Tension Roller

(idler), a loose pulley mounted on a mobile axle and intended to maintain belt tension and to increase the span angle of the small pulley of a belt transmission. Transmissions with tension rollers are used in cases where the distance between the axles is small or the transmission ratio is high. Tension rollers should be installed on the driven side of the belt near the small pulley. The disadvantage of transmissions with tension rollers is a decrease in the service life of the belt because of additional flexure.