Combines Sieve modifications

Opening the front of the top sieve..IJ I dont know about a 1640, but with the 21 series what happens is you overload the front of the bottom sieve, and grain spills over into the cleaning fan. Case supplied these combines with the front of the top sive actually closed more than the rest of it. I was advised by a "combine expert" to do what you suggest, and guess what..IJ Case knows more about their machines than he did.. This was in dry cereals. Other things may be different.

This may work on a Gleaner because of their accelerating rolls and pre-cleaning air blast system has gotten rid a good deal of the MOG before the grain gets to the chaffer.

And if you have ever filled up a crossflow fan with corn you will understand why that is not a good thing. Cleaning it out sucks big time!!!!!!

In the CIH combines I think it is safe to say that even air flow is the goal for best performance. You are correct that the fan puts more air to the front of both the lower sieve and the chaffer. If possible, you need to close down the front in order to force more air out the back. This will help keep the MOG suspended, rather than falling through the back of the chaffer and straight into the grain return.

The Aussies often take out the first 6 rows entirely. Seems to work for themIJ Maybe one of them can explainIJ