Cam operated devices

A power tool comprising a housing, a rotary drive, a cylinder cam having a longitudinal axis of rotation and a cam track extending around a circumferential surface of the cylinder cam, the cam track having first and second opposing cam surfaces, cam follower means adapted to run in said cam track between said first and second cam surfaces, and a mounting arrangement for a tool bit, one of the cam surfaces and the cam follower means being driven by the drive means, and the mounting arrangement being associated with the other of the cam surfaces and the cam follower means, such that the actuation of the rotary drive means drives reciprocal movement of the mounting arrangement along said longitudinal axis;

• and wherein at least part of the cam track formed by said first and second cam surfaces is in the form of a wave that is symmetrical about a peak of the wave and having an amplitude and a wavelength, the wave providing peaks, troughs, or peaks and troughs that are straight portions with curved portions therebetween, a forward throw section and a rearward throw section which in use drive the mounting arrangement respectively forward and rearward, at least one of the forward throw section or rearward throw section imparting a greater forward or rearward acceleration respectively to the mounting arrangement than that imparted by a sinusoidal cam track of equivalent amplitude and wavelength.

A power tool comprising a housing, a rotary drive means, a cylinder cam having a longitudinal axis of rotation and a cam track extending around a circumferential surface of the cylinder cam, the cam track having first and second opposing cam surfaces, cam follower means adapted to run in said cam track between said first and second cam surfaces, and a mounting arrangement for a tool bit, one of the cam surfaces, and the cam follower means being driven by the drive means, and the mounting arrangement being associated with the other of the cam surfaces and the cam follower means such that actuation of the rotary drive means drives reciprocal movement of the mounting arrangement along said longitudinal axis;

• and wherein at least part of the cam track formed by said first and second cam surfaces is in the form of a wave that is symmetrical about a peak of the wave and having an amplitude and a wavelength, the wave that is symmetrical about the peak having peaks, troughs, or peaks and troughs that are straight portions with curved portions therebetween, a forward throw section and a rearward throw section which in use drive the mounting arrangement respectively forward and rearward, the length of at least one of the forward throw section or rearward throw section of the cam track being shorter than the length of the forward throw section or rearward throw section respectively of a sinusoidal cam track of equivalent amplitude and wavelength.