554 Forwarder and 574 Forwarder Hydraulic System Caterpillar

The following procedure is used to adjust the maximum pressure to the steering cylinders when the proportional steering switch is used. The maximum pressure is controlled by two signal limiter valves in the implement control valve. One signal limiter valve controls the maximum pressure for a left turn. The other signal limiter valve controls the maximum pressure for a right turn.

Before testing or adjusting the signal limiter valves, ensure that the standby pressure and the high pressure cutoff are adjusted correctly. In order to accurately adjust the steering cylinder pressure, the valve spool for the steering system must be moved fully from the HOLD position. The proportional solenoid for the valve spool must be fully activated. To ensure that the solenoid is fully activated, adjust the maximum current from the proportional steering switch above 680 mA.

ReferenceFor more information on the maximum current setting, refer to Testing and Adjusting, "Implement Control - Test and Adjust" for the machine that is being serviced.

ReferenceFor more information on the standby pressure, refer to Testing and Adjusting, "Implement Pump Standby Pressure - Test and Adjust" for the machine that is being serviced.

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

ReferenceFor more information on the steering metering unit that is used in the steering system, refer to Testing and Adjusting, "Pressure Reducing Valve (Steering Signal) - Test and Adjust" for the machine that is being serviced.

Table 1

Required Tools
Part Number	Description	Quantity
8T-5320	Hydraulic Test Group	1
8T-0860	Pressure Gauge 0 to 40000 kPa (0 to 5800 psi)	1
161-8958	Wrench	1

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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.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates.

1. Ensure that the hydraulic oil in the system is at normal operating temperature. Park the machine on a level surface.

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Illustration 1	g00800993
Bogie Float Switches are located on the Right Side of the Cab.

2. Ensure that all of the wheels are on the ground. Place each bogie float switch in the FLOAT position.

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Illustration 2	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 3	g00658192
Parking Brake Switch

4. Install the steering frame lock. Place the parking brake switch in the ON position. Block the wheels. Stop the engine.

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Illustration 4	g00801000
Location of the Implement Control Valve

5. Move the cover off the implement control valve.

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Illustration 5	g00659660
End View of the Implement Control Valve on 554 Forwarder (1) Pressure tap for implement pump pressure. (2) Pressure tap for signal pressure.

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Illustration 6	g00647313
End View of the Implement Control Valve on 574 1FM1-410 Forwarders (1) Pressure tap for implement pump pressure. (2) Pressure tap for signal pressure.

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Illustration 7	g00800837
End View of the Implement Control Valve on 574 1FM411-Up Forwarders (1) Pressure tap for implement pump pressure. (2) Pressure tap for signal pressure.

6. Install a 0 to 40000 kPa (0 to 5800 psi) pressure gauge on pressure tap (2).

   Note: Pressure tap (2) is at the "PL" port of the implement control valve for the 554 Forwarder and the 574 1FM411-Up Forwarders. Pressure tap (2) is at the "LS" port of the implement control valve for the 574 1FM1-410 Forwarders.

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Illustration 8	g00800981
Operating Mode Switch on the Right Hand Control Unit

7. 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 9	g00659806
Implement Control Valve (3) Steering section. (4) Signal limiter valve (LEFT TURN). (5) Signal limiter valve (RIGHT TURN).

8. Perform step 9 in order to adjust the pressure for a left turn. Perform step 10 in order to adjust the pressure for a right turn.

9. Left Turn:
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   Illustration 10	g00805786
   Steering Activation Switch

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   Illustration 11	g00805790
   Proportional Steering Switch

   1. Move the proportional steering switch fully to the LEFT TURN position. The steering frame lock will prevent the machine from turning. The pressure gauge should indicate 17500 kPa (2550 psi).

   2. If the pressure setting is not correct, release the proportional steering 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 9.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.

10. Right Turn:
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    Illustration 12	g00805786
    Steering Activation Switch

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    Illustration 13	g00813448
    Proportional Steering Switch

    1. Move the proportional steering switch fully to the RIGHT TURN position. The steering frame lock will prevent the machine from turning. The pressure gauge should indicate 17500 kPa (2550 psi).

    2. If the pressure setting is not correct, release the proportional steering 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 10.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.