Patent ID: 6921998

Claim:
An energy storage flywheel system, comprising: a shaft; a flywheel assembly mounted on the shaft; one or more primary bearing assemblies each configured to selectively rotationally support the shaft; one or more secondary bearing assemblies each configured to selectively rotationally support the shaft; one or more secondary bearing position sensors each configured to supply position signals representative of a position of one or more of the secondary bearing assemblies; a secondary bearing control circuit adapted to receive (i) one or more signals representative of primary bearing assembly operability and (ii) the secondary bearing assembly position signals and operable, in response thereto, to selectively supply actuator control signals; and one or more secondary bearing actuator assemblies each coupled to one or more of the secondary bearing assemblies, each actuator assembly further coupled to receive the actuator control signals from the control circuit and operable, in response thereto, to move the secondary bearing assemblies to one of (i) an engage position, in which each secondary bearing assembly rotationally supports the shaft, and (ii) a disengage position, in which each secondary bearing assembly does not rotationally supports the shaft.