BACKGROUND OF THE INVENTION

Field of the Invention. The present invention relates generally to spiral staircases and more particularly to central column or pole staircases as opposed to center well type spiral staircases.

Prior Art. The development of spiral staircases has tak several directions utilizing both the center well type stairca and the central column, or pole type staircase in both singula and sectional modes, as illustrated in the following patents:

Patent Number I nventor Issued Title

U.S. 3491498 Wm.J . Hughes ,0 r. 01/27/70 Spiral Staircases U.S. 3207259 Dave F. Gebhart ^• 09/21/65 Spiral Stairway U.S. 424533 Reuben 0. Belles 04/01/1890 Spiral Stairway

There are various problems encountered by each type of staircase. The center pole type typically requires either a very large diameter center pole or a tread which is so narrow at its end adjacent to the center pole that it is unsafe and nconvenient. Additionally, unless the center pole is very w-i-d there can be no center handrail .

The center well type typically requires wasted space for the center well which increases the overall diameter of the staircase and limits its applications particularly with smaller area constructions becoming more common. Center well type sys¬ tems also tend to be springy and thus less safe. Finally, with the sectional mode center well systems, the riser column sectio reduce the available tread space. SUMMARY OF THE INVENTION

Therefore, one object of this invention is to provide a center pole staircase which utilizes a small diameter center pole but retains treads of sufficient width adjacent to the pole for convenience and safety and allows for the incorporatio of an nner hand rail .

_______ ^~

Another object of this invention is to provide a stair¬ case which minimizes wasted center space and hence reduces the diameter of the entire system, thus enlarging its appli¬ cations.

Another object of this invention is to provide a sectional mode staircase which is rigid, thus minimizing the spring effect.

Still another object of this invention is to provide a sectional mode staircase which maximizes available tread area.

Other objects and advantages of this invention shall become apparent from the ensuing descriptions of the invention.

Accordingly, a spiral staircase is provided comprising a center pole, a plurality of treads which are spirally placed around said center pole in an ascending mode, a plurality of riser support sections which are placed between the treads and a tension means which traverses the riser support sections and the treads through coordinated openings placed in each. BRIEF DESCRIPTION OF THE DRAWINGS

Figure T is an exploded view of a preferred embodiment of the invention.

Figure 2 ^' s an exploded view of a preferred embodiment of the center pole of the invention.

Figure 3 ^* s a side view of a preferred embodiment of the riser support section of the invention.

Figure 4 is an overhead view of the invention. PREFERRED EMBODIMENTS OF THE INVENTION

Without limiting the scope of this invention, the pre¬ ferred features will be described using a particular preferred embodiment of this invention.

Referring to Figure 1, starter riser support section 1 is rigidly attached to floor 2 by attachment means 3. Tread 4 is placed on starter riser support section 1 so that hole 5

OMPI

coordinates with opening 6 in starter riser support sec¬ tion 1 and holes 5a and 5b in tread 4 coodinate with pegs 6a and 6b respectively in starter riser support sction 1. Center pole 7 is attached to tread 4 at its near interior corner and is extended up to landing 8.

Referring now to Figure 2, and in a preferred embodiment, tread 4 is attached to center support pole 7 by means of a screw 7a which traverses attachment dowel 4a into tread 4. Attachment dowel 4a is routed at the top to give it a smaller diameter to correspond with that of center pole 7 so that center pole 7 can tightly fit around attachment dowel 4a at it top end. In like fashion intermediate tread 13 can be attache to cneter pole 7 by means of attachment dowel 13a which is routed at both ends to allow center pole to fit snugly around both ends of attachment dowel 13a which is in turn attached to tread 13 by means of screw 7b. In like fashion attachment dowel 8a is fastened to landing 8 by means of screw 7c. Similarly attachment dowel 8a is routed at its bottom end to allow center pole 7 to snugly fit around attachment dowel 8a.

Now referring back to Figure 1 riser support sections 9, 10, and 11 are placed in succeeding steps between treads 4, 12, 13 and 14 respectively so that holes 5, 15, 16 and 17 cor¬ respond with openings 18, 19 and 20 to allow tension means 21 traverse the entire assembly and so holes 15a, 15b, 16a, 16b, 17a and 17b correspond with pegs 18a, 18b, 19a, 19b, 20a and 20b respect ely. As can also be noted, treads 12, 13 and 14 are lined up adjacent to center pole 7 at the near interior corner where grooves 22, 23 and 24 have been placed in treads 12, 13 and 14 respectively for that purpose.

Now referring to Figure 3, riser support section 1, which is identical to riser support sections 1, 9, 10 and 11 in Figure 1, is angled at 60 degrees from the horizontal in

OMPI

this particular preferred embodiment.

Additionally, as can be seen in Figure 4, treads 25, 26 and 27 are rotated around center pole 7, so that interior edges 28, 29 and 30 of each succeeding tread form a angle of 30 degrees.

Referring back to Figure 1, the positioning procedure is repeated with additional treads and riser support sections until landing treae 8 is reached. After proper alignment is completed, tension cable 21 is tightened by means already cur¬ rent in the art thus pulling the entire invention together in a rigid fashion.

There are, of course, many obvious alternate embodiments and modifications to this invention which are intended to be included within the scope of th s. i nvent on as described by the following claims.

OMPI