... 1 10089-88diameter20-600materialsCopper alloy, zinc alloy 1,Worm gears are used when large gear reductions are needed. ... It is common for worm gears to have reductions of 20:1, and even ... to 300:1 or greater.2,Many worm gears have an interesting property that no other gear ... not turning. One other very interesting usage of worm gears is in the Torsen differential, which is used ...