Retractable column and method of forming

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.

2. The extendable and retractable column of claim 1 wherein;

the extendable and retractable structure has three sidewalls and a substantially triangular cross section;

the second outer guide tower has a generally rigid triangular shape substantially congruent with the extendable and retractable structure;

the second outer guide tower further including three ring posts, with a ring post positioned at each corner of the triangular shape; and

a first reaction ring carried by the three ring posts, extending around the structure and closely confronting the extendable and retractable structure.

3. The extendable and retractable column of claim 2 and further including a second reaction ring carried by the three ring posts, positioned below and spaced from the first reaction ring and closely confronting the sidewalls of the extendable and retractable structure.

4. The extendable and retractable column of claim 3 and further including a third reaction ring carried by the three ring posts, positioned below and spaced from the second reaction ring and closely confronting the sidewalls of the extendable and retractable structure.

5. The extendable and retractable column of claim 4 and further including a plurality of rollers carried by the first, second and third reaction rings, the rollers engaging the sidewalls of the extendable and retractable structure to urge the sidewalls toward the first guide tower to keep the drive engaged with the sidewalls.

6. The extendable and retractable column of claim 5 wherein the links of each sidewall include two spaced apart struts and a plurality of the rollers are positioned on at least one reaction ring to contact both struts of the links of the extendable and retractable structure.

7. The extendable and retractable column of claim 2 and further including a plurality of rollers carried by the first reaction ring and contacting the sidewalls of the extendable and retractable structure, the plurality of rollers cooperating with one another to urge the sidewalls toward the first guide tower to keep the drive engaged with the sidewalls.

8. The extendable and retractable column of claim 2 and further including:

three outer posts fixed to the base, an outer post being positioned adjacent each ring post and spaced from the ring post; and

three rigid tongues, a rigid tongue fixed to each ring post and extending toward an outer post, each tongue movably mounted to the outer post to allow slight movement of the second guide tower relative to the extendable and retractable structure to maintain engagement between the structure and the drive when wind forces are applied to the structure.

9. The extendable and retractable column of claim 2 and further including:

three outer posts fixed to the base, an outer post being positioned adjacent each ring post and spaced from the ring post; and

three rigid tongues, a rigid tongue extending between each ring post and the adjacent outer post, each of the tongues fixed to one of the posts and movably mounted to the post adjacent the post to which the tongue is fixed so as to allow slight movement of the second guide tower relative to the extendable and retractable structure to maintain engagement between the extendable and retractable structure and the drive when wind forces are applied to the extendable and retractable structure.

10. The extendable and retractable column of claim 8 and further including a plurality of rollers carried by the first reaction ring and engaging the sidewalls of the extendable and retractable structure to urge the sidewalls toward the first guide tower to keep the sidewalls engaged with the drive.

11. The extendable and retractable column of claim 1 wherein:

the second guide tower has a polygonal cross section whose corners are equal in number to the number of sidewalls of the extendable and retractable structure;

the second guide tower further including a plurality of ring posts, with a ring post positioned at each corner of the polygonal cross section of the second guide tower; and

a first reaction ring carried by the ring posts, extending around the extendable and retractable structure and closely confronting the extendable and retractable structure.