Gear / Sprockets / Chains - A Gear is a component within a transmission device that transmits rotational force to another gear or device. The beauty about the gear is that gears of unequal diameter can be combined to produce mechanical advantages, so that the rotational speed and torque of the second gear are different from that of the first.
A Sprocket is a profiled wheel with teeth that meshes with a chain, track or other perforated or indented material. Chains are a series of connected links that are used for transferring power in machines that have links designed to mesh with the teeth of the sprockets of machine, and are flexible in only one dimension.