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 definitely brown in colour, just has one tooth but it is similar to a screw worm gear and worm wheel thread. The worm wheel, coloured yellow, is like a normal equipment wheel or spur equipment. The worm at all times drives the worm wheel round, it is never the opposite way round as the system will lock and jam