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 like a screw thread. The worm wheel, coloured yellow-colored, is like a normal gear wheel or spur equipment. The worm always worm gear and worm wheel drives the worm wheel round, it is never the contrary way round as the system will lock and jam