330D Material Handler Hydraulic System Caterpillar

Main Relief Valve Adjustment

1. Position the machine on level ground and stop the engine.

2. Release the pressure in the hydraulic system. Refer to Testing And Adjusting, "Hydraulic System Pressure - Release".

3. Disconnect the hoses from the rotator. Plug the ends of the hoses and the tubes.
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   Illustration 1	g01437453
   Top view (1) Valve bank (2) Pressure tap (3) Main relief valve adjustment screw

4. Attach a 40000 kPa (5800 psi) pressure gauge to pressure tap (2).

5. Start the engine.

6. Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for engine rpm settings.

7. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

8. Set the pilot pressure to the specifications in Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust".

9. Calibrate the solenoid valves for medium pressure. Refer to Testing and Adjusting, "Solenoid Valve (Proportional Reducing) - Calibrate".

10. Depress the device for activation for clockwise rotation or counterclockwise rotation.

11. Check the relief valve pressure setting on the pressure gauge.

12. Release the device for activation.

13. The main relief valve pressure should be 14000 kPa (2030 psi). The line relief valve pressure is not adjustable.

    1. Turn adjustment screw (3) clockwise in order to increase the pressure. Turn adjustment screw (3) counterclockwise in order to decrease the pressure.

14. After the adjustment is completed, repeat Step 10 through 13 until the pressure is within the specification.