I probably dont know what seive(s) you are talking about, but if you are meaning an air foil chaffer that has no physical adjustment, it uses air or fan speed to make the adjustment. They seem to work best in crops with a larger weight difference betwen the chaff and grain. I've used one in light weight grass seed, and it works, but not as well as I think it should because of the weight between the chaff and seed being so close.
Advantage is, theoretically, lots of air makes for a cleaner sample and faster ground speeds if you have the power.
HHHHMMM I was wondering if the seed and chaffe was close to the same in weight with this kind of setup it would just blow more out the back. The reason I was ask about this ..... for one I have limited experience operating a combine and have never heard of this style before. Secondly would this work well for wheat and soybeans?
We used to run non-adjustable air foil chaffers in our axial flow machines. Dad said they worked pretty good in wheat, but he thought it sometimes needed to be closed a little. We haven't been too happy with the 11/8in cloz slat chaffer in the 2388, so we got an adjustable air foil last winter. Not sure how it will work, but we'll know in a month.
Ok, keep in mind, I am way out west and harvest conditions are different for me than they likely are for you. However, like Okpanhandle said, sometimes a little adjustment would have been nice. What happens is each time you eliminate an adjustment, you dont remove the need for it, you simply imply that adjustment to one or more other elements of the machine.
If you have access to an adjustable stock chaffer, maybe run it instead of the air foil at first, then if you see and feel confortable with the concepts and how things are working, install the airfoil the last day of runing to see and learn what takes place when you eliminate that adjustment. ?
Got any pics of your 915? A neighbor runs a diesel hydro 915 and it does a fine job in his ryegrass.
Thank You for the info Guys! I Greatly appreciate it! I haven't bought this combine as of yet. I looked at it last Monday. It has been sheded and appears to be in good shape. 2800 hrs on the tach. It comes with a 20ft head that can flex or blot up ridged. He's also has another 915 for parts.The owner has upgraded to newer equipment and has been using this as a secondary machine for the past 5 years. My reason for looking at this type of machine instead of a rotor type is mainly for baling small square bales of straw to sell at the local farm/home store. Then double crop with soybeans. I only have 50 acres. Soo .... I'm not needing to get anything too pricey. I live in NE Okla.