US Patent 7581460 Drive assembly

A drive assembly, particularly for driving arms around a compartment in a waste material digester, comprises a rotatable hub having an inner drive plate and a ratchet plate secured thereto for rotation therewith. Positionally opposed, parallel piston and cylinder drive reciprocatably drive an outer drive plate, drive arms pivotally carried on the outer drive plate engaging with drive pins on the inner drive plate to drive the hub in one direction. Movement of the hub in the opposite direction is prevented by latches engaging with respective shoulders of the ratchet plate when the outer drive plate moves in said opposite direction.