A John Deere combine first gathers crops at the front of the machine using crop dividers. The reel moves the crops to the cutter, where the cutter bar's teeth remove the crops from their base. The machine then moves the crops by spinning augurs to a conveyor, which travels to the center of the combine; there, a threshing drum breaks up the crops and removes the grains from their stalks. Grains fall into sieves and are collected in a tank.
Any excess materials continue along conveyors, which are also called straw walkers, and exit through the back of the combine, where they are thrown across the field by a spreader. Meanwhile, any excess grain continues to fall into the sieves and into the collection tank.
When the operator wishes to empty the full collection tank, a separate tractor moves up alongside the combine. The combine shoots the grain out of its unloader, which is the pipe coming out of the side of the combine, and into a trailer attached to the tractor.
Different John Deere combines are equipped with different types of headers. Wider headers generally cut fields faster. They are typically powered by hydraulics that allow the header to be moved in many directions and contort to many angles. In order to move through narrow rows of crops, the header can be taken from the front of the combine and towed lengthwise through the rows.