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. Install the steering frame lock. Refer to Operation and Maintenance Manual, "Steering Frame Lock".
Test and Adjust the System Pressure
- Remove the dust cap and attach a 35000 kPa (5000 psi) pressure gauge to the test fitting for the piston pump (brake, hoist, and fan).
ReferenceRefer to Testing and Adjusting, "General Information" for the location of the test fitting for the machine that is being tested.
- Start the engine and run the engine at maximum speed.
- Move the hoist control to the RAISE position. When the dump body has reached full travel, 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.
- The system pressure should be 20700 ± 700 kPa (3000 ± 100 psi).
If the system pressure is correct, proceed to step 12.
If the system pressure is incorrect, the system pressure must be adjusted.
- Tilt the cab in order to access the piston pump and the pump control valve. Refer to Operation and Maintenance Manual, "Cab - Tilt".
- Remove cover (9m) from pump control valve (9a) . This removal will allow access to the adjustment screw.
 | |
| Illustration 1 | g01037210 |
Pump control valve (9a) is located beneath the cab. | |
- Loosen jam nut (9n) . Turn adjustment screw (9o) 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).
 | |
| Illustration 2 | g01037211 |
(9a) Pump control valve (9m) Cap nut (9n) Jam nut (9o) Adjustment screw | |
- Return cover (9m) to the original position.
- Lower the cab. Refer to Operation and Maintenance Manual, "Cab - Tilt".
- Run the engine at maximum speed.
- Repeat the procedure from step 3 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 braking system, the fan system, or the hoist system.
- Shut off the engine.
- Remove the pressure gauge from the machine.
- Remove the steering frame lock. Refer to Operation and Maintenance Manual, "Steering Frame Lock".
Test and Adjust the Margin Pressure
- Ensure there sufficient overhead clearance so that the dump body can be fully raised.
- Tilt the cab in order to access the piston pump and the pump control valve. Refer to Operation and Maintenance Manual, "Cab - Tilt".
- Install a suitable tee fitting between pump control valve (9a) and load sensing line (9l) .
 | |
| Illustration 3 | g01037212 |
- Install a 34500 kPa (5000 psi) differential pressure gauge between the test fitting for the piston pump (brake, hoist, and fan) and the tee fitting. 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.
- Lower the cab. Refer to Operation and Maintenance Manual, "Cab - Tilt".
- Start the engine and run the engine at maximum speed.
- 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 tee fitting. Subtract the pressure at the tee fitting from the pressure at the test fitting. This pressure will also be the margin pressure.
- The margin pressure should be 2200 ± 350 kPa (320 ± 50 psi). If the margin pressure is incorrect, the margin pressure must be adjusted.
- 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".
- Remove cap nut (9p) from pump control valve (9a) and loosen jam nut (9q) .
 | |
| Illustration 4 | g01037213 |
(9a) Pump control valve (9p) Cap nut (9q) Jam nut (9r) Adjustment screw | |
- Turn the adjustment screw clockwise in order to increase the margin pressure. Turn adjustment screw (9r) 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).
- Tighten jam nut (9q) to a torque of 21 N·m (15 lb ft).
- Install cap nut (9p) . Tighten the cap nut to a torque of 21 N·m (15 lb ft).
- Lower the cab. Refer to Operation and Maintenance Manual, "Cab - Tilt".
- Repeat the procedure from step 6 until the margin pressure is correct.
- Shut off the engine and remove the pressure gauge from the machine.
Test the Standby Pressure
The standby pressure must be tested when the machine is cold. This procedure ensures that there is no demand on the fan drive system.
The standby pressure is not adjustable.
- Remove the dust cap and attach a 34500 kPa (5000 psi) to the test fitting for the piston pump (brake, hoist, and fan).
ReferenceRefer to Testing and Adjusting, "General Information" for the location of the test fitting for the machine that is being tested.
- Start the engine and run the engine at low idle.
Do not operate the brake or operate the body hoist.
- Record the reading that is displayed on the pressure gauge. This pressure is the standby pressure for the steering system. The standby pressure should be 2750 ± 700 kPa (400 ± 100 psi).
If the standby pressure is incorrect there may be a problem with one of the components of the brake system, the fan system or hoist system.
- Shut off the engine and remove the pressure gauge from the machine.
Test the Case Drain
A parameter of the piston pump (brake, hoist, and fan) that can be checked is the case drain. This procedure can be done in the following way:
- Ensure there sufficient overhead clearance so that the dump body can be fully raised.
- 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.
- Tilt the cab in order to access the piston pump. Refer to Operation and Maintenance Manual, "Cab - Tilt".
- Disconnect hose (a) from tee (b) . Disconnect hose (c) from tee (b) . Use a 6V-8733 Face Seal Union and connect hose (a) to hose (c) .
 | |
| Illustration 5 | g01051318 |
- Remove tee (b) from piston pump (8) .
- 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.
- Place the end of the 5P-2094 Hose into a suitable container that has a minimum capacity of 35 L (9.2 US gal).
- Lower the cab. Refer to Operation and Maintenance Manual, "Cab - Tilt".
- Start the engine.
Run the engine at low idle and move the hoist control to the RAISE position. When the dump body has reached full travel, 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.
- 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 11.
If the amount of oil that is collected in the container exceeds 15 L (4 US gal), remove the piston pump from the machine.
- Remove the hose clamp, the hose, and the elbow from piston pump (8) and install tee (b) .
- Disconnect hoses (a) and (c) from the face seal union before connecting hoses (a) and (c) to tee (b) .