Patent ID: 7246843

Claim:
An extendable and retractable support system for raising and lowering a structure which comprises: a base; a structure to be raised and lowered relative to the base; a plurality of telescopic assemblies coupled between the base and the structure to be raised and lowered; a plurality of spring elements having first and second ends with the second ends of the spring elements being coupled to the plurality of telescopic assemblies; and a lift tube assembly coupled to the first ends of the spring elements, the lift tube assembly including a mechanism which, when activated, selectively extends or retracts each of the plurality of spring elements therefrom, each of the telescopic assemblies comprising at least two tube members that are telescopically coupled together and each of the at least two tube members comprising an inboard side, and outboard side, opposed ends and an internal structure that extends into the interior of the tube members from one of the inboard and outboard sides and defines an internal channel that is spaced apart from the opposite ends and extends through the tube members, said channel having a central axis that is parallel to and proximal to a center of the tube members, tough which channel one of the plurality of spring elements extends.