2001/05/14 Caterpillar

Forwarders:

574 (S/N: 1FM1-UP)

Description of Change: A new plate is used in the implement pump of forwarders. Also, a new hose routing is also used. The modifications cause the implement pump to operate with less noise. Also, the modifications yield a better response from the hydraulic system.

Adaptable To: The modifications are effective with 574 (S/N: 1FM295 and 401-UP) Forwarders. The modifications are adaptable to first production of the listed forwarders.

1. Refer to Disassembly and Assembly, RENR3025, "554 Forwarder and 574 Forwarder", "Piston Pump (Implement) - Remove" for instruction on removing the implement pump. Remove the pump.

2. Refer to Disassembly and Assembly, RENR3025, "554 Forwarder and 574 Forwarder", "Piston Pump (Implement) - Disassemble" for instruction on the disassembly of the implement pump. Perform Step 1 through Step 14 in the material that was referenced.

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Illustration 1	g00795963

3. Replace former plate (1) with the new 201-9662 Plate .

4. Refer to Disassembly and Assembly, RENR3025, "554 Forwarder and 574 Forwarder", "Piston Pump (Implement) - Assemble" for instruction on the assembly of the implement pump. Assemble the pump.

5. Refer to Disassembly and Assembly, RENR3025, "554 Forwarder and 574 Forwarder", "Piston Pump (Implement) - Install" for instruction on the installation of the implement pump. Install the pump.

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Illustration 2	g00796046
Implement control valve

6. Locate the implement control valve. The valve is located behind the cab under a cover. Remove tee (3) .

7. Remove hose (7). Remove the connector in the "PL" port.

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Illustration 3	g00796097

8. Remove swivel tee (5) and nipple (5). Install tee (5) and nipple (5) in position (8) between hose (2) and the shuttle valve.

9. Move elbow (4) to "PL" port (9) .

10. Move nipple (6) to "PX" port (10) .

11. Install a 9S-4191 Straight Thread Plug with a 3J-1907 O-Ring Seal in "LS" port (11) .

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Illustration 4	g00796334

12. Remove former hose (12) .

13. Install a 164-5865 Hose As in place of former hose (12). Use a 6V-8723 Elbow and a 3K-0360 O-Ring Seal between the 164-5865 Hose As and the tank. Use a 6V-8636 Connector and a 3J-1907 O-Ring Seal between the 164-5865 Hose As and the valve.

14. Purge the air from the pilot hydraulic system. Refer to Testing and Adjusting, RENR3031-02, "554 Forwarder and 574 Forwarder Hydraulic System", "Pilot Hydraulic System - Purge" for instruction on purging the pilot hydraulic system.

15. Refer to Testing and Adjusting, RENR3031-02, "554 Forwarder and 574 Forwarder Hydraulic System", "Implement Pump High Pressure Cutoff - Test and Adjust". Perform the test that was referenced.

    Note: The pressure taps are now located in the "PL" and "PX" ports.

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

17. Connect the low pressure port of the 1U-5796 Pressure Differential Gauge Group to the "PL" pressure tap.

18. Connect the high pressure port of the 1U-5796 Pressure Differential Gauge Group to the "PX" pressure tap.

19. Start the engine. Increase the engine speed to approximately 1400 rpm. Turn the boom switch to the ON position.

20. Raise the boom at half of the maximum speed. The margin pressure will be indicated on the differential pressure gauge. If two pressure gauges are used, the margin pressure is the difference between the pressure readings on the two pressure gauges. The margin pressure should be approximately 3500 kPa (500 psi).

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Illustration 5	g00796627

21. To adjust the margin pressure, Loosen locknut (13). Turn adjustment screw (14) until the differential pressure gauge indicates approximately 3500 kPa (500 psi).

22. Tighten locknut (13). Raise the boom again in order to verify the pressure setting. Repeat Step 21, if necessary.

23. Lower the boom to the ground. Stop the engine. Remove the pressure gauges.