Threshing Machine Definition

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How does threshing machine work? What is the function and history of threshing machine? Information about threshing machine.

THRESHING MACHINE, a device formerly used for separating grain from straw and chaff. Before the development of the threshing machine about 1840, the separation was accomplished by trampling with the feet of men or animals or by flailing on threshing floors. The resultant mixture was then tossed into the air and the chaff was blown away by the wind or fanned away.

Threshing Machine

The principles of impact and abrasion employed in primitive threshing were incorporated in threshing machines. The simple threshing machine had a revolving cylinder with teeth or rasp bars operating against stationary bars called concaves. The space between the revolving and stationary bars was adjustable and set for each type of grain. The unhusked grain was fed between the rotating and stationary bars. The grain or seeds fell through the bars into a collecting pan. More complex machines incorporated devices for cleaning, grain recovery and elevating, and removing and stacking straw. The peripheral speed of the cylinder was regulated so that it was high enough to remove the seed covering, but low enough so as not to crack or otherwise damage the grain. The optimum speed for wheat is between 5,000 and 6,000 feet (1,500 to 1,800 meters) per minute.

At first, animal-powered equipment was used to run threshing machines. It was succeeded by steam engines, internal combustion engines, and electric motors as they become available.

The threshing machine was used in North America and other developed grain-growing areas of the world from 1840 to about 1940. Today the combine, or combined harvester-thresher, has replaced the threshing machine.

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