336D MHPU Mobile Hydraulic Power Unit Hydraulic System Relief Valve (Auxiliary) - Test and Adjust - Line, System 18 Caterpillar

Test for the Line Relief Valve on the Attachment Control Valve

Note: A temporary setting of the main relief valve pressure is required before any line relief valve pressure setting is adjusted. Refer to the temporary setting of the main relief valve pressure in Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine.

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Illustration 1	g01197980
(1) Up key (2) Right key (3) Home key (4) Main menu key (5) Left key (6) Down key (7) Cancel key (8) OK key

1. Position the machine on level ground and stop the engine.

2. Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "Hydraulic System Pressure - Release" for the machine.

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Illustration 2	g01534994
Pump Compartment 323D and 329D (9) Pressure tap (drive pump ) (10) Pressure tap (idler pump ) (11) Pressure tap (power shift)

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Illustration 3	g01240884
Pump Compartment 336D (9) Pressure tap (drive pump pressure) (10) Pressure tap (idler pump pressure) (11) Pressure tap (power shift pressure)

3. Install a pressure gauge with a 6000 kPa (870 psi) capacity on pressure tap (11) for the power shift.

4. Install a pressure gauge with a 60000 kPa (8700 psi) capacity on pressure tap (9) for the drive pump.

5. Start the engine.

6. Place the machine controls at the following settings: engine speed dial 10 and AEC switch OFF. Refer to Testing and Adjusting, "Engine Performance - Test (Engine Speed)" for the machine for engine rpm settings.

7. Warm the hydraulic oil to 50 °C (122 °F).

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

9. Use the following procedure to access the "SERVICE" mode of the monitor.

   1. From the default screen, press the main menu key (4) .

   2. Use the right key (2) or the left key (5) in order to scroll through the menu options.

   3. When the "SERVICE" option is highlighted, press the OK key (8) .

      Note: In order to access the "SERVICE" screen, the password for service must be entered.

   4. When "PASSWORD" screen appears, use the right key (2) and the left key (5) in order to scroll through the characters. When the desired character is highlighted, press the OK key (8). Enter the password for service FFF2 in order to continue to the "SERVICE" screen.

   5. After the password has been entered the "SERVICE" screen should appear. Refer to Illustration 4.

      Note: For more detailed steps with entering passwords or entering the service mode, refer to Testing and Adjusting, "Service Mode - Enter" for the Tool Control System.

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Illustration 4	g01200022
Typical example of the "SERVICE" menu for the monitor

10. Use the down key (6) in order to scroll through the menu options.

11. When the "DEVICE TEST" option is highlighted, press the OK key (8) .

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Illustration 5	g01200028

12. After the OK key is pressed, the "DEVICE TEST" menu should appear.

13. Use the down key (6) in order to scroll through the menu options.

14. When the "POWER SHIFT PRESS" option is highlighted, press the OK key (8) .

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Illustration 6	g01200030

15. Use the down key (6) in order to highlight the value of the power shift pressure.

16. Use the right key (2) in order to decrease the value of the power shift pressure. Use the left key (5) in order to increase the value of the power shift pressure.

    Pressing the left key (5) one time decreases the power shift pressure 10 kPa (1.5 psi). Pressing the right key (2) one time increases the power shift pressure 10 kPa (1.5 psi).

    Note: The value for power shift pressure on the monitor may not always match the pressure reading on the pressure gauge. Adjust the value on the monitor until the desired power shift pressure is attained on the pressure gauge that is connected to the pressure tap for power shift pressure. The actual power shift pressure must be 2900 kPa (420 psi) on the pressure gauge.

    Note: To prevent a change in power shift pressure during the adjustment of the line relief valve for the attachment control valve, do not turn the engine start switch to the OFF position.

    Note: Refer to Systems Operation, "Monitoring System" for the machine for additional information on Service Mode.

17. Set the main relief valve to specifications. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine.

18. Calibrate the power shift pressure. Refer to Testing and Adjusting, "Calibration" for the Machine Electronic Control System.

19. The pressure setting for the top line relief valve and for the bottom line relief valve for the attachment control valve is 37000 ± 1000 kPa (5350 ± 145 psi).

Illustration 7	g01199900
Line relief valve (Typical example) (12) Locknut (13) Adjustment screw

Note: After relief valve adjustments, cancel Service Mode.

Note: Return the main relief valve pressure to the specified setting after testing and adjusting any line relief valve. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine for the main relief valve pressure setting.

Note: To prevent oil flow to the work tool during this testing and adjusting procedure, close the stop valves in the lines for the work tool.

Adjustment of the Line Relief Valve for Attachment Control Valve

1. To adjust the line relief valve pressure setting of the upper work tool, push the thumb wheel on the right joystick FORWARD. Hold the thumb wheel in this position.

2. Check the pressure in the work tool at the drive pump's pressure tap (11) .

3. Return the thumb wheel to the NEUTRAL position.

4. Compare the pressure reading to the specification 37000 ± 1000 kPa (5350 ± 145 psi). If the pressure reading is within the specification, no further adjustment is necessary. If the pressure reading is not within the specification, then proceed to Step 5.

5. Loosen locknut (14) on the line relief valve for the work tool. The relief valve is located on the top side of the main control valve. Turn adjustment screw (15) until the pressure gauge reading at pressure tap (11) is 37000 ± 1000 kPa (5350 ± 145 psi).

6. To adjust the line relief valve pressure setting of the lower work tool, push the thumb wheel on the right joystick BACKWARD. Hold the thumb wheel in this position.

7. Check the pressure in the work tool at pressure tap (11) .

8. Return the thumb wheel to the NEUTRAL position.

9. Compare the pressure reading to the specification 37000 ± 1000 kPa (5350 ± 145 psi). If the pressure reading is within the specification, no further adjustment is necessary. If the pressure reading is not within the specification, then proceed to Step 10.

10. Loosen locknut (14) on the line relief valve for the work tool. The relief valve is located on the bottom of the main control valve. Turn adjustment screw (15) until the pressure gauge reading at pressure tap (11) is 37000 ± 1000 kPa (5350 ± 145 psi).

11. After completion of line relief valve adjustment, tighten locknut (14) .

Note: Turning adjustment screw (15) clockwise increases the pressure. Turning adjustment screw (15) counterclockwise decreases the pressure.

Note: Always make final pressure adjustment on pressure rise.

Note: After relief valve adjustments, cancel Service Mode.

Note: Return the main relief valve pressure to the specified setting after testing and adjusting any line relief valve. Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust" for the machine for the main relief valve pressure setting.