worm gear and worm wheel

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