Abstract: A portable folding orthopedic seat unit for use on a chair, automobile seat, or the like. A semirigid seat member is hinged to a back member. Vertical rigid support means extends from the bottom to the top of the back member and supports a back-support assembly, comprising two separate, generally elliptically-shaped, padded back-support members, spaced apart from each other, and a substantially vertically rigid and laterally flexing connecting member joining them together. The connecting member serves to transfer forces from one back-support member to the other. Releasable locking means holds the assembly at a selected vertical position on the rigid support means.

Abstract: An inertial energy storage rotor defined by a plurality of independent, concentric rotor rings rotatable about a vertical axis. A spacer ring connects each outer rotor ring to its adjacent inner rotor ring and is constructed of a substantially rigid material. The spacer ring has a cylindrical configuration and a plurality of slots which alternatingly extend from opposing axial ends of the ring towards the opposite end of the ring. The slots terminate short of such opposite end. The spacer ring includes first and second connecting tabs which are disposed at the respective axial ends of the ring for engaging and rotationally interlocking the rings, supporting the outer ring on the inner ring, maintaining the rings concentric with respect to each other, and permitting differential dilations in the rings during high rates of rotation of the wheel.