953D, 963D and 973D Track-Type Loaders Implement Cycle Time Is Slow for All Implements Caterpillar


Implement Cycle Time Is Slow for All Implements
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1.1. Probable Causes
2.1. Recommended Actions
3.2. There May Be A Internal Leak Or Internal Blockage In The Load Sensing Signal Circuit
4.2. Blockage of The Main Suction Hose
5.2. The Flow Compensator Spool May Not Move
6.2. System Pressure Is Low
7.2. The Margin Pressure Is Set Too Low
8.2. The Pump Is Not Upstroking
9.2. The Pump Is Worn
10.2. The Pressure Compensator Valve Is Adjusted Incorrectly
11.2. The Pilot Pressure Is Low
12.2. The Engine Speed Is Too Low
13.2. The Control Lever Is Not Calibrated Properly

Probable Causes

  • 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.

Recommended Actions

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 1g00850889
(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.

System Pressure Is Low

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.

The Pump Is Not Upstroking

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.

The Pump Is Worn

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.

The Pilot Pressure Is Low

Make sure that the pilot pressure is within the proper specification. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.

The Engine Speed Is Too Low

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.

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