Worm gears are used when large gear reductions are needed. It is common for worm gears to have reductions of 20:1, and even up to 300:1 or greater.
Worm gears are widely used in packaging machinery, material handling, machine tools, indexing and food processing. They are used widely in conveyor systems. They are also used in torsen differential, used on some high-performance cars and trucks. They serve as speed reducers in many different industries.