The primary good thing about worm gears is their ability to provide high reduction ratios and correspondingly high torque multiplication. They can be employed as speed reducers in low- to medium-rate applications. And, because their decrease ratio is founded on the quantity 
of gear teeth by itself, they are more compact than other styles of gears. Like fine-pitch business lead screws, worm gears are typically self-locking, making them well suited for hoisting and lifting applications.
Although the sliding contact decreases efficiency, it provides incredibly quiet operation. (The use of dissimilar metals for the worm and equipment also plays a part in quiet procedure.) This makes worm gears suitable for use where sound should be minimized, such as for example in elevators. In addition, the application of a softer material for the apparatus means that it can absorb shock loads, like those knowledgeable in hefty equipment or crushing equipment.
The meshing of the worm and the apparatus is a mixture of sliding and rolling actions, but sliding contact dominates at high reduction ratios. This sliding action causes friction and heat, which limits the proficiency of worm gears to 30 to 50 percent. To be able to minimize friction (and therefore, heating), the worm and gear are made from dissimilar metals – for instance, the worm could be made of hardened metal and the gear made of bronze or aluminum.
Such as a ball screw, the worm in a worm gear might have an individual start or multiple starts – and therefore there are multiple threads, or helicies, on the worm. For a single-start worm, each total flip (360 degrees) of the worm advances the equipment by one tooth. And so a gear with 24 teeth provides a gear reduced amount of 24:1. For a multi-start worm, the gear reduction equals the number of teeth on the apparatus, divided by the number of starts on the worm. (This is different from almost every other types of gears, where in fact the gear reduction is definitely a function of the diameters of both components.)
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