US78797A - John foreman - Google Patents

Description

JOHN FOREMAN, 0F POT'IST()WN, PENNSYLVANIA.

Letters Patent No. 78,797, lated June 9, 1868.

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TO ALL WHOM IT MAY CNGERN:

Be it known that I, JOHN FOREMAN, of Pottstown, Pennsylvania, haveinvented an Improvement in Truss- Frame Bridges; and Ido hereby declare the following to he a full, clear, and exact description of the same.

My invention consists of a. truss-frame bridge, the posts of one-hait' of which are inclined in one direction, and those of the other half Ain the opposite direction, in combination with the system of suspension-rodsherein described, or the equivalent to the same, the bridge being thereby increased in strength, while it can be built at a. less expense than ordinary'truss-hridges.

In order toeuable others skilled in the art to maken and apply my invention, I will now proceed t0 describe its construction and operation, reference being had to the accompanying drawing, which forms n part of this specification, und in which- Figure 1 (Drawing No. 1,) is a side'view of my improved truss-frame bridge.

Figuire (Drawing No. 2,) a perspective -view of the some, and

Figure 3 a side view of part of-the frame.

Similar letters refer to similar-parts throughout the several views. l

IIlhe main peculiarity ofmy improved truss-frame bridge is the absence of the usual -vertical posts or ver'-A tical rods, which have heretofore been considered indispensable in bridges of this class.

The opposite end posts or frames, A and A', only are vertical, the remaining posts being inclined, those marked a, b, c, and d, in one direction, and those marked a', b, c', and d', in a contrary direction, as best observed on reference to iig. 1 (Drawing No. 1;) These posts, or, as they may be termed, on account of their inclination, main braces, are tted to cast-iron' sockets, secured to the upper chord B and lower` chord D.

.At the centre ofthe bridge,`on' the lower chord D, meet the two postsfandf, (inclined in contrary directions,) and the two diagonale or counter-braces, it and 7L', the postf meeting the post d, and the postf meeting the post d at the upper chord, while the counter-brace h meets the inclined post c, and the counter-brace t the inclined post c at the upper chord. A diagonal or main brace, z', Yextends from the point where the end postor frame A meets the inclined post or brace a at the lower chord, to the point where the post b is connected to the vupper chord, and a similar main brace, j, extends from the point where the inclined post is connected to the lower chord, to the point where the inclined post e and counter-brace h meet at the upper chord` Similar main braces, z" and j', are arranged in a. similar manner at the opposite end of the bridge.

On reference to the perspective View, g. 2, it will be seen that the above-mentioned posts, braces, and counter-braces, consist each oi'two timbers, and that the upper and lowerchords consist of a number of longitudinal beams, arranged a short distance from each other, and bolted together. n

By adopting this arrangement of inclined posts or braces, and by the system of suspension-bolts, the disposal oi' which is indicated i'n the drawings too clearly to need description, I am enabled to. dispense with the usual system of heavy counter-braces, common to wooden-truss bridges, there being inmy improved bridge but two counter-braces, L and li.

While the bridge is thus made much lighter than'others of this class, it is increased in rigidity, especially a'siregards its resistance of the strains to which it must be subjected by passing trains'.

This will be readily Vunderstood on supposing a heavy train to be passing on to and over the bridge, in the direction of the arrow, iig. l.V Whatever tendency the bridge may have to yield in the same direction, is met by the resistance afforded by the inclinedposts or braces a, Z, c, and d.

In like manner, if a train 'be passing in the opposite direction onV to the bridge, the strain to which the latter is subjected will be resisted bythe inclined posts or braces a', b', c', and d.

l It will thus be seen that by inclining one half of the posts of the bridge in one direction, and the other half in the other direction, these posts perform a duty which no vertical posts can accomplish.

It will be understood that the number and arrangement of the timbers composing the several parts of the bridge, and, in a. measure, the disposal of the diagonal rods, will depend upon the span and size of the bridge;

Without confining myself, therefore, to the precise'eonstructon and arrangement 'of parts herein described, I laifn as my invention, and desire to secure by Letters Patent- The arrangement, substantially as described, of the inclined posts, suspension-rods, and di-agonals, for the purpose specified. 4

In testimony whereof, I have signedfmy name to this specication inthe presence of two subscribing witnesses.

JOHN FOREMAN.

Witnesses:

l JOHN WHITE, C. B. PRICE.

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