US28845A - Iron bridge - Google Patents

Description

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NTTED sTATns T errno.

J. P. FISHER, OF ROCHESTER, NElV YORK.

IRON BRIDGE.

Specification of Letters Patent No. 28,845, dated June 26, 1860.

structed according to my invention. Fig. 2 is an inverted plan of the same. Fig. 3 is a transverse section of the same. Fig. l

is an inverted plan view exhibiting the Inanner of applying the lower tension braces of each truss frame.

Similar letters of reference indicate cor responding parts in the several ligures.

My invention consists in a certain construction of a bridge of a cast and wrought iron and wire rope whereby the truss and suspension principles are combined in an advantageous manner, and a bridge of great strength and stiffness is obtained with extreme lightness.

To enable others skilled in the art to make and use my invention I will proceed to describe its construction and operation.

A, A, are the sections of the lower chord of the truss frames which form the sides of the bridge, one for each panel made of cast iron of an arched longitudinal form and of any suitable transverse sectional form and with an upright dovetail groove c, in each end as shown in Fig. 2, to receive onehalf of the'lower part b, of one of the upright cast iron posts B, B, such part b, being made of double dovetail form in its horizontal section as shown in Fig. 2, where the lower end of one of the posts is left exposed, and a shoulder being formed above the dovetail portion b, to rest upon the sections A, A. C, C, are the sections of the top chord of the truss, made of cast iron each of the length of a single panel or of two or more panels, made of bridge form in the transverse section, to fit over the tops of the posts B, B, as shown in Fig. 3.

cl, d, are string pieces of flat bar iron fitted to the interior of the sections C, O, of the top chord on the top of the posts. The posts B, B, are each cast with a wrought iron rod running right through and projecting from its ends and the projecting parts e, j", of these rods are screwed to receive at their ends nuts g, z.. The lower projecting parts c, of the said rods are each fitted with a plate c', large enough to lap some distance under the bottom of the seg ments A, A, all around the portions of the posts; and above the top of each post a cast iron saddle j, is fitted over the top chord and the upper parts f, f, of the post passes through the top chord and saddle. The nuts g, and la., serve to hold the parts of the truss together vertically and they are held together. longitudinally or horizontally by the dovetails b, on the posts, but the parts are further secured by oblique tension braces lc, 7c, of wire rope of which there are four to each panel two of which are connected with each post by passing through eyes Z, Z, provided in the post to receive'.

them. The four tension braces of each panel are connected together by a screw E, iitted with a nut fm, and a swivel piece a, t-he two upper braces passing through eyes provided on the nut and the two lower ones through eyes provided on the swivel piece which is so attached to the screw that the latter may turn freely within it but may have no longitudinal movement independent of it. By turning the screw E, all four braces are tightened up together and a uniform strain is brought upon each one. Besides these tension braces there are oblique braces w, w, of wrought or cast iron applied between the posts and the top chord, to stiffen the top chord in every panel of the truss. At each end of the truss instead of one of the sections A, there is a short section F, iitted to the end post, with a dovetail and secured by a nut g, and plate c', as before described said sections being intended to rest on the abutments.

G, G, are the transverse girders which support the floor P, of the bridge made of cast iron iitted to the sections A, of each truss frame at the center of each panel lapping both over and under the said sections and being secured by screw bolts p, p, passing through them. These girders are arched at their bot-toms and tend to keep the side truss frames at the proper distance apart.

H, I-I, are tension braces applied to the truss frames under each panel of the lower chord consisting each of one or more lengths of wire rope passed one or more times back and forth around two adjacent posts and the downwardly projecting extremities of the sections A, A, or A, F, which fit to the farthest sides of the said posts as shown in Fig. 4L, and having their ends spliced or otherwise secured together. The downwardly projecting extremities of the sections A, A and F, are grooved as shown at g, g, in Figs. l and 2 to receive the rope and prevent it slipping out of its place. Between that half of each tension brace H, which passes on the outer side of the sections A, A, or A, F, and the half which passes on the inner side thereof there is inserted a screw r, fitted with a nut s, in opposite sides of which there are either eyes 5, 5, or notches for the two sides of the braces to pass through. By using this screw as a lever the two halves of the brace may be twisted once or more times around each other as shown in Figs. 2 and t, and so caused to draw the lower parts of the sections very tightly together and when they are drawn as tight as is desirable by this means, one end of the said screw is placed in a recess provided for it in the bottom of its respective section A, of the chord, and the screw turned like a jackscrew by applying a wrench at the other end to tighten up the brace still further by giving it a downward flexure. The screws r, r, besides serving to tighten up the braces H, serve when their ends are inserted in the recesses provided for them in the sections A, to secure the proper tension of the braces. These braces H, counteract the tendency of the load to elongate the' lower portion of the chord.

I, I, are tension braces, precisely like H, H, applied to the floor girders, passing around the ends of the said girders and eX- tending across the arches thereof as shown in Fig. 8 tightened up by means of screws t, and nuts u, applied and operating precisely like those r, s, the ends of the said screws resting when the braces are tight in recesses provided for them in the bottoms of the girders.

J, J, are diagonal tension braces made of wire rope substantially like H, H and I, I, passing around the downwardly projecting grooved parts g, g, of the sections A, A, and A, F, from one side to the other obliquely to the sides of the truss and crossing each other near where they also cross the braces I, I. These braces are represented without separate tightening screws but are connected with each other and with the braces I, I,

by rings o', o, in such a. manner that by screwin up the screws t, t, against the girders Gr, the said braces are tightened up in a similar manner to I, I.

K, L, M, are double tension braces applied at different elevations to each end o each truss frame and anchored in the ground. The braces K, and L, are tightened by screws Q, nuts N, and swivel pieces O, like the screws nuts and swivel pieces E, and m, before described, the brace K, passing through eyes in the swivel pieces and the brace L, through eyes in the sides of the nuts, and the tightening of the braces being effected by turning the screws to force apart the swivel pieces and nuts.

In this construction of bridge the truss frames are self sustaining without any of the tension braces which serve to draw up all the parts of the truss close together and to counteract any strain on the truss and are so applied that the heavier the load the tighter will they draw the parts of the truss together and the stiffer will be the bridge.

What I claim as my invention and desire to secure by Letters Patent isl. Combining the posts and the sections A, A and F, of? the lower chord of the truss by means of the double dovetail lower portions of the posts, the dovetail grooves in the ends of the said sections the shoulder and the screws e, on the posts and the plates z', z', and nuts g, g, the whole applied and operating substantially as herein set forth.

2. In combination with the sections A, and C, posts B, saddles j, connected and secured together as described I claim the transverse girders G, and the tension braces H, I and J applied and arranged relatively to each other and to the said sections and posts substantially as herein specified.

3. The tightening of the wire rope braces H, H, and I, or any other wire rope tension braces of a bridge by means of screws and nuts r, s, and t, u, constructed and applied substantially as herein described that 1s to say so that the screws tighten the braces by twisting their parts together and hold them tight and serve to tighten them further by bearing in recesses in a rigid part of the structure substantially as herein specified.

J. P. FISHER.

IVitnesses:

Houmt H. WooDwARD, JOHN PHILIP BECK.

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