Patent ID: 9546499
Date: 2017-01-17
CPC Classifications: B66F,E04G,E04H

Claim:
1. An extendable and retractable column comprising: a base; a drive for extending and retracting the column; an extendable and retractable structure supported on the base and having a central axis, the structure comprising at least three separate sidewalls constructed and arranged to selectively releasably retain one another and connectable to one another to define a central interior chamber within the connected sidewalls, each sidewall being extendable and retractable and including a multiplicity of rigid links pivotally connected to one another, each link pivoting about a pivot axis and all the pivot axes of the links comprising each sidewall being oriented substantially parallel to one another and substantially perpendicular to and spaced from the central axis; the drive engaging at least one link of each sidewall to extend and retract the sidewalls of the structure; a first guide tower fixed to the base and positioned within the central interior chamber, the first guide tower positioned closely adjacent at least one link of each of the sidewalls to provide support to at least one link of each sidewall; and a second outer guide tower fixed to the base and positioned outside the extendable and retractable sidewalls, the second outer guide tower being stationary relative to the first guide tower and positioned closely adjacent at least one link of each of the sidewalls and cooperating with the first guide tower to contain the sidewalls therebetween and inhibit disengaging of the drive from the links of each sidewall located between the first and second guide towers and to inhibit the sidewalls located between the first guide tower and second outer guide tower from disengaging from one another.