953D, 963D and 973D Track-Type Loaders Implement Droops Before Raising Caterpillar

The implement droops when the implement is moved from a partially RAISED position to a fully RAISED position.

Probable Causes

• There may be a internal leak or internal blockage in the load sensing signal circuit.

• The flow compensator spool may not be adjusted properly.

• The flow compensator spool may not move.

• The margin pressure is set too low.

• There may be air in the load sensing signal circuit.

• System pressure is low

• The implement valve has a problem.

Recommended Actions

There May Be A Internal Leak Or Internal Blockage In The Load Sensing Signal Circuit

Make sure that the signal passages in the main spool of the control valve 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.

The Flow Compensator Spool May Not Be Adjusted Properly

Make sure that the flow compensator spool in the compensator valve is adjusted correctly. Perform the margin pressure test. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.

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.

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.

There May Be Air In The Load Sensing Signal Circuit

There may be air in the load sensing signal circuit. Purge the air from the hydraulic system by cycling the system several times.

System Pressure Is Low

Check the system pressure. Refer to Testing and Adjusting, "Hydraulic Pump - Test and Adjust" for your machine.

The Implement Valve Has A Problem

Inspect the implement valve for damage, cracks, leaks, or loose connections.