In the 18th century there were efforts to create a power-driven threshing machine. True industrialization of threshing began in 1786 with the invention of the threshing machine by Scot Andrew Meikle. In this the loosened sheaves were fed, ears first, from a feeding board between two fluted revolving rollers to the beating cylinder. This cylinder or "drum" was armed with four iron-shod beaters or spars of wood parallel to its axle, and these striking the ears of corn as they protruded from the rollers knocked out the grain. The drum revolved at 200 to 250 revolutions per minute and carried the loose grain and straw on to a concave sieve beneath another revolving drum or rake with pegs which rubbed the straw on to the concave and caused the grain and chaff to fall through. Another revolving rake tossed the straw out of the machine. The straw thus passing under one peg drum and over the next was subjected to a thorough rubbing and tossing which separated the grain and chaff from it. These fell on to the floor beneath, ready for winnowing. A later development of the beater-drum was to fix iron pegs on the framework, and thus was evolved the Scottish "peg-mill," which remained the standard type for nearly a hundred years, and was adopted across the US.

https://en.wikipedia.org/wiki/Threshing