Actuator Response Is Sluggish; Pressure Or Flow Instability - Danfoss D1 Series Service Manual

Service Manual
D1 High Power Open Circuit Pumps Size 65/130/145/193/260
Troubleshooting

Actuator Response is Sluggish

Pressure or Flow Instability

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