A sprocket[1] or sprocket-wheel[2] is a profiled wheel with the teeth, or cogs,[3][4] that 
mesh with a chain, monitor or other perforated or indented material.[5][6] The name ‘sprocket’ applies generally to any wheel where radial projections engage a chain passing 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 teeth and chain sprocket pulleys are clean.
Sprockets are used in bicycles, motorcycles, vehicles, 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. Perhaps the most common form of sprocket could be within the bicycle, where the pedal shaft carries a large sprocket-wheel, which drives a chain, which, subsequently, drives a little sprocket on the axle of the trunk wheel. Early automobiles had been also largely driven by sprocket and chain mechanism, a practice generally copied from bicycles.
Sprockets are of varied designs, a maximum of efficiency becoming claimed for each by the originator. Sprockets typically do not have a flange. Some sprockets used with timing belts have flanges to keep carefully the timing belt centered. Sprockets and chains are also used for power transmission from 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 could be run at high speed plus some types of chain are so constructed concerning be noiseless actually at high speed.