This might seem like a sponsored ad for Gleaner's new Super 7 series combines, but I'm putting this up because of the cutaway pics and videos they have released for promotional purposes. I've been looking for some good examples for some time. Besides, I've got a soft spot in my heart for Silver Seeders - I've mentioned before how much I enjoyed running the old L2 and N7 models back in the day. As far as I'm concerned, their cab ergonomics are superior as well.
OK. Picture credits first. This picture is from Agco's Gleaner Super 7 promo page, and the following pics are screen captures from three videos they've released, also linked on that page. These combines are "Class Seven" sized combines - their larger competitors are "Class Eight." So, there are bigger machines out there. These are also considered to be "rotary" combines. The "conventional" combines have the threshing cylinder located in the feederhouse - which is the stub below the cab and between the drive wheels that the header attaches to. A rotary has a MUCH larger cylinder located further in the innards and may run lengthwise as opposed to crosswise as shown here. The main benefit of a rotary is increased production. A conventional cylinder spins, whacking the wheat with the cylinder bars on a single concave. The rotaries thresh over a larger surface area and the concaves are much larger. Concaves are adjusted closer or further away from the cylinders depending on the crop and the conditions. Cylinder speeds are adjustable as well. I think the last large conventional combines were made by John Deere - as far as I know, all of 'em are rotaries these days (unless you buy a test plot machine or something similarly exotic - and they're pretty tiny in the scheme of things).
This is a screen cap from the first video - which is six minutes long. This is also animated in the movie. At any rate, this shows the feeder house chains that take the crop mat from the header platform to the rotor.
This would be the rotor. On a conventional machine, the cylinder bars run the width of the rotor. On a Gleaner, they are small individual pads - you can see the spiral pattern inside the mesh. Grain is being knocked out of the heads of wheat in all areas of the rotor, rather than just at the concave bars (the contact point) on a conventional machine.
The augers help bring material across to the pinch rollers. When threshing, this "space" would be full of material. Gleaner uses "pinch rollers" - which are the interlocking rollers below the augers. Their idea is to accelerate the grain into the stream of air from the fan, so they can run more air from the fan than their competitors. This is helpful on uneven terrain, so one part of the combine goes under utilized while another is overloaded. That would be a sieve underneath - which filters the grain from the chaff.
This shows how the air is actually directed over the sieves. The fan speed can be altered for different crops and conditions. The sieves have to be changed for different grains - one size does not fit all - but they, too can be adjusted. Another thing not shown is the grain return system. A partially broken down head of wheat is normally (hopefully) too heavy to be blown out the rear, but it's too large to drop through the sieves. That material is augered back up to the rotor for another trip through the threshing process. The cleaned grain that is captured by the sieves is augered into the bin, where it can be unloaded later.
There are a myriad of adjustments that have to be made in order for the grain to thresh cleanly and to capture all of it. These things come with a huge manual with plenty of initial settings and advice for certain conditions for each crop. For example, winter wheat would have slightly different settings that spring wheat, which would be radically different than soybeans. Corn requires different sieves and a corn header instead of a small grain table. Different varieties of grain and moisture levels figure into the adjustments as well. I wouldn't dream of setting a machine up without the manual available.
I hate putting up a bunch of videos in one post (for loading times on slower connections, plus it hogs memory), so I'll just put up the links for the videos. The animated mechanical shots are worth it if you are interested in seeing how it all works, even if the videos are all around six to eight minutes. Plus, I gotta give a shout out to Bruce Baldwin, who appears in the second and third videos (first video here) - he's the local Agco dealer at Kalvesta Implement - just up the road from The Poor Farm.
This is the S77 with a forty foot wide small grain header table. You'll notice that it is asymmetrical - it isn't centered. The right side (of the machine - left looking at this picture) is wider. This is because unloading augers can only be so long before they collapse while unloading. So, the headers are offset so the combine can still pull up to a truck or grain cart without hitting anything. This small grain table has an auger that pulls the crop to the feeder house - most of the really wide headers have a flex table and use a wide flat belt - and are called "draper" headers. Draper headers (the last I knew) go up to forty six feet wide. There may be wider ones - I don't keep up that much. If you watch the videos, you see the combine pull up to a trailer to drop it's header and you'll also see it booking down the road without it's header with a pickup pulling the header on that trailer. These things are so wide now that they can't get down the road without partial disassembly. I've heard some of the Class 8 combines used for custom harvest have to remove their wheels for transport to the next stop - they're too wide and too tall loaded on their trailers to go down the highways otherwise.
So, Agco's thinking with this design is to make the threshing process more efficient within the limitations of a smaller, lighter machine. The benefits are less fuel consumption and compaction of soil, plus a better job of cleaning the grain. Whether that is true or not will undoubtedly be argued with great passion over coffee at the local cafes and other various farmer hangouts!