M312 Excavator Hydraulic System Caterpillar

The engine performance test is done in order to verify that the engine is able to meet the hydraulic horsepower demand.

Table 1

Required Tools
Part Number	Part Description	Qty
123-6471 (1) (2)	Diagnostic Tool Group	1
126-7877	M300 to PC RS-232 Cable	1

( 1 )	123-6472 Portable Diagnostic Tool (PDT) is included in 123-6471 Diagnostic Tool Group .
( 2 )	A laptop computer may be used as a substitute. The laptop computer must use M300 Technician.

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Illustration 1	g00293505
The pressure taps are located in the battery compartment. (1) Main pump pressure (2) Proportional reducing valve pressure (Main pump)

1. Connect a 60000 kPa (8700 psi) pressure gauge to tap (1) .

2. Connect a 4000 kPa (580 psi) pressure gauge to tap (2) .

3. Start the engine.

4. Place the AEC switch in the OFF position and move the heavy lift switch to the OFF position.

M300 Technician

1. Place the engine speed dial at the HIGH IDLE position.

2. Lower the left console.

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Illustration 2	g00852888
Main control valve (4) Locknut (5) Adjustment screw (main relief valve pressure)

3. Loosen locknut (4) .

4. Turn adjustment screw (5) by three full turns counterclockwise.

5. Stall the bucket.

6. Turn adjustment screw (5) clockwise and watch the pressure gauge on pressure tap (1). Continue turning the adjustment screw clockwise until the pressure is 10000 kPa (1450 psi).

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Illustration 3	g00447907
Left side of seat Service connector

7. Connect the laptop computer to the service connector.

   Note: Refer to Special Instruction, REHS0701, "Instructions for the Use of the M300 Technician Software with a Laptop Computer".

8. Start M300 Technician.

9. Select the "Configuration" button.

10. Use the arrow keys to select the "Operation Mode" option.

11. Select the "Change Value" button.

12. Select the "Current Main PRV" option.

13. Select the "OK" button.

14. Select the "Constant Value" option.

15. Select the "Change Value" button.

16. Use the arrow keys to change the numeric value until the pressure on the gauge at tap (2) is approximately 3000 kPa (435 psi). Start with a numeric value of 96.

    Note: Whenever you change the value, you must choose the "OK" button.

17. Select the "Status" button.

18. Verify that "Engine Speed" is shown. If "Engine Speed" is not shown, add "Engine Speed" to the parameter list.

19. Turn the engine speed dial to the HIGH IDLE position and activate Mode II.

20. Move the joystick to the full BUCKET CLOSE position.

21. Turn the adjustment screw on the main relief valve clockwise until the engine speed is approximately 2000 to 2050 rpm.

    Note: The pressure at tap (1) should be a minimum of 19000 to 19500 kPa (2760 to 2830 psi).

    Note: If the pressure is not reached, check the engine.

22. After the engine speed has been checked, return the main relief valve to the original setting.

    Note: Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

Note: In order to return the machine to the normal operation mode, turn the engine start switch to the OFF position and back to the ON position without starting the engine.

Note: Do not use the "Teach" option.

PDT

1. Place the engine speed dial at the HIGH IDLE position.

2. Lower the left console.

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Illustration 4	g00852888
Main control valve (4) Locknut (5) Adjustment screw (main relief valve pressure)

3. Loosen locknut (4) .

4. Turn adjustment screw (5) by three full turns counterclockwise.

5. Stall the bucket.

6. Turn adjustment screw (5) clockwise and watch the pressure gauge on pressure tap (1). Continue turning the adjustment screw clockwise until the pressure is 10000 kPa (1450 psi).

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Illustration 5	g00447907
Left side of seat Service connector

7. Connect the 123-6472 Portable Diagnostic Tool to the service connector.

   Note: Refer to Special Instruction, SEHS9825 for the use of the 123-6471 Diagnostic Tool Group .

8. Select the "F1 Config/Cal" function.

9. Select the "8 Test Operation" function.

10. Select the "Operation Mode" function.

11. Select the "Const" function.

12. Select the "2 Current Adjust" function.

13. Use the arrow keys in order to change the numeric value until the pressure on the gauge is approximately 3000 kPa (435 psi). Start with a numeric value of 96.

14. Select the "PROC STATUS" function.

15. Select the "5 Engine RPM" function that is located on the "Alternate Menu".

16. Turn the engine speed dial to the HIGH IDLE position and activate Mode II.

17. Move the joystick to the full BUCKET CLOSE position.

18. Turn the adjustment screw on the main relief valve clockwise until the engine speed is approximately 2000 to 2050 rpm.

    Note: The pressure at tap (1) should be a minimum of 19000 to 19500 kPa (2760 to 2830 psi).

    Note: If the pressure is not reached, check the engine.

19. After the engine speed has been checked, return the main relief valve to the original setting.

    Note: Refer to Testing and Adjusting, "Relief Valve (Main) - Test and Adjust".

20. Select the "F1 Config/Cal" function.

21. Select the "8 Test Operation" function.

22. Select the "1 Operation Mode" function.

23. Use the arrow keys to select the "Normal Operation" function.

24. Press the "ENTER" button.