793F AC Off-Highway Truck Hydraulic Fan and Steering System Caterpillar

Introduction

The following instructions provide test and adjust information for the steering solenoid and relief valve.

This test will show the following conditions if the conditions exist.

• The steering solenoid and relief valve operates correctly.

• The steering solenoid and relief valve (8) is correctly set.

Tools Needed

Machine Preparation

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Sudden movement of the machine or release of air or oil under pressure can cause possible injury or death to persons on or near the machine. To prevent possible injury or death, do the procedure that follows before testing and adjusting the Hydraulic System.

1. Move the machine to a smooth horizontal location. Move away from any machines that are working and any personnel.

2. Move the shift control lever to the NEUTRAL position. Activate the parking brakes.

3. Fully raise the dump body of the truck.

4. Stop the engine. Move the engine start switch to the OFF position.

   Note: The pressure will not be released from the steering accumulators when you use the battery disconnect switch or the engine shutdown switch.

5. While the engine is not running, turn the steering wheel completely in both directions. Continue to turn the steering wheel in both directions until the front wheels will not move.

6. Turn the engine start switch key to the ON position. Do not start the engine. Turn the engine start switch key to the OFF position.

   Note: This process releases any pressure that is in the solenoid valve which is used to purge the accumulator. Refer to Operation and Maintenance Manual, "Steering Accumulator Pressure - Release" for more information.

7. Ensure that all air pressure and oil pressure is released before any fittings, hoses, or components are worked on.

8. Permit only one operator on the machine. Either keep other personnel away from the machine, or keep other personnel in the sight of the operator.

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

10. Install the retaining pin for the dump body.

11. Make sure that the shift control lever is in the NEUTRAL position.

Test Procedure

Use a bench test to achieve an accurate pressure test. The steering relief valve must be removed and tested on a test bench before any adjustments.

Adjustment Procedure

Illustration 1	g00281966
Steering solenoid and relief valve (1) Port to right front steering accumulator (2) Port for the Auxiliary Power Unit (APU) (3) Port to right rear steering accumulator (4) Inlet port (5) Port to steering control valve (6) Setscrew (7) Nut (8) Steering relief valve

Use the following procedure to change the pressure setting of steering relief valve (8) :

Note: Steering relief valve (8) must be adjusted on a test bench.

1. Loosen nut (6) .

2. Turn setscrew (7) clockwise in order to increase the pressure setting.

   1. Turn setscrew (7) counterclockwise in order to decrease the pressure setting.

      Note: One revolution of setscrew (7) will change the pressure setting by 3800 kPa (550 psi).

Worksheet

Note: Other components in the steering system will keep the pressure from reaching this value.