake cable

Fill with OEM
recommend oil capacity
level of 2.7 quarts

While holding the pulley in
place with a adjustable
spanner wrench tighten the
nut to 55-70 ft lbs.

Orient the slot opening
towards “A” & “B” ports. Insert
long hex head bolt
through brake cable bracket
motor flange hole and nose
cup install the other three
large hex head bolts.

While holding the brake cable
bracket in position tighten the
hex nut to specification.
Visually inspect bracket
through-hole flange is flat
against the housing and bolt
head. Tighten the other three
bolts to specification.

Add 2.7 quarts of OEM
recommend oil. Secure
dipstick hand tight. Fill to
correct height on dipstick.
Hand tighten to 36 – 60 in lbs.

Install pump fan spacer

Place spacer over pump shaft
with the taper of washer to fit
the taper of the pump shaft

43

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Install fan
Note: If assembly does

not have Fan. Install
shaft cover by applying
Loctite ™ 242 to bottom
edge and tap (gently) into
top housing bore until
seated.

Install fan washer

Install bolt to secure
fan

Place fan on top of pump
washer with the blades face
down as shown in picture.

Place fan washer with the
tangs in-between fan tabs

Apply Loctite ™ 242 to the
threads of bolt. Start fan bolt
by hand and torque to 108 –
144 in lbs.

By pass lever

Install snap ring

Slide the by pass lever over
the by pass valve knob
handle pointing towards the
motor out put shaft

Place snap ring over the by
pass arm and release snap
ring into groove

44

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

HY13-1521-M2/US Service Manual

General Information Series HB Hydrostatic Transmission

Secure snap ring in
groove

Make sure snap ring is secure
in groove keep the by pass
lever position towards output
shaft of drive motor

Assembly complete

With the rear tires jacked up

Start up and purge
vehicle

off the ground cycle
transmissions full speed for
30 seconds each direction.
Recheck reservoir dipstick to
make sure reservoir level is
full.

45

Parker Hannifin Corporation

Hydraulic Pump/Motor Division
Greeneville, Tennessee USA

System Maintenance Tips

Adjust fluid level in reservoir as necessary.



Encourage all operators to report any malfunction or accident that may have damaged the hydraulic



system or component.

Do not attempt to weld any broken component. Replace the component with original OEM equipment



only.

Do not cold straighten, hot straighten, or bend any part.



Prevent dirt or other foreign matter from entering the hydraulic system. Clean the area around the oil



dipstick cap before checking oil level.

Investigate and correct any external leak in the hydraulic system, no matter how minor the leak.



Comply with manufacturer’s specifications for cleaning or replacing the filter.



CAUTION

CA

UTION

CAUTION

during operation or in an accident. Replace any component that is damaged or that is questionable.

CAUTION

internally.

CAUTION

Maintain the proper fluid level in the reservoir. When changing fluid, completely drain old oil from the system. It is
suggested also that you flush the system with clean oil.

Do not weld, braze, solder or in any way alter any UHT component.

Maximum operating pressure must not exceed recommended pressure capacity.

Always carefully inspect any system component that may have been struck or damaged

Do not force any coupling onto the UHT coupling shaft as this could damage the unit

Do not mix oil types. Any mixture, or an unapproved oil could deteriorate the seals.

Parker Hann

Hydraulic Pu
2745 Snapps Ferry Road
Greeneville, TN 37745 USA

ifin Corporation

mp/Motor Division