330F MHPU Mobile Hydraulic Power Unit Machine System Caterpillar

Introduction

The boom hydraulic circuit contains a regeneration circuit. This regeneration circuit allows the return oil from the head end of the boom cylinders to be supplied to the rod end of the boom cylinders during the BOOM DOWN operation. The proportional reducing valve (PRV) for the boom regeneration valve controls the amount of pilot pressure from the joystick to the boom down regeneration valve. The PRV for the boom regeneration valve is controlled by the machine ECM.

Required Tools

Illustration 1	g02571852
Tooling group "A" 198-4240 Digital Pressure Indicator Gp

Machine Preparation

1. The following procedures must be completed before performing the calibration.

   • Set the pilot pressure to the specifications in Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust" for the machine.

   • Calibrate the power shift pressure. Refer to Testing and Adjusting, "Solenoid Valve (Proportional Reducing) - Calibrate (Power Shift Pressure)" for the machine.

   • Calibrate the proportional reducing valve for negative flow control. Refer to Testing and Adjusting, "Solenoid Valve (Proportional Reducing) - Calibrate (Negative Flow Control)" for the machine.

2. Position the machine on level ground.

3. Stop the engine.

4. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "System Pressure - Release".
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   Illustration 2	g03413885
   Pressure tap for the proportional reducing valve (boom regeneration valve)

5. Connect a 3,447 kPa (500 psi) pressure sensor to the pressure tap for the boom regeneration valve. The pressure tap can be found on the left side of the main control valve.

6. Start the engine.

7. Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

8. Place the machine implements on the ground at maximum reach.

9. Place the hydraulic activation lever to the UNLOCK position.

Calibration Procedure

1. Enter the service mode. Input the password "9992".
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   Illustration 3	g02550247

2. Select "Boom Down Regen Valve" from the "Calibrations" menu.

3. Press the OK key in order to start the calibration. The engine RPM will automatically drop to the equivalence of engine speed dial 1.

4. Confirm the notes on the monitor display. Set up the test conditions in accordance with the instructions. Press the OK key.

5. Move the joystick for BOOM DOWN to the full down position and hold the joystick in this position.
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   Illustration 4	g02550277

6. Use the arrows to adjust the pressure until the pressure reading for the boom regeneration valve is at 500 ± 50 kPa (73 ± 7 psi). Press the OK key.

7. Move the joystick for BOOM DOWN to the NEUTRAL position.

8. Confirm notes on the monitor display. Set up the test conditions in accordance with the instructions. Press the OK key.

9. Move the joystick for BOOM DOWN to the full down position and hold the joystick in this position.
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   Illustration 5	g02550318

10. Use the arrows to adjust the pressure until the pressure reading for the boom regeneration valve is at 2500 ± 50 kPa (363 ± 7 psi). Press the OK key.

11. Move the joystick for BOOM DOWN to the NEUTRAL position.
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    Illustration 6	g02550516

12. If calibration was successful and no errors occurred, the display will indicate that the calibration is complete.
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    Illustration 7	g02550596

13. The "Error" screen will be displayed on the monitor if an error occurs. The process of calibration will not be saved and the process must be restarted.