Product (whole cut wheat/barley/canola etc.) will enter the feeder house (Assembly in front and under the cab) in which the conveyor chain will grab the product and feed it up toward the feed accelerator. The feed accelerator is basically a fast spinning drum that will "accelerate" and force the stalks and heads into the feed ramp from which the rotor will pull the product. The rotor (or cylinder on other style combines) will then thresh the product against the concave's in a screw type motion and separate the kernels or seed from the head or shells.