A fixed frame portion of an injection-molding machine carrier behind its movable platen a crank to which, at points approximately equispaced from its fulcrum, a pair of arms are articulated. One of these arms is pivoted to the movable platen whereas the other one is pivoted to a carrier connected with a set of ejector pins or a stripper plate. The spacing of the points of articulation of the two arms on the crank is so chosen that the separation of these points in the direction of platen motion is relatively wide in one limiting position and relatively narrow in the other limiting position of platen reciprocation whereby the carrier is thrust forward with reference to the platen as the latter is retracted.