M318 Excavator Hydraulic System Caterpillar

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Illustration 1	g00294248
The pressure tap is located in the battery compartment. (1) Main pump pressure

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Illustration 2	g00294250
Main control valve (2) Main relief valve (3) Load sensing signal limiter valve

1. Connect a 60000 kPa (8600 psi) pressure gauge to pressure tap (1) .

2. Start the engine. Place the engine speed at the HIGH IDLE position.

3. Lower the left console.

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

5. Loosen the locknut on load sensing signal limiter valve (3) .

6. Turn the adjustment screw of the load sensing signal limiter valve (3) inward until the screw contacts the stop.

   Note: Make sure that the "Heavy Lift" option is not selected.

   Note: For machines that are equipped with the "Heavy Lift" option, turn the nut and the spindle inward until the nut and the spindle contact the stop. Refer to Testing and Adjusting, "Relief Valve (Signal Limiter Heavy Lift)".

7. Loosen the locknut on main relief valve (2) .

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NOTICE
To avoid damage to the hydraulic components, do not turn the main relief valve adjustment screw into the stop.

8. Turn the adjustment screw inward by one half turn.

   Note: Do not overtighten the adjustment screw.

Test and Adjust

1. Ensure that no brakes are applied. Lower the armrest and place the parking brake switch in the OFF position.

2. Chock the wheels.

3. Move the gear switch to the SECOND GEAR position.

4. Completely depress the wheel brake pedal.

   Note: Do not lock the pedal.

5. Slowly depress the travel pedal in the forward direction.

6. Check the pressure at pressure tap (1). Refer to Testing and Adjusting, "Specifications" for the correct travel system pressure.

7. Slowly depress the travel pedal in the reverse direction.

8. Check the pressure at pressure tap (1). Refer to Testing and Adjusting, "Specifications" for the correct travel system pressure.

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Illustration 3	g00729012
Travel motor (4) Line relief valve (travel)

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To prevent injury or death, never work under a machine while a test is being performed.

9. If the line relief valves of the travel motor are not set to the proper specification, adjust the appropriate relief valve at the travel motor.

10. Loosen the locknut of line relief valve (4) .

11. Turn the adjustment screw until the pressure at pressure tap (1) is set to the proper specification.

12. Tighten the locknut for line relief valve (4) to the specified torque.

    Note: After checking the line relief valve pressure settings, return the main relief valve and the load sensing signal limiter valve to the original settings. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust", Testing and Adjusting, "Relief Valve (Signal Limiter) - Test and Adjust" and/or Testing and Adjusting, "Relief Valve (Signal Limiter Heavy Lift) - Test and Adjust".