Worm gears are used when huge gear reductions are needed. It is common for worm gears to possess reductions of 20:1, and also up to 300:1 or greater.
Many worm gears have 
a fascinating property that no various other gear arranged has: the worm can easily turn the gear, but the gear cannot turn the worm. This is because the position on the worm is indeed shallow that when the apparatus tries to spin it, the friction between your equipment and the worm retains the worm in place.
This feature pays to for machines such as for example conveyor systems, where the locking feature can act as a brake for the conveyor when the motor isn’t turning. One other very interesting usage of worm gears is planetary gearbox certainly in the Torsen differential, which is utilized on some high-performance vehicles.
