Angular Momentum

Two masses (M) rest on a track that rotates around the axis (A). If they are not fixed, centrifugal force will fling them outwards. These masses are synchronously pushed further inwards by an actuator. The speed of the masses causes the system to rotate faster. However, since the actuator must work against the centrifugal force, additional energy is supplied to the system, and it rotates even faster.
Conservation of angular momentum:
To change the speed of a rotating disk, a force must be applied. It's like a lever: at half the radius, twice the force is required.

Ludwig Resch