Danfoss Series 20 Setup guide

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MAKING MODERN LIVING POSSIBLE
Service Manual and Repair Instructions
Axial Piston Motors
Series 20

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
2
General Information
Introduction
Description
The purpose of this manual is to provide you with the information necessary for the normal
maintenance and servicing of the 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 filters 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.
Danfoss axial pistons fixed 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 flow.
The output torque is proportional to the differential pressure applied to the main pressure ports.
The direction of motor (output) shaft rotation depends on flow input to the main pressure ports.
The full-length shaft with a highly efficient 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.
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.

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
3
Contents
General Information
Model Code
Recommended Tools and
Installation
Start-up procedure
System Maintenance
Troubleshooting
Disassembly and Assembly
Introduction................................................................................................................................................................................ 2
Description.................................................................................................................................................................................. 2
Model Code................................................................................................................................................................................. 4
Tools for Minor Repairs and Unit Maintenance ............................................................................................................. 5
Additional Tools for Complete Stripping of Units......................................................................................................... 5
Measurement Instruments.................................................................................................................................................... 5
Troubleshooting, Gauge Installation and Information............................................................................................... 6
Preconditions for Trouble-free Operation....................................................................................................................... 7
Cleanliness ............................................................................................................................................................................ 7
Preconditions for trouble-free operation (continued)................................................................................................ 8
Plumbing Installation (Variable Displacement Pump - Fixed Displacement Motor) ....................................... 9
System Circuit Description .................................................................................................................................................. 10
Inlet Filter ................................................................................................................................................................................... 11
Changing the oil...................................................................................................................................................................... 11
Leak Test ..................................................................................................................................................................................... 11
Cleanliness................................................................................................................................................................................. 11
Checking the oil level ............................................................................................................................................................ 11
Recommended oils................................................................................................................................................................. 11
Transmission Operates in one Direction Only.............................................................................................................. 12
System Response is sluggish .............................................................................................................................................. 12
System Operating hot ........................................................................................................................................................... 13
System will not operate in either direction................................................................................................................... 13
Inspection Instructions......................................................................................................................................................... 14
Checking the high pressure relief valve ................................................................................................................... 14
Preparation for Assembly .................................................................................................................................................... 15
Checking the shuttle valve............................................................................................................................................ 15
Mounting block ................................................................................................................................................................. 15
Sectional View.......................................................................................................................................................................... 16
Axial piston fixed displacement motor..................................................................................................................... 16
Exploded View ......................................................................................................................................................................... 17
Minor Repairs............................................................................................................................................................................ 18
Changing the shaft seal (disassembly)...................................................................................................................... 18
Changing the shaft seal (assembly) ........................................................................................................................... 19
Changing the valve manifold assembly...................................................................................................................20
Repair the manifold valve assembly.......................................................................................................................... 21
Installation Torque Values..............................................................................................................................................22
Changing the valve and bearing plate (disassembly).........................................................................................23
Changing the valve and bearing plate (assembly)............................................................................................... 24
Changing the cylinder block kit, the swash plate and the motor shaft (disassembly)...........................25
Changing the cylinder block kit, the swash plate and the motor shaft (assembly)................................. 27

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
4
Model 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
pbar 70 105 140 175 210 245
[psi] [1015] [1520] [2030] [2540] [3050] [3550]
characteristic number 28 31 35 38 (40)* (42)*
pbar 280 315 350 385 (400) (420)
[psi] [4060] [4570] [5080] [5580] [5800] [6090]
* level of high pressure in parenthesis:
after application engineer approval
2typical 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 fixed 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

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
5
Recommended Tools and
Installation
Tools for Minor Repairs and
Unit Maintenance
Additional Tools for
Complete Stripping of Units
Measurement Instruments
yCirclip pliers ∅2 to 2.5 mm
yScrew drivers 3, 6 and 9mm
yPlastic hammer - small
yPointed pliers (can also be slightly bent)
yTorque key to 14.9 Nm [132 lbf•inch]
ySet of ring spanners 5/16 to 11/4
ySet of Allenkeys 1/4to 3/8
yFixed spanner 15/6for high pressure relief valve
yPuller retainer seal
(Major repairs should not be carried out during the warranty period.)
yRight angle screw driver 16 mm
ySet of drifts 2 to 10 mm
yPlastic hammer - large
yBearing puller 80 x 120 mm
yBearing puller 200 x 250 mm
yEach fixed spanner for servo cylinder 36, 41, 46, 50, 55, 60, 65 mm
yDepth gauge 300 mm
ySet of fixed or open ended spanners 7/16 to 11/4
yFitting block - see page 14
At least 2 pressure gauges up to 60 bar damped (charge pressure - servo pressure)
y1 vacuum gauge to +1.0 ÷ -1.0 bar [14.5 ÷ -14.5 psi]
(vacuum measurement at the charge pump)
y2 pressure gauges to 600 bar [8700 psi] (high pressure measurement at the valve block)
y1 pressure gauge to 8 bar [116 psi] (casing pressure measurement)
Additional: Torque spanners, separate order!

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
6
Troubleshooting, Gauge
Installation and Information
Recommended Tools and
Installation
Gauge Information
ACharge Pressure 60 bar [870 psi] - Gauge 7/16 - 20 UNF O-ring Fitting
BSystem pressure 600 bar [8700 psi] - Gauge 7/16 - 20 UNF O-ring Fitting
CInlet Vacuum Vacuum gauge Tree Into Inlet Line
DCase pressure 8 bar [116 psi] - Gauge Adapt to Bottom Drain Port

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
7
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 filter.
Operating fluid
HLP fluid 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 flow 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 flow 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 flow 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 filter
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 filters 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 filter 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 flow to the oil reservoir must be free of bubbles. After venting the system, check the fluid
level and fill to proper level if necessary.
Carry out a leak test on the transmission (inlet line, filter, 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 fluid 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 first-time operation.
The second oil change should be after max. 500 hours of operation but at the latest one year after the
first change of fluid.
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 filter each time the oil is changed or when the inlet pressure of the charge pump
falls below the permissible tolerance.
Clean the air filter whenever too much dirt has accumulated.
The max. speed is as specified in the catalogue L1003621 Series 20 Axial Piston Pumps, Technical
Information or L1003465 Series 20 Axial Piston Motors, Technical Information.

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
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Start-up procedure
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 fluid. As soon as oil emerges from the end of the disconnected charge
pump inlet line tighten the pipe connector (see table to page 27 for the correct tightening torque)
and continue to fill the reservoir.
Only use oil reservoirs that are fitted with air filters.
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.
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.
In the case of electric prime mover: Allow to turn for approx.1 minute.
After initial fluctuations in pressure, the charge pressure should settle down to 10 bar [145 psi] or
12 bar [174 psi].
8. Check the pressure fluid level.
9. Raise the speed to approx. 1500 min-1 (rpm). The gauge should now indicate a pressure of approx.
15 bar [217.6 psi].
10. If the charge pressure falls to below 8 bar [116 psi], stop the prime mover, find the fault in
accordance with the trouble-shooting guide and take the appropriate remedial action.

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
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Start-up procedure
First-time operation
(continued)
11. Stop the prime mover and attach the control linkage to the control handle. Check the fluid level in
the sight glass and fill 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 final position of stroke
per L1003621 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 fluid level in sight glass of the reservoir and fill to proper level if necessary.
The system is now ready for operation.
Plumbing Installation
(Variable Displacement
Pump – Fixed Displacement
Motor)

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
10
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

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
11
The filter 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 filter
must also be exchanged each time the pressure fluid is changed. Filtration grade = 10 µm [394 µinch]
nominal.
Under normal operating conditions, the oil should be changed at the following intervals:
The first oil change should be carried out after max. 80-100 hours of operation but at the latest one
year after first-time operation. The second change should take place after max. 500 hours of
operation but at the latest one year after the first 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 fluid 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 correspondingly
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 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, filter, pipe and hose lines and connections, 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 filter 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 filler cap is free from foreign objects. The oil,
which can be kept clean by using a filter 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 rectified.
Important: Use only recommended fluids! (See Fluid Manufacturers, Technical Information.) It is not
permissible to mix.
HLP - hydraulic fluids according to DIN 51524
ATF - automatic transmission fluids type A, SUFFIX A
HD - SAE motor oils
see Danfoss manual Fluid Manufacturers, Technical Information.
Inlet Filter
Changing the oil
Leak Test
Cleanliness
Checking the oil level
Recommended oils
System Maintenance

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
12
Transmission Operates in
one Direction Only
Troubleshooting
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
DefectiveDefective
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)
DefectiveDefective
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

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
13
System Operating Hot
System will not Operate in
either Direction
Troubleshooting
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

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
14
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 five seconds in both directions to final position.
Pressure setting should be in accordance to machine specification.
Troubleshooting
When the problem occurs in one direction 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
specification.
CCaution!
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
Inspection Instructions

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
15
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 fitted at
the front and rear of the motor body.
It is recommended that an mounting block should be used in order to facilitate a professional
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 separately (see page 20).
Washer Shuttle spool
Inspection Instructions
(continued)
Preparation for Assembly
Troubleshooting
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

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
16
Disassembly and Assembly
Sectional View
P005 118E
Output
shaft
Shaft seal
Cylinder block
assembly
High pressure
relief valves
(adjustable)
Pu
rge
relief valv
e
Valve block
Shuttle valveSwashplate
Axial piston fixed displacement motor

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
17
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
Disassembly and Assembly

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
18
Disassembly and Assembly
Minor Repairs
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.
CCaution!
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.
Utilize the lifting gear and mounting block in
accordance with the fitting 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 first.
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 072
Changing the shaft seal (disassembly)
77
71 Bronze ring
77 Seal-stationary 75
Clamp seal puller
on seal-stationary
77

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
19
Changing the shaft seal (assembly)
Disassembly and Assembly
Minor Repairs (continued)
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.
CCaution!
Protect parts from damage by the shaft.
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 first. Be
certain that the retaining ring has snapped into
the groove completely.
71 Bronze ring
Seal stationary
Cone bearing
Clamp seal puller
on seal-stationary
77

Service Manual and Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
20
Changing the valve manifold assembly
Disassembly and Assembly
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
further 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
fit in the ports with the machined grooves. The
O-ring should be installed first and then the
back-up ring.
Resume re-assembly procedure.
Torque spanner 1 2 10 3
6 5
3 4 6 5
3 4 5+6
Minor Repairs (continued)