An agricultural harvester has a chassis carrying a header for gathering a crop. The header is removably attached to a feeder housing for feeding the crop into the agricultural harvester to be processed. A threshing and separating system is connected to the feeder housing for separating grain from Material Other than Grain (MOG). A grain cleaning system is connected to the threshing and separating system for further cleaning the separated grain. The grain cleaning system has at least one sieve operable to oscillate fore and aft and a side shaker mechanism operable to produce a side to side shaking motion in the at least one sieve. A control system is connected to the side shaker mechanism and operable to automatically proportionately increase an amount of the side to side shaking motion as a function of an amount and type of crop being processed.