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Open or close chaffer sufficiently to let grain fall through before it passes the whole length of sieve. If chaffer is excessively open, this may overload grain sieve with chaff. If chaffer is not sufficiently open, some grain can be lost.
Final cleaning is done by the grain sieve. It has to be sufficiently open to allow clean grain fall easily and straw and chaff be retained. If grain sieve is excessively closed, grain will move to tailings. There might be grain damage in tailings procedure. If grain sieve is excessively closed, impurities will be conveyed to grain tank.
Grain losses in the cleaning unit may be caused by:
1.
Too little fan blast or too narrow chaffer openings, facilitating plugging.
2.
Too much fan blast, blowing grain out of combine.
It is important to know which of the reasons above is causing grain losses to be able to carry out correct adjustment.
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IMPORTANT:
Always check results before attempting further adjustments.
If caused by overthreshing or insufficient fan blast. Check amount and condition of straw. If straw seems excessively broken or chewed, threshing cylinder and concave should be adjusted to reduce overthreshing.
If straw is not broken or cut, more air is required to lift it slightly. Before attempting further adjustments, check results. If the problem is excessive fan blast, there will be little chaff and straw in chaffer. Reduce fan speed and check results.
Consult more detailed information under "Cleaning System", in section "Threshing System, Separation and Cleaning".
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