US1059272A - Counterbalanced stair. - Google Patents

Description

. UNITED v srarns rarENr ornion CHARLES HENRY BURCH AND.WAINWRIG-I-I'LB. GERVAIS, OF CHICAGO, ILLINOIS, ASSIGNORS T0 VARIETY MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION or iILLINOIS.

COUNTERBALANCED STAIR.

Specification of Letters Patent.

PatentedApr. 15, 1913;

Application filed June 17, 1912. SerialNo. 704,004.

To all whom 2'15 may concern: 1

Be it known that we, CHARLES HENRY Boson and TAI'NWRIGHT BACOT GnnvAIs, citizens of the United States, and residents of Chicago, inthe county of Cook and State of Illinois, have invented a certainnew and useful Improvement in Counterbalanced Stairs, of which the following is a full, clear, concise, and exact description,.referonce beinghad to the accompanyingdrawings, forming a part of this specification.

Our invention relates to counterbalanced stairs such as are associated with theplatforms of fire-escapes, at. a convenient distance above the ground and its object is to provide an improved. stair wherein the proper relation of the parts is maintained by providing improved means whereby distortion or. sagging; of the. parts of the structure, due to unbalanced. strains, is prevented. It a is usual. in the art in the construction of Stairways of this kind to mount two. parallel side beams.

or stringers upon a suitable pivot rod and to secure suitable treads or steps between these side beams or stringers. The stair structure thus formed extendslin but one direction from the pivot rod,which pivot rodusually extends from the side of thebuilding, and in order to counterbalancethe stairway to keep it normally off the ground in a horizontal position, a bar secured to one of the stringers is extended beyond the pivot rod in the opposite direction and is provided with a weight. Since but one of the stringers is thus counter-weighted, and since theavhole stairway is held up in this manner, it follows that there will be a tendency for the uncounterweighted st-ringer to sag. out of parallel alinement with the other stringer. This has been found to be the case whenever provision against such sagging is not made.

The means for supportingthe uncounter weighted stringer of the counterbalanced stair of our invention supports the said stringer without causing or allowing the stairway to buckle or twist, as has often been found to be the case when the braces and other devices heretofore proposed have been used.

Our invention is illustrated in the accompanying drawings, in which-- Figure 1 is a side elevational View of a counter-balanced stairway embodying our invention; Fig. 2 is a view showingthe arrangement of our improved supporting. means underneath the stairway; and F ig; 3

is a cross-sectional view taken on the line 3-3 of. Fig. 1.

At 1 we have shown an ordinary fire-= escape platform. with a short stationary stairway portion 2 extending downwardly therefrom. At the bottom of this short staw tionary stairway is located the pivot. rod 3 which may extend from the side of a build ing with. which the counterbalanced. stairway is associated, or it may be carried by r any suitable supporting means; indicated at 4. Upon this pivot rod 3 are mounted the of gravity when the stairway is in itslhoriaontal position. When thestairway. is in its lowered position, however, the ecnter of gravity is below the pivot rod. Thus when the stairway is lowered it will. remain in that position. -Whenit is raised to its horizontal position it will be there held by the counterweight. The stringer 6 does not eX- tend rearwardly beyond the pivotrod 3 any considerable"distance. The stringers may be providedavith suitable railings ,9 carried by the supports 10, and the front. of the. stringers may be supplemented by struts 11; withthese features, however, our invention has nethingto do.

The stringer 6 consists of two parallel pieces 12, 12, this arrangen'lent being employed for the purpose of lightness, andbetween thetwo stringers the treads 13, .13 are secured. The stringer 5 may, if desired, be formed of two parallel pieces as is the stringer 6, but we have found that the metah saved by so doing is not sufficient to repay for the labor necessary to construct the other. 1

transverse cambered bar bolted to the.

stringers 5 and 6. This bar 15 at its middle and lowest point, carries a saddle 16, as

clearly shown in Fig. 3. A bent supportingbar 17 slotted at one end as shown at 18 ispassed through the saddle 16 and the slotted portion fitted over the pivot rod 3 inside and against the bearing 7, as shown.

The other end of this bent supporting bar is bolted to the stringer 6 at its free end. As is shown by the drawings, the stringer 6 is prevented from sagging by the bent bar 17, which is bent in the form of an arch and therefore forms a very strong brace for the stringer 6. Thietransverse supporting bar 15 engaging the off-set portion of the bar 17, serves to retain the said bar in proper position at all times. The bent bar 17 may be raised by tightening the nuts 18, 18, there by raising thesaddle 16. This raising of the bent bar-17 serves to exert a strain upon the free end of the stringer 6, thereby serving to support the same. An advantage of,

our improved supporting means is thatjthe strain exerted upon the end of the stringer,

6 is largely in an upward direction, there-bein-g little if any strain tending to cause the stairway to twist or buckle.

a It will be readily seen th at our bent supporting bar 17 may be raised at-any time byv tightening the nuts 18, 18, thereby exciting an increased strain upon the, free end of the stringer 6. While we have shown the member 17 in the form of a T-bar, this being the preferred form, it should be under stood that this bar may be of any suitable conformation without departing from the spirit of our invention. a

While we have shown our invention in the particular embodiments herein disclosed, we do not, however, limit ourselvesto the exact constructions shown, but may employ any equivalents that will suggest themselves to :those skilled in the art.

What we claim is: n

1. In a counterbalanced stairway, a pair low the same and engaging said bent truss bar at substantially its middle point, and

means carried by saidstrut for adjusting the a amount of bend of said bent truss bar.

2. In a counterbalanced stairway, a pair of stringers-hung upon' a p1vot rod, treads carried by said str1ngers, a welght secured to one of said stringers, a bent supporting bar.

having a bifurcated end fitting over said pivot rod, 'sa'i-d' bent supporting bar extend.- ing diagonally of the stairway and secured to the free end of the unweighted stringer to aid in the support of thesame, and means carried by-the stairway exerting upon said bent supporting bar a stress tending to straightenthe same, a bifurcated end of said supporting bar being adapted to turn upon said pivot rod as the amount of bend of said supporting bar becomes less.

3. In a stairway, a pair of stringers hung.

upon a pivot rod, means for holding-up the 'free end of. said stairway applied to one of said stringers, a bent supporting bar eXE :tending diagonally ofsaid stairway, said .bent supporting bar being positively secured to the free end of the other one of said stringers and being pivotally mounted upon said pivot rod, and means carried by said stairway engaging said bent supporting bar and exerting thereon a stress tending, to straighten the same.

4. Ina stairway, a pair of stringers hung jupon a pivot rod, means for holdingup the {free end of said stairway applied to one of said stringers, a truss member consisting of an integral bent supporting bar extending Zdiagonally of said stairway to aid in the gsupport of the other stringer, and adjustable 1 means carried by the stairway engaging said ithereon tending to straighten the same.

iupon a pivot rod, means for holding up the said stringer-s, a truss member consisting'iof an integral bent supporting bar extending Tcliagonally of said stairway to aid in the 5. In a stairway, a pair of stringers hung supportof the other stringer, and an ad- I {justable strut carried by the stairway exertting upon said bent supporting bar a stress atending to straighten the same. V

I In witness whereof, we hereunto subscribev %our names, this 13th dayof June, 1912.

of stringers hung upon a pivot, treads care ried by said stringers, a weight carried by I one of said stringers, a bent truss bar extending diagonallyof the stairwayto aid in 1 the support of the other stringer, a strut carried by said stairway and extending be- CHAS. HENRY BURCH. WAINWRIGHT B. oERvAis Witnesses JOHN ERwooD,

WALTER H. BARRY.

Copies of this patent-may be obtained for five cents each, by addressing the Commissioner of Patents,

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