1. Troubleshooting Hydraulic Pumps
Jack Weeks
GPM Hydraulic Consulting, Inc.

2. The Difference Between
The single most important concept that separates PARTS CHANGERS from TROUBLESHOOTERS:
The Difference Between
PRESSURE
&
FLOW

3. Pressure is the result of resistance to flow
The pump does NOT pump pressure!

7. Checking the Fixed Displacement Pump
Check the pump housing for heat

8. Check the current draw on the electric drive motor HP = FLOW X PRESSURE
If the pump is bypassing and the flow is reduced, then the drive motor’s current draw will also be reduced.

9. Variable Displacement Pumps
Variable Displacement Pumps are used when the volume requirements change in the system

10. Pressure Compensating Pumps
The Pressure Compensating Pump delivers maximum volume until the compensator setting is reached
When the setting is reached, the pump delivers only the oil required by the system.

11. Flow Meter

28. Checking the Variable Displacement Pump
Is it a pressure or a volume problem?

29. Volume Problem Feel the relief valve tank line
Check your case drain for excessive bypassing
Check the electrical current on the drive motor
Ensure that the compensator is set 200 PSI above the maximum operating pressure

30. Pressure Problem
If the pressure is very low, the problem is probably the relief valve
The pump compensator may be bad
Check the case drain

31. Thank You For Attending! GPM Hydraulic Consulting, Inc.
Jack Weeks
GPM Hydraulic Consulting, Inc.
Office: (770)
Cell: (770)