The primary advantage of worm gears is their ability to provide high reduction ratios and correspondingly high torque multiplication. They may also be utilized as acceleration reducers in low- to medium-swiftness applications. And, because their lowering ratio is founded on the number of gear teeth only, they are more compact than other styles of gears. Like fine-pitch business lead screws, worm gears are usually self-locking, which makes them well suited for hoisting and lifting applications.
Although the sliding contact decreases efficiency, it provides incredibly quiet operation. (The usage of dissimilar metals for the worm and gear also contributes to quiet operation.) This makes worm gears suitable for use where sound should be minimized, such as for example in elevators. Furthermore, the usage of a softer material for the gear means that it can absorb shock loads, like those experienced in major equipment or crushing equipment.
The meshing of the worm and 
the gear is a mixture of sliding and rolling actions, but sliding contact dominates at high reduction ratios. This sliding actions causes friction and high temperature, which limits the efficiency of worm gears to 30 to 50 percent. So as to minimize friction (and for that reason, high temperature), the worm and equipment are constructed of dissimilar metals – for example, the worm could be made of hardened metal and the gear manufactured from bronze or aluminum.
Like a ball screw, the worm in a worm gear could have an individual start or multiple starts – meaning that there are multiple threads, or helicies, on the worm. For a single-start worm, each total flip (360 degrees) of the worm increases the gear by one tooth. Consequently a gear with 24 teeth provides a gear reduced amount of 24:1. For a multi-begin 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 most other types of gears, where in fact the gear reduction is a function of the diameters of both components.)
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