Impact protected cam drive free of backlash

Abstract

The invention is directed to a backlash-free cam drive which can be subjected to an impact load. The cam drive includes: a housing defining a longitudinal axis; a cam follower assembly mounted in the housing so as to be displaceable along the axis fixed against rotation about the axis; an adjusting member mounted on the housing so as to be rotatable about the axis and relative to the cam follower assembly; and, a cam formed in said adjusting member so as to define two mutually adjacent guide cams extending along a guide path. The cam follower assembly includes: a frame; first and second contact rollers mounted on the frame so as to be displaceable relative to each other; a spring for resiliently biasing the first and second contact rollers relative to each other and against corresponding ones of the guide cams whereby the cam follower assembly is displaced along the axis as the adjusting member is rotated; an ancillary part fixedly mounted to the frame to extend into the guide path between the guide cams but not touching the guide cams during normal operation of the cam drive in the absence of the impact load; the ancillary part including a shock absorber for contact engaging one of the guide cams in response to the impact load applied transversely to the guide cams; and, the adjusting member defining the guide cams being made of a first material and the shock absorber being made of a second material elastically softer than the first material.