Worm gears are often used when large acceleration reductions are needed. The reduction ratio depends upon the number of begins of the worm and quantity of tooth on the worm equipment. But worm gears have sliding contact which is silent but tends to produce heat and also have relatively low transmission performance.
As for the materials for creation, in general, worm is made of hard metal as the worm gear is made from relatively soft metallic such as for example aluminum bronze. This is because the number of teeth on the worm equipment is relatively high in comparison to worm with its number of begins being generally 1 to 4, by reducing the worm gear hardness, the friction on the worm the teeth is reduced. Another characteristic of worm manufacturing may be the need of specific worm wheel machine for gear reducing and tooth grinding of worms. The worm equipment, on the other hand, may be made out of the hobbing machine used for spur gears. But due to the different tooth shape, it isn’t possible to cut many gears at once by stacking the gear 
blanks as can be done with spur gears.
The applications for worm gears include equipment boxes, angling pole reels, guitar string tuning pegs, and in which a delicate swiftness adjustment by utilizing a sizable speed reduction is necessary. While you can rotate the worm equipment by worm, it is usually extremely hard to rotate worm by using the worm gear. That is called the personal locking feature. The self locking feature cannot continually be assured and another method is recommended for accurate positive reverse prevention.
worm wheel
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