How to Solve CASE 7120 IH 20 Series Axial-Flow Combine Creep Problem

Here is the instruction show you guide on how to solve CASE 7120 IH 20 Series Axial-Flow Combine creep problem.The main area for troubleshooting would be a unit that wants to creep.There are two areas that could cause a creep problem;it is NOT intended for the electronics to prevent creepage.

 

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Possible Solutions:

1 Disconnect the electrical connection to the solenoids.Does the creeping stop?If so it would be an electrical problem.

 

2 If the machine still creeps,it may be that the servo piston is not centered.Using ahose,connect the two gauge ports X1 &X2 so that the servo piston is balanced hydraulically.Install two gauges at port MA &MB (3)to monitor the drive pressure, they should be equal.Using the servo centering adjustment (2),balance the pressures at port MA &MB.

 

3 Monitor the servo pressure at ports X1 and X2,they should be equal ±10 psi.If NOT,manually readjust the centering of the primary spool (1);there will be two screws at this location,one is used to lock the adjusting screw.The procedure would be to turn the screw until the machine creeps in one direction,then turn the screw until it creeps in the opposite direction (do not rotate more then 90o)and center the screw between the two extremes.If the pressure is not equal it would indicated that the servo piston and springs have not been adjusted correctly.As long as the system can be manually adjusted it should perform satisfactorily.