953D, 963D and 973D Track-Type Loaders Implement Movement Without Request Caterpillar


Implement Movement Without Request
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1.1. Probable Causes
2.1. Recommended Actions
3.2. The Flow Spool Or The Bore Is Worn
4.2. Hydraulic Cylinders Seals Are Leaking
5.2. Hydraulic Lines May Have A Leak
6.2. The Solenoid For The Control Valve Has Current Or The Solenoid Has Contamination
7.2. The Makeup Valves Are Open
8.2. The Dead Electric Lower Valves Are Open

Probable Causes

Any of the implements move, when the control lever is in the HOLD position.

  • The flow spool or the bore is worn.

  • Hydraulic cylinders seals are leaking.

  • Hydraulic lines may have a leak.

  • The solenoid for the control valve has current or the solenoid has contamination.

  • The makeup valves are open.

  • The dead electric lower valves are open.

Recommended Actions

The Flow Spool Or The Bore Is Worn



Illustration 1g00850889
(1) Flow compensator spool
(2) Orifice

The flow spool (1) or the bore for the flow spool may be worn excessively. Excessive wear of the flow spool or of the bore of the flow spool can cause leaks. Check the flow spool for wear. Inspect the bore of the flow spool for wear as well.

Repair the compensator valve, if necessary.

Hydraulic Cylinders Seals Are Leaking

Check for leakage in the seals or around the piston seals in the cylinders that are affected. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.

Repair the piston seals, if necessary.

Hydraulic Lines May Have A Leak

There is a leak in the lines between the control valve and the cylinders. Kinks or restrictions in hydraulic lines or hoses may act like an orifice that creates excessive noise and heat as the high pressure oil is forced through a passage that is smaller than the original opening.

Be sure to check for these conditions on all hydraulic oil hoses, lines, and tubes in the system or the circuit that are in question. Correct any problems that are found. Then retest the hydraulic system for any symptoms.

The Solenoid For The Control Valve Has Current Or The Solenoid Has Contamination

Inspect the solenoid for contamination. Check the solenoid for current. Refer to Testing and Adjusting, "Calibration" for your machine.

If necessary, replace the solenoid.

The Makeup Valves Are Open

Check the makeup valves that are affected for leaks. Refer to Testing and Adjusting, "Relief Valve - Test and Adjust" for your machine. If necessary, replace the relief valve.

The Dead Electric Lower Valves Are Open

Check the dead electric lower valves that are affected for leaks. Refer to Systems Operation, "Lift Circuit" for your machine. If necessary, replace the dead electric lower valve.

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