蠕虫和小齿轮

蜗轮蜗杆是由一个蜗杆和一个齿轮(有时称为蜗轮)组成的，具有互不平行、互不相交的轴，轴向彼此90度。蜗杆类似于带有v型螺纹的螺钉，齿轮类似于直齿圆柱齿轮。蜗杆是典型的驱动部件，蜗杆的螺纹推动齿轮的齿。像滚珠丝杠一样，蜗轮中的蜗杆可能有一次启动或多次启动，这意味着蜗杆上有多个螺纹或螺旋。对于单次启动的蜗轮，每转一圈(360度)的蜗轮推进齿轮一个齿。所以一个24齿的齿轮将提供24:1的齿轮减速。对于多启动蜗杆，齿轮减速器等于齿轮上的齿数，除以蜗杆上的启动次数。(这是不同于大多数其他类型的齿轮，齿轮减速是一个函数的直径的两个组件。)蜗杆和齿轮的啮合是滑动和滚动作用的混合，但在高减速比时滑动接触占主导地位。这种滑动动作会产生摩擦和热量，这将蜗轮的效率限制在30%到50%。 In order to minimize friction (and therefore, heat), the worm and gear are made of dissimilar metals – for example, the worm may be made of hardened steel and the gear made of bronze or aluminum.Although the sliding contact reduces efficiency, it provides very quiet operation. (The use of dissimilar metals for the worm and gear also contributes to quiet operation.) This makes worm gears suitable for use where noise should be minimized, such as in elevators. In addition, the use of a softer material for the gear means that it can absorb shock loads, like those experienced in heavy equipment or crushing machines.The primary benefit of worm gears is their ability to provide high reduction ratios and correspondingly high torque multiplication. They can also be used as speed reducers in low- to medium-speed applications. And, because their reduction ratio is based on the number of gear teeth alone, they are more compact than other types of gears. Like fine-pitch lead screws, worm gears are typically self-locking, which makes them ideal for hoisting and lifting applications.