Danfoss Series 20 Service Manual And Repair Instructions
powersolutions.danfoss.com
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 Installa tion (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
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 cm
3
6 = 6000 psi SAE J518 (414 bar)
for displacement 166 - 334 cm
3
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 V
g
= 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
y Circlip pliers ∅ 2 to 2.5 mm
y Screw drivers 3, 6 and 9mm
y Plastic hammer - small
y Pointed pliers (can also be slightly bent)
y Torque key to 14.9 Nm [132 lbf•inch]
y Set of ring spanners
5
/
16 to 1
1
/
4
y Set of Allenkeys
1
/
4 to
3
/
8
y Fixed spanner 1
5
/
6 for high pressure relief valve
y Puller retainer seal
(Major repairs should not be carried out during the warranty period.)
y Right angle screw driver 16 mm
y Set of drifts 2 to 10 mm
y Plastic hammer - large
y Bearing puller 80 x 120 mm
y Bearing puller 200 x 250 mm
y Each fixed spanner for servo cylinder 36, 41, 46, 50, 55, 60, 65 mm
y Depth gauge 300 mm
y Set of fixed or open ended spanners
7
/
16 to 1
1
/
4
y Fitting block - see page 14
At least 2 pressure gauges up to 60 bar damped (charge pressure - servo pressure)
y 1 vacuum gauge to +1.0 ÷ -1.0 bar [14.5 ÷ -14.5 psi]
(vacuum measurement at the charge pump)
y 2 pressure gauges to 600 bar [8700 psi] (high pressure measurement at the valve block)
y 1 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
A Charge Pressure 60 bar [870 psi] - Gauge 7/16 - 20 UNF O-ring Fitting
B System pressure 600 bar [8700 psi] - 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
Service Manual and
Axial Piston Motors Series 20
Repair Instructions
L1003443 • Rev BA • Jun 2014
7
Start-up procedure
Preconditions for Troublefree 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 mm
2
/s [4630 SUS*] (cSt) (for a short time only on a cold start).
min. = 7 mm
2
/s [49 SUS*] (cSt).
Recommended viscosity range: 12-60 mm
2
/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
8
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 =
150 0 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 discon nected 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 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, 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
9
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 Installa tion
(Variable Displacement
Pump – Fixed Displacement
Motor)
Loading...