Roller chain or bush roller chain is the type of chain drive mostly used for transmitting of mechanical power on many kinds of domestic, commercial and agricultural machinery, including conveyors, wire- and tube-drawing machines, printing presses, cars, motorcycles, and bicycles. It consists of a series of brief cylindrical rollers held together by side links. It is Leaf Chain driven by a toothed wheel known as a sprocket. It is a straightforward, reliable, and efficient[1] means of power transmission.
Though Hans Renold is credited with inventing the roller chain in 1880, sketches by Leonardo da Vinci in the 16th century show a chain with 
a roller bearing.