Abstract: A rotary-to-linear motion converter comprising a frame having a roll axis, and a pitch axis passing through a common point. The axes are mutually orthogonal. The common point is positioned between an input end and an output end. An input shaft rotates on the roll axis and has an offset drive cam on its interior end. The offset drive cam has a central point positioned at the frame common point. A rocker housing has a pitch axis and a yaw axis. The pitch axis and yaw axis are mutually orthogonal and pass through a common reference point. Pitch bearings mount the rocker housing pitch axis for rotation on the frame pitch axis and position the rocker housing common reference point to be coincident with the frame common point. A rocker cam means rotates the rocker housing yaw axis and couples rotary motion from the offset drive cam into oscillatory rocker housing pitch motion. An output shaft is slidably coupled to the frame.