What Is a Reduction Gear?
A reduction gear is part of a mechanical system of gears and shafts used to reduce the rotational speed of the input shaft to a slower rotational speed on the output shaft. This reduction in output speed helps increase increase torque. Reduction gears are commonly used in automobile and truck drivetrains to reduce the high rotational speeds of the engine to a usable, slower speed at the tires. A simple reduction gear consists of two gears that have the same size teeth but are of different diameters. The number of teeth is proportional to the circumference of the gear; the smaller circumference gear will have fewer teeth than the larger one. For example, a gear with a circumference of 16 inches (40.64 cm) will have twice as many teeth as one with a circumference of 8 inches (20.32 cm). When these gears mesh in a reduction gearbox, the smaller gear makes two revolutions for every one revolution of the larger gear — it spins twice as fast. Conversely, the amount of torque available on the
