Sauer Danfoss 20 Series User manual

Series 20
Axial Piston Motors
Service Manual and
Repair Instructions
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:301

2DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Introduction, Description
INTRODUCTION
DESCRIPTION
The purpose of this manual is to provide you with the information necessary for the
normal maintenance and servicing of the Sauer-Danfoss hydrostatic series 20 units.
This includes a description of the units and their components as well as troubleshooting,
pressure setting and repair procedures.
Minor repairs may be performed without affecting the warranty. Major repairs performed
during the warranty time could eventually affect the warranty.
To facilitate easy servicing, the unit has been designed with this in mind.
Many of the individual parts and assemblies are interchangeable throughout the entire
series 20 family. This includes such items as the servo valve, the charge pumps and the
manifold components.
In addition, many repairs and adjustments can be performed without having to remove
the unit from the vehicle, provided that the unit is easily accessible and a thorough
cleaning of the unit is possible before beginning with repairs.
Dirt or other forms of contamination are in most cases the reason for the breakdown
of a hydraulic unit. Please pay attention to cleanliness, not only when making repairs,
but also when putting the unit into operation, changing the oil, changing lters or any
other procedures.
The following manual will provide you with comprehensive instructions for preventative
maintenance and recognition of causes of failure of the axial-piston units.
Sauer-Danfoss axial pistons xed displacement motors are of swash plate design with
preset displacement suitable for hydrostatic transmissions with closed loop circuit.
The output speed is proportional to the motor’s input ow.
The output torque is proportional to the differential pressure applied to the main
pressure ports.
The direction of motor (output) shaft rotation depends on ow input to the main
pressure ports.
The full-length shaft with a highly efcient tapered roller bearing arrangement offers a
high loading capacity for external radial forces.
High case pressures can be achieved without leakage even at the lowest temperatures
by using suitable shaft seals.
Sauer-Danfoss axial piston units are designed for easy servicing. Complete dismantling
and reassembly can be carried out with standard hand tools, and all components or
sub-assemblies are replaceable.
© 1984 -2002, Sauer-Danfoss
Sauer-Danfoss can accept no responsibility for possible errors in catalogues, brochures and other printed material. Sauer -Danfoss reserves the
right to alter its products without prior notice. This also applies to products already ordered provided that such alterations can be made without
subsequent changes being necessary in specications already agreed. All trademarks in this material are properties of the respective companies.
Sauer-Danfoss and the Sauer-Danfoss logotype are trademarks of the Sauer-Danfoss Group. All rights reserved.
Front page: F000 248, F000 249, F000 150, F005 101
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:302-3

3
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Contents
CONTENTS Introduction and description ................................................................................................................................... 2
Model Code ....................................................................................................................................................................... 4
Recommended tools and installation .................................................................................................................. 5
List of tools necessary for minor repairs and maintenance of units of all sizes ................................... 5
Additional tools list for complete stripping of units ...................................................................................... 5
Measuring instruments ............................................................................................................................................ 5
Trouble shooting, gauge installation and information ................................................................................. 6
Start-up procedure ....................................................................................................................................................... 7
Preconditions for trouble-free operation .......................................................................................................... 7
First-time operation ................................................................................................................................................... 8
Plumbing installation (variable displac. Pump - xed displac. Motor) .................................................... 9
System circuit description ....................................................................................................................................... 9
System maintenance ................................................................................................................................................. 10
Inlet lter (between uid reservoir and charge pump) ............................................................................. 10
Changing the oil ...................................................................................................................................................... 10
Leak test ...................................................................................................................................................................... 10
Cleanliness ................................................................................................................................................................. 10
Checking of the oil level ....................................................................................................................................... 10
Recommended oils ................................................................................................................................................. 10
Trouble shooting ......................................................................................................................................................... 11
Transmission operates in one direction only ................................................................................................ 11
System response is sluggish ................................................................................................................................ 11
System operating hot ............................................................................................................................................ 12
System will not operate in either direction ................................................................................................... 12
Inspection instructions ......................................................................................................................................... 13
Checking the high pressure relief valve ............................................................................................................. 13
Checking the shuttle valve ................................................................................................................................... 14
Mounting block ......................................................................................................................................................................... 14
Preparation for assembly ...................................................................................................................................... 14
Disassembly and assembly .................................................................................................................................... 15
Sectional view .......................................................................................................................................................... 15
Exploded view .......................................................................................................................................................... 16
Minor repairs ............................................................................................................................................................. 17
Changing the shaft seal disassembly .................................................................................................................. 17
Changing the shaft seal assembly ....................................................................................................................... 18
Changing the valve manifold assembly ............................................................................................................. 19
Repair the manifold valve assembly ................................................................................................................... 20
Major repairs ............................................................................................................................................................. 22
Changing the valve and bearing plate disassembly ......................................................................................... 22
Changing the valve and bearing plate assembly .............................................................................................. 23
Changing the cylinder block kit, the swash plate and the motor shaft disassembly .................................. 24
Changing the cylinder block kit, the swash plate and the motor shaft assembly ....................................... 26
Installation torque values ....................................................................................................................................... 27
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:302-3

4DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Model Code
TYPE DESIGNATION AND ORDER CODE
End cap execution
end cap (not assembled)
no entry = basic making
MS valve block with washing function
MR additional shorting valve with connection plate
AM 01000 without valve block
typical numbers for possible levels of high pressure
(pressure drop) in port A and/or B
1. characteristic number for setting of pressure port A
2. characteristic number for setting of pressure port B
characteristic number 07 10 14 17 21 24
p bar 70 105 140 175 210 245
[psi] [1015] [1520] [2030] [2540] [3050] [3550]
characteristic number 28 31 35 38 (40)* (42)*
p bar 280 315 350 385 (400) (420)
[psi] [4060] [4570] [5080] [5580] [5800] [6090]
* level of high pressure in parenthesis:
after application engineer approval
2 typical number for flushing pressure 12 bar [174 psi]
(different setting of flushing pressure on request)
Producer mark
A1 producer specifi-
cation according
to construction
(at present = A1)
S M F 2 B A 1
Series of product
SMF motor fixed
2 association
type 20
Orientation of rotation
B reversible
Input port
working port SAE-flange
3 = 3000 psi SAE J518 (207 bar)
for displacement 033 - 119 cm3
6 = 6000 psi SAE J518 (414 bar)
for displacement 166 - 334 cm3
Displacement cm3 [in3]
033 = 33.3 [2.03]
052 = 51.6 [3.15]
070 = 69.8 [4.26]
089 = 89.0 [5.43]
119 = 118.7 [7.24]
166 = 165.8 [10.12]
227 = 227.3 [13.87]
334 = 333.7 [20.36]
Shaft end
SAE-spline shaft 16/32
= 21 teeth for displacement 033 - 070
Z = 23 teeth for displacement 089
= 27 teeth for displacement 119 - 227
= 40 teeth for displacement 334
K* conic shaft end with toleranced key
* available on request
Units with working mark
3 - letter combination e.g.:
Cxx making all seals in Viton
special copies with or without
mark of copy
035 3 - letter combination eg.
with industrial valve block,
with brake pneumatic valve
and all seals in Viton
Order example:
Axial piston xed displacement motor SMF 2
Displacement Vg = 333.7 cm3, Orientation of rotation: reversible
Input port 6000 psi SAE J518
SAE spline shaft 40 teeth
End cap execution: connection plate
Order mark:
SMF 2/334-B6Z-AM 01000-A1
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:304-5

5
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Recommended Tools and Installation
LIST OF TOOLS
NECESSARY FOR MINOR
REPAIRS AND
MAINTENANCE OF UNITS
OF ALL SIZES
ADDITIONAL TOOLS LIST
FOR COMPLETE
STRIPPING OF UNITS
MEASURING
INSTRUMENTS
1 Circlip pliers ∅ 2 to 2.5 mm
1 Screw driver 3 mm
1 Screw driver 6 mm
1 Screw driver 9 mm
1 Plastic hammer - small
1 Pointed pliers (can also be slightly bent)
1 Torque key to 14.9 Nm [132 lbf•inch]
1 Set of ring spanners 5/16 to 11/4
1 Set of Allenkeys 1/4 to 3/8
1 Fixed spanner 15/6 for high pressure relief valve
1 Puller retainer seal
(Major repairs should not be carried out during the warranty period.)
1 Right angle screw driver 16 mm
1 Set of drifts 2 to 10 mm
1 Plastic hammer - large
1 Bearing puller 80 x 120 mm
1 Bearing puller 200 x 250 mm
1 Each xed spanner for servo cylinder 36, 41, 46, 50, 55, 60, 65 mm
1 Depth gauge 300 mm
1 Set of xed or open ended spanners 7/16 to 11/4
1 Fitting block - see page 14
At last 2 pressure gauges up to 60 bar damped (charge pressure - servo pressure)
1 Vacuum gauge to +1.0 ÷ -1.0 bar [14.5 ÷ -14.5 psi] (vacuum measurement at the charge
pump)
2 Pressure gauges to 600 bar [8700 psi] (high pressure measurement at the valve block)
1 Pressure gauge to 8 bar [116 psi] (casing pressure measurement)
Additional: Torque spanners, separate order!
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:304-5

6DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
P000 341
TROUBLE SHOOTING, GAUGE INSTALLATION AND INFORMATION
Gauge Information
A Charge Pressure 60 bar [870 psi] - Gauge
7/16 - 20 UNF O-ring Fitting
B System Pressure 600 [8700 psi] bar - Gauge
7/16 - 20 UNF O-ring Fitting
C Inlet Vacuum Vacuum gauge
Tree Into Inlet Line
D Case Pressure 8 bar [116 psi] - Gauge
Adapt to Bottom Drain Port
Recommended Tools and Installation
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:306-7

7
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Start-up procedure
PRECONDITIONS FOR
TROUBLE-FREE
OPERATION
Cleanliness: Ensure that the pipes, pipe connections and hoses as well as all other
components are completely clean.
Ventilation and venting of the oil reservoir via an air lter.
Operating uid: HLP uid according to DIN 51524, ATF type A SUFFIX A, HD-SAE motor
oils, see Fluid Manufacturers, Technical Information.
Oil level: (The inlet pipe and return ow port must always be below the surface of the
oil). No funnel-shaped eddying at the inlet connection pipe. No formation of foam at
the return ow pipe. The inlet connection pipe must be substantially above the bottom
of the reservoir. A partition plate should be located between the inlet and return ow
connection pipes.
Filtration: Filtration grade = 10 µm [394 µinch] nominal.
Inlet pressure of charge pump: 0.85 bar [12.3 psi] absolute (- 0.15 bar [-2.2 psi]) with a
new lter element and at an operating temperature of approx. 50 °C [122 °F].
A charge pump inlet pressure less than 0.75 bar [10.9 psi] absolute (-0.25 bar [-3.6 psi]) is
permissible for a short time with a reservoir temperature of less than 50 °C [122 °F] on a
cold start in order to warm up the system under no-load.
If frequent cold starts are to be made, the system should be warmed up by a reservoir
heater.
If the charge pump inlet pressure is less than 0.75 bar [10.9 psi] absolute (-0.25 bar [-3.6
psi]) on operating temperatures higher than 50 °C [122 °F], the lters must be changed.
A charge pump inlet pressure of less than 0.5 bar [7.3 psi] absolute (- 0.5 bar [-7.3 psi])
is not permissible.
The lter requires changing or the operating temperature is too low.
Venting the pump and motor housing as well as the connection lines and other
components.
The return ow to the oil reservoir must be free of bubbles. After venting the system,
check the uid level and ll to proper level if necessary.
Carry out a leak test on the transmission (inlet line, lter, pipe and hose lines, valves,
control elements, pump and motor) giving due consideration to the service life of the
transmission, environmental protection and the reduction of oil consumption.
Tighten up any leaking joints and other connections while the system is not under
pressure.
Pressure uid temperature range: min. = -40 °C [-40 °F], max. = 95 °C [203 °F].
Viscosity range:
max. = 1000 mm2/s [4630 SUS*] (cSt) (for a short time only on a cold start).
min. = 7 mm2/s [49 SUS*] (cSt).
Recommended viscosity range: 12-60 mm2/s [66-278 SUS*] (cSt).
*SUS (Saybolt Universal Second)
Changing the oil: The oil should be changed after max. 80-100 hours of operation, but at
the latest one year after rst-time operation.
The second oil change should be after max. 500 hours of operation but at the latest one
year after the rst change of uid.
Thereafter, the oil should be changed every 1000 hours of operation but at least once a
year. It is not permissible to mix oil.
Renew the inlet lter each time the oil is changed or when the inlet pressure of the
charge pump falls below the permissible tolerance.
Clean the air lter whenever too much dirt has accumulated.
The max. speed is as specied in the catalogue Series 20 Axial Piston Pumps, Technical
Information or Series 20 Axial Piston Motors, Technical Information.
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:306-7

8DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Start-up procedure
PRECONDITIONS FOR
TROUBLE-FREE
OPERATION (continued)
FIRST-TIME OPERATION
The charge pressure measured at the charge pressure gauge connection port of the
pump with the adjusting lever in the neutral position should be approx. 15 bar [217.6 psi]
at a pump input speed n = 1500 min-1 (rpm).
The charge pressure measured at the charge pressure gauge connection port of the
pump with the adjusting lever engaged should be approx. 2 bar lower at a pump input
speed n = 1500 min-1 (rpm).
1. After installing the transmission and the corresponding pipeline connections,
remove the plug from the charge pressure gauge port of the variable displacement
pump. Fit a gauge with a measuring range up to 60 bar [870 psi] to this port.
The charge pressure gauge port has a straight 7/16-20 UNF-2 B SAE thread.
2. Disconnect the charge pump inlet line from the charge pump inlet connection pipe.
3. Fill the pump case and the motor case with the recommended oil through the drain
port.
4. Fill the oil reservoir with uid. As soon as oil emerges from the end of the discon-
nected charge pump inlet line tighten the pipe connector (see table to page 27 for
the correct tightening torque) and continue to ll the reservoir.
Only use oil reservoirs that are tted with air lters.
5. Disconnect the control linkage from the control handle. The pump must be in the
zero position.
6. Allow the prime mover to turn for approx. 15 sec. by using the starter.
6A. If the prime mover is an electric motor: Switch on and off again.
7. Then start the prime mover and allow the pump to turn at idling speed (approx. 750
min-1) for approx. 5 minutes.
7A. In the case of electric prime mover: Allow to turn for approx.1 minute.
After initial uctuations in pressure, the charge pressure should settle down to 10 bar
[145 psi] or 12 bar [174 psi].
8. Check the pressure uid level.
9. Raise the speed to approx. 1500 min-1 (rpm). The gauge should now indicate a pres-
sure of approx. 15 bar [217.6 psi].
10. If the charge pressure falls to below 8 bar [116 psi], stop the prime mover, nd
the fault in accordance with the trouble-shooting guide and take the appropriate
remedial action.
11. Stop the prime mover and attach the control linkage to the control handle. Check the
uid level in the sight glass and ll to proper level if necessary.
12. Restart the prime mover and, under no-load, adjust the zero position by means of the
control handle - or even better by the control linkage - so that in both directions nal
position of stroke per Series 20 Axial Piston Pumps, Technical Information is achieved.
13. Allow the prime mover to turn at 1500 min-1 (rpm). The charge pressure should now
be 15 bar [217.6 psi].
14. Slowly move the control handle backwards and forwards. If the pump is working
properly, the charge pressure drops by about 2 bar [29 psi] from the value stated in
step 13 above as the control handle initiated.
15. Allow the system to work under full load with a pump speed of approx.1500 min-1
(rpm). It must be possible to achieve the values stated in steps 13 and 14 above.
16. Check all joints and connections for leaks.
17. Stop the prime mover. Remove the gauge from the connection port. Replace the
7/16-20 UNF-2 B plug and tighten with the tightening torque stated in the table to
page 27.
Check the pressure uid level in sight glass of the reservoir and ll to proper level
if necessary.
The system is now ready for operation.
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:308-9

9
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
P000 341
PLUMBING INSTALLA-
TION (VARIABLE
DISPLACEMENT PUMP -
FIXED DISPLACEMENT
MOTOR)
SYSTEM CIRCUIT DESCRIPTION
HEAT EXCHANGER BYPASS VALVE
RESERVOIR
VACUUM GAUGE
HEAT EXCHANGER
OUTPUT SHAFT
MOTOR SWASHPLATE
FIXED
DISPLACEMENT MOTOR
LOOP FLUSHING VALVE
PURGE RELIEF VALVE
CHARGE PRESSURE
RELIEF VALVE
SERVO
PRESSURE
RELIEF VALVES
SERVO CONTROL CYLINDER
SERVO CONTROL CYLINDER
PUMP SWASHPLATE
REVERSIBLE VARIABLE
DISPLACEMENT PUMP
CONTROL
HANDLE
INPUT SHAFT
WORKING LOOP (LOW PRESSURE) SUCTION LINE CASE DRAIN FLUIDCONTROL FLUIDWORKING LOOP (HIGH PRESSURE)
P000 027E
Start-up procedure
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:308-9

10 DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
The lter element must be exchanged as soon as the pressure drops below 0.75 bar
[10.9 psi] absolute (-0.25 bar [-3.6 psi]) when the transmission is at normal operating
temperature. The lter must also be exchanged each time the pressure uid is changed.
Filtration grade = 10 µm [394 µinch] nominal.
Under normal operating conditions, the oil should be changed at the following intervals:
The rst oil change should be carried out after max. 80-100 hours of operation but at the
latest one year after rst-time operation. The second change should take place after max.
500 hours of operation but at the latest one year after the rst change.
Thereafter, the oil should be changed at least every 1000 hours of operation or at least
once a year.
To change the oil, the used uid must be drained off when the system is at operating
temperature! Remove any residual dirt or sludge from the reservoir!
In extremely dusty atmospheres, the intervals between oil changes must be correspon-
dingly shortened.
Oil samples should be taken every 500 hours of operation. To do this, take approx. 0.5l
of oil from a point on a level with the inlet (suction) connection. Fill the sample into a
closable container that is free of residues.
Have the oil examined for serviceability by Sauer-Danfoss, by Oil Manufacturer or by an
appropriate institution.
Important: Use only recommended oils! (See Fluid Manufacturers, Technical Information).
It is not permissible to mix oils.
Carry out a leak test on the transmission (inlet line, lter, pipe and hose lines and connec-
tions, valves, control elements, pump and motor) giving due consideration to the service
life of the transmission, environmental protection and reduction of oil consumption.
Tighten up any leaking joint and other connections while the system is not under
pressure.
Make certain that the air lter for ventilation of the oil reservoir is regularly cleaned,
since the input pressure may be affected if it is dirty. If there is an oil cooler, the cooler
surface should be kept free from contamination. On units which have hose couplings
on the connecting pipes, contamination of any sort must be avoided. Cotton rags or lint
cleaning cloths may not be used for cleaning. Use only lint-free materials.
When changing the oil, be sure the area around the ller cap is free from foreign objects.
The oil, which can be kept clean by using a lter cloth, should be added by means of
a clean funnel.
The level of the oil should be checked daily using the gauge glass. In case of loss of oil,
the leak must be rectied.
Important: Use only recommended uids! (See Fluid Manufacturers, Technical Informa-
tion.) It is not permissible to mix.
HLP - hydraulic uids according to DIN 51524
ATF - automatic transmission uids type A, SUFFIX A
HD - SAE motor oils
see Sauer-Danfoss manual Fluid Manufacturers, Technical Information.
INLET FILTER (BETWEEN
FLUID RESERVOIR AND
CHARGE PUMP)
CHANGING THE OIL
LEAK TEST
CLEANLINESS
CHECKING OF THE OIL
LEVEL
RECOMMENDED OILS
System Maintenance
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3010-11

11
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
TRANSMISSION
OPERATES IN ONE
DIRECTION ONLY
Trouble Shooting
Check control
linkage
Repair
or replace
Inspect high pressure
relief valve
(see page 13)
Insert charge check valves
(see Series 20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Repair
or replace
(see page 20,21)
Inspect shuttle valve
in valve block
(see page 14)
Repair or replace
the valve block
(see page 19)
OK
Defective Defective
OK OK
Repair or replace
(see Series 20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Inspect control valve
(see Series 20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Replace control valve
(see Series 20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Defective
Defective Defective
OK
SYSTEM RESPONSE IS SLUGGISH
Check charge
pressure
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Inspect
control valve
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Inspect motor
by-pass valve
(if used)
Replace
control valve
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
OK
Defective
OK
OK
Repair
or replace
Defective
Replace
transmission
(pump + motor)
OK
Inspect charge
pressure relief valve
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Repair or replace
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Inspect purge
relief valve
at motor
(see page 21)
Inspect charge
pressure relief valve
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Repair or
replace the
valve block
(see page 19)
Defective Defective
Repair or replace
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Defective
Inspect
inlet filter
OK OK
Replace
Clogged
Inspect
charge pump
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Repair or replace
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Defective
to low
in
neutral
to low in neutral and
forward or reverse
to low inforward
or reverse
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3110-11

12 DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
SYSTEM OPERATING HOT
SYSTEM WILL NOT OPERATE IN EITHER DIRECTION
Trouble Shooting
Check fluid
level in
reservoir
Fill to
proper level
Inspect heat
exchanger
Inspect
inlet filter
Repair
or replace
OK
to Low Defective
OK OK
Replace
Replace
transmission
(pump + motor)
Clogged
Inspect motor
by-pass valve
(if used)
OK OK
Repair
or replace
Defective
Check system
pressure
(see page 13)
Reduce
machine load
Defective
Check fluid
level in
reservoir
Check control
linkage
Inspect motor
by-pass valve
(if used)
Repair
or replace
OK
Defective
OK
Fill to
propper level
to Low
Repair
or replace
Defective
Check charge
pressure
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
OK
Inspect
charge pump
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Inspect
inlet filter
Repair or replace
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Defective
Replace
Defective
Inspect charge
pressure relief valve
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Repair or replace
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Clogged
Inspect purge
relief valve
at motor
(see page 21)
Repair or
replace the
valve block
(see page 19)
Defective
Replace
transmission
(pump + motor)
Inspect
control valve
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Replace
control valve
(see Series20 Axial Piston
Pumps, Service Manual
and Repair Instruction)
Defective
Inspect motor
by-pass valve
(if used)
Repair
or replace
Defective
Check system
pressure
(see page 13)
to low in
neutral and
forward or
reverse
to low in
forward or
reverse
to low in
neutral
OK
OKOK OK
OK OK OK
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3112-13

13
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Checking the high pressure relief valve
Pressure on ports A or B in accordance to high pressure relief valve setting on the
opposite side to the port.
To check high pressure relief valve setting, pump should be driven under load by a prime
mover with rated speed.
Stroke control lever for ve seconds in both directions to nal position.
Pressure setting should be in accordance to machine specication.
Trouble Shooting
When the problem occurs in one direc-
tion only, interchange the relief valve
cartridges to see if the problem changes
to the other direction. If so, one relief
valve cartridge is either malfunctioning
or does not have the proper setting. The
three (3) digits of the pressure setting
are stamped on the end of the cartridge.
Compare to machine specication.
INSPECTION
INSTRUCTIONS
CAUTION!
The relief valves are factory
set and should not be
disassembled further.
350 for 350 bar [5000 psi]
315 for 315 bar [4500 psi]
280 for 280 bar [4000 psi]
245 for 245 bar [3500 psi]
210 for 210 bar [3000 psi]
175 for 175 bar [2500 psi]
140 for 140 bar [2000 psi]
High pressure relief valve
103 120
F000 059
F000 059
F000 059
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3112-13

14 DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Checking the shuttle valve
Mounting block
The areas of repair indicated may be serviced, following the procedures in this manual,
without invalidating the warranty.
When using a lifting device, the hooks at the end of the slings, are to be fastened in the
rings tted at the front and rear of the motor body.
It is recommended that an mounting block should be used in order to facilitate a profes-
sional operation.
The shuttle spool must be easily movable
in the bore.
Any wear, dirt or cracks, indicate that
the complete valve block needs to be
replaced, the spool and manifold are
matched and cannot be replaced separa-
tely (see page 20).
F000 081
Washer Shuttle spool
INSPECTION
INSTRUCTIONS
(continued)
PREPARATION FOR
ASSEMBLY
Trouble Shooting
Ø10 Pin
[Ø0.394]
70
[2.756]
5x45˚
20
[0.787]
10
[0.394]
ca. 5 mm Chamfer
[ca. 0.2 in]
Ø130
[Ø5.118]
165
[6.496]
250
[9.843]
250
[9.843]
P005 112E
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3114-15

15
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Disassembly and Assembly
SECTIONAL VIEW
P005 118E
Output
shaft
Shaft seal
Cylinder block
assembly
High pressure
relief valves
(adjustable)
Purge
relief valve
Valve block
Shuttle valve Swashplate
Axial piston xed displacement motor
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3114-15

16 DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Description of parts:
1 Hexagonal screw 19 Retainer spring 39 Plug-pipe
2 Washer 20 Spring guide 71 O-ring
3 Kit manifold valve 21 Spring 75 O-ring
4 O-ring 22 Spring seat 77 Ring retaining
5 O-ring 23 Retainer spring 103 High pressure valve assembly
6 Back up ring 24 Cylindrical pin 104 O-ring
7 Hexagonal screw 25 Cylinder block 105 Back up ring
8 Hexagonal screw 26 Retainer guide 106 O-ring
9 Washer 27 Slipper retainer 107 Back up ring
10 End cap 28 Piston assembly 118 O-ring
11 Shim 29 Swash plate 119 Back up ring
12 Gasket 30 Shaft 120 High pressure valve assembly
13 Bearing 31 Bearing 196 Compl. manifold assembly
14 Cylindrical pin 32 Cylindrical pin 197 Seal kit
15 Valve plate 33 Plug 198 Cylinder block kit
16 Bearing plate 34 O-ring 199 Shaft seal kit
17 Bearing plate pilot ring 35 Motor housing
18 Ring retaining 38 Cylindrical pin
EXPLODED VIEW
P005 117
Disassembly and Assembly
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3116-17

17
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Disassembly and Assembly
MINOR REPAIRS
CAUTION!
These parts can be easily
damaged. Use care in
handling.
Each part should be
inspected separately if
parts are to be reused.
Always replace the O-rings.
Lubricate the small O-ring
with petroleum jelly and
insert into the I. D. of the
bronze rotating ring.
Lubricate the large O-ring
and place the O. D. of the
seal-stationary.
The seal-stationary is removed next. It
is held in place by the friction of the
O-ring on its O. D. Remove seal-stationary
with the help of a seal puller to prevent
damage to outer edge.
Utilize the lifting gear and mounting
block in accordance with the tting
instructions on page 14.
It is recommended that all shaft seal
parts be replaced. If parts are to be
reused, they must be protected from
being damaged by the shaft during
removal. Remove the large retaining ring
located on the shaft end of the motor.
Remove the side opposite the tangs from
the groove rst.
The rotating seal ring (bronze ring) is also
held in its position by the O-ring. It can
be removed with the help of two screw
drivers.
F000 070
F000 072
F000 071
Changing the shaft seal (disassembly)
77
71 Bronze ring
77 Seal-stationary 75
Clamp seal puller
on seal-stationary
77
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3116-17

18 DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Changing the shaft seal (assembly)
Disassembly and Assembly
MINOR REPAIRS
(continued)
CAUTION!
Protect parts from damage
by the shaft.
Slide seal-stationary into place against
the bronze sealing ring.
Slide the bronze sealing ring over the
shaft and onto the shaft pilot diameter
with the O-ring facing the unit. Work the
ring into place using hand force only.
Compress the seal-stationary to expose
the retaining ring groove. Install the
retaining ring with the beveled side
out, putting the side opposite the tangs
into the groove rst. Be certain that
the retaining ring has snapped into the
groove completely.
F000 073
F000 212
F000 075
F000 074
71 Bronze ring
Seal stationary
Cone bearing
Clamp seal puller
on seal-stationary
77
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3118-19

19
DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Changing the valve manifold assembly
Disassembly and Assembly
MINOR REPAIRS
(continued)
The valve manifold assembly can be
removed from the motor and replaced
in its entirety. The following procedure
shows removal of the entire manifold
from the motor before performing fur-
ther disassembly.
The three (3) ports are sealed with
O-rings and the two (2) adjacent ports
also have back-up rings on top of the
O-rings. These are rectangular in cross-
section and slightly cupped on one side
where they mate with the O-rings.
Remove the six (6) hex. cap screws and
lift the manifold off the motor end cap.
The O-ring should be placed in the port
with the full counterbore. The O-rings
and back-up rings t in the ports with
the machined grooves. The O-ring should
be installed rst and then the back-up
ring.
Resume re-assembly procedure.
F000 125
F000 127
F000 128
F000 126
Torque spanner 1 2 10 3
6 5
3 4 6 5
3 4 5+6
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3118-19

20 DKMH.PS.330.C1.02 520L0534
Series 20 – Axial Piston Motors
Service Manual and Repair Instructions
Repair the manifold valve assembly
Disassembly and Assembly
MINOR REPAIRS
(continued)
Hex-plugs
with springs
To repair the shuttle valve, remove
both hex. plugs, springs, washers and
spool from the manifold. These parts are
interchangeable and can be installed on
either side of the manifold. The spool and
manifold are a select t and must be
replaced together.
Washer Shuttle spool
To install, slide the spool into the bore,
place a washer on each end, then slide
both springs In place. Install the hex.
plugs and tighten.
F000 130
F000 081
High pressure relief valve High pressure relief valve
103 Valve block 120
O-rings +
back up rings
Washer Washer
Hex-plug Shuttle valve
Low pressure Spring Shuttle spool Spring
relief valve Hex-plug
Hex-plug Shims Spring Valve cone
Shuttle spool, valve cone and manifold housing are matched and should not be replaced
separately.
F000 129
Series 20 Axial Piston Motors_SR.indd 24.4.2002, 13:3120-21