ROD AS 3744595 - Caterpillar

The following tests are performed in order to determine if a line relief valve is damaged or if a line relief valve is incorrectly set.Before any tests are performed, prepare the machine for troubleshooting. Refer to Testing and Adjusting, "Machine Preparation". Before any tests are performed, visually inspect the complete hydraulic system. Refer to the Testing and Adjusting, "Visual Inspection".
Engage the parking brake. Stop the engine.
Raise the cab of the machine. Refer to the Operation and Maintenance Manual, "Cab Support Operation" for the correct procedure.
Illustration 1 g00788648
Install one 8T-0860 Gauge to test port (1) with a 1U-5755 Hose .
Illustration 2 g00788659
Illustration 3 g00563593
(2) Main relief valve for the work tool (3) Cap (4) Locknut
Remove the end cap (3) from the main relief valve (2) .
Loosen the locknut (4). Turn the adjustment screw on the main relief valve clockwise for one and one-half turns. This will increase the main relief valve setting by 13500 kPa (1960 psi).
Tighten the locknut (4) and install the cap (3) .
Lower the cab. Secure the hydraulic line so that the pressure gauge can be viewed by the operator during the test. Make sure that the hoses are not pinched when the cab is lowered.
Sit in the operator's seat. Fasten the seat belt and lower the armrest. Start the engine. Disengage the parking brake.
Tilt back the work tool.
Run the engine at high idle.
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Do not stall the hydraulic system for more than 10 seconds. If necessary, release the work tool from the stall condition and wait 30 seconds before you repeat the following step.
Press and hold the left side of the control switch for the auxiliary circuit on the pilot operated hydraulic control ( work tool). Record the pressure at the stall condition. Press and hold the right side of the control switch for the auxiliary circuit. Record the pressure at the stall condition.
Move the hydraulic control and hold the hydraulic control until a stall condition exists in the following positions: RAISE, TILT FORWARD and TILT BACK. Record the pressures that exist at each of the positions.
The pressures that are recorded should be equal to the pressures that are listed in the following table:
Table 2
LINE RELIEF VALVE PRESSURES    
Position     236/ 246    
Lift Cylinder Head
RAISE position    
27600 700 kPa (4000 100 psi)    
Tilt Cylinder Head
TILT FORWARD position    
24500 700 kPa (3555 100 psi)    
Tilt Cylinder Rod
TILT BACK position    
27600 700 kPa (4000 100 psi)    
Auxiliary Circuit    
25000 700 kPa (3625 100 psi)    
Tilt the work tool until the work tool is parallel with the ground. Stop the engine. If the pressure readings are within specifications, proceed to step 21. If the pressure readings are not within specifications, proceed to step 15.
Release the hydraulic system pressure. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the correct procedure.
Raise the cab of the machine.
Illustration 5 g00788701
(5) Auxiliary line relief valve (6)