worm gear and worm wheel

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