HEAD-CASTING 2404827 - Caterpillar

Personal injury or death can result from sudden machine movement.Sudden movement of the machine or the release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury before testing and adjusting the hydraulic system, perform the procedure in the Testing and Adjusting, "General Information" section.
Start the engine. Operate the engine at high idle.
Move the hoist control to the RAISE position. Hold the hoist control 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 temperature of the hydraulic oil is above 38°C (100°F). Lift Time for Hoist Cylinders
Lower the dump body to the truck frame.
Operate the engine at high idle.
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 18 seconds.Cylinder Drift
Note: Perform this test with an empty dump body and hydraulic oil above 38°C (100°F).
Move the hoist control to the RAISE position.
When the first stage of the hoist cylinders is extended by 305 mm (12 inch), move the hoist control 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. See the following table.
Table 1
Acceptable Cylinder Drift
Minutes Oil Temperature Cylinder Drift
12.4 38°C (100°F) 6.40 mm (0.25 inch)
9.6 43°C (110°F) 6.40 mm (0.25 inch)
7.8 49°C (120°F) 6.40 mm (0.25 inch)
6.4 54°C (130°F) 6.40 mm (0.25 inch)
5.3 60°C (140°F) 6.40 mm (0.25 inch)
4.4 66°C (150°F) 6.40 mm (0.25 inch)
3.8 71°C (160°F) 6.40 mm (0.25 inch)
3.2 77°C (170°F) 6.40 mm (0.25 inch)
2.8 82°C (180°F) 6.40 mm (0.25 inch) Excessive cylinder drift can be caused by the following conditions:
Leaks in the lines between the hydraulic tank and the hoist cylinders
Worn control valve spool
Worn seals in the hoist cylinders