315C Excavator Hydraulic System Relief Valve (Main) - Test and Adjust Caterpillar


Relief Valve (Main) - Test and Adjust
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1.1. Test
2.1. Adjust
3.1. Temporary Setting of the Main Relief Valve



Illustration 1g00825521

Note: Adjustment screw (4) of main relief valve (8) must always be set to the maximum clockwise position. All pressure adjustments of the main relief valve must be made with adjustment plug (6). Do not loosen locknut (5) or turn adjustment screw (4) of the main relief valve in order to adjust the main relief valve pressure setting.

Test

Note: Refer to Testing and Adjusting, "Specifications" for the pressure setting of the main relief valve.

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

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



    Illustration 2g00764110

    Pump compartment

    (1) Pressure tap (right pump delivery pressure)

    (2) Pressure tap (left pump delivery pressure)

    (3) Pressure tap (power shift pressure)

  1. Attach a 60000 kPa (8700 psi) pressure gauge to pressure tap (1) .

  1. Start the engine.

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

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

  1. Slowly move the joystick for the bucket to the BUCKET CLOSE position (full extension of the bucket cylinder rod). Check the pressure gauge reading at pressure tap (1) .

  1. Return the joystick for the bucket to the NEUTRAL position.

  1. If the main relief valve pressure setting is not within the specification, adjust the main relief valve pressure setting.

Adjust




    Illustration 3g00825567

    (6) Adjustment plug

    (7) Locknut

    (8) Main relief valve

  1. In order to adjust the pressure setting of the main relief valve, loosen locknut (7) and turn adjustment plug (6) until the pressure gauge reading at pressure tap (1) is the correct relief pressure.

    Note: Turning adjustment plug (6) clockwise increases the pressure. Turning adjustment plug (6) counterclockwise decreases the pressure.

    Note: Always make final pressure adjustments on pressure rise.

  1. Tighten locknut (7) .

Temporary Setting of the Main Relief Valve

Note: A temporary setting of the main relief valve is required before any line relief valve can be adjusted.

  1. The main relief valve pressure setting should be set to the correct specification. Refer to Testing and Adjusting, "Specifications" for the pressure setting of the main relief valve. If the main relief valve is not within the specification, adjust the main relief valve pressure setting to the correct pressure specification before performing Step 2. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".



    Illustration 4g00825567

  1. Loosen locknut (6) and turn adjustment screw (7) clockwise for one half turn. Tighten locknut (6) to the specified torque.

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