Pulleys are on the market that permit an adjustment in the width of the groove. The effective pitch diameter of the pulley is thus varied, and moderate changes in the speed ratio can be secured.

It has considerable relation to the diameter of pulley groove that the wire rope can or can't work all right and reach normal service life.

The robot was supported and driven by umbrella shaped wheels, whose motions of spanning obstacles were controlled by groove pulley and cam mechanism .