345C MHPU Mobile Hydraulic Power Unit Hydraulic System Relief Valve (Auxiliary) - Test and Adjust - Main (Medium Pressure), System 17 Caterpillar

Complete the following steps in order:

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

2. Release the pressure on the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the machine.

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Illustration 1	g01207646
(1) Auxiliary Pump (2) 6V-9007 Elbow (3) 6V-8397 O-Ring Seal (4) 7X-0873 Tee (5) Coupling (6) Hose (7) 3J-1907 O-Ring Seal (8) 6V-3965 Nipple Assembly (9) 6V-4143 Coupler Assembly (10) 6V-3989 Unvalved Nipple (11) 8T-0861 Pressure Gauge

3. Remove hose (6) from elbow (2) and auxiliary pump (1) .

4. Assemble and install tee (4) to elbow (2) .

5. Install hose (6) to elbow (2) .

6. Assemble and install seal (7) and nipple assembly (8) to tee (4) .

7. Connect hose (9) to nipple assembly (8) .

8. Assemble and install a 60000 kPa (8700 psi) pressure gauge (11) to hose (9) .

9. Start the engine.

10. 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 the machine for engine rpm settings.

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

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

13. Move the left joystick thumbwheel to the FORWARD position, or move the joystick thumbwheel to the BACKWARD position.

14. Check the pressure setting of the main relief valve for the auxiliary control valve (medium pressure) on pressure gauge (11) .

15. The pressure setting of the main relief valve for the auxiliary control valve (medium pressure) should be within the specifications. If the pressure setting of the main relief valve is not within the specifications, adjust the main relief valve for the medium pressure circuit to a pressure setting of 20600 ± 500 kPa (2990 ± 72 psi).

Note: Turn adjustment screw clockwise in order to increase the pressure. Turn the adjustment screw counterclockwise in order to decrease the pressure.

Note: Always make final pressure adjustments on pressure rise.

16. Return the left joystick thumbwheel control to the NEUTRAL position.