Gears are mechanical components with teeth on their rim that can continuously mesh to transmit motion and power. They are interlocking toothed mechanical parts, where the diameter of the larger gear is twice that of the smaller gear.

Gears have been used in transmission for a long time; more than 300 years BC, the ancient Greek philosopher Aristotle discussed the issue of transmitting rotational motion using bronze or cast iron gears in his work "On the Mechanica." By the end of the 19th century, the principle of formative gear cutting and the subsequent appearance of machine tools and cutting tools utilizing this principle made gear manufacturing more sophisticated. With the development of production, the smoothness of gear operation has become a priority.