- There may be a internal leak or internal blockage in the load sensing signal circuit.
- Blockage of the main suction hose
- The flow compensator spool may not move.
- System pressure is low
- The margin pressure is set too low.
- The pump is not upstroking.
- The pump is worn.
- The pressure compensator valve is adjusted incorrectly.
- The pilot pressure is low.
- The engine speed is too low.
- The control lever is not calibrated properly.
There May Be A Internal Leak Or Internal Blockage In The Load Sensing Signal Circuit
Make sure that the signal that is flowing to the compensator valve is not blocked. Perform the margin pressure test. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.
If necessary, adjust the flow compensator spool in order to set the correct margin pressure. If the correct margin pressure cannot be achieved, there may be blockage in the load sensing signal circuit. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine. Repair the circuit, if necessary.
Blockage of The Main Suction Hose
Blockages or restrictions in the main suction oil line will stop the supply of hydraulic oil flow to the pumps. Components cannot operate without oil flow from the pump. Components cannot operate properly with reduced flow or pressure available to motors, cylinders, actuators, etc. Correct any problems that are found then retest the hydraulic system for any symptoms.
The Flow Compensator Spool May Not Move
Illustration 1 | g00850889 |
(1) Flow compensator spool
(2) Orifice |
Make sure that flow compensator spool (1) moves freely. Repair the compensator valve, if necessary.
for the circuit that is affected.
Check the system pressure. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.
The Margin Pressure Is Set Too Low
Perform a margin pressure test. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.
Make sure that the pump is destroking. Ensure that the swashplate is not blocked and ensure that the actuator piston is not stuck. Repair the pump, if necessary.
Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.
The Pressure Compensator Valve Is Adjusted Incorrectly
The pressure compensator valve may be set too low. Make sure that the pressure compensator spool is adjusted correctly. Perform the high pressure stall test on the implement pump. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.
Make sure that the pilot pressure is within the proper specification. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.
Make sure that the engine speed is within the proper specification. Refer to Testing and Adjusting, "Final Hydrostatic Speed - Test" for your machine.
If running the machine in "Fuel Efficient Reverse" (FER) mode then the speed of the implements when engaged will be lower. You can disable the function if you need more implement speed.
The Control Lever Is Not Calibrated Properly
Be sure that the control lever position sensor is calibrated properly. Refer to Testing and Adjusting, "Hystat Operator Control Calibrations" for your machine.