2003/08/04 Caterpillar

Correction to the Service Manual , "Pressure Limiter Valve - Test and Adjust " {5069, 5070, 5117}

Usage:

Asphalt Paver: AP-1055B (S/N: ABB1-UP; 8BM1-UP) BG-2455C (S/N: ACM1-UP; 6TN1-UP)

Service Manual, KENR5013, "Caterpillar AP-1055B and Barber Greene BG-2455C Asphalt Pavers Propel System", "Charge Relief Valve - Test and Adjust". The procedure is used to record the gauge pressure for the pump charge relief valve for the right propel pump and for the left propel pump.

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Illustration 1	g01014653

(1) Control valve
(2) Coil
(3) Nut

Remove nut (3) and slide the coil (2) off the stem of the brake solenoid. The solenoid can be identified by two wires.
- 307-br
- 202-br

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Illustration 2	g01014663
Pump Compartment (4) Test port for the right reverse pressure limiter valve (5) Reverse pressure limiter (6) Forward pressure limiter (7) Test port for the right forward pressure limiter valve

Note: The right propel pump is shown in the photo. With the exception of the orientation of the pump and the test ports, the left propel pump is identical to the right propel pump. Test port (4) on the top of the right propel pump is the reverse test port. The test port on top of the left propel pump is the forward test port. The test ports on the bottom of the propel pumps are also reversed.

Attach one end of the test hose to the gauge and attach the other end of the test hose to test port (7) for the right forward pressure limiter valve.

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Illustration 3	g01014683
Operator Station (8) Maximum propel speed potentiometer (9) Parking brake control (10) Travel/pave/maneuver speed control (11) Throttle control

Start the engine and run the engine. Place throttle control (11) in low idle. Disengage parking brake control (9). Place the travel/pave/maneuver speed control in travel position. Do not start to conduct the test until the hydraulic oil has reached normal operating temperature.

Note: The pressure setting of the forward pressure limiter must be checked with the machine in the stall condition.

Position maximum propel speed potentiometer (8) to the maximum clockwise position.

Place throttle control (11) in high idle in order to increase the engine RPM.

Place the propel lever in full forward position.

Observe the gauge reading. 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 42000 ± 1035 kPa (6090 ± 150 psi).

If the pressure reading is not correct, adjustment is necessary. Locate relief valve (6) directly opposite relief valve test port (7). The adjustment screw requires a 5 mm internal hex wrench. Insert the wrench and loosen the locknut. Turn the adjustment screw in order to obtain the proper pressure.
Note: When you turn the adjustment screw in order to complete one full turn, the pressure limiter setting will change approximately 9300 kPa (1350 psi).

Return all the controls to neutral and lower the engine RPM to low idle.

Stop the engine.

Tighten the locknut to 16 N·m (12 lb ft). Remove the test hose from test port (7) for the right forward pressure limiter valve. Connect the end of the test hose to test port (4) for the right reverse pressure limiter valve.

Start the engine and run the engine.

Place throttle control (11) in high idle in order to increase the engine RPM.

Position the travel/pave/maneuver speed control (10) in the TRAVEL position.

Place the propel lever in the full reverse position.

Observe the gauge reading. This pressure reading is not the correct pressure limiter setting. In order to obtain the correct pressure limiter setting, subtract the pressure reading of the pump charge relief valve that was recorded in a previous procedure. After you subtract the pressure reading of the pump charge relief valve from the pressure from the gauge reading, the pressure limiter setting should be 42000 ± 1035 kPa (6090 ± 150 psi).

If the pressure reading is not correct, adjustment is necessary. Locate relief valve (5) directly opposite relief valve test port (4). The adjustment screw requires a 5 mm internal hex wrench. Insert the wrench and loosen the locknut. Turn the adjustment screw in order to obtain the proper pressure.
Note: When you turn the adjustment screw in order to complete one full turn, the pressure limiter setting will change approximately 9300 kPa (1350 psi).