Patent attributes
A number of cam-operated devices such as power tools (10) are described, the tools having a rotary drive device (24) for rotating a drive shaft (36) having a cylinder cam (42) mounted thereon. A pair of cam followers (54) are located within a cam track (44) provided on the cam member (42), such that rotation of the cam (42) causes axial movement of the cam followers (54), which may be attached to a drive shaft (48) and a tool bit (12). A range of shapes of cam track (44) are described, each of which is non-sinusoidal in shape. Various embodiments of the invention provide non-sinusoidal cam tracks having forward or rearward throw sections which are respectively steeper, shorter, or provide greater acceleration of the cam followers than sinusoidal cam tracks of equivalent wavelength and amplitude. Related piston and cylinder devices and reciprocal drive devices are also described.
