An apparatus for rapidly displacing an object comprises a lever with an object end and a power end. The lever is mounted to a fulcrum between the ends. A driven cam has a trunnion attached proximal to an outer edge thereof, and a tie rod member has an end pivotally attached to the power end of the lever and a second end pivotally attached to the trunnion such that about 180.degree. of rotation of the cam causes about 90.degree. displacement of the power end of said lever. Also, a tension member is coupled to the power end such that restorative force of the tension member contributes to displacement of the power end in one direction. A motor drives rotation of the cam.