The primary benefit of worm gears is their capability to provide high reduction ratios and correspondingly high torque multiplication. They can also be utilized as acceleration reducers in low- to medium-velocity applications. And, because their decrease ratio is based on the amount of gear teeth by itself, they are smaller sized than other styles of gears. Like fine-pitch lead screws, worm gears are usually self-locking, making them ideal for hoisting and lifting applications.
Although the sliding contact reduces efficiency, it provides very quiet operation. (The use of dissimilar metals for the worm and equipment also plays a part in quiet procedure.) This makes worm gears ideal for use where noise should be minimized, such as in elevators. In addition, the application of a softer material for the gear means that it can absorb shock loads, like those knowledgeable in weighty 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 temperature, which limits the performance of worm gears to 30 to 50 percent. So as to minimize friction (and for that reason, warmth), the worm and gear are made from dissimilar metals – for instance, the worm may be made of hardened steel and the gear made of bronze or aluminum.
Such as a ball screw, the worm in a worm gear may well have a single start or multiple starts – meaning that there are multiple threads, or helicies, on the worm. For a single-start worm, each complete transform (360 degrees) of the worm advances the gear by one tooth. Therefore a gear with 24 teeth will provide a gear reduced amount of 24:1. For a multi-start worm, the gear reduction equals the number of teeth on the gear, divided by the amount of begins on the worm. (This is different from most other types of gears, where in fact the gear reduction is definitely a function of the diameters of the two components.)