Service Manual
Series 45 J Frame Open Circuit Axial Piston Pumps
520L0607
• Rev AI • Sep 2013
18
Troubleshooting
Excessive Noise and/or
Vibration
Actuator Response is
Sluggish
Item
Description
Action
Check fluid level in reservoir.
Insufficient hydraulic fluid causes
cavitation.
Fill the reservoir to proper level.
Check for air in system.
Air in system causes noisy, erratic
control.
Purge air and tighten fittings. Check
inlet for leaks.
Check pump inlet pressure/vacuum.
Improper inlet conditions cause
erratic behavior and low output
flow.
Correct pump inlet pressure /
vacuum conditions. Refer to
Hydraulic parameters
, page 10.
Inspect shaft couplings.
A loose or incorrect shaft coupling
causes excessive noise and/or
vibration.
Repair or replace coupling and
ensure that correct coupling is
used.
Check shaft alignment.
Misaligned shafts create excessive
noise and/or vibration.
Correct shaft misalignment.
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
operating, or use fluid with the
appropriate viscosity grade for
expected operating temperatures.
See
Hydraulic Fluids and Lubricants
Technical Information Manual,
520L0463
.
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 PC and LS control setting.
Low PC setting prevents the pump
from achieving full stroke. Low LS
setting limits output flow.
Adjust PC and LS setting. Refer to
Adjustments
, page 21
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.
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.
See
Hydraulic Fluids and Lubricants
Technical Information Manual,
520L0463
.
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.