Method of cleaning threshed grain in a combine

摘要

A method for cleaning threshed grain in a combine harvester is disclosed wherein the threshed grain is conveyed into a cleaning cylinder that is rotatably driven at a sufficient speed to impart centrifugal forces on the threshed grain to urge the grain through sieve openings during each entire 360 degree revolution of the cleaning cylinder. The cleaning sieves are mounted within axially extending cleaning shoes connected to the rotating cleaning cylinder for individual reciprocatory movement along a generally axial direction inclined inwardly toward the axis of rotation to convey the threshed grain rearwardly and help the cleaned grain pass through the sieve openings. Simultaneously with the rotating of the cleaning cylinder and the reciprocating of the cleaning shoes, a fan blows air through the sieves in the cleaning cylinder to make the unwanted residue airborne for discharge rearwardly from the cylinder, the air also being directed through the threshold grain twice before it is received on the sieves. Unthreshed heads are received within a tailings section for return to the threshing and separating mechanism for further harvesting treatment before being discharged from the cleaning cylinder.