The primary advantage of worm gears is their ability to provide high reduction ratios and correspondingly high torque multiplication. They may also be applied as rate reducers in low- to medium-quickness applications. And, because their decrease ratio is founded on the quantity of gear teeth by itself, they are smaller sized than other types of gears. Like fine-pitch business lead screws, worm gears are usually self-locking, making them suitable for hoisting and lifting applications.
Although the sliding contact minimizes efficiency, it provides incredibly quiet operation. (The use of dissimilar metals for the worm and gear also plays a part in quiet procedure.) This makes worm gears suited to use where sound should be minimized, such as for example in elevators. In addition, the use of a softer materials for the gear means that it could absorb shock loads, like those skilled in hefty equipment or crushing machines.
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 warmth, which limits the performance of worm gears to 30 to 50 percent. So as to minimize friction (and therefore, heating), the worm and gear are constructed of dissimilar metals – for instance, the worm may be made of hardened steel and the gear manufactured from bronze or aluminum.
Just like 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 full flip (360 degrees) of the worm advances the equipment by one tooth. Therefore a gear with 24 teeth provides a gear reduced amount of 24:1. For a multi-begin worm, the apparatus reduction equals the number of teeth on the apparatus, divided by the amount of begins on the worm. (That 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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