The primary benefit of worm gears is their capability to provide high reduction ratios and correspondingly high torque multiplication. They can also be applied as swiftness reducers in low- to medium-quickness applications. And, because their lowering ratio is based on the amount of gear teeth only, they are more compact than other types of gears. Like fine-pitch business lead screws, worm gears are usually self-locking, which makes them perfect for hoisting and lifting applications.
Although the sliding contact reduces efficiency, it provides extremely quiet operation. (The make use of dissimilar metals for the worm and gear also plays a part in quiet operation.) This makes worm gears well suited for use where noises should be minimized, such as in elevators. In addition, the usage of a softer materials for the gear means that it can absorb shock loads, like those knowledgeable in heavy equipment or crushing devices.
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 that you can minimize friction (and for that reason, temperature), the worm and equipment are constructed of dissimilar metals – for example, the worm could be made of hardened steel and the gear made of bronze or aluminum.
Just like a ball screw, the worm in a worm gear may have a single start or multiple starts – and therefore there are multiple threads, or helicies, on the worm. For a single-start worm, each total convert (360 degrees) of the worm advances the gear by one tooth. So a gear with 24 teeth will provide a gear reduction of 24:1. For a multi-commence worm, the apparatus reduction equals the quantity of teeth on the gear, divided by the amount of begins on the worm. (That is different from most other types of gears, where the gear reduction is normally a function of the diameters of the two components.)
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