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 material.[5][6] The name ‘sprocket' applies generally to any wheel upon which radial projections engage a chain passing over it. It really is distinguished from a equipment in that sprockets are never meshed together directly, and differs from a pulley for the reason that sprockets have teeth 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 movement to a monitor, tape etc. Probably the most typical form of sprocket could be found in the bicycle, where the pedal shaft bears a large sprocket-wheel, which drives a chain, which, subsequently, drives a little sprocket on the axle of the trunk wheel. Early automobiles were also largely powered by sprocket and chain mechanism, a practice mainly copied from bicycles.
Sprockets are of various designs, no more than efficiency being claimed for each by the originator. Sprockets typically do not have a flange. Some sprockets used with timing belts possess flanges to keep carefully the timing belt centered. Sprockets and chains are also utilized for power transmission in one shaft to another where slippage is not admissible, sprocket chains becoming used instead of belts or ropes and sprocket-wheels rather than pulleys. They can be operate at high speed plus some forms of chain are so built concerning be noiseless also at high speed.