SCREW-HEX HEAD 5553392 - Caterpillar

Introduction
Drift of the stick OUT can be caused by leakage past the main control valve spool or the stick cylinder head end line relief valve. This test determines the cause for stick drift OUT exceeding service limits. 1. Check stick for drifting OUT.a. Place the machine on level ground.b. Increase the hydraulic oil temperature to the normal operating temperature.c. Fill the bucket.d. RAISE the boom, CLOSE the bucket, and bring the stick IN. Position the boom high enough to allow the bucket to clear the ground when the stick is brought IN.e. Return the stick pilot control lever to NEUTRAL and stop the engine.f. After 3 minutes have elapse, measure cylinder drift at the stick cylinder rod. Expected Result:Stick cylinder drift should be within 12.0 mm (.47 in) for a new cylinder and 18.0 mm (.71 in) for a rebuilt cylinder in 3 minutes. Drift should not exceed the service limit of 30.0 mm (1.18 in). Results:* OK - STOP.* NOT OK - Proceed to Step 2.2. Perform Line Relief Valve Test And Adjustment. For further information refer to the section, "Line Relief Valve Test And Adjustment". Results:* REPAIRE, OK - STOP.* OK - Proceed to Step 3.3. Perform Residual Pilot Supply Pressure Test. For further information refer to the section, "Residual Pilot Supply Pressure Test". Results:* REPAIRED, OK - STOP.* OK - Proceed to Step 4.4. Check shock reducing valve for restriction.Check return orifice in the shock reducing valve in stick OUT pilot supply for being restricted. Results:* OK - Proceed to Step 5.* NOT OK - Repair or replace the stick OUT shock reducing valve. STOP.5. Perform Control Valve Leakage Test. For further information refer to the section, "Control Valve Leakage Test". Results:* OK - Determine whether or not the problem is still present. If stick drift OUT still exceeds limit, the excessive drift may be caused by a combination of leaks. From the tests just run, determine which component(s) contribute the most to stick drift OUT. Make repairs to bring drift within acceptable limits. STOP.* REPAIRED, OK - STOP.