Abstract: The drive for rotating the drum of a vehicular cement mixer includes a mechanical power train mounted in a first chamber of a drive housing and a hydrostatic motor disposed in a second housing chamber substantially surrounded by yet another chamber defined in part by an outer wall of diecast aluminum formed on an outside surface with a plurality of outwardly extending fins and on an inside surface with a plurality of support plates connected to an inner housing well defining the inner chamber. The outer chamber communicates with the inner chamber by means of an overflow outlet at the top of the inner housing wall, oil escaping from the inner chamber via the outlet flowing down the support members to the inner surface of the outer housing wall.