953D, 963D and 973D Track-Type Loaders Hydraulic Cylinder Drift Caterpillar


Hydraulic Cylinder Drift
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1.1. Probable Causes
2.1. Recommended Actions
3.2. Hydraulic Cylinders Seals Are Leaking
4.2. The Line Relief Valves Are Set Too Low.
5.2. The Line Relief Valve Or The Makeup Valve Is Leaking
6.2. The Dead Electric Lower Valves Are Open
7.2. The Main Control Valve May Have A Leak
8.2. The Flow Spool Or The Bore Is Worn

Probable Causes

  • Hydraulic cylinders seals are leaking

  • The line relief valves are set too low.

  • The line relief valve or the makeup valve is leaking.

  • The dead electric lower valves are open.

  • The main control valve may have a leak.

  • The flow spool or the bore is worn.

Recommended Actions

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.

The Line Relief Valves Are Set Too Low.

Check the line relief valves that are affected. Make sure that the pressure setting is correct and not too low. Refer to Testing and Adjusting, "Relief Valve - Test and Adjust" for your machine.

The Line Relief Valve Or The Makeup Valve Is Leaking

Check the line relief valves or 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.

The Main Control Valve May Have A Leak

Inspect the main control valve for any signs of leaks. Repair the control valve if a leak is found.

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.

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