Worm gear system is comprised of worm shaft and worm wheel. Worm gear is similar to a spur gear, whereas worm shaft is like a screw thread. Worm gear system is used to reduce the input speed and transmit torque to the further system.
As compared to typical spur gear system, the size of worm gearbox will be small. Depending on the number of starts, the gear ratio can be maintained. A worm wheel having 30 teeth will have a reduction ratio of 30:1.