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 even.
Sprockets are used in sprockets bicycles, motorcycles, vehicles, tracked vehicles, 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 common form of sprocket may be found in the bicycle, in which the pedal shaft carries a huge sprocket-wheel, which drives a chain, which, subsequently, drives a little sprocket on the axle of the rear wheel. Early automobiles were also largely driven by sprocket and chain system, a practice mainly copied from bicycles.
Sprockets are of various designs, a maximum of efficiency being claimed for each by the originator. Sprockets typically don’t have a flange. Some sprockets used in mixture with timing belts have flanges to keep the timing belt centered. Sprockets and chains are also used for power transmission from one shaft to another 
where slippage isn’t admissible, sprocket chains getting used rather than belts or ropes and sprocket-wheels instead of pulleys. They may be operate at high speed plus some forms of chain are so constructed concerning be noiseless actually at high speed.
