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 usually brown in colour, only has one tooth nonetheless it is like a screw thread. The worm wheel, coloured yellow-colored, is like a normal equipment wheel or spur gear. The worm usually worm gear and worm wheel drives the worm wheel round, it is never the opposite way circular as the system tends to lock and jam