Abstract: A drive unit having a toothed endless member for driving a conveyor. The drive unit includes an endless driving chain having tooth-like projections extending outwardly from the driving chain, each tooth-like projection having a bearing surface which coacts with the toothed side of the endless member to drive the endless member in response to movement of the driving chain. The driving chain engages a pair of sprockets to be moved around each in response to the rotation of one of the sprockets by a drive motor. Each tooth-like projection is inserted into or removed from a respective groove defined by the teeth of the endless member when that tooth-like projection is advanced around a circular path defined by the endless chain driven around one of the sprockets.