US Patent 7811162 Combine rotor assembly with progressive pitch element pattern

A rotor assembly for a threshing system of a combine provides effective grain threshing and separation, while doing so in a manner that conserves power and avoids usage spikes and the like, by providing at least two helical patterns of elements for threshing and separating, having a helical pitch that progressively changes by an advantageous extent, while spacing between adjacent ones of the elements of each pattern is held about constant.