Editing Flywheel (section)

== Applications ==
[[File:Landini VL30(Italien)2.JPG|thumb|A [[Landini (tractor)|Landini]] tractor with exposed flywheel]]

Flywheels are often used to provide continuous power output in systems where the energy source is not continuous. For example, a flywheel is used to smooth the fast angular velocity fluctuations of the [[crankshaft]] in a reciprocating engine. In this case, a crankshaft flywheel stores energy when torque is exerted on it by a firing [[piston]] and then returns that energy to the piston to compress a fresh charge of air and fuel. Another example is the [[friction motor]] which powers devices such as [[toy car]]s. In unstressed and inexpensive cases, to save on cost, the bulk of the mass of the flywheel is toward the rim of the wheel. Pushing the mass away from the axis of rotation heightens [[rotational inertia]] for a given total mass.

A flywheel may also be used to supply intermittent pulses of energy at power levels that exceed the abilities of its energy source. This is achieved by accumulating energy in the flywheel over a period of time, at a rate that is compatible with the energy source, and then releasing energy at a much higher rate over a relatively short time when it is needed. For example, flywheels are used in [[power hammer]]s and [[riveting machines]].

Flywheels can be used to control direction and oppose unwanted motions. Flywheels in this context have a wide range of applications: [[gyroscope]]s for instrumentation, [[ship stability]], satellite stabilization ([[reaction wheel]]), keeping a toy spin spinning ([[friction motor]]), stabilizing magnetically-levitated objects ([[spin-stabilized magnetic levitation]]).

Flywheels may also be used as an electric compensator, like a [[synchronous compensator]], that can either produce or sink reactive power but would not affect the real power. The purposes for that application are to improve the power factor of the system or adjust the grid voltage. Typically, the flywheels used in this field are similar in structure and installation as the synchronous motor (but it is called synchronous compensator or synchronous condenser in this context). There are also some other kinds of compensator using flywheels, like the single phase induction machine. But the basic ideas here are the same, the flywheels are controlled to spin exactly at the frequency which you want to compensate. For a synchronous compensator, the voltage of rotor and stator also must be kept in phase, which is the same as keeping the magnetic field of rotor and the total magnetic field in phase (in the [[Rotating reference frame|rotating frame reference]]).