US3556251A

US3556251A - Adjustable staircase structures

Info

Publication number: US3556251A
Application number: US808505A
Authority: US
Inventors: John I Whitehead
Original assignee: Individual
Current assignee: Individual
Priority date: 1969-03-19
Filing date: 1969-03-19
Publication date: 1971-01-19
Anticipated expiration: 1988-01-19

Abstract

A prefabricated staircase is adjustable to be fitted between floors and comprises at least one parallelogram truss supported at its two lower corners to the two floors by respective supporting members; the truss upper chord member forms the handrail, while the lower chord member supports the stairtreads; a preselected number of vertically-extending panel members extend between the chord members and are pivotally connected thereto; each panel member comprises an arcuate portion engaging the corresponding arcuate portion of the immediately adjacent panel member, these engaging portions being slotted and clamped rigidly together by bolts passing through the slots when adjustment of the staircase is completed; the stairtreads remain parallel and horizontal at all times as the truss is adjusted to fit between the floor levels.

Description

United States Patent John I. Whitehead [72] inventor B R. 4 Brantfordt Ontario. Canada [21] Appl. No. 808,505 [22] Filed Mar. 19, 1969 [45] Patented Jan. 19, 1971 [54] ADJUSTABLE STAIRCASE STRUCTURES 13 Claims, 4 Drawing Figs.

[52] US. Cl 182/93, 182/194, 182/106, 52/182 [51] Int. Cl E06c 9/02 [50] Field of Search 182/ 1 94 Primary Examiner-Reinaldo P. Machado Att0rney-Church and Rogers ABSTRACT: A prefabricated staircase is adjustable to be fitted between floors and comprises at least one parallelogram truss supported at its two lower corners to the two floors by respective supporting members; the truss upper chord member forms the handrail, while the lower chord member supports the stairtreads; a preselected number of vertically-extending panel members extend between the chord members and are pivotally connected thereto; each panel member comprises an arcuate portion engaging the corresponding arcuate portion of the immediately adjacent panel member, these engaging portions being slotted and clamped rigidly together by bolts passing through the slots when adjustment of the staircase is completed; the stairtreads remain parallel and horizontal at all times as the truss is adjusted to fit between the floor levels.

II 10 I3 27 PATENTED mslsm 3556251 IN VliN ()R. JOHN l. WHITEHEAD 30 3 26 PATENT AGENTS ADJUSTABLE STAIRCASE STRUCTURES ADJUSTABLE STAIRCASE STRUCTURES Field of the Invention The present invention relates to adjustable staircase structures and to panel members therefor and is concerned especially with a staircase structure in which the handrail or handrail support is incorporated and utilized as a structural member.

DESCRIPTION OF THE PRIOR ART It is a common practice in staircases to support the entire stair load on a comparatively shallow stringer disposed beneath the staircase.

SUMMARY OF THE INVENTION It is an object of the present invention to utilize the materials of which the staircase structure is composed to a maximum advantage, while maintaining the adjustable features which are so desirable.

Another important object is to provide related adjustment of all stair treads so that their differences in elevation will remain constant and their surfaces will remain level without individual stair adjustment.

A further object is to facilitate prefabrication and selection of any size of staircase from a relatively limited variety of basic parts.

In accordance with the present invention in an adjustable staircase, a supporting truss having upper and lower ends and composed of an upper chord member forming or supporting a handrail and providing lateral stability to the truss in compression; a lower chord member providing lateral stability to the truss in tension; several panel members pivotally connected to said chord members and operatively connecting them to form the said truss, each panel member having two spaced upwardly extending edges to resist opposing stresses in the two edges and providing a support for a respective horizontallydisposed stair tread adjacent its lower end; means for supporting the upper end of the truss on an upper floor; means for supporting the lower end of the truss on a lower floor and fastening means for establishment of a fixed angular relationship between the panel members and said upper and lower chord members after adjustment.

Also in accordance with the present invention there is provided a panel member for use in an adjustable staircase-comprising. strut means having upper and lower ends, means for pivotally connecting the strut means upper end to an upper chord member, an arcuate lower member connected to the strut means lower end and adapted to be pivotally connected to a lower chord member, wherein the said arcuate lower member has an arcuate outer surface engageable with the corresponding outer surface of the arcuate member of the immediately adjacent panel member, and fastening means are operative to clamp together the mutually engaging arcuate members. 7

The upper and lower chord members are pierced at regular intervals and are pivotally connected at these pierced points to the said panel members, thus forming a series of parallelograms, each one of which will support the end of a stair tread and insure its parallelism and equal spacing with all other treads, as the trusses are adjusted to span the space between the upper and lower floors.

After adjustment has been made it is necessary to secure the panel members against further pivotal action relative to the chord members, for which purpose slots may be provided in mutually engaging parts of the panel members that are immediately adjacent one another, together with means passing through the slots for clamping the panel members against movement.

A tread support is provided in each panel member of a nature to support the treads, which may be of any suitable material and form, with their upper surfaces horizontal.

The uppermost panel member in each truss is formed to furnish anchorage of the staircase to an upper level capable of supporting the stair load, and also to provide a part tread or nosing support to match the intermediate treads.

The lowermost panel member on each side may have additional supporting means for attachment thereof to a lower floor level bracket capable of resisting the end reaction of the stair load and at the same time preserve the common spacing and adjustment of all other panels.

DESCRIPTION OF THE DRAWINGS A particular preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawing in which:

FIG. 1 shows the lower end of a staircase in one adjusted position,

FIG. 2 shows a complete staircase in another adjusted position,

FIG. 3 shows on an enlarged scale a detail of one form of clamping means, and

FIG. 4 shows on an enlarged scale a section of the upper chord or handrail taken in the direction of arrows 4-4 in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred form of the staircase in accordance with the invention takes the form of a truss, having an upper chord member I of general L or angular cross section which comprises a handrail therefor. The upper chord member 1 is formed with a generally horizontal top flange to provide the desired lateral stiffness, and has a vertically-downwardly extending web along its inner edge pierced at regular intervals to provide a required number of panel pivots 2. The chord member may be covered with a suitable material, or may have a dependent skirt on its outer edge to provide a smooth and uninterrupted handhold throughout its length. It must also be of sufficient size and cross-sectional area to resist the compressive stresses resulting from the stair load.

A lower chord member 4 is also of general L or angular cross section form to resist tension stresses from the stair load, having a horizontal lower flange joined to a vertical web which is pierced to provide pivot points 3 at the same intervals as the corresponding web of the upper chord 1. At its lower end it carries a formed tab which is pierced for the insertion of a bolt 29 to permit the adjustable connection of the chord member to a brass bracket which is described below. I

The above-described upper and lower chord members are connected together to form the truss by means of a number of stair tread panel members, designated A, B, and C, which are all of the same effective length.

The panel members B are intermediate and usually a plurality thereof are required, the actual number being equal to the number of intermediate stair treads involved. In this particular embodiment a complete panel member B consists of two spaced vertically-extending

struts

6 and 7, having their upper ends joined to a gusset 5 and each constituting a respective edge to its panel. A stair tread support member 18 is connected chordwise at its ends to an arcuate member 9, which has the lower spaced ends of the

struts

6 and 7 connected thereto, to result in a generallytriangular configuration. Each of these arcuate members 9 has an outside radius of approximately half the distance between pivot points on the member lower chord 4, and is provided along its length at

points

16 and 17 with respective slots which receive bolts 22 and are of suffrcient length to provide the necessary adjustment on the bolt 22, as will be described below. The arcuate members shown herein are continuous to provide further stiffness in the panel B, but instead separate arcuate sections can be used suitably joined together. A tread 15 is fastened to the support 18 by screws or other means which are not shown. If further rigidity for the panel member is desired this may be provided by means of an insert 31 fastened to the

struts

6 and 7 and to the arcuate member 9.

Panel members A are used only at the lower end of the truss, and differ from panel members B only by the addition of a brace 19 connected between the extreme front end of the arcuate member 9 and the tread support 18 and providing additional strength at this point. This front end of panel member A engages a lower level floor bracket 24 having a base plate 31 adapted to be fastened to the floor 30 by means such as bolts which are not shown. A member fastened to the base plate provides a flat face 20 which extends parallel to the brace 19, the face 20 and the brace being pierced to receive a bolt 26 by which they can be fastened together.

With the staircase in the position shown in FIG. 2 the brace is in direct contact with the face 20, while in the position shown in FIG. 1, a spacer 25 of the required height is interposed between them.

Said bracket 24 provides an arcuate piece 23 which is slotted to receive a bolt 29 for connection thereof to a corresponding arcuate piece 32 attached to the bottom end of the lower chord member 4, and an arcuate piece 21, which is similar to the rear end of arcuate member 9, and is slotted and fastened to the front end of the arcuate member 9 of the panel A by a bolt 22.

The particular panel C member illustrated differs from panel members A and B in that the arcuate member 10 is smaller in length than the members 9 and a rear strut 8 replacing the strut 7 is fastened at its lower end to the horizontal portion ofa bent plate 13. The rear end of the arcuate member 10 is fastened to the strut, and a brace 11 of a shape to provide a suitable decorative finished appearance is connected between the strut 8 and the plate 13. This plate 13 is of sufficient width to provide the required lateral stability to the assembly, and provides a horizontal portion for connection to an upper floor 27 and a vertical portion for connection to the vertical faces of beams or other floor members 28, for which purpose these portions are pierced for fasteners.

The front end of the arcuate member is further reinforced in panel member C by a vertical piece 12 which also carries on a flange thereof a part tread or nosing 14 which corresponds to the front edge of the treads 15 and is used to give a uniform finish and position to the upper stair.

An important feature of a staircase in accordance with this invention is the ease of operation of the adjusting means, further clarified in FIG. 3, which is permitted by the intimate contact at all positions of adjustment of the arcuate faces provided by the

members

21, 9 and 10, which after adjustment are clamped firmly together by bolts 22 and appropriate nuts and washers.

The treads 15 may be of any suitable material and shape. The sections shown are of wood and are deeper at the nose than at the rear to provide a stiffer tread with a given amount of material. For this purpose the tread support 18 is shown tilted downward at the front to provide a level top surface of the tapered tread when mounted.

A refinement shown is that in any of the panel members the

struts

6 and 7 and the member at 9 may be further stiffened by panels or scrolls 31 fastened between them for decorative purposes.

A preferred procedure to be followed at installation of a staircase in accordance with the invention is as follows:

Pairs of upper and lower chord members are selected of a length which will be determined from a prepared table, so that the resulting staircase will be within the usual limits of inclination. The chord members are then supplied together with two lower panel members A, two upper panel members C and the requisite member of intermediate panel members B.

The two upper panel members C are then mounted on the upper floor the requisite transverse distance apart. The other panel members A and B are assembled to the appropriate top and bottom chord members with the bolts 22 omitted, the brackets 5 being pivotally connected to the upper chord members l at points 2, while the rear ends of the tread supports 18 are pivotally connected to the lower chord members 4 at points 3.

The complete assemblies ofchord members and other panel members are then fastened at pivot points 2 to the two' panel members C.

The lower end of each truss constituted by the lower end of lower chord member 4 and the front edges of the panel mem bers A, is supported by the bracket 24 which, after levelling. moving back and forth to adjust for height, and insertion of the appropriate spacers 25, are fastened to the floor 30 by fasteners not shown.

The

bolts

22, 26 and 29 may now be inserted and clamped, or if previously inserted before finalising the adjustment are tightened to clamp the staircase in its final position.

Since the panel members C are located in the proper vertical attitude by the bent plate 13 and form one side of an upper parallelogram it follows that all other parallelograms as formed by the panel members and chord members are held in similar attitude.

Because of the design of the panel members it follows that all of the treads are now level and equally spaced and are now rigidly clamped in this position by tightening all

bolts

22, 26 and 29.

lclaim:

1. In an adjustable staircase, a supporting truss having upper and lower ends and composed of an upper chord member forming or supporting a handrail and providing lateral stability to the truss in compression, a lower chord member providing lateral stability to the truss in tension; several panel members pivotally connected to said chord members and operatively connecting them to form the said truss, each panel member having two spaced-upwardly extending edges to resist opposing stresses in the two edges and providing a support for a respective horizontally-disposed stair tread adjacent its lower end; means for supporting the upper end of the truss on an upper floor; means for supporting the lower end of the truss on a lower floor and fastening means for establishment of a fixed angular relationship between the panel members and said upper and lower chord members after adjustment.

2. The invention as claimed in claim 1, in which the upper chord member is continuous through the length of the truss and is formed to provide a handgrip at a suitable height above the stair treads.

3. The invention as claimed in claim 1, wherein each of the said panel members comprises an arcuate lower member adapted to be pivotally connected to the respective lower chord member, and having an arcuate outer surface engageable with the corresponding outer surface of the arcuate member of the immediately adjacent panel member, and the said fastening means are operative to clamp together the mutually-engaging arcuate members.

4. The invention as claimed in claim 3, in which the clamping means comprise mutually-registering slots in the said arcuate members and bolts adapted to pass through the said slots.

5. The invention as claimed in claim 1 wherein each of the said panel members comprises a pair of spaced strut members connected at their upper ends to a common pivot member adapted to be pivotally connected to the upper chord member, an arcuate lower member adapted to be pivotally connected to the respective lower chord member and having the said spaced strut members connected thereto, and a stair support member connected to the respective arcuate member and extending chordwise with respect thereto.

6. The invention as claimed in claim 5, wherein each arcuate lower member has an arcuate outer surface engageable with the corresponding outer surface of the arcuate member of the immediately adjacent panel member, and the said fastening means are operative to clamp together the mutuallyengaging arcuate members.

7. The invention as claimed in claim 2 wherein the means for supporting the lower end of the truss comprises a floor bracket having an arcuate segment corresponding the rear end of a panel member arcuate member and adapted to adjustably engage the arcuate member of the lower most panel member.

8. The invention as claimed in claim 7, wherein each lower chord member has at its lower end an arcuate segment matching and clamped to a corresponding arcuate segment of the floor bracket.

9. The invention as claimed in claim 2 wherein the means for supporting the upper end of the truss on the upper floor comprise an angular bracket member having a horizontal and a vertical portion. having an uppermost panel member rigidly fixed thereon, and having fixed thereon for cooperating engagement with the arcuate member of the next lower panel member an arcuate segment member corresponding to the front segment of an arcuate member of said next lower panel member.

10. The invention as claimed in claim 1 wherein each panel member is reinforced by a centrally disposed panel or scroll.

11. The invention as claimed in claim 1 and comprising a complete staircase constituted by two spaced parallel trusses, means for supporting the upper ends of the trusses on an upper floor, means for supporting the lower ends of the trusses on a lower floor, and stair treads extending between corresponding panel members of the two trusses.

12. A panel member for use in an'adjustable staircase as claimed in claim 1, comprising strut means having upper and lower ends, means for pivotally connecting the strut means upper end to an upper chord member. and an arcuate lower member connected to the strut means lower end and adapted to be pivotally connected to a lower chord member, wherein the said arcuate lower member has an arcuate outer surface engageable with the corresponding outer surface of the arcuate member of the immediately adjacent panel member. and fastening means are operative to clamp together the mutuallyengaging arcuate members.

13. A panel member as claimed in claim 12, and comprising a stair tread support member connected to the respective arcuate member and extending chordwise with respect thereto. the stair tread support member also constituting means for pivotally connecting the panel member to a lower chord member.

Claims

6. The invention as claimed in claim 5, wherein each arcuate lower member has an arcuate outer surface engageable with the corresponding outer surface of the arcuate member of the immediately adjacent panel member, and the said fastening means are operative to clamp together the mutually-engaging arcuate members.

9. The invention as claimed in claim 2 wherein the means for supporting the upper end of the truss on the upper floor comprise an angular bracket member having a horizontal and a vertical portion, having an uppermost panel member rigidly fixed thereon, and having fixed thereon for cooperating engagement with the arcuate member of the next lower panel member an arcuate segment member corresponding to the front segment of an arcuate member of said next lower panel member.

12. A panel member for use in an adjustable staircase as claimed in claim 1, comprising strut means having upper and lower ends, means for pivotally connecting the strut means upper end to an upper chord member, and an arcuate lower member connected to the strut means lower end and adapted to be pivotally connected to a lower chord member, wherein the said arcuate lower member has an arcuate outer surface engageable with the corresponding outer surface of the arcuate member of the immediately adjacent panel member, and fastening means are operative to clamp together the mutually-engaging arcuate members.

13. A panel member as claimed in claim 12, and comprising a stair tread support member connected to the respective arcuate member and extending chordwise with respect thereto, the stair tread support member also constituting means for pivotally connecting the panel member to a lower chord member.