Patent ID: 8286531

Claim:
An automatic balancing device for counterbalancing an out-of-balance mass present in a body which is rotatable about an axis of a dynamic system having a critical speed, comprising: a plurality of counterbalancing masses, each of which is movable in a circular path about the axis so as to generate an individual balancing force, wherein the individual balancing forces combine to generate a resultant balancing force having a magnitude that is variable between a minimum value and a maximum value depending, at least in part, on relative positions of the counterbalancing masses, and a restraint configured to restrain at least two of the counterbalancing masses in a fixed relationship to each other when the at least two counterbalancing masses move at a first speed of rotation that is below the critical speed, and to allow the at least two counterbalancing masses to move relative to each other when the at least two counterbalancing masses move at a second speed of rotation that is equal to or greater than the critical speed, wherein when the at least two counterbalancing masses are restrained in the fixed relationship to each other, the restrained counterbalancing masses are movable, in the fixed relationship, about the axis and independent from the body so as to generate a substantially constant non-zero resultant balancing force that is freely movable about the axis.