US Patent 7118514 Playground equipment

A playground device, in the nature of a teeter-totter, includes first and second spaced base members. An arcuate rail is coupled to the base members in an upright arc. An arcuate member surrounds at least a portion of the rail and is mounted for to-and-fro movement relative to the rail. User platforms or other user-friendly features are mounted on the tube. A biasing mechanism coacts between the member and the rail to bias the member toward a predetermined preferably central position on the rail, while allowing the tube to move to-and-fro on the rail.