V-gearing, in which the teeth are at a very small angle with the plane of rotation, makes a perfectly silent of transmission of power.
Transmission ratio: 2
Small worm: 1 start, lead: t1, pitch diameter: D1
Large worm: 2 starts, lead: t2 = 2.t1, pitch diameter: D2 = 2.D1When helix angle is near 90 deg.