308C CR Excavator Hydraulic System – Relief Valve (Swing) – Test and Adjust

Note: Refer to Testing and Adjusting, “Specifications” for the pressure setting of the swing relief valves.

  1. Position the machine on level ground.
  1. Stop the engine.
  1. Release the pressure in the hydraulic system. Refer to Testing And Adjusting, “Hydraulic System Pressure – Release”.



    Illustration 1 g00858167

    Pump compartment

    (1) Pressure tap (right pump delivery pressure)

    (2) Pressure tap (left pump delivery pressure)

  1. Connect a 60000 kPa (8700 psi) pressure gauge to pressure tap (1) .
  1. Perform the following steps in order to engage the swing parking brake.



      Illustration 2 g00858398

      (3) Connector

      (4) Pilot line

    1. Disconnect pilot line (4) from connector (3) at the main control valve.
    1. Install 4J-5477 O-Ring Seal and 6V-9828 Cap on connector (3) .
    1. Leave the end of pilot line (4) open to the atmosphere.
  1. Start the engine.
  1. Place the machine controls at the following settings: engine speed dial “10” and Low idle switch OFF. Refer to Testing and Adjusting, “Engine Performance – Test” for engine rpm settings.
  1. Place the hydraulic activation control lever in the UNLOCKED position.
  1. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).
  1. Slowly move the swing joystick and make sure that the swing parking brake is activated.



    Illustration 3 g00858403

    Swing motor

    (5) Relief valve (right swing)

    (6) Locknut

    (7) Setscrew

    (8) Relief valve (left swing)

    (9) Locknut

    (10) Setscrew

  1. Slowly move the swing joystick for a full SWING RIGHT operation and check the pressure setting for relief valve (5) at pressure tap (1) .
  1. Return the swing joystick to the NEUTRAL position.
  1. If the pressure reading at pressure tap (1) is not within the specification, adjust the pressure setting of swing relief valve (5) .
  1. In order to adjust the pressure setting of the swing relief valve, loosen locknut (6). Turn setscrew (7) until the pressure gauge reading at pressure tap (1) is the correct pressure for the relief valve.

    Note: Turn setscrew (7) clockwise in order to increase the pressure. Turn setscrew (7) counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustments on pressure rise.

  1. Tighten locknut (6) .
  1. Slowly move the swing joystick for a full SWING LEFT operation and check the pressure setting for relief valve (8) at pressure tap (1) .
  1. Return the swing joystick to the NEUTRAL position.
  1. If the pressure reading at pressure tap (1) is not within the specification, adjust the pressure setting of swing relief valve (8) .
  1. In order to adjust the pressure setting of the swing relief valve, loosen locknut (9). Turn setscrew (10) until the pressure gauge reading at pressure tap (2) is the correct pressure for the relief valve.

    Note: Turn setscrew (10) clockwise in order to increase the pressure. Turn setscrew (10) counterclockwise in order to decrease the pressure.

    Note: Always make final pressure adjustments on pressure rise.

  1. Tighten locknut (9) .
  1. After completing the test and/or the adjustment procedures for the swing relief valves, stop the engine.
  1. Release the pressure in the hydraulic system. Refer to Testing And Adjusting, “Hydraulic System Pressure – Release”.
  1. Remove the cap from connector (3) at the main control valve. Connect pilot line (4) to connector (3) .