Print Friendly and PDF

Parker Hydraulic Pump Troubleshooting

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 the Hydraulic Parameters topic.
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.
Actuator response is sluggish
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 the
Adjustments chapter.
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.
System operating hot
Check fluid level in reservoir. Insufficient volume of hydraulic fluid will not meet cooling demands of system. Fill reservoir to proper level. Verify proper size of reservoir.
Inspect heat exchanger. Check air flow and input air temperature for the heat exchanger. Insufficient air flow, high input air temperature, or undersized heat exchanges will not meet cooling demands of the system. Clean, repair, or replace heat exchanger as required. Verify proper size of heat exchanger.
Troubleshooting
Check external system relief valve setting. Fluid passing through relief valve adds heat to system. Adjust external system relief valve setting following manufacturer’s recommendations. External relief valve setting must be above PC setting for proper operation.
Check pump inlet pressure/vacuum. High inlet vacuum adds heat to system. Correct inlet pressure/vacuum conditions.
Low pump output flow
Check fluid level in reservoir. Insufficient hydraulic fluid will limit output flow and cause internal damage to pump. Fill the reservoir to proper level.
Hydraulic fluid viscosity above acceptable limits. 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.
Check external system relief valve setting. Eternal relief valve set below PC setting causes low output flow. Adjust external relief valve following manufacturer’s recommendation. External relief valve 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. Adjust PC and LS setting. Refer to the
Adjustments chapter.
Check pump inlet pressure/vacuum. High inlet vacuum causes low output flow. Correct inlet pressure conditions.
Check input speed. Low input speeds decrease flow. Adjust input speed.
Check pump rotation. Incorrect rotational configuration causes low flow. Use pump with appropriate rotational configuration.
Pressure or flow instability
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 control spools. Sticking control spools cause erratic operation. Inspect spools for free movement in bore. Clean or replace.
Check LS setting. Low LS setting may cause instability. Adjust LS setting to proper level. See the
Adjustments chapter.
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.
Troubleshooting
System pressure not reaching PC setting
Check PC control setting. System pressure will not rise above PC setting. Adjust PC to appropriate setting. Refer to the
Adjustments chapter.
Check external relief valve. External relief valve setting below PC setting presents pressure compensation. Adjust external relief valve according to manufacturer’s recommendations. External relief valve must be set above PC setting to operate properly.
Inspect PC control spring. Broken, damaged, or missing spring will cause erratic operation. Replace the spring as required.
Inspect PC spool for wear. Wear of PC spool causes internal leakage in the control. Replace the spool as required.
Inspect PC spool for proper orientation. Improper orientation results in poor operation. Correct orientation of spool.
Check PC control for contamination. Contamination may interfere with movement of the PC spool. Clean PC control components, take appropriate action to eliminate contamination.
High inlet vacuum
Check fluid temperature. Low temperature increases viscosity. High fluid viscosity causes high inlet vacuum. Allow system to warm up before operating.
Inspect inlet screen. Blocked or restricted inlet screen causes high inlet vacuum. Clean screen/remove blockage.
Check inlet piping. Too many fittings, bends, or long piping causes high inlet vacuum. Eliminate fittings to make path more direct.
Hydraulic fluid viscosity above acceptable limits. High fluid viscosity causes high inlet vacuum. Select fluid with appropriate viscosity for expected operating temperature. See Hydraulic Fluids and Lubricants Technical Information Manual, 520L0463.

Parker Hydraulic Pump Troubleshooting is a comprehensive guide for engineers who are faced with a hydraulic pump problem. Written by an experienced engineer, this book walks you through the steps needed to diagnose and fix hydraulic pump problems. With Parker Hydraulic Pump Troubleshooting, you'll be able to quickly and easily solve your hydraulic pump problems.