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

Gears have been used in transmission since ancient times. Over three centuries before Christ, the ancient Greek philosopher Aristotle discussed the use of bronze or cast iron gears to transmit rotational motion in his work "On the Mechanika." By the late 19th century, the principle of involute gearing and the subsequent appearance of machinery and tools designed to cut gears using this principle provided more comprehensive means for gear manufacturing. With the advancement of production, the smoothness of gear operation has become a priority.