D7E Track-Type Tractor Hydraulic, HVAC, and Electrical Systems Hydraulic Cylinder Collapse - The Lift Cylinder Will Collapse When The Control Is In The Raised Position Caterpillar

Probable Causes

• The lift control lever and/or the position sensor may be worn or damaged.

• The control current to the solenoid is incorrect.

• The piston seals and/or the lift cylinders are worn.

• The main control valve is contaminated or damaged.

• The makeup valve is sticking.

• The load check valve is not closing because the spring is weak or broken,or because there is dirt or debris in the check valve.

Note: Ensure that there are no active diagnostic codes for the hydraulic system.

Recommended Actions

The Lift Control Lever And/Or The Position Sensor May Be Worn Or Damaged

Refer to Testing and Adjusting, "Operational Checks (Hydraulic System)" in this manual.

The Control Current To The Solenoid Is Incorrect

Refer to Testing and Adjusting, "Calibration" in this manual.

Note: Ensure that the strainer is present in the filler tube before adding the recommended hydraulic oil.

The Piston Seals And/Or The Lift Cylinders Are Worn

Inspect the main suction tube for blockages or damage that could restrict the volume of oil drawn from the tank. (The suction tube draws oil from the bottom of the tank.) Removing the filler cap and the strainer will allow you to view the inside of the tank. It may be necessary to remove the tank in order to inspect the tank for any damage. Refer to Disassembly and Assembly, KENR5166, "Hydraulic Tank - Remove and Install".

The Main Control Valve Is Contaminated Or Damaged

Refer to Testing and Adjusting, "Calibration" in this manual.

The Makeup Valve Is Sticking

Need Info

The Load Check Valve Is Not Closing Because The Spring Is Weak Or Broken,Or Because There Is Dirt Or Debris In The Check Valve

Refer to Testing and Adjusting, "Operational Checks (Hydraulic System)" in this manual.

1. Ensure the machine is on a level surface.

2. LOWER the blade all the way in order to raise the machine off of the ground.

3. Move the implement control handle to the HOLD position.

4. Shut off the engine.

   Watch the lift cylinder rods for movement (cylinder rods retracting).