CLUTCH 7D2649 - Caterpillar

Personal injury or death can result from sudden machine movement.Sudden movement of the machine or release of air pressure or oil pressure can cause injury to persons on or near the machine.To help prevent possible injury before testing and adjusting any air system or hydraulic system, perform the procedure in the Testing and Adjusting, "General Information" section.
Start the engine. Operate the engine at high idle.
Move the modular handle (hoist) to the RAISE position. Hold the modular handle (hoist) in the RAISE position for five seconds after the dump body is fully raised. Then, lower the dump body all the way to the truck frame.
Repeat Step 2 until the hydraulic oil is at operating temperature. Lift Time for Hoist Cylinders
Lower the dump body to the truck frame.
Operate the engine at 1800 RPM.
Raise the dump body to the fully raised position. Use a stopwatch to measure the required time. The required time for full extension of the hoist cylinders is approximately 23.5 seconds. The required time may be up to 29 seconds at high altitude (ambient air pressure down -42 kPa (-6.1 psi).Lower Time for Hoist Cylinders
Raise the dump body fully.
Operate the engine at 1800 RPM.
Lower the dump body to the frame. Use a stopwatch to measure the required time. The required time for full retraction of the hoist cylinders is approximately 17.5 seconds. Float Time for Hoist Cylinders
Raise the dump body fully.
Operate the engine at 1800 RPM.
Lower the dump body to the frame in the float position. Use a stopwatch to measure the required time. The required time for full retraction of the hoist cylinders is approximately 21.4 seconds. Cylinder Drift
Note: Perform this test with an empty dump body and hydraulic oil above 38°C (100°F).
Move the modular handle (hoist) to the RAISE position.
When the first stage of the hoist cylinders is extended by 305 mm (12 inch), move the modular handle (hoist) to the HOLD position.
The dump body will push the cylinder head of the first stage by 6.40 mm (0.25 inch) onto the second stage of the hoist cylinders. Use a stopwatch and record the required time. The acceptable time for cylinder drift is relative to the temperature of the hydraulic oil in the hoist cylinders. At normal operating temperature the cylinder drift is 6.40 mm (0.25 inch) in 5.3 minutes.Excessive cylinder drift can be caused by the following conditions:
Leaks in the lines between the hydraulic oil tank and the hoist cylinders
Worn control valve spool
Worn seals in the hoist cylinders