An actuator for use in or with a glassware forming machine for driving a member through an arcuate path, such member being a pusher cylinder for moving glassware articles. The pusher member comprises a linearly movable piston for linearly moving a convoluted shaft attached thereto. The convoluted shaft has three surfaces thereon which act as tracks for three roller bearings mounted on a hub which is disposed about the shaft. Linear motion of the shaft is converted into rotary motion in the hub by the action of the bearings running on the convoluted sides of the linearly moving shaft.