Abstract: A drive system to move a moveable beater assembly of a harvesting machine in a back and forth movement comprises a housing, a drive, and a drive compensating component. The drive drives the beater assembly in a back and forth movement so that a beater assembly force is exerted on the housing, this force being directed along an alignment axis. The drive compensating component comprises first and second eccentrically revolving weights mounted to the housing for rotation. It further comprises a drive transmission to rotate the first and second weights to produce a net compensating force that is colinear with the alignment axis. In a timed relationship with the back and forth movement of the beater assembly, the net compenating force opposes colinearly the beater assembly force, whereby an equilibrium of the housing is able to be maintained.