US150153A - Improvement in iron truss-bridges - Google Patents

Description

D. HAMMOND & 1. ABBOTT.

Iron Truss Bridges.

Patented. April 28, 1874.

NO.150,I53.

v fnucntans.

NITED STATES PATENT OFFICE.

DAVID HAMMOND AND JOB ABBOTT, OF CANTON, OHIO.

IMPROVEMENT IN IRON TRUSS=B-RIDGES.

Specification forming part of Letters Patent No. 150,153, dated April 28, 1874; application filed February 20, 1874.

CASE B.

' tain new and useful Improvements in Iron Truss-Bridges; and that the following is a full, clear, and exact specification thereof, which will enable others skilled in the art to make and use the said .invention.

()ur invention is specially designed to afford a cheap and durable wrought-iron truss-bridge for spans of fifty to one hundred feet, although its special features can be applied to any length of span and it is intended to meet the want for a low trussbridge with straight top chord, which could be'built for highway-spans within The above limits at a cost not much exceeding that of the ordinary arch-bridge. To this end said invention consists in the construction of the lower chord angle-block for truss-bridges of rolled angle-bar, or of wrought-iron plate,

having its edges fitted in notches in the lower chord, thereby obviating the liability toaccident due to the cracking of cast-iron an gleblocks, as is hereinafter more fully shown.

Said invention also consists in the construction of a wrought-iron truss-girder, havin g its top chord constructed of two..rolled channelbars united by a top plate, posts of rolled I- beam, having a pin-connection with top chord, lower chords of plate-iron placed edgewise and abreast, and diagonal rods secured by eyes to pins in top chord, and fastened by nuts in angle-blocks beneath the lower chord, as is hereinafter more fully shown.

In the accompanying drawing, Figure 1 is a I perspective view of a portion of a truss-girder embodying our improvements. Figs. 2 and 3 are longitudinal sections of the lower angleblocks" and of the post-head, respectively. Fig. 4 is a s ctional view of the wrought angle-block.

A A are rolled channel-bars, and B the top plate, forming the ordinary box form of contin uous top chord. O is the end post, having its lower end rounded off and fitting in a concave seat between the walls of the shoe I L L arethe lower chords of plate-iron, placed two or more abreast, and secured in the shoe'I by the pin '2 which runs through the shoe-walls, chord ends, andheads of the post 0, the web or which is cut awaytoallow' the passage of the pin. The ti e-rods'G H are made with eyes atv their upper ends, and are secured by pins a in v the top chord (4. Their lower ends are secured by nuts in angle-blocks K, placed under the lower chords, and fitting in notches, Z, in the chords L L, the said block K being ordinarily made of castiron in the general form shown. In order to hold the chords in place, lips m are cast on the ends of said blocks, and fit up against the chords L, as shown in Fig. 1. The cast angle-block is not, however, a desirable detail, as it is liable to crack under sudden strains, especially in cold weather, to ob viate which objection we use the block K, (shown in Fig. 1,) which consists of rolled angle-har cut up in proper lengths to extend about one-half inch outside the chords on each side, or which'can be made of wrought plateiron bent up at right angles atthe center, or welded up of two pieces at the angle. In either case,'the separate notches l l are cut in the chords L to receive the edges of the'bloek K, by which the spreading of the block-arms by the tie-rod strains isprevented, so that each arm acts with its full strength to brace the other arm against the tie-rod strains, thus rendering it unnecessary to use very heavy plate or angle iron for said blocks. The posts .15 are made of rolled I bean1, and, instead of bearin g on a castiron base set on the chords,

as in prior constructions, are run down be tween the chords L L and rest on theangleblock K, as shown in'Figs. 1 and 2, where they are secured by an arm, k, on the block K, riveted to the web 0 of the post E. When the wrought angle-block K is used, the end of the post E can be dressed oft to fit in the block, as shown in Fig. 4, or a cast block can be used to fill up the angle and give a square end bearing to the post, the post being held in either case by a bolt, h, run through the chords L L and heads of the post E, as shown in Figs 1 and 4. The head D is secured to thc postE by a flange, d, riveted to the web 0 of the post,

and has a dressed bearing for the pin a, on'

I which it has a bearing, as shown in Fig. 3, so that the pin a serves as the means of transferring the tic-rod strains directly to the post, thus obviating any expensive post-head under the top chord, such as is usually required.

edgesof the lower chords, substantially as and for the purpose specified.

2. A wrought-iron truss-girder having its top chord composed of two channel-bars and top plate, posts of rolled I-beam, having a pineonneetion with top chord, lower chords of plate-iron placed edgcw'ise and abreast, and diagonals secured by eyes to pins in top chord, and fastened by nuts in angle-blocks beneath the lower chord, substantially as and for the purpose specified.

As evidence of the foregoing witness our hands this 30th day of January, A. D. 1874.

DAVID HAMMOND. JOB ABBOTT.

Vitnesscs:

CHARLES C. UPHAM, WVM. MOKINLEY, Jr.

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