1st concave is large wire,2 cover plates for wheat and for early soya's
2cd concave is small wire for wheat large wire for soya & corn
3rd concave is large wire for all crops ( this is for capacity IMO)
1st & 2cd grates are smooth for wheat (we want all straw.we cut
with 30' 1020 flex in flex mode)
3rd grate is always a keystock (we don't want any little wheats
escaping and making the country side any GREENER! lol )
ps both cover plates come off for dry soyas and all corn. They are
made by Harvest and take 2 minutes to take off and 3 minutes to
In my experience one cover plate is necessary in wheat. That's how we ran with the Kuchar concaves in the old machines. A few years ago we had some really hard threshing wheat that needed a second plate, but conditions like that are rare around here. When we got the 2388 last year it came with small wire concaves and we couldn't get the white caps out of the sample, so we made a cover plate one morning and that helped a lot. It still wasn't as good as I like, but it was acceptable. It got better in mid-afternoon when everything was drier, too.
Our cover plate was easy to make since we had a Kuchar plate from the 1480 laying around. We welded some bolts to a large wire concave, cut the Kuchar plate in half so it would fit against the wires, and bolted it together. Took about 45 minutes. The combine is currently equipped with three large wire concaves for corn and I think we're going to leave the rear two in for wheat to see what happens. We've got a helical front concave ordered and I hope we can put a cover plate on it easily.
I have all small wire begining of wheatseason I usually use two cover this year used three for the first time really burnt in wheat after the first 1/10" of ain usually drop down to one cover if by a miracle it rains more than a half inch after it is ripe can usually take all them off.