worm gear and worm wheel

The arrangement of gears seen above is named a worm and worm wheel. The worm, which in this example is brown in colour, only has one tooth but it is like a screw thread. The worm wheel, coloured yellowish, is like a worm gear and worm wheel standard equipment wheel or spur equipment. The worm at all times drives the worm wheel round, it is never the contrary way circular as the system tends to lock and jam