GUARD FOOT LH 0822569 - Caterpillar

TECHNICAL INFORMATION BULLETIN November 10, 2004
PAVING PRODUCTS AP-650B (9DN)
AP-1000B (7HN)
AP-1050B (6ZN)
AP-1055B (8BM,ABB)
BG-225C (5GN)
BG-260C (8GN)
BG-2455C (6TN,ACM)
BG-245C (4XN)
Component Code(s) 6631SUBJECT: FEEDER SYSTEM DIAGNOSIS ON ASPHALT PAVERS
PROBLEM:
The auger "ratchets" at low speed. The auger operation is not smooth and steady as the speed is gradually reduced 75 rpm to 0 using the paddle or sonic sensor. Unstable auger operation can also cause the conveyor movement to be uneven because the auger and conveyor motor circuits are in series.
SOLUTION:
To diagnose this feeder system problem the attached fault tree chart should be used. The electrical tests are performed first to rule out electrically induced problems before diagnosing hydraulic control valves and adjustments. During the bleeding procedure the load sense line flow rate should be observed. This oil flows through an orifice(.026") in the feeder control manifold and out the "LS" port then to the pump compensator. When bleeding the load sense lines the oil flow at the left and right pumps should be compared. Both should be a small steady stream. If the orifice is not in place the load sense line flow rate will be visibly greater. This condition results in unstable auger performance that cannot be corrected until the proper orifice is installed. Proper margin pressure adjustment and bleeding procedures should be performed prior to replacing hydraulic components.
TESTS
Conduct this test with a digital multimeter installed in series with the auger control valve coil. The current range is 0-1100ma. Turn the key on, engine not running, apply parking brake, propel lever forward, speed dial 50%. Select auto mode for the auger and conveyor system. Adjust the feeder sensor and mix height dial to obtain approximately 700 ma output to the auger coil. The current should remain steady with no fluctuation to pass this test.
Test the input duty cycle to the MPC-10 from the mix height pot and PWM buffer using pin #5 & #39 (left side) and pins #6 & #39 (right side). The duty cycle is increased and decreased by turning the mix height dial. Test the duty cycle at 30%, 50% & 70% the output signal from the PWM buffer should remain steady with no fluctuation to pass this test. If the duty cycle fluctuates test the mix height pot resistance for steady and incremental increase / decrease as the knob is rotated, replace if faulty. If the mix height pot is functioning properly, replace the PWM buffer. Re-calibrate the feeder system MPC-10.
Test the input duty cycle to the MPC-10 from the feeder sensor, sonic or paddle, pins #27 & #39 (left side) and pins #28 & #39 (right side). Test the paddle sensor by adjusting the wand to obtain 30%, 50% & 70% , the sonic sensor is tested by aiming at a fixed object and positioning the sensor to test. The output duty cycle should remain steady with no fluctuation. If the duty cycle fluctuates the sensor should be replaced. Re-calibrate the feeder system MPC-10.
NOTES
For this procedure, refer to The Service Manual KENR3506(6HN,8GN), KENR2895(8BM,6ZN), KENR2907(6TN,4XN) or KENR3555(9DN,5GN). Also refer to