TRANSMISSION AR 3844037 - Caterpillar

Hydraulic oil pressure can remain in the hydraulic oil system on this machine 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 procedure in Testing and Adjusting Manual, "Release of Pressure in the Hydraulic System".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.Be sure the swing parking brakes and the travel parking brakes are on and the brake release lines are disconnected and plugged.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 being made.
Table 1
Tools Needed     Qty    
4C-4892 ORFS Fittings Group     1    
8T-0857 Pressure Gauge     1    
8T-0856 Pressure Gauge     1    Note: Always warm the hydraulic oil to a minimum temperature of 50°C (122°F) before starting the testing and adjusting procedure.Note: Always set the high pilot system pressure before setting the lowpilot system pressure.Note: After an adjustment to the pilot relief valve, recalibrate the Caterpillar underspeed system.Relief Valve for the High Pressure Circuit
Preparation
Illustration 1 g00847193
Pilot manifold (1) Pilot relief valve for the high pressure circuit
Illustration 2 g00847214
Pilot hydraulic oil filter (2) High pilot pressure tapConnect a 10000 kPa (1450 psi) pressure gauge to the high pilot pressure tap (2) on the pilot hydraulic oil filter.
Start the engine.
Warm the oil to a minimum temperature of 50 °C (122 °F). Refer to the Testing and Adjusting, "General Information" for the proper procedure for warming the hydraulic oil.
Set the throttle switch to position 10. Monitor the engine speed and verify that the high idle setting is at 1850 20 rpm. The pilot pressure at the high pilot pressure tap should be 6750 100 kPa (980 15 psi).
Illustration 3 g00434667
Pilot relief valve (3) Locknut (4) Adjustment screw
To adjust the pilot pressure for the high pressure pilot circuit, loosen the locknut (3) on the relief valve (1). Turn the adjustment screw (4) until the pressure gauge indicates 6750 100 kPa (980 15 psi). Tighten locknut (3) .Note: Always make pressure adjustments on the pressure rise.Pressure Reducing Valve for the Low Pressure Circuit
Preparation
Illustration 4 g00847195
Pilot manifold (5) Pressure reducing valve for the low pressure circuit (6) Low pilot pressure tapConnect a 5515 kPa (800 psi) pressure gauge to low pilot pressure tap (2) on the pilot manifold.
Start the engine.
Warm the oil to a minimum temperature of 50 °C (122 °F). Refer to the Testing and Adjusting, "General Information" for the proper procedure for warming the hydraulic oil.
Set the throttle switch to position 10. The pilot pressure at the low pilot pressure tap (2) should be 4500 100