Drive unit

A drive unit, in particular for a closing unit, an injection unit, or an ejector of an injection molding machine, comprising a hydraulic power converter with two piston units movable relative to each other and having different effective surfaces which delimit a pressure chamber jointly with an intermediate part axially displaceable through the intermediary of guide means, wherein the smaller piston unit preferably is driven electrically, and the intermediate part is adapted to be fixed relative to a stationary frame through the intermediary of a holding means in order to apply an axial force, characterized in that the holding means has at least one supporting member which is supported on the frame and adapted to be positively connected with a clamping member that is capable of being displaced together with the intermediate part and substantially separate from the guide means in terms of function.