Grain cleaning system for a combine harvester

摘要

A drive linkage is described for reciprocating a sieve that is suspended within a frame of a combine harvester for movement in mutually orthogonal directions. The drive linkage comprises a cranking mechanism for imparting a reciprocating motion to the sieve in the direction of travel of the harvester and a pivot arm pivotably connected at one end to one side of the sieve to cause the sieve to move in an arc centered on a pivot axis at the opposite end of the pivot arm as the sieve is reciprocated. In the invention, the pivot axis of the pivot arm is displaced relative to the frame in synchronism with the reciprocation of the sieve in such a manner as to cause the sieve to follow a substantially rectilinear path relative to the frame.