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 passing over it. It really is distinguished from a gear in that sprockets should never be meshed together straight, and differs from a pulley for the reason that sprockets have the teeth and pulleys are easy.
Sprockets are found in bicycles, motorcycles, vehicles, tracked automobiles, and other machinery either to transmit rotary movement between two shafts where gears are unsuitable or to impart linear motion to a monitor, tape etc. Probably the most common form of sprocket could be within the bicycle, in which the pedal shaft bears a huge sprocket-wheel, which drives a chain, which, in turn, drives a small sprocket on the axle of the rear wheel. Early automobiles had been also largely driven by sprocket and chain mechanism, a practice mainly 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 in combination 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 is not admissible, sprocket chains getting used rather than belts or ropes and sprocket-wheels instead of pulleys. They could be operate at high speed plus some types of chain are so constructed as to be noiseless also at high speed.