Rolamite, mechanical roller-band device that functions as an almost frictionless suspension system for rollers; it consists of a flexible metal band formed in an S-shaped loop. In the , rollers A and B are suspended within the loops of the flexible metallic band C, fastened at D and E to the parallel guide rails F and G. The sum of the roller diameters and twice the band thickness is greater than the distance between the guide rails, so that when the band is pulled taut and anchored to the guide rails at D and E, the band is wrapped around the rollers so tightly that slippage is prevented. If the guide rails in the figure were tilted clockwise slightly, roller A would rotate counterclockwise and roll out the band on the upper guide rail to some position such as A′, and roller B would rotate clockwise and roll in the band on the lower guide rail to position B′. The frictional forces restraining the motion of the rollers would be about one-tenth the friction for ball and roller bearings.
The Rolamite was invented in 1966 by the U.S. engineer Donald F. Wilkes, who gave it its name.