Cub Cadet P Series User Manual
PK
PW
PG/PE
PC
PR
PJ
P Series
Hydrostatic Pumps
Service and Repair Manual
BLN-52503
August, 2010
Table of Contents
Section Page
Description and Operation ................................................................................................. 1
Introduction .................................................................................................................................................. 1
General Description ..................................................................................................................................... 1
External Features ...................................................................................................................................... 2-7
PC Series .............................................................................................................................................. 2
PG/PE Series ........................................................................................................................................ 3
PJ Series ............................................................................................................................................... 4
PK Series ............................................................................................................................................... 5
PR Series .............................................................................................................................................. 6
PW Series .............................................................................................................................................. 7
Hydraulic Schematic ................................................................................................................................. 8-9
PC, PG, PE, PJ, PK and PR Series ...................................................................................................... 8
PW Series .............................................................................................................................................. 9
Graphical Schematic ................................................................................................................................. 10
Technical Specications ..............................................................................................................................11
Product Identication ................................................................................................................................. 12
Safety .................................................................................................................................. 13
Personal Safety .......................................................................................................................................... 13
Tool Safety ................................................................................................................................................. 13
Work Area Safety ....................................................................................................................................... 13
Servicing Safety ......................................................................................................................................... 13
Troubleshooting ...........................................................................................................14-15
P Series Flow Test Kit Instructions ........................................................................................................ 16-17
Service and Maintenance............................................................................................. 18-20
External Maintenance ................................................................................................................................ 18
Service and Maintenance Procedures ....................................................................................................... 18
Fluids ......................................................................................................................................................... 18
Fluid Volume and Level .............................................................................................................................. 19
Fluid Change .............................................................................................................................................. 19
Filters ......................................................................................................................................................... 19
Purging Procedures ................................................................................................................................... 19
Return to Neutral Setting ........................................................................................................................... 20
Repair .......................................................................................................................... 21-126
PC Series Pump ................................................................................................................................... 21-36
PG/PE Series Pump ............................................................................................................................. 37-54
PJ Series Pump .................................................................................................................................... 55-72
PK Series Pump .................................................................................................................................... 73-90
PR Series Pump ................................................................................................................................. 91-108
PW Series Pump ............................................................................................................................... 109-126
Glossary of Terms .................................................................................................... 127-128
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 the
Hydro-Gear 6cc (0.37 cu in.) PC Series, the 10
cc (0.61 cu in.) PG Series, the 12 cc (0.73 cu
in.) PJ Series, the 16 cc (0.98 cu in.) PR Series,
and the 21 cc (1.28 cu in.) PW Series pumps.
Also included is a glossary of terms that are
frequently used throughout the industry and in
Hydro-Gear service publications. Understanding terminology is very important!
It is necessary , and good shop practice, that your
service area be equipped with proper tools and
the mechanics to be supplied with the latest
information available. All rep air procedures illustrated in this guide are suggested, but
preferred methods of repair .
Some repair procedures require that the pump
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 the OPEESA (Outdoor Power
Equipment and Engine Service Association)
(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.
iv
P Series
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.
SECTION 1. DESCRIPTION AND OPERATION
INTRODUCTION
The purpose of this manual is to provide information useful in servicing the Hydro-Gear PC, PG, PJ,
PK, PR and PW Pumps. This manual includes the
pump’s general descriptions, hydraulic schematics,
technical specications, servicing and troubleshooting procedures for the pumps.
The P Series Pumps 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 pump will need to be thoroughly
cleaned before beginning most procedures.
GENERAL DESCRIPTION
The P Series Pumps can be combined with wheel
motors and other remotely located units. These
pumps provide an innitely variable speed range
between zero and full displacement in both forward
and reverse modes of operation.
The P Series Pumps are of the axial piston design,
utilizing spherical nosed pistons. A compression
spring, located inside each piston, holds the nose
of the piston against a thrust bearing race.
The variable displacement pump features a cradle
swashplate with a direct-proportional displacement
control. Movement of the directional control shaft
produces a proportional swashplate movement and
a change in pump ow and/or direction.
In some applications of the P Series Pumps, it is
desirable to move the machine for short distances at
low speeds without operating the engine. A screwtype bypass valve is utilized in the pumps to permit
movement of the machine. The bypass valve is fully
opened when unscrewed two (2) turns maximum.
The bypass valve allows oil to be routed from one
side of the pump/motor circuit to the other, thus
allowing the motor to turn with minimal resistance.
An increase in resistance will occur with movement
at higher speeds. The bypass valve must be fully
closed during normal operation.
Additionally, some pumps may be equipped with
an Auxiliary Pump. The Auxiliary incorporates the
principles of the charge gerotor assembly and pro-
vides the capability of an external auxiliary ow for
an alternate hydraulic circuit to operate accessories
without loss of drive.
Reversing the direction of the angle of the swash-
plate reverses the ow of oil from the pump and thus
reverses the direction of motor output rotation.
A fixed displacement gerotor charge pump is
provided in P Series Pumps. Oil from an external
reservoir and lter is pumped into the closed loop
by a charge pump. Fluid not required to replenish
the closed loop ows either into the pump housing
through a cooling orice, or back to the charge pump
inlet through the charge pressure relief valve.
Check or shock valves are included in the pump end
cap to control the makeup oil ow for the system.
The size and type of check valve can play an im-
portant role on the system pressure, response, and
amount of heat generated, due to the recirculation
of makeup oil ow. Shock valves are factory preset
pressure regulating check valves.
1P Series
EXTERNAL FEATURES - PC SERIES
Figure 1. PC Pump with Standard Charge Pump
2 P Series
EXTERNAL FEATURES - PG SERIES
SAE “A” PAD
FLANGE STYLE
STANDARD CHECK
VALVE OR SCR
CASE DRAIN
OPTION
“A” and “B”
PORTS
CHARGE
COVER
BYPASS VALVE
CHARGE
PRESSURE
DIAGNOSTIC
PORT
STANDARD CHECK
VALVE OR SCR
INLET
INPUT SHAFT
TRUNNION
ARM
CASE DRAIN
OPTION
Figure 2. PG Pump With Standard Charge Pump
3P Series
EXTERNAL FEATURES - PJ SERIES
Figure 3. PJ Pump with Standard Charge Pump
4 P Series
EXTERNAL FEATURES - PK SERIES
Figure 4. PK Pump With Standard Charge Pump
5P Series
EXTERNAL FEATURES - PR SERIES
BYPASS
VALVE
SAE “A” PAD
FLANGE STYLE
TRUNNION ARM
INPUT SHAFT
CHARGE PRESSURE
DIAGNOSTIC PORT
“A” and “B” PORTS
SYSTEM CHECK VALVE
OR SHOCK VALVE
CASE DRAIN
BYPASS VALVE
CHARGE
COVER
INLET
SYSTEM CHECK VALVE
OR SHOCK VALVE
CASE DRAIN
Figure 4. PR Pump With Standard Charge Pump
6 P Series
EXTERNAL FEATURES - PW SERIES
SAE “B” PAD
FLANGE STYLE
TRUNNION ARM
INPUT SHAFT
BYPASS VALVE
“A” and
“B”
PORTS
CASE DRAIN
CHARGE
PRESSURE
DIAGNOSTIC
PORT
STANDARD CHECK VALVE
OR SHOCK VALVE
Figure 5. PW Pump With Standard Charge Pump
CHARGE
COVER
STANDARD CHECK VALVE
OR SHOCK VALVE
7P Series
HYDRAULIC SCHEMATIC
System Check & Relief Valve Options
Orice size
No Bleed
.024 Bleed
.031 Bleed
.044 Bleed
Relief pressure (psi)
Check ball
1740
2320
2900
Relief pressure (bar)
Check ball
120
160
200
SYSTEM
CHARGE
RELIEF
CHARGE PUMP
INLET
CHARGE
DIAGNOSTIC
OR
OR
PORT “A”
PORT “B”
BYPASS VALVE
BLEED OPTIONS
1) NO BLEED ORIFICE
2) .031” BLEED ORIFICE
Figure 6. PC, PG, PJ, PK and PR Pumps with Standard Charge Pump
System Check & Relief Valve Options
Orice size
No Bleed
.024 Bleed
.031 Bleed
.044 Bleed
Relief pressure (psi)
Check ball
1740
2320
2900
AUXILIARY DISCHARGE
Relief pressure (bar)
Check ball
120
160
200
AUXILIARY RETURN
650 PSI
AUX RELIEF
SYSTEM
CHARGE
RELIEF
OR
OR
PORT “A”
PORT “B”
CHARGE PUMP
INLET
CHARGE DIAGNOSTIC
BYPASS VALVE
BLEED OPTIONS:
1) NO BLEED ORIFICE
2) .031” BLEED ORIFICE
Figure 7. PC, PG, PJ, PK and PR Pumps with AuxiliaryCharge Pump
8 P Series
HYDRAULIC SCHEMATIC
System Check & Relief Valve Options
Orice size
No Bleed
.024 Bleed
.031 Bleed
.044 Bleed
Relief pressure (psi)
Check ball
1740
2320
2900
Relief pressure (bar)
Check ball
120
160
200
OR
PORT “A”
PORT “B”
System Check & Relief Valve Options
Orice size
No Bleed
.024 Bleed
.031 Bleed
.044 Bleed
Relief pressure (psi)
Check ball
1740
2320
2900
AUXILIARY
DISCHARGE
CHARGE DIAGNOSTIC
CHARGE PUMP
INLET
Figure 8. PW Series Pump With Standard Charge Pump
Relief pressure (bar)
Check ball
120
160
200
AUXILIARY
RETURN
AUXILIARY
DISCHARGE
AUXILIARY
RETURN
650 PSI
CHG
REL
OR
BYPASS VALVE
BLEED OPTIONS
1) NO BLEED ORIFICE
2) .031” BLEED ORIFICE
PORT “A”
CHARGE
CHARGE PUMP
DIAGNOSTIC
INLET
Figure 9. PW Series Pump With Auxiliary Charge Pump
PORT “B”
BYPASS VALVE
BLEED OPTIONS
1) NO BLEED ORIFICE
2) .031” BLEED ORIFICE
9P Series
GRAPHICAL SCHEMATIC
Figure 10. P Series Pump With Standard Charge Pump
Figures 10 represents a graphical schematic of the
P Series Pump with standard charge pump. Figure
10 provides a graphical illustration of the hydraulic
oil circuit.
The input shaft and pump cylinder block are turned
in one direction only by the engine/drive belt/pulley
combination or direct drive gear box.
The oil is drawn through an external lter by the
charge pump. The lter prevents contaminants
within the reservoir from entering into the charge
pump gerotor.
The charge pump supplies uid to keep the closed
loop pressurized, preventing cavitation and provid-
ing cooling oil ow for the system.
The charge relief valve is used to maintain charge
at a predetermined pressure.
Output of the system oil ow is controlled by the
direction and amount that the swashplate is
angled. As the pump pistons compress, they force
oil into one of two passageways (“A” or “B”) in the
system hydraulic circuit. Oil is supplied externally
under pressure to an external load, (e.g., a vehicle
wheel motor).
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 wheel motor.
Reversing the angle of the swashplate will reverse
the direction of the oil ow. During the operation
of the pump, uid is “lost” from the hydraulic loop
through leak paths designed into the product for
lubrication and cooling purposes (around pistons,
under the rotating cylinder block, etc.). This “lost”
uid returns to the reservoir through the case drain.
This uid must be made up in the loop. The charge
pump makes up this uid loss.
The makeup ow is controlled (or directed) by the
system check valves. The check valves are used
to direct makeup uid into the low pressure side
of the closed loop. Each check valve will either be
held open or closed, depending upon the direction
of the vehicle operation: Closed in a pressurized
system passage, open in a low pressure, “charged”
system passage.
10 P Series
TECHNICAL SPECIFICATIONS
Product Type PC PG PJ/PK PR PW
Displacement in3/rev 0.37 0.62 0.73 0.97 1.33
[cc/rev] [6.1] [10.2] [12] [16] [21.8]
Input Speed
Maximum Unloaded rpm 3600 3600 3600 3600 3600
Minimum Loaded rpm 1800 1800 1800 1800 1800
System Operating Pressure
Continuous psi 750 1000 1000 1250 1250
[bar] [51] [70] [70] [86] [86]
Intermittent psi 1750 2100 2100 2500 2500
[bar] [120] [145] [145] [172] [172]
Peak psi 2500 3500 3500 3750 3750
[bar] [172] [240] [240] [260] [260]
Pump Performance
@2400 rpm/1000 psi gpm [l/min] 3.6 [13.6] 6.1 [23.1] 7.1 [26.8] 9.6 [36.3] 13.1 [49.6]
@3000 rpm/1000 psi gpm [l/min] 4.5 [17.0] 7.6 [28.8] 8.9 [33.6] 12 [45.4] 16.4 [62.1]
@3600 rpm/1000 psi gpm [l/min] 5.4 [20.4] 9.2 [34.8] 10.8 [40.8] 14.4 [54.5] 19.6 [74.2]
Case Pressure
Maximum @ Cold Start psi [bar] 10 [0.7] 10 [0.7] 10 [0.7] 25 [1.7] 25 [1.7]
Continuous - Max. psi [bar] 4 [0.3] 4 [0.3] 4 [0.3] 10 [0.7] 10 [0.7]
Inlet Vacuum
Maximum Continuous Inches Mercury 4 4 4 4 4
Charge Pump Displacement(s)
in
[cc/rev] [2.1] [1.9/2.1] [3.2] [2.1/3.2] [2.1/3.2]
Auxiliary Pump Displacement
in3/rev 0.19 0.19 0.19 0.19 0.19
[cc/rev] [3.2] [3.2] [3.2] [3.2] [3.2]
Auxiliary Pump Relief Setting
psi 650 650 650 650 650
[bar] [45] [45] [45] [45] [45]
Auxiliary Pump Performance
@3200 rpm, 500 psi, 70 SUS
[13 Cst] oil, & 180°F gpm 1.8 - 2.0 1.8 - 2.0 1.8 - 2.0 1.8 - 2.0 1.8 - 2.0
[l/min] [6.8 - 7.6] [6.8 - 7.6] [6.8 - 7.6] [6.8 - 7.6] [6.8 - 7.6]
Control Torque Required to Stroke Pump
[Approximate - 20°External Stroke Angle]
lb-in / 1000 psi 75 85 85 95 105
[N-m / 70 bar] [8.5] [9.6] [9.6] [10.7] [11.9]
lb-in / 500 psi 55 60 60 75 85
[N-m / 35 bar] [6.2] [6.8] [6.8] [8.5] [9.6]
Pump Oil Temperature
Maximum Intermittent (hottest point) °F 230 230 230 230 230
[°C] [110] [110] [110] [110] [110]
Normal Operating Range °F -10 to 200 -10 to 200 -10 to 200 -10 to 200 -10 to 200
[°C] [-23 to 93] [-23 to 93] [-23 to 93] [-23 to 93] [-23 to 93]
3
/rev 0.13 0.11/0.13 0.19 0.13/0.19 0.13/0.19
Fluid Viscosity Limits @ 230°F [110°C]
Optimum SUS [cSt] 70 [13] 70 [13] 70 [13] 70 [13] 70 [13]
Minimum SUS [cSt] 55 [9] 55 [9] 55 [9] 55 [9] 55 [9]
Weight of Unit
lbs [kg] 7 [3.2] 8 [3.6] 12.65 [5.7] 12 [5.4] 14 [6.3]
Inlet Filtration Requirement
Nominal micron 25 25 25 25 25
Table 1: P Series Pump Technical Specications
11P Series
PRODUCT IDENTIFICATION
HYDRO-GEAR
MADE IN U.S.A.
Model Number
PC-AGCC-MV1X-XXXX
4 244 P1 0192
Year Built
Date
(Julian - day of year)
Type of Product and Build Information
Serial Number
(unique number for that model - for that day)
The label in Figure 11 is located on the pump housing. It identies the model and conguration of the
pump.
Figure 11. P Series Pump Conguration Label
12 P Series
SECTION 2. SAFETY
This symbol points out important safety
instructions which, if not followed, could en-
danger the personal safety and/or property
of yourself and others. Read and follow all instructions in this manual before attempting maintenance
on your P Series Pump. When you see this symbol
- HEED ITS WARNING.
WARNING
POTENTIAL FOR SERIOUS INJURY
Inattention to proper safety, operation, or
maintenance procedures could result in
personal injury, or damage to the equipment. Before servicing or repairing the P
Series Pump, read fully and understand
the safety precautions described in this
section.
PERSONAL SAFETY
Wear appropriate clothing. Loose or hanging clothing or jewelry can be hazardous. Use the appropriate safety equipment, such as eye and hearing
protection, and safety-toe and slip-proof shoes.
Never use compressed air to clean debris from
yourself or your clothing.
TOOL SAFETY
Use the proper tools and equipment for the task.
Inspect each tool before use and replace any tool
that may be damaged or defective.
WORK AREA SAFETY
Keep the work area neat and orderly. Be sure it is
well lit, 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 oor should be clean and dry, and all extension
cords or similar trip hazards should be removed.
Certain safety precautions must be observed while
servicing or repairing the P Series Pump. This section addresses some of these precautions but must
not be considered an all-inclusive source on safety
information. This section is to be used in conjunction with all other safety material which may apply,
such as:
• Other manuals pertaining to this machine
• Local and shop safety rules and codes
• Governmental safety laws and regulations
Be sure that you know and understand the equip-
ment 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.
SERVICING SAFETY
Certain procedures may require the vehicle to be
disabled in order to prevent possible injury to the
servicing technician and/or bystanders.
The loss of hydrostatic drive line power may result
in the loss of hydrostatic braking capability.
Some cleaning solvents are ammable. Use only
approved cleaning materials: Do not use explosive
or ammable liquids to clean the equipment.
To avoid possible re, do not use cleaning solvents
in an area where a source of ignition may be present.
Discard used cleaning material in the appropriate
containers.
13P Series
SECTION 3. TROUBLESHOOTING
In many cases, problems with the P Series Pump
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!
Possible Cause Corrective Action
VEHICLE DOES NOT DRIVE/TRACK STRAIGHT
are not related to a defective pump 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 adjust-
ments outlined in Section 3 before assuming the
pump is malfunctioning. Table 2 below provides
a troubleshooting checklist to help determine the
cause of operational problems.
Vehicle tires improperly inated Refer to vehicle manufacturer suggested pressure
Control linkage bent, loose or out of adjustment Repair, adjust or replace vehicle linkage
Bypass loose Tighten pump bypass per External Maintenance
step 9, page 17
Inlet Leak Check all external lines and connections to pump
inlet
UNIT IS NOISY
Excessive input speed Adjust input speed above 1800 rpm and below
3600 rpm
Oil level low or contaminated oil Fill reservoir to proper level or change oil
Excessive loading Reduce vehicle load
Air trapped in hydraulic system Purge hydraulic system per Purging Procedures
on page 18
Bypass loose Tighten pump bypass per External Maintenance
step 9, page 17
Inlet leak, line or lter partially blocked or Check all external lines and connections
and lter
damaged to pump inlet
Table 2. Pump Troubleshooting Checklist
14 P Series
Possible Cause Corrective Action
UNIT HAS NO/LOW POWER
Engine speed low Adjust to correct rpm setting
Control linkage bent, loose or out of adjustment Repair or replace vehicle linkage
Drive belt slipping or pulley damaged Repair or replace drive belt or pulley
Oil level low or contaminated oil Fill reservoir to proper level or change oil
Excessive loading Reduce vehicle load
Bypass loose Tighten pump bypass per External Maintenance
step 9, page 17
Air trapped in hydraulic system Purge hydraulic system per Purging Procedures
on page 18
Inlet leak Check all external lines and connections to pump
inlet
Inlet lter clogged Replace inlet lter
Suspected internal damage Check pump by performing Flow Test on page 15
UNIT OPERATING HOT
Debris buildup Remove debris from pump and fan
Cooling fan or heat exchanger damaged Repair or replace cooling fan or heat exchanger
Oil level low or contaminated oil Fill reservoir to proper level or change oil
Excessive loading Reduce vehicle load
Air trapped in hydraulic system Purge hydraulic system per Purging Procedures
on page 18
Inlet leak Check all external lines and connections to pump
inlet
PUMP LEAKS OIL
Damaged seals and gaskets Remove debris, replace seals
Air trapped in hydraulic system Purge hydraulic system per Purging Procedures
on page 18
15P Series
P SERIES FLOW TEST KIT INSTRUCTIONS
(This Instruction Sheet supersedes all previous ow testing instructions)
BLN-51334 JULY 2010
Description: P Series Flow Test Kit (Part Number 70661)
(Part Number 70661 Supersedes Part Numbers 70511 and BB-76810)
Purpose: The design purpose of the P Series Flow Test Kit is to allow the customer to isolate the pump from the
wheel motor and determine if the pump is acceptable. The following information can be used to install and test the
pump by simulating a wheel motor load.
WARNING
Certain procedures require the vehicle engine
to be operated and the vehicle to be raised off
of the ground. To prevent possible injury to the
servicing technician and/or bystanders, insure
the vehicle is properly secured.
Do not attempt any adjustments with the engine
running. Use extreme caution while working in
or around all vehicle linkage! High temperatures
can be generated. Follow all safety procedures
outlined in the vehicle owner’s manual!
WARNING
INSTALLATION AND TESTING PROCEDURES:
1. Disconnect the system hoses at the wheel motor, or system hoses from the pump and connect the
P Series Flow Test Kit. (Special care should be taken to prevent contamination debris from entering
pump or wheel motor system ports)
Note: Using the Bi-Directional Flow Test Kit, determination of directional ow is not necessary. The ow
meter may be connected in either direction into the forward and reverse high pressure system lines.
CAUTION: Ensure all ttings and hoses are attached securely. This test is being completed on the
vehicle’s high pressure system lines. Failure to perform this properly could result in bodily injury.
TESTING PROCEDURES:
1. Raise the drive tires off of the ground. Block the remaining tires on the ground to prevent accidental
vehicle movement.
2. Open the restriction valve all the way.
3. Make certain all external pump directional control stops are removed or backed off on the vehicle
linkage to obtain full pump directional control arm travel.
4. Start the engine and engage the drive pulley if necessary.
5. Bring the engine to maximum operating speed.
(This should not exceed 3600 rpm input speed on the PC, PL, PG, PE, PK and PJ Series Pumps)
(This should not exceed 3400 rpm input speed on the PR)
(This should not exceed 2800 rpm input speed when testing the PW)
Engine speed adjustment may be necessary to obtain 2800 rpm.
CAUTION: Ensure all ttings and hoses are attached securely. This test is being completed on the
vehicle’s high pressure system lines. Failure to perform this properly could result in bodily injury.
6. With the directional control lever (on the vehicle) for the pump being tested, move the control arm in
full forward motion. (It may be necessary to lock the control arm into full forward position to prevent
false readings).
7. Operate without any load for approximately 30 seconds to 1 minutes. This allows the system oil temperature to rise.
16 P Series
Note: Raising the system oil temperature will make a difference in the readings you receive. It has been
determined that to complete this test accurately, the oil temperature must be near system operating temperatures.
Suggested temperature range is 160°- 210°F (71.1° - 98.9°C).
8. On the PC, PG, PE, PJ, PK, PL, PR and PW, tighten the ow meter restriction valve until the gauge reads 300
psi (21bar). Record the ow reading on the Bi-Directional Flow Meter.
9. Increase the pressure to 1100 PSI (76 bar) for all models (PC, PG, PJ, PK, PL, PR and PW). Record the ow
reading on the Bi-Directional Flow Meter.
10. The acceptable gpm “ow droop” or (difference) is:
PC 1.0 gpm (3.7 l/min)
PG/PL/PE 1.5 gpm (5.6 l/min)
PJ/PK 2.0 gpm (7.6 l/min)
PR 2.5 gpm (9.4 l/min)
PW 2.5 gpm (9.4 l/min)
If the difference exceeds these values the pump would not be operating efciently and should be repaired or
replaced.
TEST EXAMPLE: PG/PL
300 psi (21 bar) reading 7 gpm (26 l/min) (1st reading)
1100 PSI (76 bar) reading 3 gpm (11 l/min) (2nd reading)
(PG/PL/PE)
300 psi (21 bar) reading 7 gpm (26 l/min) (1st reading)
1100 psi (76 bar) reading -3 gpm (11 l/min) (2nd reading)
4 gpm (15 l/min) (the difference)
Subtract the 1st reading from the 2nd.
(In this example, 4 gpm difference would
indicate further pump examination).
17P Series
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 a P Series Pump
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.
2. Check uid level in reservoir in accordance with
vehicle manufacturer’s recommendations.
NOTE: After the oil has been drained
and maintenance has been performed,
clean oil should be poured directly into
the pump inlet and high pressure ports
prior to plumbing connections and pump
start-up.
3. Inspect the vehicle drive belt, idler pulley(s), and
idler spring(s). Insure that belt slippage is not
causing low input rpm to the pump.
4. Inspect all external plumbing for possible leaks
or loose ttings. An air leak may be difcult to
detect on the “suction side” or inlet line to the
pump. Refer to Purging Procedures page 18.
5. Insure correct inlet lter(s) has been installed
in accordance with the vehicle manufacturer
recommendations.
8. Inspect the vehicle control linkage to the
directional control arm on the P Series Pump.
Also, insure the control arm is securely fastened
to the trunnion arm.
9. Inspect the bypass on the P Series Pump to
insure it is properly engaged for operation. If
the bypass is not fully engaged (rotated fully
clockwise) it will not function properly. For
vehicle movement without engine power, the
bypass may be backed out (2) turns maximum.
This is only recommended for movement of
short distances at low speeds.
WARNING
Loosening the bypass will result in loss
of hydraulic braking capability.
SERVICE AND MAINTENANCE
PROCEDURES
NOTE: Damage to P Series Pumps may
result from external or internal contamination, heat from excess debris or lack
of lubrication and over-pressurization
of the hydrostatic system. Follow guidelines established in this manual and the
vehicle manufacturer’s recommendations.
All the service procedures presented on the following pages can be performed while the P Series
Pump is mounted on the vehicle. Any servicing
beyond those presented in this section must be
performed after the pump has been removed from
the vehicle.
6. Insure the reservoir is free of contaminants and
is properly vented.
7. Inspect the P Series Pump cooling fan (if
applicable) for broken or distorted blades and
remove any obstructions (grass clippings,
leaves or dirt). Inspect oil cooler (if applicable)
for damaged ns and debris.
18 P Series
FLUIDS
The uids used in Hydro-Gear products have been
carefully selected, and only equivalent, or better
products should be substituted.
Typically, an engine oil with a minimum rating of 55
SUS (9.0 cSt) at 230
ing temperature and an API classication of SJ/CD
is allowed. Refer to the vehicle manufacturer for
recommended oil.
°
F (110° C) maximum operat-
FLUID VOLUME AND LEVEL
Certain situations may require additional uid to
be added or even replaced. Refer to the vehicle
manufacturer’s recommendations for the proper ll
location and level. After maintenance or oil change,
follow purging procedures below and check the
uid level once the unit has been operated for ap-
proximately 1 minute.
FLUID CHANGE
In the event of oil contamination or degradation,
oil addition or change may alleviate certain performance problems. Refer to the vehicle manufacturer’s recommended oil change frequency. Refer to
purging procedures below after changing uids.
FILTERS
An inlet lter is required to insure that only clean uid
enters the system. Refer to the vehicle manufacture
for approved lter replacement.
PURGING PROCEDURES
Due to the effects air has on efciency in hydrostatic
drive applications, it is critical that air is removed or
purged from the system.
These purge procedures must be preformed anytime a hydrostatic system has been opened for
maintenance or repair, or if any additional oil has
been added to the system.
Air creates inefciency because it has compression and expansion rates that are higher than that
of oil.
Air trapped in the oil may cause the following
symptoms:
1. Noisy operation.
2. La ck of powe r or dr i ve af ter short-ter m
operation.
3. High operation temperature and excessive
expansion of oil.
WARNING
POTENTIAL FOR SERIOUS INJURY
Certain procedures require the vehicle
engine to be operated and the vehicle to
be raised off of the ground. To prevent
possible injury to the servicing technician and/or bystanders, insure the vehicle is properly secured.
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
in the reservoir 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 P Series Pump moves
forward and reverse at normal speed and the
reservoir oil remains at a constant level, purging
is complete.
Cleanliness is a key factor in the successful repair of
pumps. Thoroughly clean all exposed surfaces prior
to any type of maintenance. Cleaning of all parts
by using a solvent wash and air drying is usually
adequate. As with any precision equipment, all parts
must be kept free of foreign material and chemicals.
Protect all exposed sealing areas and open cavities
from damage and foreign material.
Upon removal, all seals, O-rings, and gaskets
should be replaced. During installation, lightly lu-
bricate all seals, O-rings, and gaskets with clean
petroleum jelly prior to assembly. Also protect the
inner diameter of seals by covering the shaft machined features with plastic wrap or equivalent.
Before starting, make sure the reservoir is at the
proper oil level. If it is not, ll to the vehicle manufacturer’s specications.
The following procedures should be performed
with the vehicle drive wheels off the ground, then
repeated under normal operating conditions.
19P Series
RETURN TO NEUTRAL SETTING
WARNING
POTENTIAL FOR SERIOUS INJURY
Inattention to proper safety, operation, or
maintenance procedures could result in
personal injury, or damage to the equipment. Before servicing or repairing the P
Series Pump, fully read and understand
the safety precautions described in this
manual.
The return to neutral mechanism on the pump is
designed to set the directional control into a neutral
position when the operator releases the vehicle
hand control. Follow the procedures below to
properly adjust the return to neutral mechanism on
the pump:
1. Conrm the pump is in the operating mode
(bypass disengaged). Raise the vehicle’s drive
tires off the ground to allow free rotation.
2. Remove the Original Equipment Manufacturer’s
(OEM’s) control linkage at the control arm.
3. Start the engine and increase the throttle to full
engine speed.
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.
4. Check for axle rotation. If the axle does not
rotate, go to Step 5. If the axle rotates, go to
Step 6.
5. Stop the vehicle’s engine. Reattach and adjust
the vehicle’s linkage according to the vehicle
owner’s manual.
6. Note the axle directional movement. Stop the vehicle engine. Loosen the RTN adjustment screw
until the control arm can be rotated. Rotate the
control arm in the proper direction until neutral is
obtained (motor shaft does not rotate). Tighten
the RTN adjustment screw. Recheck according
to steps 3 and 4. Refer to Figure 12.
RTN Adjusting Screw
Figure 17. P Series Pump RTN Adjustment
Speed & Direction
Control Arm
20 P Series
REPAIR - PC SERIES PUMP
Repair - PC Series Pump ..................................................................................................... 21-36
How to Use This Manual..............................................................................................................21
General Instructions ....................................................................................................................21
T ools and Torques .......................................................................................................................22
Return to Neutral Linkage ............................................................................................................23
St andard Control Arm Linkage.....................................................................................................24
Fan Assembly..............................................................................................................................24
Input Shaft Seal ...........................................................................................................................25
Trunnion Arm Seal.......................................................................................................................25
Shock V alves...............................................................................................................................26
Bypass ........................................................................................................................................26
Charge Pump-Standard or Thru Shaft .........................................................................................27
Auxiliary Pump.............................................................................................................................28
End Cap ......................................................................................................................................29
Cylinder Block .............................................................................................................................30
Block Spring and Thrust Bearings...............................................................................................31
Swashplate and Cradle Bearings................................................................................................31
Input Shaft ...................................................................................................................................32
Trunnion Arm ...............................................................................................................................33
Parts List ............................................................................................................................... 34-35
HOW TO USE THIS MANUAL
Each assembly is provided with an exploded view
showing the parts involved. The item
reference numbers in each illustration are for
assembly instructions only . See pages 34 and 35
for part names and descriptions. A
complete exploded view and item list of the pump is
provided at the end of this section.
GENERAL INSTRUCTIONS
Cleanliness is a primary means of ensuring
satisfactory life on repaired pumps. Thoroughly clean
all exposed surfaces prior to any type of
maintenance. Cleaning of all parts by using a solvent
wash and air drying is usually adequate. As with
any precision equipment, all parts must be kept free
of foreign material and chemicals.
Protect all exposed sealing surfaces and open
cavities from damage and foreign material. The
external surfaces should be cleaned before
beginning any repairs.
Lip-type seals (shaft seals) are used on the input
shaft and directional control shaft of each pump.
These seals can be replaced without major
disassembly of the unit. However, replacement of
these seals generally requires removal of the pump
from the machine. Upon removal, it is recommended
that all seals, O-rings and gaskets be replaced.
During installation, lightly lubricate all seals,
O-rings and gaskets with clean petroleum jelly prior
to assembly. Also protect the inner diameter of the
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 BLN51427 (CD).
21PC Series
Miscellaneous 3/8-Inch Drive Ratchet and Sockets
P Series Service & Repair Manual 7/16-inch Socket
Torque Wrench 1/2-Inch Socket
Scribe, Paint Pen, or Marker 11/16-Inch Socket
Seal Hook with a Magnet 10-mm Socket
Flat Blade Screwdriver
Combination Wrenches
Pliers
7/16 Inch
Internal Snap Ring 1/2 Inch
Allen Wrenches
11/16 Inch
1/8 inch 10 mm
1/4 inch
TOOLS AND TORQUES
Table 1. Required T ools
Item # and/or Description
Case Drain (fitting torque)
System Port (fitting torque)
Inlet (fitting torque)
Fan Nut, Hex Lock 5/16-24 UNF
4, End Cap/Adapter Plate Bolts
10, Cap Screw
15, Bypass V alve
42A, 42B, Shock V alves/Check Plugs
44, System Charge Relief Kit (Aux Chg)
45, Aux Relief V alve Kit
56, Diagnostic Plug
66, Filter Cover Plug
67, Filter Cover
103, Screw 5/16 x .875
106, Nut, Hex Lock 5/16-24 UNF
164, Plug, Metal 7/16-20
T orque
200-250 lb-in (22.6-28.2 Nm)
370-470 lb-in (41.8-53.1 Nm)
200-250 lb-in (22.6-28.2 Nm)
120-160 lb-in (13.5-18.1 Nm)
180-220 lb-in (20.3-24.9 Nm)
180-220 lb-in (20.3-24.9 Nm)
1 10-130 lb-in (12.4-14.7 Nm)
180-240 lb-in (20.3-27.1 Nm)
180-240 lb-in (20.3-27.1 Nm)
180-240 lb-in (20.3-27.1 Nm)
84-120 lb-in (9.4-13.5 Nm)
55-85 lb-in (6.2-9.6 Nm)
200-275 lb-in (22.6-31.1 Nm)
200-240 lb-in (22.6-27.1 Nm)
180-220 lb-in (20.3-24.9 Nm)
84-120 lb-in (9.4-13.5 Nm)
T able 2. PC Pump Torque Values
22 PC Series
PC SERIES PUMP REPAIR
REMOVAL, INSPECTION AND/OR
REPLACEMENT OF RETURN TO
NEUTRAL ASSEMBLY
Refer to Figure 1.
Prior to disassembly , note the position of the scissor
arm brackets and the tab on the outer control arm
bracket.
Disassembly
CAUTION: The spring used on the return to neutral
linkage is under tension. To avoid possible injury,
use care and proper protection during disassembly
and assembly of the return to neutral linkage.
1. Loosen (but do not remove) the nut (106).
2. T o relieve spring tension, carefully pry up on the
outer scissor control arm until it releases from
the tab on the outer control arm bracket.
3. Remove the spring (102), nut (106) washer (104)
and outer scissor control arm bracket.
4. Remove bushing (101), washer (105), and the
inner scissor control arm bracket.
5. Remove the outer control arm bracket, bolt
(103), washer (104) and the inner return arm
bracket.
Inspection
1. With the arm control linkage removed, inspect
the trunnion arm (37) and trunnion arm seal (49).
2. Inspect bushing (101) and all other linkage parts
for damage, corrosion or wear.
Assembly
1. Install the inner return arm bracket, washer (104)
and bolt (103).
NOTE: Do not over tighten the bolt (103). The
bracket must move freely .
2. Install the outer control arm bracket, washer
(105) and bushing (101).
3. Install the inner scissor control arm bracket,
washer (105), and outer scissor control arm
bracket.
4. Install washer (104), and nut (106). Tighten to
the correct torque value. See page 22.
5. Install the spring (102).
49
104
103
37
105
110
Figure 1. Return to Neutral Assembly
105
101
104
106
102
23PC Series
REMOV AL, INSPECTION AND/OR
REPLACEMENT OF CONTROL ARM
REMOVAL, INSPECTION AND/OR
REPLACEMENT OF F AN ASSEMBLY
Refer to Figure 2.
Disassembly
1. Remove the nut (106), washer (104) and bushing
(101).
2. Remove the outer control arm bracket.
3. Remove bolt (103), washer (104) and the inner
control arm bracket.
Inspection
1. With the arm control linkage removed, inspect
the trunnion arm (37) and trunnion arm seal (49).
2. Inspect bushing (101) and all other linkage parts
for damage, corrosion or wear.
Assembly
1. Install the inner control arm bracket, washer
(104) and bolt (103).
NOTE: Do not over tighten the bolt (103). The
bracket must move freely .
Refer to Figure 3.
Disassembly
1. Remove the fan shroud (210) from the mounting
bracket (209) by carefully pushing down on the
shroud tabs.
2. Remove the nut (106) and fan assembly (90).
3. Remove the bolts (10) and bracket (209).
Inspection
Inspect the fan shroud (210), fan assembly (90) and
mounting bracket (209) for damage.
Assembly
1. T o install the mounting bracket (209), align and
insert the bolts (10) into the bracket and charge
pump cover. While holding the charge cover in
place, tighten the bolts (10) per table 2, page
22.
2. Install the fan and washer assembly onto the
shaft.
2. Install the outer control arm bracket, bushing
(101), washer (104) and nut (106). Tighten to
the correct torque value. See page 22.
49
104
103
37
101
110
Figure 2. Standard Control Arm
104
106
3. Install the nut (106) and tighten per table 2, page
22.
4. Install the fan shroud (210) onto the mounting
bracket (209). Make sure that all shroud lock
tabs are fully engaged in the mounting bracket
slots.
209
(2X) 10
90
106
210
Figure 3. Fan Assembly
24 PC Series
REMOV AL, INSPECTION AND/OR
REPLACEMENT OF INPUT SHAFT
SEAL
REMOV AL, INSPECTION AND/OR
REPLACEMENT OF TRUNNION ARM
SEAL
Refer to Figure 4.
Disassembly
1. Remove retaining ring (22) from housing.
2. Remove lip seal (20). Care must be taken to
prevent damage to the housing bore, shaft
sealing surface, or bearing. Once removed, the
seal is not reusable.
Inspection
With seal removed inspect the spacer (21) and
housing (1) bore for damage, corrosion or wear.
Assembly
1. Lubricate the new lip seal (20) inside diameter
with petroleum jelly .
2. Wrap the input shaft (18) with plastic wrap to
prevent damage to the inner surface of the lip
seal (20).
3. Slide spacer (21) and seal (20) over shaft (18)
so that lettering on the seal faces out.
4. Press the lip seal (20) into the housing bore.
Insure the lip seal (20), shaft (18) or housing (1)
bore do not become damaged. Remove the
plastic wrap.
5. Install the retaining ring (22) into the housing (1)
bore groove. Refer to Figure 4.
Refer to Figure 5.
Disassembly
1. Remove the RTN assembly or control arm.
2. Remove the retainer and lip seal (49) from the
housing. Care must be taken to prevent damage
to the housing trunnion bore, trunnion arm and
sealing surface. Once removed the retainer and
lip seal are not reusable.
Inspection
With the lip seal (49) removed, inspect the area for
corrosion and wear. Inspect the trunnion bore area
sealing surface for damage or wear.
Assembly
1. Lubricate the new lip seal (49) inside diameter
with petroleum jelly .
2. Wrap the trunnion arm with plastic wrap to
prevent damage to the inner surface of the lip
seal (49).
3. Slide the lip seal (49) over the trunnion arm so that
the lettering on the seal (49) faces out.
4. Press the lip seal (49) into the housing bore.
Insure the seal (49), trunnion arm, and housing
bore do not become damaged. Remove plastic
wrap.
5. Install the retainer from (49) over the trunnion
arm on top of the lip seal. Press into the trunnion
seal bore in the housing until the retainer mates
against the trunnion seal.
Figure 4. PC Pump Input Shaft Seal
6. Install the RTN assembly or control arm.
Figure 5. Trunnion Arm Seal
25PC Series
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