M313C, M315C, M316C, M318C and M322C Excavators and M318C and M322C Material Handlers Hydraulic System Caterpillar

• Stick

• Boom

• VA boom

• Bucket

The line relief valves limit the maximum line pressure in each circuit.

Note: If the machine is equipped with drift reduction valves in the implement circuits, refer to Testing and Adjusting, "Check Valve (Stick Drift Reduction) - Test and Adjust".

Note: Prior to performing this test, the Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust" must be performed.

Preparation

Show/hide table



Illustration 1	g01205986
The remote pressure taps are located behind the left rear access door. (1) Pressure tap (Load sensing signal pressure)

Show/hide table



Illustration 2	g01253813
Main Control Valve ( M313C, M315C, and M316C) (2) Main relief valve (3) Load sensing signal limiter valve (4) Line relief valve

Show/hide table



Illustration 3	g01206012
Main Control Valve ( M318C, M318C MH, M322C, and M322C MH) (2) Main relief valve (3) Load sensing signal limiter valve (4) Line relief valve

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

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

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

4. Start the engine.

5. Adjust the engine speed to LOW IDLE by turning the engine speed dial to position 1.

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

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

Test and Adjust

1. Adjust the engine speed to position 5 by turning the engine speed dial.

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

Show/hide table

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

3. Operate the implement that will be tested. Refer to Testing and Adjusting, "Specifications" in this manual for the correct pressures of the following cylinders: boom cylinder, stick cylinder, bucket cylinder and VA boom cylinder.

4. If the line relief valve pressure is not set to the correct specification, adjust the pressure at the appropriate relief valve.

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

6. Turn the adjustment screw of line relief valve (4) until the pressure at pressure tap (1) is set to the correct specification. Refer to Testing and Adjusting, "Specifications" in this manual for the correct main relief valve pressure specification.

   Note: Turn the adjustment screw clockwise by a quarter turn in order to increase the pressure by approximately 4500 kPa (650 psi).

   Note: Always make the final pressure adjustments on the pressure rise.

7. Tighten locknut (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" and Testing and Adjusting, "Relief Valve (Signal Limiter) - Test and Adjust".

   Note: Head end line relief valves of boom, stick, bucket, and VA boom are located under the main control valve.