AP-655C and BG-2255C Asphalt Pavers Propel System Caterpillar

Testing and Adjusting the Pressure Limiter Valve

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Do not operate or work on this machine unless you have read and understand the instructions and warnings in the Operation and Maintenance Manual. Failure to follow the instructions or heed the warnings could result in injury or death. Contact any Caterpillar dealer for replacement manuals. Proper care is your responsibility.

Illustration 1	g00930412
There are two identical piston pumps (propel) on the machine. The propel pumps are located on the left side of the machine in the pump compartment.

The following procedure will use the left propel pump. This procedure should be performed on both of the propel pumps.

Introduction

The pressure limiter acts to rapidly destroke the pump in order to limit the system pressure. The pressure limiter acts as a pilot for the high pressure relief valve spool. The pressure limiter is built into the multifunction valve on the pump.

Required Tools

Hydraulic test procedures may be performed using either one of the following test equipment:

• Caterpillar DataView

• Standard Pressure Gauges

Caterpillar DataView Tool

Illustration 2	g00920192
Caterpillar DataView Caterpillar DataView is a PC based diagnostic tool. The Caterpillar DataView accepts a maximum of nine standard Caterpillar sensors for measurements on the machine. The signal is transmitted to a personal computer and the information is displayed.

The following table provides a list of the required tools if Caterpillar DataView is used in order to perform the following test procedure. Caterpillar DataView is not shown in the following test procedure.

Standard Tools

Illustration 3	g00988537
Gauges and Couplers

Test Procedure for Forward Direction

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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.

1. Perform the following procedure before you follow the test procedure:
   • Park the machine on a level area that is clear from equipment and material.

   • Verify that the service brake system and the parking brake system are in good working condition.

   • Move the propel lever to the neutral position.

   • Apply the parking brake.

   • Make sure that the hydraulic oil is at the correct operating temperature.

2. Assemble 8T-0861 Pressure Gauge (A1) with the proper fittings from the 6V-4157 Hydraulic Test Fitting Gp .

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Illustration 4	g00931884
The hydraulic pumps are located on the left side of the machine in the pump compartment. (1) Left propel pump (2) Right propel pump (3) Port "M2" for the left propel pump "REVERSE" (4) Port "M1" for left propel pump "FORWARD" (5) Port "M1" for right propel pump "FORWARD" (6) Port "M2" for right propel pump "REVERSE"

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Illustration 5	g00988549
Left Propel Pump (1) Left propel pump (4) Port "M1" for left propel pump "FORWARD"

3. Attach 8T-0861 Pressure Gauge (A) to Port "M1" (4) on left propel pump (1) .

   Note: Port "M1" will reflect the pressure for "FORWARD" travel. The flow output is from Port "B".

Note: For this test, the ECM must be overridden before you start the engine.

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Illustration 6	g00953890
Left Side of the Machine

4. Locate the auxiliary bank valve. The auxiliary manifold is located on the left side of the machine behind the rear access door. The auxiliary manifold is located on the right upper side of the hydraulic tank.

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Illustration 7	g00988624
Left Side of the Machine

5. Locate the coil for the parking brake solenoid valve. Loosen the retaining nut. Remove the coil from the valve stem. This will disable the parking brake during this test.

6. Start the engine. Run the engine at high idle.

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Illustration 8	g00989005
Operator Station (7) Speed control switch (8) TRAVEL position (9) Parking brake control (10) Throttle control switch (11) High idle position (12) Propel lever (13) Propel speed potentiometer

7. Ensure that parking brake control (9) is in the DISENGAGED position.

8. Move speed control switch (7) to TRAVEL position (8) .

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Illustration 9	g00989014
Operator Station (13) Propel speed potentiometer (14) Minimum setting

9. Move propel speed potentiometer (13) counterclockwise to minimum setting (14) .

10. You will need to monitor Tooling (A) during this test. As the pump goes on full stroke, record the readings.

11. Move propel lever (12) fully forward.

12. Turn propel speed potentiometer (13) slowly in the clockwise direction. Continue until the pump goes on full stroke. There will be a distinct sound from the pump compartment as the pump goes on full stroke.

13. Observe the gauge reading at Port "M1" (4) . This pressure reading is not the correct pressure limiter setting. In order to obtain the correct pressure limiter setting, subtract the pressure reading from the pump charge relief valve that was recorded in a previous procedure. After you subtract the pressure reading from the gauge reading, the pressure limiter setting should be 37300 ± 1400 kPa (5410 ± 200 psi).

14. If the pressure at Port "M1" (4) is not within these limits, an adjustment needs to be made.

Adjustment Procedure for Forward Direction

1. Locate the multifunction valves on the side of left propel pump (1) . The multifunction valves are located on both sides of the charge inlet and charge outlet coupler.

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Illustration 10	g01208077
Left Propel Pump (21) Adjustment locknut (22) Adjustment screw FORWARD (23) Adjustment locknut (24) Adjustment screw REVERSE

2. Loosen adjustment locknut (21) .

3. Use an allen wrench in order to adjust FORWARD adjustment screw (22) . Turning the adjustment screw clockwise will increase the pressure. Turning the adjustment screw counterclockwise will decrease the pressure. One revolution is equal to approximately 9300 kPa (1350 psi). Turn FORWARD adjustment screw (22) until the pressure at Port "M1" (4) reads 37300 ± 1400 kPa (5410 ± 200 psi).

4. Tighten adjustment locknut (21) as you hold FORWARD adjustment screw (22) in place.

5. Shut off the engine.

6. Repeat this procedure for the FORWARD direction on the right propel pump.

Test Procedure for Reverse Direction

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Illustration 11	g00931884
The hydraulic pumps are located on the left side of the machine in the pump compartment. (1) Left propel pump (2) Right propel pump (3) Port "M2" for the left propel pump "REVERSE" (4) Port "M1" for left propel pump "FORWARD" (5) Port "M1" for right propel pump "FORWARD" (6) Port "M2" for right propel pump "REVERSE"

1. 8T-0861 Pressure Gauge (A) should still be attached to Port "M2" (3) on left propel pump (1) .

   Note: Port "M2" will reflect the pressure for "REVERSE" travel. The flow output is from Port "A".

2. Start the engine. Run the engine at high idle.

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Illustration 12	g00989005
Operator Station (7) Speed control switch (8) TRAVEL position (9) Parking brake control (10) Throttle control switch (11) High idle position (12) Propel lever (13) Propel speed potentiometer

3. Ensure that parking brake control (9) is in the DISENGAGED position.

4. Move speed control switch (7) to TRAVEL position (8) .

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Illustration 13	g00989014
Operator Station

5. Move propel speed potentiometer (13) counterclockwise to minimum setting (14) .

6. You will need to monitor Tooling (A) during this test. As the pump goes on full stroke, record the readings.

7. Move propel lever (12) fully to the REVERSE position.

8. Turn propel speed potentiometer (13) slowly in the clockwise direction. Continue until the pump goes on full stroke. There will be a distinct sound from the pump compartment as the pump goes on full stroke.

9. Observe the gauge reading at Port "M2" (3) . This pressure reading is not the correct pressure limiter setting. In order to obtain the correct pressure limiter setting, subtract the pressure reading from the pump charge relief valve that was recorded in a previous procedure. After you subtract the pressure reading from the gauge reading, the pressure limiter setting should be 37300 ± 1400 kPa (5410 ± 200 psi).

10. If the pressure at Port "M2" (3) is not within these limits, an adjustment needs to be made.

Adjustment Procedure for Reverse Direction

1. Locate the multifunction valves on the side of left propel pump (1) .

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Illustration 14	g00932436
Left Propel Pump (21) Adjustment locknut (22) Adjustment screw FORWARD (23) Adjustment locknut (24) Adjustment screw REVERSE

2. Loosen adjustment locknut (23) .

3. Use an allen wrench in order to adjust REVERSE adjustment screw (24) . Turning the adjustment screw clockwise will increase the pressure. Turning the adjustment screw counterclockwise will decrease the pressure. One revolution is equal to approximately 9300 kPa (1350 psi). Turn REVERSE adjustment screw (22) until the pressure at Port "M2" (3) reads 37300 ± 1400 kPa (5410 ± 200 psi).

4. Tighten adjustment locknut (23) as you hold REVERSE adjustment screw (24) in place.

5. Shut off the engine.

6. Return all controls to normal operation.

7. Remove Tooling (A) from the machine.

8. Repeat this procedure for the REVERSE direction on the right propel pump.

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Illustration 15	g00988624
Left Side View of the Machine

9. Install the coil for the parking brake solenoid valve. Put the coil on the valve stem. Tighten the retaining nut.

10. Ensure that parking brake control (9) is operational.