The most critical aspect of setting up a JD Straw Walker combine to work successfully with a stripper header is to first ensure that the concave and rasp bars are in good working order (i.e. there is minimal wear and no damage). The wear on the concave can be visually checked by removing the side inspection covers. Wear will always be in the centre of the concave. In order for the combine to perform correctly with a Stripper Header; the centre of the concave must be no more than 1/8th inch lower than the outside. The same applies to the rasp bars. Ensure that there are no broken wires or damaged bars. Once the condition of the concave has been checked it is very important to correctly adjust it. The concave should be adjusted so that it is level from side to side and as close as it will go to the rasp bars without touching them. This adjustment is made by loosening the actuator stop on the right side. First lower the concave a little then raise it and adjust the level from side to side (it is important to perform any adjustments immediately after operating the concave in an upwards direction). Once the concave has been levelled the clearance can be adjusted by raising it until it hits the cylinder then lowering the concave a small clearance is attained then re-tightening the actuator stop. The concave clearance in the rear inspection hole is generally around 1/4 inch and 1/8 inch at the front inspection door.
Combine Straw Walker loss is experienced:
Raise concaves to ensure grain is forced through, adjust cylinder speed and check grain loss monitor. If loss persists check that the concave is not plugged, remove front concave blanking plates if the sample is clean and Straw Walker loss persists.
Combine sieve loss is experienced:
Generally opening up the sieves more and increasing the fan speed will give greater sieve capacity, ensure that the balance is correct of splitting the load between the sieves and straw walkers, it may be that the walkers are way under capacity yet you are overloading the sieves. In this case it will be necessary to fit 2 rows of rear concave inserts to prevent such a high proportion of material falling onto the sieves.
Unthreshed heads appear in grain sample:
In this case it will be necessary to either close the concave a little to provide better threshing or fit additional concave blanking plates. In particularly tough threshing varieties it may be necessary to close the bottom sieve and run these unthreshed heads through the combines return system.