Transmission Operates Normally in One Direction Only
Item Description Action
Input to pump control. Input to control module is operating improperly. Check control input and repair or replace as necessary.
Control orifices Control orifice(s) are blocked. Clean control orifices.
Control screens Control screen(s) are blocked. Replace control screens. Only a Danfoss Authorized Service
Center may remove the unit’s endcap without voiding the
warranty.
Exchange system pressure
limiters
Exchanging the pressure limiter valves will show if the
problem is related to the valve function.
If the problem changes direction, replace the valve that
does not operate correctly.
Exchange high pressure
relief valves
Exchanging the high pressure relief valves will show if the
problem is related to the valve function.
If the problem changes direction, replace the valve that
does not operate correctly.
Servo pressure low or
decaying
Damaged servo seals may prevent servo piston from
stroking the pump.
Check for torn/missing servo seals. Replace and retest. Only
a Danfoss Authorized Service Center may remove the servo
piston without voiding the warranty.
Bypass function open Open bypass will cause one or both directions to be
inoperative.
Close bypass function.
Service Manual
H1 Pumps 069/078, 089/100, 115/130, 147/165, 210/250
Troubleshooting
30 |
©
Danfoss | May 2018 520L0848 | AX00000087en-US0308
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