It serves as a reservoir by absorbing mechanical energy and storing energy during the period when the supply of energy is more than the required and the same is released during the period when the requirement of energy is more than the supply. Flywheel is connected to a crankshaft on one end whereas the clutch lies on its other side. Flywheel absorbs the energy during a power stroke (when the crankshaft is being pushed by engine). The energy is released during compression stroke, i.e., when the piston is pushed by the crankshaft. They are also used for Delivering energy at rates beyond the reach of a continuous energy source. This is achieved by collecting energy in the reservoir over time and then releasing the energy quickly, at rates which exceed the abilities of an energy source. It is used for controlling the orientation of a mechanical system. In such applications, the angular momentum of a flywheel is deliberately transferred to a load when energy is transferred to or from the flywheel. A flywheel also functions to smooth out vibrations in the shaft due to torque fluctuations and to store the momentum thereby, acting as reservoir. The Flywheels are generally made of steel and rotate on regular bearings which are limited to a revolution rate of a few thousand RPM whereas some modern flywheels are made of carbon fiber materials which employ magnetic bearings thus, enabling them to revolve at speeds up to 60,000 revolutions to the minute. Recently manufacturers have added Carbon – composite flywheel batteries which are proving to be viable in real – world tests on mainstream cars. Further, their disposal is more environment friendly.