769D Off-Highway Truck: Relief Valve (Secondary Steering Backup) - Test and Adjust

Table 1

Tools Needed	Qty
198-4240 Digital Pressure Indicator	1
198-4239 Pressure Sensor	1

WARNING: Personal injury or death can occur if personnel are trapped between the wheel and the frame. The steering system is hydraulically controlled and wheels can crush personnel during movement.Use caution when working between the wheels and the frame. If the wheels must be turned, ensure that all personnel are clear of the machine before any movement.

BBB1-221, BCA1-172, BDA1-258 and BEC1-201 (1) Brake release and secondary steering pump(2) Plug

BBB222-UP, (BCA173-UP), BDA259-UP and BEC202-UP (1) Pump and Motor (secondary steering, brake release, prelubrication and high speed oil change -quickevac)(2) Plug for the main relief valve on the secondary steering system

The main relief valve for the secondary steering system is located behind plug (2) on the brake release and secondary steering pump (1).

(3) Steering check and relief valve (4) Backup relief valve for the secondary steering system(SS) Pressure tap for the steering system

The steering system check and relief valve is located behind the front suspension cylinder on the right side.

1. Operate the engine at HI IDLE. Turn the steering wheel to the right or turn the steering wheel to the left until the steering cylinder stop is reached. Then continue turning the steering wheel against the stop. Hold the steering wheel in this position for three seconds and then release the steering wheel. Continue this step until the oil in the steering system reaches at least 38 °C (100 °F).

2. Stop the engine.

Note: The backup relief valve for the secondary steering system (4) has a higher pressure setting than the main relief valve for the secondary steering system.
Note: Do not increase the pressure setting of the relief valve too much. If the pressure setting of the relief valve is set too high, damage to the components of the system could occur.


3. Remove plug (2) from brake release and secondary steering pump (1). Use the setscrew that is located behind plug (2) in order to increase the pressure setting of the main relief valve for the secondary steering system. Turn the setscrew clockwise. Approximately 3 turns of the setscrew will increase the pressure setting of the main relief valve for the secondary steering system above the pressure setting of the backup relief valve for the secondary steering system. Count the number of turns so that you can return the setscrew to the original setting.

4. Install the 198-4240 Digital Pressure Indicator with a 198-4239 Pressure Sensor at the pressure tap (SS) for the steering system. Pressure tap (SS) is located on steering check and relief valve (3) behind the right front suspension cylinder.

5. Place blocks in front of the wheels and behind the wheels.

Note: When the parking brake control is in the ON position, friction from the wheel brakes will not allow the secondary steering system to turn the wheels all the way to the cylinder stops.


6. Turn the parking brake control to the OFF position.

NOTICE
To minimize battery drain, leave the switch in the MANUAL position only long enough to test the secondary steering. Return the switch to the AUTO position immediately after testing.



7. Use the secondary steering and brake release control in the cab in order to operate the brake release and secondary steering pump (1) .

8. Check the pressure on the pressure gauge. The pressure setting of the backup relief valve for the secondary steering system is 20700 ± 400 kPa (3002 ± 58 psi).

(4) Backup relief valve for the secondary steering system (5) Locknut(6) Setscrew



9. If the pressure needs to be adjusted, loosen locknut (5). Use setscrew (6) to change the pressure setting.

10. With an allen wrench, rotate the setscrew clockwise by 1/4 turn in order to raise the pressure. Rotate the setscrew counterclockwise by a 1/4 turn in order to lower the pressure. Each 1/4 turn of the setscrew changes the pressure approximately 690 kPa (100 psi).

11. Repeat Steps 7 through 10 until the pressure setting is correct.

12. When the pressure setting of backup relief valve for the secondary steering system (4) is correct, adjust the pressure setting of main relief valve for the secondary steering system to the original pressure setting.

13. Install plug (2). Remove the gauge from pressure tap (SS) .

14. Turn the parking brake control to the ON position in order to apply the parking brakes.

MARYGAR

769D Off-Highway Truck: Relief Valve (Secondary Steering Backup) - Test and Adjust 2012-12-04T16:45:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown