US17722A - Truss-bridge - Google Patents

Description

UNITED STATES PATENT OFFICE.

JOSIAH BROWN, JR., O11` BUFFALO, NEW YORK.

TRUSS-BRIDGE.

Specification of Letters Patent No. 17,722, dated July '7, 1857.

To all 'whom it may concern:

Be it known that I, J osrAH BROWN, Jr., of Bulialo, in the county of Erie and State of New York, have invented a new and useful Improvement in Truss-Bridges; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accom anying drawings, forming part of this specilgication, in Whiii- Figure 1, is a side view of a truss frame constructed with my im rovements. Fig. 2, is a vertical section of t e same. Fig. 3, isa plan of ditto. Fig. 4, is a side view of an old style of bridge wherein only the main braces are shouldered and passed up between the timbers of the chords. Fi 5, is also a side view of another old sty e of bridge wherein the counter braces only are shouldered and passed up between the timbers of the chords.

The object of my invention is to unite all the timbers of each of the chords in such a manner that they shall become as it were one piece, and consequently when the strain or weight comes upon the bridge each set of braces shall act at one point, and upon all the timbers as united, instead of upon them as separated, whereby all chance of the main braces acting upon one timber of each of the chords and the counter braces upon the other timber of each of the same separately or in a manner to twist or rend asunder the said timbers is completely avoided.

The nature of my invention consists in providing each of the main and counter braces with two gains at top and bottom, and each of the timbers of the chord with a gain at the point where the braces are applied corresponding with the gains in the braces and passing the braces thus formed up between the timbers, with the gains of the braces in such relation to the gains of the timbers that when the timbers of the chords are brought together they shall all be combined in such a manner as to become as it were only one piece no part of which can be o erated upon or affected independently of t e other by the downward and upward thrusts common to truss bridges, even if the bolt which passes laterally through and intersects each set of braces and the timbers of the chord were removed, so long as the chords have no lateral lay.

To enable others skilled in the art to make and use my invention, I will proceed to de'- scribe its construction and operation.

A, represents the upper and B the lower chord of the bridge; each is composed of four timbers a., a, a, a, as shown in Fig. 2.

O, C, are the main braces, and D the counter braces.

b, l), are the gains cut in the timbers of the upper and lower chords, and c, c, the gains cut in the main and counter braces. The outer timbers of both chords have only one gain cut in them at top and bottom, while the intermediate timbers have each two gains to correspond to the gains ofthe braces which, both main and counter, have each two gains, both at top and bottom. The gains in the braces and in the timbers all match when the parts are brought together, as shown in Fig. 2, or so that the shoulders, formed by the gains on each brace, bear u on two timbers of the bottom and top c ord, both on the upper and underside of the same, and thus by the gains of the three braces and the gains of the timbers the wholestructure is united together in such a manner as to become one piece, as it were, no portion of which will be aifected independently of another in a manner to twist or break asunder the same.

E, E, are the bolts which pin the parts laterally together after they have been brought together as described.

It should be observed that the bolts E have no other ol'lice to serve than to hold the parts laterally together, and if removed the two chords and the timbers thereof would still be united and capable of resisting all p vertical strain just as eiiiectually as if the bolts were in.

I am aware that a bridge with the counter braces having gains and passed between the timbers of the chords is not new, such an arrangement having been contrived by Geo. W. Thayer in 1848 but in this arrangement, as will be seen from Fig. 5 of the drawing, the counter braces and main braces are not combined so as to act unitedly at one point, and upon all the timbers of the chords connected or as one piece. The bearing of the counter braces also extends so far forward or in rear of the main braces which abut against vertical posts that a considerable length of leverage is furnished Wherewith to spring or rend asunder the chords when the weight is applied to the bridge. This will be understood by imagining the to be the fulcrum of the counter brace, andy the distance from to to be the levera e of the counter brace wherewith to spring t e intermediate timbers of the chords, as illustrated by the red line.

I am also aware that two braces Awith a l single gain at their upper and lower end crossed diagonally and passed up between two timbers of a chord and united by a bolt have been employed in the constructionof a bridge by Jas. I-I. Stewart, but in this arrangement the timbers of the chord are not combined with each other by the shoulders formed by the gains and consequently the braces, instead of acting upon the timbers of the chord as united in one piece, they act luplln the timbers as separated, and thus e one forces the other trated by the red and blue ulls, as illusnes in Fig. 4c,

What I do claim as my invention7 and desire to secure by Letters Patent, is*

Providing each of the main and counter b races with two gains at top and bottom, and each of the timbers of the chord with a gain at the point where the braces are a plied corresponding with the gains in the braces, and passing the braces thus formed, up between the timbers, with the gains of the braces in such relation to the gains ofthe timbers thatwhen the timbers of the chords are brought together they are combined and become, as it were, only one piece, no part of which can be operated upon or affected independently of the other by the downward and upward thrusts common to truss bridges, even if the bolt which passes laterally through and intersects each set of braces and the timbers of the chord were removed, substantially as and for the purposes herein set forth.

JosrAH BROWN, JR.

Witnesses:

B. W. FENWIOK, GOODWIN Y. AT LEE.

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