Combines Air Flow Dirction System Review

Farm kid 2,

Dave, You are welcome. I know how difficult it can be to get unbiased 3rd party info in the ag industry. Drop me an email if you have questions or need additional info. Mike

Thanks for the report Mike, and for all the detail. Just a few follow up Questions..Was your clean grain sample absent of chaff and hulls as well and do you think the dramatic results were from the combination or is the air deflecter the big differenceIJ thanks Steve

Im a little embarrassed to say that I forgot to open the bottom of the return elevator and check to see what was in there! I kept thinking that I would do that, but just never got around to it. We were getting a few husks on the smaller kernels, so I didnt want to back off on the threshing, so we kept the concave clearance tight and the rotor speed high. We had a little cracked grain from the high rotor speed. To answer your question, I really think the bulk of the improvement came from the deflector. The air foil chaffer and lower sieve may have contributed to the total lack of chaffer loss, and they may have let us run higher fan speed, but I feel the real benefit came from even air flow front-to-rear. The cross flow fan does a good job of getting the air even left-to-right, but it just doesnt cut it with respect to front-to-rear air flow. We put the adjustable chaffer in so that we could pinch down on the front to force more air out the back. As it turned out, we didnt even have to do that, the deflector compensated quite nicely, even over a pretty wide range of fan speeds (thats based on watching flags tied to the chaffer, not on cutting). When we were cutting we kept the fan maxed because we couldnt seem to blow any grain out no matter what we did. We were using one keystock grate in the very rear position with nine disruptor lugs mounted in it. So, Im sure there was a bunch of ground-up straw getting dumped on the chaffer, but it evidently could stay suspended over the full length of the chaffer, otherwise it would have shown up in the return, which was nearly non-existent. If I were to do it over again, I would add the deflector first, by itself. Then, I would get that hole in the top of the upper return auger capped off with a piece of tin. Those two things will let you accurately diagnose the rest of your machine and then you can fine tune the threshing and separation if you want to. We wanted to get the sample ultra-clean, and we pretty much succeeded in the conditions we encountered this year. The extra capacity we picked up was a nice bonus too.

The hole in the top of the return auger lets some of the return fall down outside the rotor cage. If you have unthreshed crop that goes out the hole then it goes straight back to the sieves and either goes into the bin as MOG or makes another loop. By capping off the hole All of the return has to go back into the rotor where it can be threshed. I suspect that the hole is a safety valve of sorts, letting excess return go somewhere. You won't have to worry much about excess return if you can get the air distributed through the sieves properly. It just makes sense to ensure that all of the return makes it into the rotor.