Topic – Changing Direction: Worm Gears

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Changing Direction: Worm Gears

Spur gears and bevel gears have several teeth. A worm gear has just one tooth. The tooth spirals along a rod that looks a lot like the thread on a screw. A worm gear can be used to make a spur gear turn.

The diagram shows a motor turning a worm gear. The worm gear makes the spur gear turn. The two gears turn at a right angle to each other. (Notice the direction arrows.)

You can use a worm gear to make a spur gear turn, but you cannot use a spur gear to make a worm gear turn. Friction will stop the gears from turning.

This toy clock helps children learn to tell time. By turning the knob at the top, you make the clock’s hands move to show any time. This toy uses a worm gear and spur gears.

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