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 nonetheless it is similar to a screw thread. The worm wheel, coloured yellow, is like a worm gear and worm wheel standard equipment wheel or spur gear. The worm often drives the worm wheel circular, it is never the opposite way circular as the system tends to lock and jam