DISC-FRICTION-YM 4179495 - Caterpillar

Drift Tests for the Ripper Cylinder
Table 12
Lift Cylinder Drift of the Ripper    
Oil Temperature    
38° to 49°C (100° to 120°F)    
49° to 66°C (120° to 150°F)     Above
66°C (150°F)    
Maximum Permissible Drift    
9.6 mm (0.38 inch)    
9.6 mm (0.38 inch)    
9.6 mm (0.38 inch)    
Minutes     5     2.7     1.7    Tests
Raise the rear of the machine off the ground by lowering the ripper. Put the ripper control lever in the HOLD position. Shut off the engine. Watch the ripper lift cylinder rod for movement.
Raise the rear of the machine off the ground by lowering the ripper. Position the control lever in the HOLD position. Shut off the engine. Position the control lever in the LOWER position. Watch the ripper lift cylinder rod for movement.
Raise the ripper off the ground. Put the control lever in the HOLD position. Shut off the engine and watch the ripper lift cylinder rod for movement.
Raise the ripper off the ground. Shut off the engine. Keep the ripper lift control lever in the RAISE position. Watch the ripper lift cylinder rod for movement.
Table 13
Ripper Cylinder    
Test Results     Most Probable Causes (1)    
Drifting occurs in Tests 1 and 3.     Leakage between the spool and the body of the lift valve    
Drifting occurs in Tests 1 and 2.     Leakage in the rod end of the valve in the ripper circuit    
Drifting occurs in Tests 2 and 4.    
Leakage between the piston and the cylinder    
( 1 ) Note that an O-ring seal failure in the circuit will have the same effect as a major component failure.Main Relief Valve
The main relief valve is a component of the implement control valves. The main relief valve is in all the implement hydraulic circuits.Move the machine to a level location before the pressure test.Raise the hydraulic oil to operating temperature. Stop the engine. Move the control levers for the bulldozer and for the ripper to each position several times. This operation releases the pressure in the lines.
Hydraulic oil pressure can remain in the hydraulic systems after the engine and pump have been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent possible injury, refer to the section, Testing and Adjusting, "Hydraulic System Pressure - Release" before any fitting, hose or component is loosened, tightened, removed or adjusted.When possible, the bucket must always be lowered to the ground before service is started. When it is necessary for the boom to be in the raised position while tests or adjustments are done, be sure that the boom, stick and bucket have correct support.The swing lock (if equipped) must be engaged before service is started.Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are