A mechanism converts rotational displacement to linear displacement with ramped driver discoidal elements and ramped driven discoidal elements on a common central axis. The ramped surfaces of the two elements are complementarily shaped and opposed so that, when in contact and completely interengaged, they form an assembly of minimum length. The driver elements are rotated by an external force. The driven elements are allowed to translate along the common axis while being prevented from rotating about the common axis, whereby a rotational displacement of the driver elements by an externally applied force causes the elements to separate by camming action of the interengaged ramp surfaces to produce a linear displacement of the driven elements. A spring is coupled to the driven elements so as to restore the assembly to its minimum length in the absence of the externally applied force.
