MH3022, MH3024 and MH3026 Material Handlers Hydraulic System Caterpillar

Specification

Introduction

This procedure is utilized to adjust the horsepower control spool to change the pressure that starts to destroke the main pump.

Note: Prior to performing this test, the Testing and Adjusting, "Main Pump (Destroke Characteristic) - Calibrate" must have been performed and this test must have failed.

Required Tools

Illustration 1	g02726620

Machine Preparation

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

2. Start the engine.
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   Illustration 2	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. Increase the hydraulic oil temperature to 46° to 60° C (115° to 140° F).

8. Lower the stabilizers and the blade tip.

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

10. Stop the engine.

11. Release the pressure in the hydraulic system.

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

12. Raise the left console.
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    Illustration 3	g03793038
    The pressure tap is located behind the left front access door. (1) Main pump pressure tap (2) Main pump powershift pressure tap

13. Attach Tooling (B2) 60,000 kPa (8,702 psi) pressure sensor to main pump pressure tap (1) and (B2) 6,000 kPa (870 psi) pressure sensor to main pump powershift pressure tap (2).
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    Illustration 4	g03722485
    Service connector on the right side of cab behind the seat

14. Connect tooling (E) to the service connector.

15. Start the engine.
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    Illustration 5	g02454660
    Engine speed dial

16. Set the engine speed dial at "7".

17. Lower the left console.

18. Lower the stabilizers, the blade tip, and/or the implement to raise the front axle and the rear axle. This step will allow the wheels to turn freely.

    Note: All tires must be fully off the ground.

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    Illustration 6	g02446738
    Power mode control button on the soft panel switch

19. 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	g02453444
    Transmission control button on the soft panel switch

20. Push down on the transmission control button to select FIRST GEAR.

    Note: The first indicator light will illuminate when the transmission is in FIRST GEAR.

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    Illustration 8	g02453447
    Creeper speed control button on the soft panel switch

21. Push down on the creeper speed control button to activate the creeper speed control.

    Note: The indicator light will be illuminated when the creeper speed control is activated.

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    Illustration 9	g02447036
    Automatic Engine Speed Control (AESC) as displayed on the programmable function key in the monitor.

22. Disable the automatic engine speed control through the monitor by pressing the programmable button.
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    Illustration 10	g03722432
    Hydraulic modulation switch on left joystick

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    Illustration 11	g06174873
    Hydraulic modulation medium mode (monitor display)

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

24. The air conditioning should be turned off for the following test.

Test 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.

1. Release the service brake pedal.

2. Fully depress the travel pedal and stall the bucket in the full Bucket Open position.

3. Override the “Main Pump Solenoid Current” until the engine speed has reached the correct value.

   Note: Refer to Table 1 in this manual for the correct value.

   1. Start the Electronic Technician.

   2. Select the Machine ECM and then select “OK”.

   3. Select “Diagnostics” from the main menu.

   4. Select “Diagnostic Tests”.

   5. Select “Override Parameters”.

   6. Select “Main Pump Solenoid Current” and set the current to 0.0 amp.

   7. Select “Travel Pilot Solenoid Current Override” and set the current to 0.8 amp.

   8. Select “Main Pump Power Shift Solenoid Current” and set the current to 1.0 amp.

   9. Then adjust “Main Pump Power Shift Solenoid Current” until the main pump power shift pressure reaches the required specification in Table 1.

   10. Select “Main Pump Solenoid Current” and set the current to 0.4 amp.

   11. Then adjust the “Main Pump Solenoid Current” by 0.2 amp until the “Main Pump Solenoid Current” reaches 1 amp.

       Note: Perform Step 3.k with a fully depressed travel pedal and the bucket in the full Bucket Open position.

4. Verify the engine speed and transmission output speed in Cat ET. and the main pump pressure at pressure tap (1).

5. Disable all overrides, and release the travel pedal and the bucket.

6. Multiply the calculation factor by the engine speed, then divide by the main pump pressure to get the target transmission output speed.

7. If the target transmission output speed that was calculated in Step 6 does not meet the transmission output speed that was obtained in Step 4, then proceed to the "Adjustment Procedure".

Adjustment Procedure

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Illustration 12	g03856631
Main pump (MH3022 and MH3024 (FB71-UP)) (3) Horsepower control valve

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Illustration 13	g03858523
Main pump (MH3024 (FM41-UP, FB51-UP) and MH3026) (3) Horsepower control valve

1. Remove the cap from horsepower control valve (3).

2. Loosen the locknut on horsepower control valve (3).

3. Turn the adjustment screw on horsepower control valve (3) clockwise to increase the destroke pressure and turn adjustment screw (1) counterclockwise to decrease the destroke pressure.

   Note: Always make the final adjustments as the flow increases.

4. While the adjustment screw is being held, tighten the locknut to the specified torque on horsepower (3).

5. Repeat the "Test Procedure" until the target shaft speed has been met.

6. After the destroke pressure has been set, repeat the Testing and Adjusting, "Main Pump (Destroke Characteristic) - Calibrate" to adjust the main pump torque calibration.