A sprocket[1] or sprocket-wheel[2] is a profiled wheel with the 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 where radial projections engage a chain moving over it. It really is distinguished from a gear in that sprockets are never meshed together directly, and differs from a pulley in that sprockets have tooth and pulleys are smooth.
Sprockets are used in bicycles, motorcycles, cars, tracked automobiles, and other machinery either to transmit rotary movement chain sprocket between two shafts where gears are unsuitable or even to impart linear motion to a track, tape etc. Maybe the most common form of sprocket could be found in the bicycle, where the pedal shaft bears a large sprocket-wheel, which drives a chain, which, in turn, drives a little sprocket on the axle of the rear wheel. Early automobiles were also largely powered by sprocket and chain system, a practice largely copied from bicycles.
Sprockets are of various designs, a maximum of efficiency getting claimed for each by the originator. Sprockets typically don’t have a flange. Some sprockets used with timing belts have flanges to keep the timing belt centered. Sprockets and chains are also used for power transmission from one shaft to some other where slippage is not admissible, sprocket chains becoming used instead of belts or ropes and sprocket-wheels rather than pulleys. They could be run at high speed and some kinds of chain are so built concerning be noiseless also at high speed.