A sprocket[1] or sprocket-wheel[2] is a profiled wheel with teeth, or cogs,[3][4] that mesh with a chain, track or other perforated or indented materials.[5][6] The name ‘sprocket’ applies generally to any wheel upon which radial projections engage a chain passing over it. It is distinguished from a equipment in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have tooth and pulleys are clean.

Sprockets are found in bicycles, motorcycles, cars, tracked automobiles, and other machinery either to transmit rotary movement between two shafts where gears are unsuitable or even to impart linear motion to a track, tape etc. Maybe the most typical form of sprocket could be found in the bicycle, in which the pedal shaft carries a huge sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the trunk wheel. Early automobiles were also largely driven by sprocket and chain system, a practice mainly copied from bicycles.

Sprockets are of varied designs, no more than efficiency becoming claimed for every by its originator. Sprockets typically do not have a flange. Some sprockets used in combination with chain sprocket timing belts possess flanges to keep the timing belt centered. Sprockets and chains are also used for power transmission in one shaft to some other where slippage isn’t admissible, sprocket chains becoming used rather than belts or ropes and sprocket-wheels instead of pulleys. They can be operate at high speed and some types of chain are so built as to be noiseless actually at high speed.