AP-655C and BG-2255C Asphalt Pavers Drag Conveyor and Auger Conveyor Systems Caterpillar

Testing and Adjusting the Charge Pressure

Introduction

Note: The charge pressure test and any possible adjustments to the charge pressure needs to be performed before performing any other test and adjustment procedures.

The following test procedure will verify whether the oil pressure that is controlled by the relief valve (charge pressure) is within the specified limit. The relief valve limits the maximum charge pressure in the hydraulic system to the adjusted setting. There is one relief valve for each pump stack. You will need to check each relief valve separately.

Required Tools

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

• Caterpillar DataView

• Appropriate pressure gauges

Caterpillar DataView

Illustration 1	g00920192
Caterpillar DataView

Table 1 provides a list of the required tools if Caterpillar DataView is used to perform the following test procedure. Caterpillar DataView is not shown in the following test procedure.

ReferenceRefer to Tool Operating Manual, NEHS0662, "Caterpillar DataView" for additional information about using Caterpillar DataView.

Standard Tooling

Illustration 2	g00934967

Use the tools in Table 2 to complete the following test procedure.

Test Procedure for the Lower Pump Stack

Illustration 3	g00940171
(1) Upper pump stack (2) Lower pump stack (3) Charge pump

Note: The following test procedure is for testing and adjusting the charge pressure relief valve in lower pump stack (2) . Charge pump (3) is providing charge oil for both pump stacks. This pump is part of upper pump stack (1) .

Lower pump stack (2) provides the oil for the following components:

• Left auger conveyor motor

• Right drag conveyor motor

• Vibratory motor

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Personal injury can result from rotating and moving parts. Stay clear of all rotating and moving parts. Never attempt adjustments while the machine is moving or the engine is running unless otherwise specified. The machine must be parked on a level surface and the engine stopped. Attach a "Do Not Operate" or similar warning tag to the start switch and controls before servicing, repairing, or making adjustments to the machine.

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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. Start the engine. The engine should be at high idle with engine coolant at 37.8 °C (100 °F). Warm the hydraulic oil to a minimum temperature of 37.8 °C (100 °F).

   ReferenceSee Systems Operation/Testing and Adjusting, "General Testing and Adjusting Information" for information on warming the oil.

2. Engage the parking brake.

3. Stop the engine.

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Illustration 4	g00939835

4. Open the access panel for the pump compartment that is on the left side of the machine.

   Note: There is a charge pressure relief valve in each pump stack. You will need to isolate each pump stack from the other pump stack in order to test the pressure setting for each relief valve. This is done by plugging the charge supplement line and capping the pump.

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Illustration 5	g01526576
(2) Lower pump stack (4) Port "M6"

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Illustration 6	g00940528
(5) Hose (charge pressure)

5. Remove hose (5) at port "M6" (4) .

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Illustration 7	g00940535
(4) Port "M6" (B1) Tooling (B2) Tooling

6. Install Tooling (B2) on the fitting in port "M6" (4) and install Tooling (B1) in the hose. This will isolate the charge pressure from upper pump stack (1) . As a result, the charge pressure can now be checked in lower pump stack (2) .

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Illustration 8	g00940884
(5) Charge Filter (6) Pressure Tap (A) Tooling

7. Install Tooling (A) to pressure tap (6) on charge filter (5) .

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

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Illustration 9	g00940902
Drag Conveyor and Auger Conveyor Controls

9. Make sure that all of the following controls are in the OFF position:
   • Left drag conveyor

   • Right drag conveyor

   • Left auger conveyor

   • Right auger conveyor

10. Record the pressure at Tooling (A) . The pressure setting should be 2068 ± 138 kPa (300 ± 20 psi).

11. If the pressure is 2068 ± 138 kPa (300 ± 20 psi), the test is complete for the lower pump assembly.

12. If the pressure is not within the specified limit, perform the procedure in "Adjustment Procedure for the Upper and Lower Pump Stacks".

13. If the test is complete, stop the engine.

14. Remove pressure gauge (A) from pressure tap (6) .

15. Remove Tooling (B1) and (B2) .

16. Reconnect hose (5) at port "M6" (4) .

Test Procedure for the Upper Pump Stack

Illustration 10	g00940171
(1) Upper pump stack (2) Lower pump stack (3) Charge pump

Note: The following test procedure is for testing and adjusting the charge pressure relief valve in upper pump stack (2) . Charge pump (3) is providing charge oil for both pump stacks. This pump is part of upper pump stack (1) .

Upper pump stack (1) provides the oil for the following components:

• Right auger conveyor motor

• Left drag conveyor motor

• Charge pump

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Personal injury can result from rotating and moving parts. Stay clear of all rotating and moving parts. Never attempt adjustments while the machine is moving or the engine is running unless otherwise specified. The machine must be parked on a level surface and the engine stopped. Attach a "Do Not Operate" or similar warning tag to the start switch and controls before servicing, repairing, or making adjustments to the machine.

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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. Start the engine. The engine should be at high idle with engine coolant at 37.8 °C (100 °F). Warm the hydraulic oil to a minimum temperature of 37.8 °C (100 °F).

   ReferenceSee Systems Operation/Testing and Adjusting, "General Testing and Adjusting Information" for information on warming the oil.

2. Engage the parking brake.

3. Stop the engine.

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Illustration 11	g00939835

4. Open the access panel for the pump compartment that is on the left side of the machine.

   Note: There is a charge pressure relief valve in each pump stack. You will need to isolate each pump stack from the other pump stack in order to test the pressure setting for each relief valve. This is done by plugging the charge supplement line and capping the pump.

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Illustration 12	g01526580
(1) Upper pump stack (6) Port "M6"

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Illustration 13	g01526588
(2) Lower pump stack (4) Port "M6"

5. Remove the hose at port "M6" (4) on lower pump stack (2) .

6. Install Tooling (B1) in the hose.

7. Install Tooling (B2) in port "M6" (4) .

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Illustration 14	g00940884
(5) Charge Filter (6) Pressure Tap (A) Tooling

8. Install Tooling (A) to pressure tap (6) on charge filter (5) .

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

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Illustration 15	g00940902
Drag Conveyor and Auger Conveyor Controls

10. Make sure that all of the following controls are in the OFF position:
    • Left drag conveyor

    • Right drag conveyor

    • Left auger conveyor

    • Right auger conveyor

11. Record the pressure at Tooling (A) . The pressure setting should be 2068 ± 138 kPa (300 ± 20 psi).

12. If the pressure is 2068 ± 138 kPa (300 ± 20 psi), the test is complete for the lower pump assembly.

13. If the pressure is not within the specified limit, perform the procedure in "Adjustment Procedure for the Upper and Lower Pump Stacks".

14. If the test is complete, stop the engine.

15. Remove pressure gauge (A) from pressure tap (6) .

16. Remove Tooling (B1) from the hose.

17. Remove Tooling (B2) from port "M6" (4) .

18. Reconnect the hose at port "M6" (4) .

Adjustment Procedure for the Upper and Lower Pump Stacks

Note: The following adjustment procedure is for both pump stacks. Find the relief valve on the pump stack that needs to be adjusted.

Illustration 16	g01526590
(8) Adjustment Screw (9) Locknut

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Illustration 17	g00941147

1. Loosen the locknut (9) on the charge pressure relief valve.

Note: When you turn adjustment screw (8) clockwise, this will increase the pressure setting. When you turn the adjustment screw counterclockwise, this will decrease the pressure setting.

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Illustration 18	g00940884
(5) Charge Filter (6) Pressure Tap (A) Tooling

Note: Tooling (A) (Pressure Gauge) should still be connected at pressure tap (6) .

2. Hold locknut (9) and turn adjustment screw (8) in the clockwise direction in order to increase the pressure. Hold the locknut (9) and turn the screw in the counterclockwise direction in order to decrease the pressure. A 1/4 turn will change the pressure by 276 kPa (40 psi). The correct pressure setting is 2068 ± 138 kPa (300 ± 20 psi).

3. Tighten locknut (9) to a torque of 46 to 57 N·m (34 to 42 lb ft). Check the pressure again.

4. Stop the engine.

5. After the adjustment procedure is performed, remove the tooling from the pump and the hoses.

6. Start the engine.

7. Check the auger conveyor and the drag conveyor. Make sure that both conveyors are operating correctly.