A friend in life—Worm gear

worm gearDefinition

Worm and worm gear combination is generally applied for transmitting motion and power between both crossed axes. Worm gear and worn, which locate upon its mid-plane, are equal to wheel and rack within mechanism of gear – rack. And worm gear is one of the important parts of worm and worm gear.


For getting a larger gear reduction ratio, it’s time to adopt a worm gear. Generally speaking, the reduction ratio of worm gear is around 20:1, even up to 300:1 or larger.

Functions and Characteristics

Many worm gears also have some interesting features other gear groups have not. For instance, a worn can easily rotate a gear but a gear can not rotate a worn. It’s because of too small quoin upon the screw. When a gear tries to rotate a screw, the friction between two parts will make the screw remain in the original position. This function is much playful in transmission systems and other fields. When a motor no longer keeps rotation, the kind locking function can be acted as its brake. Another amusing application in worm gears is differential mechanisms. And the kind mechanisms are mainly applied in some high performance cars and trucks. So worm gears have been important friends in our modern life.