In the 1830's at the age of 22 Cyrus McCormick invented the `Reaper,' this important invention for farming machinery immediately made life easier for the farm workers, although the problem still remained of tying the grain into bundles. In 1850 a binding machine was patented and this was added to the reaper, but the new reaper still couldn't separate the grain from the straw. A threshing machine had already been invented but the grain had to be transported to it as it remained immobile.
Throughout the 18th century many reapers and binders were produced by various companies, each one trying to combine harvesting, threshing and cleaning. All of these were horse-drawn and it wasn't until 1924 that the Australian McKay Company built a machine with an engine called the Sunshine Auto-Harvester, which not only cut and threshed the grain but was also self-propelled. In 1935 the Allis-Chalmers Company of Milwaukee, Wisconsin designed and built a combine harvester which required only one operator.
The combine works by pulling the crop onto a knife bar. The cut crop is then brought to the centre by rotating augers. The crop is gathered and drawn up into the machine where it is threshed by the separation drum. The straw is then moved by the straw-walkers to the back of the machine and dropped onto the ground.
In the meantime the grain is sieved so that the large bits are sorted out. After this process it goes through a blast of air (called winnowing) which removes all the husks and small bits of straw. The grain is then moved from the bottom of the machine, up a chain-and-flight elevator to the tank at the top where the grain auger will push it out and into a waiting trailer.
