How does a combine harvester work?

Answer 1

A combine harvestor completely threshes a plant down to its seed. A combine requires a special head or header that is specialized for an individual crop. This head serves as the first contact with the plant. Let's take corn for an example. Corn is planted in rows, so each row enters a row slot on a corn head. This rapidly pulls down the whole stock until the ear is clipped off. Some of the plant goes in the combine, but most does not. The head gathers the plant material into a feeder house, which is just a mechanical conveyor drawing the material into the middle of the combine. The material then goes through a cage called a concave that surrounds a rotor. This high rpm moving rotor has bars attached to it at various angles that basically roll the material and corn right off the cob. The grain that comes off along with some plant trash falls through the open slots on the bottom of the concave. The heavier trash or material is ejected out the back of the rotor into a trash whipper that spreads out the material outside. The falling small material and grain fall on a seive, which is kind of like holding out your fingers and shaking your hand back and forth. The small grain slips between your fingers, and the trash that is lighter than the grain is shook out the back of the combine. The clean grain then is passed through a series of augers to the grain bin of the combine. When the bin is full, there is a retractable auger on the combine to dump into a grain cart or truck.