574B Forwarder Hydraulic System Boom Tilt Cylinder and Gate Cylinder (Horizontal) Pressure - Test and Adjust Caterpillar

The maximum pressure to the boom tilt cylinder and the gate horizontal cylinder is controlled by the same valve section in the implement control valve. The procedure can be performed with either cylinder. This procedure will use the gate horizontal cylinder.

The maximum pressure to the cylinders is controlled by two signal limiter valves in the implement control valve. The signal limiter valves will be adjusted in this procedure.

Before testing or adjusting the signal limiter valves, ensure that the standby pressure and high pressure cutoff are adjusted correctly.

Reference: For more information on the standby pressure, refer to Testing and Adjusting, "Piston Pump (Implement) Standby Pressure - Test and Adjust" for the machine that is being serviced.

Reference: For more information on the high pressure cutoff, refer to Testing and Adjusting, "Piston Pump (Implement) High Pressure Cutoff - Test and Adjust" for the machine that is being serviced.

In order to accurately adjust the cylinder pressure, the valve spool must be moved fully from the HOLD position. The proportional solenoid for the valve spool must be fully activated. Ensure that the solenoid is fully activated by adjusting the maximum current from the proportional steering switch above 680 mA.

Reference: For more information on adjusting the maximum current of the proportional steering switch, refer to Testing and Adjusting, "Joystick Control Preferences - Adjust" for the machine that is being serviced.

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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

1. Park the machine on a level surface.

2. Ensure that the hydraulic oil in the system is at normal operating temperature.

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Illustration 1	g00800981
Operating Mode Switch on the Right Hand Control Unit

3. Place the operating mode switch in the ROADING MODE position.

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Illustration 2	g00919915
Parking Brake Switch

4. Place the parking brake switch in the ON position. The ladder will lower. Ensure that all personnel are clear of the ladder before you lower the ladder.

5. Stop the engine.

6. Block the wheels.

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Illustration 3	g00913309

7. Install the steering frame lock.

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Illustration 4	g00914499
Location of the Implement Control Valve

8. Move the cover off the implement control valve.

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Illustration 5	g00947790
End View of the Implement Control Valve (1) Pressure tap for piston pump (implement) signal pressure. (2) Pressure tap for piston pump (implement) supply pressure.

9. Install the 198-4240 Digital Pressure Indicator Group on pressure tap (1).

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Illustration 6	g00800981
Operating Mode Switch on the Right Hand Control Unit

10. Start the engine. Place the operating mode switch in the WORKING MODE position. Increase the engine speed to 1500 rpm.

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Illustration 7	g00659857
Implement Control Valve (3) Section (gate and boom tilt). (4) Signal limiter valve (GATE BACKWARD). (5) Signal limiter valve (GATE FORWARD).

11. Perform step 12 in order to adjust the pressure for moving the gate backward. Perform Step 13 in order to adjust the pressure for moving the gate forward.

12. Gate Backward:
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    Illustration 8	g00920213
    Switch (Gate Control)

    1. Place the switch for the gate in the GATE BACKWARD position. Allow the gate to move fully backward. Hold the switch in the GATE BACKWARD position. The pressure that is indicated on the pressure gauge should be 21000 kPa (3050 psi).

    2. If the pressure setting is not correct, release the switch. Remove the acorn nut from signal limiter valve (4) with a 13 mm wrench. Remove the grommet. Loosen the locknut for the adjustment screw with the 161-8958 Wrench .

    3. Turn the adjustment screw with an allen wrench. Tighten the locknut. Perform Step 12.a again in order to check the new pressure setting.

    4. Install the grommet and the acorn nut after the correct pressure setting is achieved. Tighten the nut.

13. Gate Forward:
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    Illustration 9	g00920213
    Switch (Gate Control)

    1. Place the switch for the gate in the GATE FORWARD position. Allow the gate to move fully forward. Hold the switch in the GATE FORWARD position. The pressure that is indicated on the pressure gauge should be 21000 kPa (3050 psi).

    2. If the pressure setting is not correct, release the switch. Remove the acorn nut from signal limiter valve (5) with a 13 mm wrench. Remove the grommet. Loosen the locknut for the adjustment screw with the 161-8958 Wrench .

    3. Turn the adjustment screw with an allen wrench. Tighten the locknut. Perform Step 13.a again in order to check the new pressure setting.

    4. Install the grommet and the acorn nut after the correct pressure setting is achieved.

14. Remove the pressure gauge.

15. Install the cover on the implement control valve.