Item
Description
Action
Check pilot pressure or control
pressure.
Insufficient pilot pressure or control
pressure.
Increase them to appropriate value.
Internal system leaks.
Worn internal parts don’t allow the
pump to operate properly.
Refer to Authorized Service Center for
required repair.
Actuator Response is Sluggish
Item
Description
Action
Check external system relief valve
setting.
Low external relief valve setting slows
down system.
Adjust external relief valve setting
following manufacturer’s
recommendations. External relief
setting must be above PC setting to
operate properly.
Check pressure compensate (PC),
load sensing (LS) and power (T)
control setting.
Low PC setting prevents the pump
from achieving full stroke. Low LS
setting limits output flow. Low T
setting limits output Torque.
Contact Danfoss Service.
Check LS control signal pressures.
Incorrect LS signal will not allow
pump to operate correctly.
Inspect system to ensure that proper
LS signal transmit to pump.
Check Pilot pressure for hydraulics
displacement control and input
current for electric displacement
control.
Incorrect input signal causes low
output flow.
Adjust input hydraulic or electric
signal to right value.
Internal system leaks.
Worn internal parts don’t allow the
pump to operate properly.
Refer to Authorized Service Center for
required repair.
Hydraulic fluid viscosity above
acceptable limits.
Hydraulic fluid viscosity above
acceptable limits or low fluid
temperature will not allow the pump
to fill or control to operate properly.
Allow system to warm up before
operation or sue fluid with the
appropriate viscosity grade for
expected operating temperatures.
Check external system valving.
Malfunctioning valving may not allow
system to respond properly.
Repair or replace system valving as
required.
Check pump case pressure.
High case pressure causes the system
to be sluggish.
Correct case drain line restrictions.
Check pump inlet pressure / vacuum. High inlet vacuum causes low output
flow.
Correct inlet pressure conditions.
Pressure or Flow Instability
Item
Description
Action
Check for air in system.
Air in system causes erratic operation. Activate PC allowing system to bleed
air. Check inlet line for leaks and
eliminate source of air ingression.
Check LS setting.
Low LS setting may cause instability.
Contact Danfoss Service.
Check LS signal line.
Blocked LS signal line interferes with
proper LS operation.
Remove blockage.
Check external relief valve and PC
setting.
Insufficient pressure differential
between PC setting and external
relief valve.
Adjust external relief valve or PC
control settings to appropriate level.
Relief valve setting must be above PC
setting to operate properly.
Check external relief valve.
Chattering external relief valve may
cause unstable feedback to pump
control.
Adjust or replace relief valve.
Service Manual
D1 High Power Open Circuit Pumps Size 65/130/145/193/260
Troubleshooting
©
Danfoss | July 2019
L1527453 | AX00000292en-CN0201 | 33