725 and 730 Articulated Trucks Steering, Suspension, and Body Hoist Hydraulic Systems Caterpillar

Ensure that the oil is at operating temperature. Refer to Testing and Adjusting, "General information" for information on warming the oil.

Park the machine on a level surface. Move the parking brake control to the ENGAGED position and shut off the engine. Install the steering frame lock. Refer to Operation and Maintenance Manual, SEBU7347, "Steering Frame Lock".

Test and Adjust the System Pressure

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Illustration 1	g00756477
Test fitting for the steering system pressure.

1. Remove the dust cap and attach a 35000 kPa (5000 psi) pressure gauge to the test fitting.

2. Start the engine and run the engine at maximum speed.

3. Rotate the steering wheel clockwise until the steering frame lock prevents the machine from articulating.

4. Record the reading which is displayed on the pressure gauge.

5. Rotate the steering wheel counterclockwise until the steering frame lock prevents the machine from articulating.

6. Record the reading which is displayed on the pressure gauge.

7. Repeat steps 3 through 6 several times in order to obtain an average reading for each rotational direction.

8. The system pressure should be 20680 ± 345 kPa (3000 ± 50 psi).

   If the system pressure is 20680 ± 345 kPa (3000 ± 50 psi), proceed to step 16.

   If the system pressure is not 20680 ± 345 kPa (3000 ± 50 psi), the system pressure must be adjusted.

9. Tilt the cab in order to access the piston pump and the pressure and flow compensator valve. Refer to Operation and Maintenance Manual, SEBU7347, "Cab - Tilt".

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Illustration 2	g00757141

10. Remove cover (1) from pressure and flow compensator valve (2). This will allow access to the adjustment screw.

11. Loosen the jam nut. Turn the adjustment screw clockwise in order to increase the system pressure. Turn the adjustment screw counterclockwise in order to decrease the system pressure.

    Note: One turn of the adjustment screw will result in a pressure change of approximately 5500 kPa (800 psi).

12. Return cover (1) to the original position.

13. Lower the cab. Refer to Operation and Maintenance Manual, SEBU7347, "Cab - Tilt".

14. Run the engine at maximum speed.

15. Repeat the procedure from step 3 until the system pressure is 20680 ± 345 kPa (3000 ± 50 psi).

    If the system pressure cannot be adjusted to 20680 ± 345 kPa (3000 ± 50 psi), there may be a problem with one of the components of the steering system.

16. Shut off the engine.

17. Remove the pressure gauge from the machine.

18. Remove the steering frame lock. Refer to Operation and Maintenance Manual, SEBU7347, "Steering Frame Lock".

Test the Standby Pressure

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Illustration 3	g00756477
Test fitting for the steering system pressure.

1. Remove the dust cap and attach a 35000 kPa (5000 psi) pressure gauge to the test fitting.

2. Start the engine and run the engine at low idle.

3. Record the reading which is displayed on the pressure gauge. This is the standby pressure.

   The standby pressure should be 3447 ± 690 kPa (500 ± 100 psi). If the standby pressure is incorrect, there may be a problem with one of the components of the steering system.

4. Shut off the engine and remove the pressure gauge from the machine.

5. Remove the steering frame lock. Refer to Operation and Maintenance Manual, SEBU7347, "Steering Frame Lock".