Applications

This system is used, for example, to drive the spools in some tape recorders. In a typical configuration, one of the cylinders is the axle of an electric motor, say 1 mm in diameter, while the other is a disk with a hard rubber rim, say 50 mm in diameter, yielding a 1:50 mechanical advantage. A gear train with the same ratio would require either much larger gears or very fine teeth, which would be much more expensive and delicate to produce.