An agricultural harvester (10) has a chassis (12) carrying a header (18) for gathering a crop, which is removably attached to a feeder housing (20) for feeding the crop into the agricultural harvester (10) to be processed. A threshing and separating system (24) is connected to the feeder housing (20) for separating grain from Material Other than Grain (MOG) and to a grain cleaning system (26) for further cleaning the separated grain. The grain cleaning system (26) has at least one sieve (46, 48, 50) that oscillates fore and aft and a side shaker mechanism (110) that produces a side to side shaking motion in the at least one sieve (46, 48, 50). A control system (122) is connected to the side shaker mechanism (110) and automatically proportionately increases an amount of the side to side shaking motion as a function of an amount and type of crop being processed.
