420E and 430E Backhoe Loaders Hydraulic and Steering System Caterpillar

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Sudden movement of the machine or release of oil under pressure can cause serious injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.

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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

Illustration 1	g01249933
(1) Hydraulic pump (2) Valve for Torque control (3) Flow compensator valve (4) Signal pressure tap

Signal pressure tap (4) is located on hydraulic pump (1). The Valve for Torque control (2) and flow compensator valve (3) are also located on hydraulic pump (1). Access is gained from the bottom of the machine or access is gained by removing the floorplate.

Note: The Valve for Torque Control (2) is factory set. Adjustment is not recommended.

Illustration 2	g01276781
(5) System pressure tap

The system pressure tap (5) is located on the block for the pump discharge pressure. Access is gained from the bottom of the machine.

Pump discharge pressures are known values. The pump discharge pressures can be tested during two specific conditions.

• low pressure standby

• high pressure stall

Note: Perform these tests in the listed sequence. Do not skip a test and do not perform a test out of the sequence.

Removal of the Floorplate

1. Remove the metal floorplate and the floor mat.
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   Illustration 3	g01249939

2. Remove two bolts (6) and plate (7).
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   Illustration 4	g01249941

3. Remove two bolts (8) and plate (9). Remove floor mat (10).
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   Illustration 5	g01249943

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   Illustration 6	g01249944

4. Remove the six bolts (11) from the perimeter of the floorplate (12). Set the floorplate (12) aside.

   Note: The machine ECM is attached to the bottom of the floorplate. The machine ECM (A) is attached to the floorplate (12).

Pump Checks

1. Install the boom lock.

2. Engage the parking brake. Start the engine. Operate the engine until the engine is in the operating temperature range.

3. Operate the hydraulics until the hydraulic oil is in the operating temperature range of 65° ± 5°C (149.0° ± 9.0°F).

Change in Torque Check

1. Run the engine at 1100 RPM.

2. Move to the backhoe operation position. Lower the stabilizers to the ground. Raise the rear tires slightly off the ground. Lower the loader arms to the ground. Raise the front tires slightly off the ground.

3. Place the backhoe control in the full BOOM DOWN position and stall the circuit.

4. Slowly raise the engine speed to 1400 RPM. Listen for a change in the tone of the engine.

   Note: If a change in the tone is present, the solenoid is being actuated. If there is no change, you may have an electrical problem, a hydraulic problem, or a speed sensor problem.

Checks for the Solenoid

Magnetic Check

1. Run the engine at 1400 RPM.

2. With all levers in the neutral position, check the solenoid for magnetic energy.

   Note: If the solenoid acts as a magnet, the solenoid is functioning. If the solenoid is not acting as a magnet, check the voltage from the ECM. If there is no voltage, use Caterpilliar ET for the diagnosis.

Double Stall Test (High Torque Mode)

When you perform the double stall test (high torque mode) and the double stall test (low torque mode), you are testing the 263-5516 Solenoid Valve Gp. There should be a difference between the cycle times for the double stall test (high torque mode) and the double stall test (low torque mode).

1. Engage the parking brake or ensure that the parking brake is still engaged.

2. Place the transmission in the NEUTRAL position.

3. Start the engine. Operate the engine until the engine is in the operating temperature range. Operate the hydraulics until the hydraulic oil is in the operating temperature range of 65° ± 5°C (149.0° ± 9.0°F).

4. Check the engine RPM at LOW idle and check the engine RPM at HIGH idle.
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   Illustration 7	g01250554

5. Install the brake pedal lock between the brake pedals. Depress the service brake pedals.

6. Disengage the parking brake. Rotate the transmission lever to the third speed position.

7. Move the accelerator lever to the HIGH idle position.

8. Place the transmission direction control lever in the FORWARD position. Keep the service brake pedals depressed.

9. Check the engine RPM. From HIGH idle, a reduction of approximately 200 RPM is typical.

10. For a parallel lift machine, place the loader control in the full TILT BACK position and stall the circuit. At the same time, raise the loader arms. The engine RPM will decrease an additional 300 RPM to 500 RPM. The approximate total reduction in the engine RPM will be 500 RPM to 700 RPM.

11. For a single tilt machine, place the loader control in the full DUMP position and stall the circuit. At the same time, raise the loader arms. The engine RPM will decrease an additional 300 RPM to 500 RPM. The approximate total reduction in the engine RPM will be 500 RPM to 700 RPM.

12. The reduction in the engine RPM will be different for each sales model.

13. Repeat Step 11 or repeat Step 12 in order to verify the engine rpm.

    Note: The reduction in engine speed signifies that there is high demand for torque from the hydraulic pump on the engine. The reduction in engine speed indicates that the solenoid is actuating correctly.

14. Lower the loader to the ground. Place the transmission direction control lever in the NEUTRAL position. Move the accelerator lever to the LOW idle position. Release the service brake pedals. Engage the parking brake.

15. Move to the backhoe operation position. Lower the stabilizers to the ground. Raise the rear tires slightly off the ground. Lower the loader arms to the ground. Raise the front tires slightly off the ground.

16. If necessary, raise the boom. Engage the boom lock. Move the bucket fully to the BUCKET CLOSE position.

17. Move the stick fully to the STICK IN position.

18. Move the accelerator lever to the HIGH idle position.

19. Stall the joystick in the BUCKET CLOSE position. At the same time, move the joystick to the STICK OUT position.

20. Document the cycle time that is needed in order to move from the full STICK IN position to the full STICK OUT position. The cycle time should be between 3 seconds and 3.5 seconds.
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    Table 2

    Stick Cycle Time
    Sales Model	Time
    420E	3.2 Seconds
    430E	3.9 Seconds

21. Repeat Step 20 and Step 21 three to five times. Calculate the average cycle time.

22. Release the joystick for the bucket. Move the stick fully to the STICK IN position. Engage the boom lock. Move the accelerator lever to the LOW idle position. Stop the engine.

Double Stall Test (Low Torque Mode)

1. Disconnect the harness from the solenoid on the pump.

2. Engage the parking brake or ensure that the parking brake is still engaged.

3. Place the transmission in the NEUTRAL position.

4. Start the engine. Operate the engine until the engine is in the operating temperature range. Operate the hydraulics until the hydraulic oil is in the operating temperature range of 65° ± 5°C (149.0° ± 9.0°F).

5. Check the engine RPM at LOW idle and check the engine RPM at HIGH idle.
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   Illustration 8	g01250554

6. Install the brake pedal lock between the brake pedals. Depress the service brake pedals.

7. Disengage the parking brake. Rotate the transmission lever to the third speed position.

8. Move the accelerator lever to the HIGH idle position.

9. Place the transmission direction control lever in the FORWARD position. Keep the service brake pedals depressed.

10. Check the engine RPM. From HIGH idle, a reduction of approximately 150 RPM to 200 RPM is typical.

11. For a parallel lift machine, place the loader control in the full TILT BACK position and stall the circuit. At the same time, raise the loader arms. The engine RPM will decrease an additional 100 RPM to 200 RPM. The approximate total reduction in the engine RPM will be 250 RPM to 400 RPM.

12. For a single tilt machine, place the loader control in the full DUMP position and stall the circuit. At the same time, raise the loader arms. The engine RPM will decrease an additional 100 RPM to 200 RPM. The approximate total reduction in the engine RPM will be 250 RPM to 400 RPM.

13. The reduction in the engine RPM will be different for each sales model.

14. Repeat Step 11 or repeat Step 12 in order to verify the engine rpm.

    Note: Compare the reduction in engine speed to the high torque mode. The engine speed signifies that there is lower torque demand on the engine from the hydraulic pump .

15. Place the transmission direction control lever in the NEUTRAL position. Move the accelerator lever to the LOW idle position. Release the service brake pedals. Engage the parking brake.

16. Move to the backhoe operation position. Lower the stabilizers to the ground. Raise the rear tires slightly off the ground. Lower the loader arms to the ground. Raise the front tires slightly off the ground.

17. If necessary, raise the boom. Engage the boom lock. Move the bucket fully to the BUCKET CLOSE position.

18. Move the stick fully to the STICK IN position.

19. Move the accelerator lever to the HIGH idle position.

20. Stall the joystick in the BUCKET CLOSE position. At the same time, move the joystick to the STICK OUT position.

21. Document the cycle time that is needed in order to move from the full STICK IN position to the full STICK OUT position. The cycle time should be between 5 seconds and 6 seconds.

22. Repeat Step 20 and Step 21 three to five times. Calculate the average cycle time.

23. Release the joystick for the bucket. Move the stick fully to the STICK OUT position. Lower the boom to the ground. Move the accelerator lever to the LOW idle position. Stop the engine.

Compare the cycle times for the double stall test (high torque mode) and the double stall test (low torque mode). There should be a difference between the cycle times for the double stall test (high torque mode) and the double stall test (low torque mode). If there is no difference between the cycle times for the double stall test (high torque mode) and the double stall test (low torque mode), replace the 263-5516 Solenoid Valve Gp.

Check for an Increase in Pump Pressure with the Torque Setting.

1. Stop the engine. Release the pressure in the hydraulic system.

2. Install the 8T-0860 Pressure Gauge to the pump. Attach one 177-7860 Hose As to the test port for the pump discharge pressure (5). Attach the second end of the hose assembly to the pressure gauge.

3. Start the engine. Run the engine at HIGH IDLE.

4. Move to the backhoe operation position. Lower the stabilizers to the ground. Raise the rear tires slightly off the ground. Lower the loader arms to the ground. Raise the front tires slightly off the ground.

   Note: Ensure that the boom lock is installed.

5. Place the backhoe control in the full BOOM DOWN position and stall the circuit.

6. Read the pressure at system pressure tap (5).

7. Move the control lever to the neutral position.

8. Run the engine at LOW idle. Stop the engine.

9. Disconnect the harness from the solenoid on the pump.

10. Repeat Step 3 to Step 8. The new pressure should be 1000 kPa (145 psi) lower.

    Note: If the pressure is not lower, the solenoid may have a hydraulic problem.

If all three checks fail, replace the 263-5516 Solenoid Valve Gp.

Margin Pressure Test

1. Stop the engine. Release the pressure in the hydraulic system.

2. Install the 1U-5793 Pressure Differential Gauge gauge to the pump. Attach one 177-7860 Hose As to the test port for the pump discharge pressure (5). Attach the second end of the hose assembly to the differential pressure gauge.

3. Attach another hose assembly to the test port for the load signal circuit (4). Attach the second end of the hose assembly to the differential pressure gauge.

4. Start the engine. Run the engine at 1200 RPM.

5. Turn the steering wheel fully to the right. Keep turning the steering wheel.

6. Read the pressure on the differential pressure gauge. The pressure should be 2150 kPa to 2450 kPa (312 psi to 355 psi).

7. Return the steering wheel to the centered position.

8. In order to verify the pressure, repeat Step 5, and Step 6.

9. Run the engine at LOW idle. Stop the engine.

10. If the pressure is correct, proceed to the "Flow Test for the Torque Limiter Control Valve". If the pressure is incorrect, adjust the flow compensator valve (3).

Flow Test for the Torque Limiter Control Valve

Note: In order to perform this test, the pump discharge pressure should be 24800 kPa to 25800 kPa (3597 psi to 3742 psi). Refer to Testing and Adjusting , KENR7656, "420E Backhoe Loader Hydraulic and Steering System ", "Relief Valve (Backhoe) - Test and Adjust".

1. Refer to Illustration 1 and Illustration 2. Remove the 1U-5793 Pressure Differential Gauge from the hoses. Remove the hose from the test port for the load signal circuit (4). Attach one 8T-0860 Pressure Gauge to the test port for the pump discharge pressure (5).

2. Position the 4C-9910 Portable Hydraulic Tester (13) so that you can read the gauges and so that you can attach fittings.

3. Install a 6K-6307 O-Ring Seal to the 8V-7764 O-Ring Adapter. Install the O-ring adapter to the right port on the 4C-9910 Portable Hydraulic Tester.

4. Install a 5P-7701 O-Ring Seal to the larger end of the 6V-8716 Connector connector. Install the connector to the 8V-7764 O-Ring Adapter.

5. Connect the 298-4007 Hose to the O-Ring Face Seal of the 6V-8716 Connector.

   Note: Use SAE -12 hose for lines between the valve and the Portable hydraulic tester

6. Repeat Step 3 through Step 5 on the left side port of the 4C-9910 Portable Hydraulic Tester.

7. Release the pressure in the hydraulic system.
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   Illustration 9	g01433039
   Bank valve for the backhoe

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   Illustration 10	g01433061
   Stick valve

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   Illustration 11	g01433040
   Hose for the rod end of the stick

8. Disconnect the hose for the rod end of the stick from the 148-8328 Connector on the bank valve. Use the 6V-9509 Plug in order to plug the hose from the rod end of the stick. Remove the 148-8328 Connector As from the bank valve.
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   Illustration 12	g01433041
   A port on the stick valve

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   Illustration 13	g01433080
   Line to tester

9. Install a 148-8327 Connector As to the A port on the stick valve. Connect the 148-8327 Connector As to the hose from the inlet of the Portable Hydraulic Tester.
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   Illustration 14	g01433065

10. Disconnect the hose for the head end of the stick from the 148-8341 Connector As. Use the 6V-9510 Plug in order to plug the hose from the head end of the stick. Remove the 148-8341 Connector As from the B port of the stick valve.
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    Illustration 15	g01433072

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    Illustration 16	g01433078
    Line to tester

11. Install a 148-8327 Connector As to the B port of the Stick Valve . Connect the 148-8327 Connector As to the hose from the outlet of the Portable Hydraulic Tester.

12. Release the pressure in the hydraulic system.

13. Ensure that the harness is disconnected from the solenoid on the pump.

14. Close the flow meter. Start the engine.

15. Move the accelerator lever to 1200 ± 50 RPM.

16. Move the stick joystick fully to the STICK OUT position. The discharge pressure should be 23500 to 24800 kPa (3400 to 3600 psi).

17. If the discharge pressure is incorrect, refer to Service Magazine, SEPD0955, 25, August 2008, "A New Relief Valve Is Now Available" and Systems Operation and Testing and Adjusting, RENR6480, "420E, 430E, 432E, 434E, 442E and 444E Backhoe Loaders Hydraulic and Steering System ", "Relief Valve (Backhoe) - Test and Adjust" for the procedure to set the discharge pressure. Make sure that the discharge pressure is correct before continuing to Step 18.

18. Open the flow meter.

19. Start the engine. Move the stick joystick fully to the STICK OUT position.

20. Move the accelerator lever to 2100 ± 50 RPM.

    Note: Use a tachometer or Electronic Technician (ET) in order to set the engine speed. Engine speed is a critical parameter of the procedure.

21. Operate the hydraulics until the 4C-9910 Portable Hydraulic Tester indicates an operating temperature of 65° ± 1°C (149° ± 2°F).

22. Adjust the needle valve so that the discharge pressure on the pressure gauge at test port (5) is 11500 ± 300 kPa (1668 ± 44 psi).

23. The display on the 4C-9910 Portable Hydraulic Tester should indicate a flow that is listed in Table 4. This is the low torque setting.
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    Table 4

    Low Torque Setting
    Pump	Minimum Flow	Target Flow	Maximum Flow
    267-2755	80 L/min (21 US gpm)	93 L/min (25 US gpm)	115 L/min (30 US gpm)
    340-6184	100 L/min (26 US gpm)	113 L/min (30 US gpm)	135 L/min (36 US gpm)

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    Illustration 17	g01270026
    Torque Limiter Control Valve on the bottom of pump

24. If the flow in Step 23 is not correct, remove cap (30). Loosen locknut (29). Turn setscrew (32) in order to ensure that inner spring (27) is under no pressure. Do not remove setscrew (32).

25. Loosen locknut (28). Turn setscrew (31).

    Note: Turn setscrew (31) until the target flow rate is reached.

    Note: When you turn the set screw clockwise, the torque is increased. When you turn the set screw counterclockwise, the torque is decreased.

    Note: The low torque setting should be to the specification before proceeding to Step 26.

26. Secure set screw (31) with locknut (28). Connect the harness to the solenoid that is on the pump.

27. Move the stick joystick fully to the STICK OUT position.

28. Set the accelerator to 2100 ± 10 RPM.

    Note: Use a tachometer or Electronic Technician (ET) in order to set the engine speed. Engine speed is a critical parameter of the procedure.

29. Operate the hydraulics until the temperature is 65° ± 1°C (149° ± 2°F).

    Note: The hydraulics may need to cool down.

30. Adjust the needle valve so the discharge pressure is 23000 ± 300 kPa (3350 ± 44 psi).

31. The display on the 4C-9910 Portable Hydraulic Tester should indicate a flow that is listed in Table 5. This is the high torque setting.
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    Table 5

    High Torque Setting
    Pump	Minimum Flow	Target Flow	Maximum Flow
    267-2755	95 L/min (25 US gpm)	105 L/min (28 US gpm)	110 L/min (29 US gpm)
    340-6184	105 L/min (28 US gpm)	115 L/min (30 US gpm)	120 L/min (32 US gpm)

32. If the flow in Step 31 is not correct, adjust set screw (32).

    Note: Turn setscrew (32) until the target flow rate is reached.

33. Secure set screw (32) with locknut (29).

34. Move the accelerator lever to LOW idle. Turn off the engine. Release the pressure in the hydraulic system.

35. Remove all the test equipment.

36. After you complete the tests and the machine is operating within specifications, the machine can be returned to service. If the torque settings are not within specifications after adjustments, replace the 280-7869 Pump Control Valve Gp and repeat the Flow Test for the Torque Limiter Control Valve.

Note: The Valve for Torque Control (2) is factory set. Adjustment is not recommended.