Vertical lift drive arrangement

Abstract From the Canadian patent

Abstract of the Disclosure A vertical lift platen is moved by a driven shaft between lower, intermediate and upper vertical positions. The platen dwells at zero speed at each position. The speed increases to a maximum speed and then returns to zero speed as the platen moves between positions. A cam member mounted to the driven shaft supports a circumferentially arranged series of three identical cams. Each cam includes a pair of radially extending linear cam edges and a pair of arcuate edges each tangent to the outer terminus of a linear cam edge. A roller support rotatably supports a pair of cam rollers at defined distances from the axis of a driving shaft to which it is attached. The …