M318F, M320F and M322F Wheeled Excavators Hydraulic System Caterpillar

Specification

Introduction

The trailer relief valve limits the maximum pressure of the trailer hydraulic system.

Required Tools

Illustration 1	g02726620

Machine Preparation

Illustration 2	g06148419
Location of trailer control valve

Illustration 3	g06154623
Trailer control valve (1) Pressure relief valve (2) Locknut (3) Adjustment screw (4) pressure port A2 (platform dump)

1. Clear all personnel from the machine and from the area around the machine.

2. Start the engine.
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   Illustration 4	g02449876
   Engine speed dial

3. Set the engine speed dial at "10".

4. Lower the left console.

5. Position the machine on level ground. Check the visibility and adjust the mirrors for the best vision close to the machine.

6. Fully depress the service brake pedal until the service brake pedal locks mechanically.

7. Lower the stabilizers and the blade tip.

8. Fully lower the trailer platform.

9. Increase the hydraulic oil temperature to 46° to 60° C (115° to 140° F).

10. Fully extend the bucket cylinder and place the bucket on the ground.

11. Stop the engine.

12. Release the pressure in the hydraulic system.

    Note: Refer to Testing and Adjusting, "System Pressure - Release".

13. Raise the left console.

14. Connect tooling (B1) 60000 kPa (8702 psi) pressure sensor to trailer dump pressure port A2 (4). Refer to Illustration 3.
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    Illustration 5	g06155692
    Trailer hydraulic connection lines (5) Trailer tailgate close (6) Trailer tailgate open (7) Trailer platform dump

15. Disconnect the trailer hydraulic lines.

Test Procedure

1. Star the engine.

2. Set the engine speed dial at "10".

3. Lower the left console.
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   Illustration 6	g02446738
   Power mode control button on the soft panel switch

4. Push down on the power mode control button to activate power mode.

   Note: The indicator light will be illuminated when power mode is activated.

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   Illustration 7	g02447036
   Automatic Engine Speed Control (AESC) as displayed on the programmable function key in the monitor.

5. Disable the automatic engine speed control through the monitor by pressing the programmable button.
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   Illustration 8	g03722432
   Hydraulic modulation switch on left joystick

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   Illustration 9	g06174873
   Hydraulic modulation medium mode (monitor display)

6. Select the hydraulic modulation mode as medium. Press the lower front switch on the left joystick to select the hydraulic modulation mode.

7. The air conditioning should be turned off for the following test.
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   Illustration 10	g06155935
   Right-hand console (8) Trailer control switch

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   Illustration 11	g06155938
   Trailer control switch (9) Unlock trailer tailgate (10) Trailer control OFF (11) Unlock trailer dump

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   Illustration 12	g06155939
   Left-hand console (12) Trailer control joystick

8. Push the unlock trailer dump switch and pull back trailer control joystick (12) to lift the trailer platform, stall the function, and check the relief valve pressure. Refer to the trailer specifications for the correct pressure.

9. Push the unlock trailer tailgate switch and pull back trailer control joystick (12) to open the trailer tailgate, stall the function, and check the relief valve pressure. Refer to the trailer specifications for the correct pressure.

10. Push trailer control joystick (12) forward to close the trailer tailgate, stall the function, and check the relief valve pressure. Refer to the trailer specifications for the correct pressure.

11. If the trailer relief valve pressure is not set to the proper specification, refer to the "Adjust Procedure".

Adjust Procedure

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

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Illustration 13	g06154623
Trailer control valve (1) Pressure relief valve (2) Locknut (3) Adjustment screw (4) pressure port A2 (platform dump)

1. Remove the cap from the trailer relief valve.

2. Loosen locknut (2).

3. Turn adjustment screw (3) on the relief valve clockwise to increase the pressure. Turn adjustment screw (3) counterclockwise to decrease the pressure.

   Note: One turn of the adjustment screw will equal approximately 4600 kPa (667 psi).

4. Repeat Steps 8 through 11 of the "Test Procedure" until the trailer relief pressure has been met. Refer to the trailer specifications for the correct pressure.

   Note: Always make the final pressure adjustments on the pressure rise.

5. While adjustment screw (3) on the relief valve is being held, tighten locknut (2) to the specified torque.

6. Install the cap onto the trailer relief valve.