D7E Track-Type Tractor Hydraulic, HVAC, and Electrical Systems Caterpillar

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Hydraulic oil pressure can remain in the hydraulic system on this machine after the engine and pump have been stopped. Serious injury can result if this pressure is not released before any service is done on the hydraulic systems. In order to prevent possible injury, release the hydraulic system pressure before working on any fitting, hose, or hydraulic component. Lower all attachments to the ground before service is started. If the hydraulic system must be serviced, tested, or adjusted with the attachment in the raised position, the attachments and lift cylinders must be supported properly. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made.

Introduction

This test will help the technician determine if the pump is providing the correct pressure to the steering motor. The test will also confirm that one of the two steering loops does not have higher pressure. If one of the steering loops has a higher pressure, the tractor may turn even without a command.

This procedure includes the following tests and the following adjustment procedures:

• "Test Procedure (Steering Loop Pressures)"

• "Test Procedure (Pressures for Crossover Relief and Makeup Valves)"

• "Test Procedure (Mechanical Neutral Position for the Actuator Piston)"

• "Test Procedure (Neutral Position for the Steering Pump Control Valve)"

• "Adjustment Procedure (Main Relief Valve)"

• "Adjustment Procedure (Crossover Relief and Makeup Valve)"

• "Adjustment Procedure (Mechanical Neutral Adjustment)"

• "Adjustment Procedure (Neutral Position for the Steering Pump Control Valve)"

Required Tools

Illustration 1	g01623868
Tooling (B)

Illustration 2	g01623860
Tooling (C)

Illustration 3	g01869097
Tooling (D)

Illustration 4	g01784963
Tooling (F)

Machine Preparation

1. Move the machine to a smooth horizontal location.

2. Place the steering control lever in the NEUTRAL position.

3. Engage the parking brake.

4. Lower the attachments to the ground.

5. Stop the engine.

6. Turn the key to the ON position, but do not start the engine.

7. Verify that the implement lockout switch is in the UNLOCKED position.

8. Move the control levers through the full range of travel several times. This will relieve any pressure that may be present in the implement hydraulic system.

9. Make sure that the pressure in the entire hydraulic system has been released.

10. Turn the key to the OFF position.

11. Observe the state of the amber hazardous voltage present lamp. If the lamp is illuminated, do not perform any type of service on the machine. Wait until the lamp is not illuminated. Then, perform the lamp test in the next step.

12. While you observe the lamp, turn the disconnect switch to the OFF position. Then turn the disconnect switch to the ON position.

    Note: When the disconnect switch is cycled, the amber hazardous voltage present lamp will illuminate briefly. Then, the lamp will turn off. This indicates that the operation of the lamp is correct.

13. If an error message for the lamp circuit is displayed, or if the operation of the hazardous voltage present lamp does not appear to be correct, refer to the Troubleshooting, "General Information" section of the manual for information on troubleshooting the lamp circuit.

14. Once the hazardous voltage level has been verified to be below 50.0 VDC, the machine can be serviced. Proceed to the next step.

15. Locate the test port for the right steering loop (HD) and the test port for the left steering loop (HC) . The test ports are located on the right side of the tractor behind the access door.

    Note: Tread plate (1) can be removed in order to improve access to some test ports.

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Illustration 5	g01942918

16. Open access door (2) .

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Illustration 6	g01942914
Right side view of steering pump (HD) Test port ("MB") (HC) Test port ("MA")

17. Attach one set of Tooling (B) or (C) to test port (HD) ("MB").

18. Attach one set of Tooling (B) or (C) to test port (HC) ("MA").

Test Procedure (Steering Loop Pressures)

1. Start the engine. Warm the hydraulic oil to a minimum temperature of 65 °C (150 °F).

2. Engage the parking brake.

3. Operate the engine at HIGH IDLE. Place all controls in the HOLD position.

4. The pressure at both test ports should be 2850 ± 100 kPa (415 ± 15 psi).

5. Fully depress the travel control pedal. The transmission must be in NEUTRAL. The steering control lever must be in the NEUTRAL position. Release the parking brake.

6. While the engine is operating at HIGH IDLE, slowly move the steering control lever to the MAXIMUM STEER RIGHT position. The steering system is in the STEER STALL CONDITION.

   Note: Do not hold the machine in a STEER STALL CONDITION for more than 5 seconds at a time.

   Note: The machine must not move. If the machine moves, check the brake system.

7. With the machine in a STEER STALL CONDITION, record the pressure in the right steering loop at test port (HD) . The pressure at test port (HD) should be 39000 ± 1000 kPa (5655 ± 145 psi).

8. Operate the engine at HIGH IDLE and slowly move the steering control lever to the MAXIMUM STEER LEFT position. The steering system is in the STEER STALL CONDITION.

   Note: Do not hold the machine in a STEER STALL CONDITION for more than 5 seconds at a time.

   Note: The machine must not move. If the machine moves, check the brake system.

9. With the machine in a STEER STALL CONDITION, record the pressure in the left steering loop at test port (HC) . The pressure at test port (HC) should be 39000 ± 1000 kPa (5655 ± 145 psi).

10. If the pressure at (HD) and (HC) are too high, the setting of the POR valve is too high.

11. If the pressure is not within the specified limit, perform the procedure in "Adjustment Procedure (POR Valve)".

Adjustment Procedure (POR Valve)

1. Perform the steps in the "Machine Preparation" and then continue to the following steps.

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Illustration 7	g01711013
Top view of the steering pump (3) POR Valve

2. Locate POR valve (3) on the steering pump.

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Illustration 8	g01098444
(3) POR Valve (4) Adjustment screw (5) Locknut

3. Loosen locknut (5) while you hold adjustment screw (4) in place.

4. Turn adjustment screw (4) in the clockwise direction in order to increase the pressure setting. Turn adjustment screw (4) counterclockwise in order to decrease the pressure setting.

5. Perform the Steps in "Test Procedure (Steering Loop Pressures)" in order to check the pressure setting.

6. When the pressure is within the specified limit, the adjustment procedure is complete.

Test Procedure (Pressures for Crossover Relief and Makeup Valve)

1. Perform the steps in the "Machine Preparation" and then continue to the following steps.

2. Start the engine. Warm the hydraulic oil to a minimum temperature of 65 °C (150 °F).

3. Engage the parking brake.

4. Fully depress the travel control pedal. The transmission must be in NEUTRAL. The steering control lever must be in the NEUTRAL position. Release the parking brake.

5. Operate the engine at HIGH IDLE and slowly move the steering control lever to the MAXIMUM STEER RIGHT position. The steering system is in the STEER STALL CONDITION.

   Note: Do not hold the machine in a STEER STALL CONDITION for more than 5 seconds at a time.

   Note: The machine must not move. If the machine moves, check the brake system.

6. Repeat Step 5 in a MAXIMUM STEER LEFT condition.

7. If the engine speed drops more than 30 rpm from HIGH IDLE in one direction or both directions during Steps 5 and 6, the corresponding crossover relief and makeup valve may be leaking or set too low.

8. Perform the procedure in "Adjustment Procedure (Crossover Relief and Makeup Valve)".

Adjustment Procedure (Crossover Relief and Makeup Valve)

Note: The crossover relief and makeup valve can not be adjusted on the machine. Use the following procedure to adjust this valve.

Bench Test

The crossover relief and makeup valve has a setting that is higher than the main relief valve for the steering. The valve cannot be adjusted on the machine.

Use the 9U-5829 Manifold to test the crossover relief and makeup valve on the test bench. The setting for the valve is 46000 ± 1000 kPa (6670 ± 145 psi) under the following conditions:

• SAE 10W hydraulic oil

• 65°C (150°F)

• Flow rate between 20 to 100 L/min (5 to 26 gpm)

If the crossover relief and makeup valve is not within the specifications, use the adjustment screw to change the pressure setting until the specifications are met.

Test Procedure (Mechanical Neutral Position for the Actuator Piston)

1. Perform the steps in the "Machine Preparation" and then continue to the following steps.

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Illustration 9	g03891513
Right side view of steering pump (HD) Test port ("MB") (HC) Test port ("MA") (6) Test port ("X1") (7) Test port ("X2")

2. Remove the plugs in test port (6) and (7) . Install one end of Tooling (D) into test port (6) ("X1"). Install the other end of Tooling (D) into test port (7) ("X2").

Note: Test port (6) ("X1") is signal pressure for the right steering loop. Test port (7) ("X2") is signal pressure for the left steering loop.

3. Attach one set of Tooling (B) or (C) to test port (HD) ("MB").

4. Attach one set of Tooling (B) or (C) to test port (HC) ("MA").

5. Start the engine. Warm the hydraulic oil to a minimum temperature of 65 °C (150 °F).

6. Engage the parking brake.

7. Operate the engine at HIGH IDLE. Place all controls in the HOLD position.

8. Check the pressures at test port (HD) and (HC) . The pressures should be within 345 kPa (50 psi) of each other.

9. If the pressures are within the specified limit, the test is complete.

10. If the pressures are not within the specified limit, perform the procedure in "Adjustment Procedure (Mechanical Neutral Adjustment)".

Adjustment Procedure (Mechanical Neutral Adjustment)

The following procedure centers the actuator piston in the steering pump. When the actuator piston is not centered, the machine will pull to the left or to the right when the steering control lever is in the NEUTRAL position.

This adjustment is usually only required for a rebuilt steering pump.

1. Perform the procedure in "Test Procedure (Mechanical Neutral Position for the Actuator Piston)".

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Illustration 10	g01515456
(8) Adjustment screw (9) Locknut

2. Locate adjustment screw (8) on the steering pump.

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Illustration 11	g01515514
(8) Adjustment screw (9) Locknut

3. Loosen locknut (9) while you hold adjustment screw (8) in place.

4. Turn adjustment screw (8) clockwise or turn adjustment screw (8) counterclockwise until the pressures at port (HC) and (HD) are within 345 kPa (50 psi) of each other.

5. If the pressures at port (HC) and (HD) can not be brought within 345 kPa (50 psi) of each other, perform the procedure in "Adjustment Procedure (Neutral Position for the Steering Pump Control Valve)".

6. When the pressures are within the specified limit, the adjustment procedure is complete.

Test Procedure (Neutral Position for the Steering Pump Control Valve)

1. Check the pressure of the charge pressure oil before adjusting the neutral position of the steering pump control valve. Also, perform the adjustment procedure for the mechanical neutral position for the actuator piston. This will ensure that the mechanical neutral position of the swashplate is correct.

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Illustration 12	g01942921
Right side view of steering pump (HD) Test port ("MB") (HC) Test port ("MA") (6) Test port ("X1") (7) Test port ("X2")

2. Install one set of tooling (F) into test port (6) ("X1"). Install another set of tooling (F) into test port (7) ("X2").

3. Attach two sets of Tooling (B) or (C) to Tooling (F) .

4. Disconnect the control wires from the solenoids on the steering pump.

   Note: When the control wires are disconnected from the solenoids, the tractor may generate several diagnostic codes. The codes can be ignored at this time. When the control wires are reconnected to the solenoids, the diagnostic codes should reset automatically.

5. Start the engine. Warm the hydraulic oil to a minimum temperature of 65 °C (150 °F).

6. Engage the parking brake.

7. Operate the engine at HIGH IDLE. Place all controls in the HOLD position.

8. Check the pressure at test port (X1) and (X2) . Both readings should be within 48 kPa (7 psi) of each other.

9. If the pressures are not within the specifications, perform the procedure in "Adjustment Procedure (Neutral Position for the Steering Pump Control Valve)".

Adjustment Procedure (Neutral Position for the Steering Pump Control Valve)

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Illustration 13	g01515531
(10) Locking screw (11) Eccentric adjustment screw

1. Locate eccentric adjustment screw (11) on the steering pump.

   Note: One-half revolution of eccentric adjustment screw (11) is the maximum adjustment. A small amount of movement of the screw makes a large pressure difference.

2. Loosen locking screw (10) while you hold eccentric adjustment screw (11) .

3. Turn eccentric adjustment screw (11) until the pressures at test port (X1) and (X2) are within 48 kPa (7 psi) of each other.

4. When the pressures at test port (X1) and (X2) are within 48 kPa (7 psi) of each other, tighten locking screw (10) . Make sure that you hold eccentric adjustment screw (11) while you tighten locking screw (10) .

5. When the pressures at test port (X1) and (X2) are within 48 kPa (7 psi) of each other, the adjustment procedure is complete.

6. If the control valve can not be adjusted, the control valve must be replaced or repaired.

7. Remove all tooling from the machine and reconnect the control wires to the solenoids.

   Note: When the control wires are disconnected from the solenoids, the tractor may generate several diagnostic codes. The codes can be ignored at this time. When the control wires are reconnected to the solenoids, the diagnostic codes should reset automatically.

Worksheet