725 and 730 Articulated Trucks Machine 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. There must be sufficient overhead clearance so that the dump body can be fully raised. Move the parking brake control to the ENGAGED position and shut off the engine.

Test and Adjust the System Pressure

Hoist System Pressure

1. Install the steering frame lock. Refer to Operation and Maintenance Manual, "Steering Frame Lock".

2. Attach a 35000 kPa (5000 psi) pressure gauge to the test fitting for the piston pump (steering and hoist).

   ReferenceRefer to Testing and Adjusting, "General Information" for the location of the test fitting for the machine that is being tested.

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

4. Move the hoist control to the RAISE position. When the dump body is fully raised, hold the hoist control in the RAISE position. Record the pressure that is displayed on the pressure gauge. This pressure is the maximum pump pressure for the hoist system.

5. The hoist system pressure should be 20700 ± 700 kPa (3000 ± 100 psi).

   If the hoist system pressure is correct, shut off the engine and remove the test equipment and the steering frame locks from the machine. Refer to Operation and Maintenance Manual, "Steering Frame Lock".

   If the hoist system pressure is incorrect, the system pressure must be adjusted. Refer to "Adjusting the System Pressure".

Steering System Pressure

1. Install the steering frame lock. Refer to Operation and Maintenance Manual, "Steering Frame Lock".

2. Attach a 35000 kPa (5000 psi) pressure gauge to the test fitting for the piston pump (steering and hoist).

   ReferenceRefer to Testing and Adjusting, "General Information" for the location of the test fitting for the machine that is being tested.

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

4. Articulate the machine fully to the left and then record the reading on the pressure gauge.

5. Articulate the machine fully to the right and then record the reading on the pressure gauge. This pressure is the maximum pump pressure for the steering system.

6. The steering system pressure should be 20700 ± 700 kPa (3000 ± 100 psi).

   If the steering system pressure is correct, shut off the engine and remove the test equipment and the steering frame locks from the machine. Refer to Operation and Maintenance Manual, "Steering Frame Lock".

   If the steering system pressure is incorrect, the system pressure must be adjusted. Refer to "Adjusting the System Pressure".

Adjusting the System Pressure

1. Ensure that the steering frame lock is installed. Refer to Operation and Maintenance Manual, "Steering Frame Lock".

2. Tilt the cab in order to access the piston pump and the pump control valve. Refer to Operation and Maintenance Manual, "Cab - Tilt".

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Illustration 1	g01037214
Pump control valve (8a) is located beneath the cab.

3. Remove cover (8m) from pump control valve (8a) . This procedure will allow access to the adjustment screw.

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Illustration 2	g01037215
(8a) Pump control valve (8m) Cap nut (8n) Jam nut (8o) Adjustment screw

4. Loosen jam nut (8n) . Turn adjustment screw (8o) 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).

5. Return cover (8m) to the original position.

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

7. Run the engine at maximum speed.

8. Repeat the procedure from Step 4 until the system pressure is 20700 ± 700 kPa (3000 ± 100 psi).

   If the system pressure cannot be adjusted, there may be a problem with one of the components of the steering system or of the hoist system.

9. Shut off the engine.

10. Remove the pressure gauge from the machine.

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

Test and Adjust the Margin Pressure

1. Ensure there sufficient overhead clearance so that the dump body can be fully raised.

2. Tilt the cab in order to access the piston pump and the pump control valve. Refer to Operation and Maintenance Manual, "Cab - Tilt".

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Illustration 3	g01037216

3. Install a 7X-2444 Swivel Tee with a 4J-5477 O-Ring Seal between the elbow on pump control valve (8a) and load sensing line (8l) . Install a 6V-3965 Fitting (TEST) with a 3J-1907 O-Ring Seal into the swivel tee.

4. Install a 34500 kPa (5000 psi) differential pressure gauge between the test fitting for the piston pump (steering and hoist) and the 6V-3965 Fitting (TEST) at the pump that was installed in Step 3. The pressure gauge must reach inside the cab.

   ReferenceRefer to Testing and Adjusting, "General Information" for the location of the test fitting for the machine that is being tested.

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

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

7. Move and hold the hoist control to the LOWER position. When the body is in the halfway point of travel of the body, observe and record the pressure that is displayed on the pressure gauge. This pressure is the margin pressure.

   Note: If you do not have a pressure differential gauge, you can install a 35000 kPa (5000 psi) pressure gauge to the test fitting. Then install a second 35000 kPa (5000 psi) pressure gauge to the 6V-3965 Fitting (TEST) at the pump that was installed in Step 3. Subtract the pressure at the fitting at the pump from the pressure at the test fitting. This pressure will also be the margin pressure.

8. The margin pressure should be 2200 ± 350 kPa (320 ± 50 psi). If the margin pressure is incorrect, the margin pressure must be adjusted.

9. Shut off the engine and raise the cab in order to access the pump control valve which is part of the piston pump. Refer to Operation and Maintenance Manual, "Cab - Tilt".

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Illustration 4	g01037217
(8a) Pump control valve (8p) Cap nut (8q) Jam nut (8r) Adjustment screw

10. Remove cap nut (8p) from the pump control valve and loosen jam nut (8q) .

11. Turn the adjustment screw clockwise in order to increase the margin pressure. Turn adjustment screw (8r) counterclockwise in order to decrease the margin pressure.

    Note: One turn of the adjustment screw will result in a pressure change of approximately 1400 kPa (200 psi).

12. Tighten jam nut (8q) to a torque of 21 N·m (15 lb ft).

13. Install cap nut (8p) . Tighten the cap nut to a torque of 21 N·m (15 lb ft).

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

15. Repeat the procedure from Step 6 until the margin pressure is correct.

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

Test the Standby Pressure

The standby pressure is not adjustable.

1. Attach a 34500 kPa (5000 psi) to the test fitting for the piston pump (steering and hoist).

   ReferenceRefer to Testing and Adjusting, "General Information" for the location of the test fitting for the machine that is being tested.

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

   Do not rotate the steering wheel or operate the body hoist.

3. Record the reading that is displayed on the pressure gauge. This pressure is the standby pressure for the steering and hoist systems. The standby pressure should be 3450 ± 700 kPa (500 ± 100 psi).

   If the standby pressure is incorrect there may be a problem with one of the components of the steering system or of the hoist system.

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

Test the Case Drain

A parameter of the piston pump (Steering and hoist) that can be checked is the case drain. This procedure can be done in the following way:

1. Ensure there sufficient overhead clearance so that the dump body can be fully raised.

2. Remove the filler cap from the hydraulic tank for the steering and the hoist systems. This procedure will relieve the pressure from the hydraulic tank.

3. Tilt the cab in order to access the piston pump. Refer to Operation and Maintenance Manual, "Cab - Tilt".

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Illustration 5	g01053152

4. Disconnect hose (a) from fitting (b) . Install a 6V-9511 Plug into hose (a) . Remove fitting (b) from piston pump (9) .

5. Install a 9U-6997 Elbow into piston pump (8) . Use a 9M-7958 Hose Clamp in order to connect a 5P-2094 Hose that is approximately 3 m (10 ft) long.

6. Place the end of the 5P-2094 Hose into a suitable container that has a minimum capacity of 35 L (9.2 US gal).

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

8. Start the engine.

   Run the engine at low idle and move the hoist control to the RAISE position. When the dump body is fully raised, shut off the engine and remove the hose from the container.

   Place the end of the hose into a second suitable container that has a minimum capacity of 35 L (9.2 US gal).

   Start the engine. Run the engine at high idle and hold the hoist control in the RAISE position for 30 seconds.

   Shut off the engine.

   Place the end of the hose into a first container.

   Start the engine and lower the body.

9. Measure the amount of oil that has been collected in the second container. This oil is case drain oil.

   If the amount of oil collected in the container less than 15 L (4 US gal) proceed to Step 10.

   If the amount of oil that is collected in the container exceeds 15 L (4 US gal), remove the piston pump from the machine.

10. Remove the hose clamp, the hose, and the elbow from piston pump (9) and install tee (b) .

11. Install fitting (b) into piston pump (9) . Remove the plug from hose (a) before connecting the hose to fitting (b) .