SENDER GP- 1472298 - 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
Required Tools    
Part Number    Part Description    Qty    
4C-4892     ORFS Fittings Group     1    
1U-5796     Pressure Differential Gauge Group     1    Note: Always warm the hydraulic oil to a minimum temperature of 50°C (122°F) before starting the testing and adjusting procedure.Preparation
Illustration 1 g00443445
Front Control Valve (1) Pressure tap for load sensing signal circuit (2) Pressure tap for pump discharge pressure (3) Margin relief valve (L) Low pressure gauge (H) High pressure gauge
Illustration 2 g00907347
Implement High Pressure Screens (2) Pressure tap for pump discharge pressure
Install 1U-5796 Pressure Differential Gauge Group between pressure tap (1) and pressure tap (2). Pressure tap (2) may be located on either the margin relief valve (3) or the implement high pressure screens. Either of the pressure taps (2) may be used.
Isolate one implement piston pump. Disconnect the power shift signal from the three implement piston pumps which will not be used. Leave the power shift signal connected to the remaining implement piston pump. Refer to Testing and Adjusting, "Piston Pump (Implement)".Relief Valve Test
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 4.Note: Do not operate any machine controls.
Illustration 3 g00445191
Regulator Control Valve for the Implement Piston Pump (4) Margin pressure adjuster
Loosen the locknut on the margin pressure adjuster (4) on the pump which is being used. Slowly turn the adjusting screw in a clockwise direction. Watch the pressure on the 1U-5796 Pressure Differential Gauge Group as the adjusting screw is turned. As the margin pressure increases, the gauge will show a pressure increase until a margin relief valve opens. When a margin relief valve opens, the pressure increase will hesitate and the margin relief valve will begin to squeal.