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 material.[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 equipment in that sprockets should never be meshed together straight, and differs from a pulley in that sprockets have tooth and pulleys are smooth.
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 track, tape etc. Maybe the most common form of sprocket could be within the bicycle, where the pedal shaft carries a sizable sprocket-wheel, which drives a chain, which, subsequently, drives a little sprocket on the axle of the rear wheel. Early automobiles had been also largely powered by sprocket and chain system, a practice largely copied from bicycles.
Sprockets are of varied designs, a maximum of efficiency becoming claimed for every by its originator. Sprockets typically don't have a flange. Some sprockets used with timing belts possess flanges to keep the timing belt centered. Sprockets and chains are also utilized for power transmission in one shaft to some other where slippage isn't chain sprocket admissible, sprocket chains getting used instead of belts or ropes and sprocket-wheels rather than pulleys. They can be run at high speed and 
some types of chain are so built concerning be noiseless even at high speed.