Abstract: A mold clamping device is provided for an injection molding machine having a stationary mold half and a movable mold half supported by a movable plate. A drive rod is connected at one end to this movable plate and is received at the other end by a driving ring piston having at least one recess within its inner shell. At least one coupling member such as a split flap is swivably connected to the other end of the rod. A suitable actuator such as a piston driven lever arm is provided to operatingly engage the coupling member with the recess, whereby the mold is clamped.