US75477A - Improvement in bridges - Google Patents

Description

FREDERICK SMITH, OF "'BALTIMORE; MARYLAND.,

` Letters Patent o. 75,477, dated Zlfmc'i 10,187'68,

IMPRQVEMBNTIN namens.-

fotti tigitnieniet-ttt "it it time @titten atent mit' mating part of tigt tame.

To] ALL WHoMLrT MAY ooNoEnN: v v t fBe lit known that I,'F1 tEDERIcK'H. SMITH, oi' Baltimore, inthe county of Baltimore, and State of Maryland,-hai'e invented ane'w'an-d@ble-Improvement inlBi'idges; and do hereby declare that the following is a 4full, clear, and exact description thereof`, which will enable others skilled in the artto make and use the saine,

reference beinghad tothe accompanying drawings, forming part of this specilication: Figui-e 1 is a side elevation of ny improved bridge.

4Figure 2 is a crosssection of the same. Y 1 VFigure 3 is a trip view of. a portionfof the same. Figure 4 represents a portion of the bottomchord, the superstructure' being removed.

Similar letters of refereucer'indicate corresponding parts. My invention'has foritsohject to improve the construction of bridgesfso that any desired. part of the bottom-chord can bc readily adjusted, tao-tighten or loosen any desired part of the bridge, or to allow any desired part ofthe woodwork to be removed and replaced; and it consists in the construction and arrangement of the bottom-chord, as hereinafter more fully described. I

In-the drawings, my .im'p'io'vedbottom-chord -is represented as applied to a 'Howe truss, but it is equally applicable to any other form"of "beam-t russ; y f Y A are the abutments, upon which the ends Nof the bridge rest. B arethe angle-blocks, the upper sides ofwhich, except tliebloeks that'rest upon the abutments,are made with twqinclined faces to support the lower ends ofthe inclined braces, C,-the inclination of said faces being such that they may be at right angles to the axis oi' said braces. lEach lineof angle-blocks is connected byclusters of rods, D. The ends of therods D pass through nut-platcs,-E, have screw-threads cut upon them, and' areadjustably secured in place by nuts F. The parts of. the'rodsD, and Aall othenl rods in. the structure which have screw-threads cut upon them, are enlarged, so that cutting vthe screw-threads may notv diminish the strength of said rods. Gr are rods, which 4have"acreiv-threads cut upon them, which pass through the angle-blocks B, and screw into the central partsof` the nut-plates E, and'whichar'of such asizethatthe'areaof their cross-section shall equal the'unitedare'as of the cross-section of all the rods'in'the cluster, so'that the clusters may be talren through the angle-blocks without weakening the chord.` H are nuts, placed upon'xthe rods G, one upon each side of the angleblock, so` that by screwing these nutsin one or-other r'direction, any desired part of 'the bridge may beloosened to allow i the timbers of said part to be removed and replaced when desired.V l i By screwing the nuts H backwards and forwards, the diagonal lines of braces in the panels are length ened or shortened, and the material of the braces being incompressible, the action of the said nuts, H, results in an upward or downward motion of the top,chord, thu s adjusting the bridge to any desired upward curve or arch.4 'The resistance to be overconein this operation ofadjusting the bridge as thetimber s easons,:is less upon the horizontal line of each panel than upon the vertical line of'each panel in all cases where the length of panel is less thanthe height, and therefrcthis adjustment can be moreeasily made by the nuts H, acting in the horizontal lino, as proposed, thanby means o i' the vertical rods as at. present performed in bridges as vcleanly built; v

vThe drawings represent eaclioluster of'rods,-D, as being formed of four rodsybut the number of rodsiu cach cluster is immaterial, and must depend upon the strain `to whichthe bridge isexpe'cted to be subjected. The number of lines of-clusters in the bottoni-chord is also immaterial, and must depend upon y the required. `strength `of the bridge, one, two, three, or more lines being used,` as may be'thought necessary. I are vertical rods, that pass through the angle-blocks. B, through the angle-blocks J', against which thc upper endsof the inclined braccs,'( l, rest, through the beams K, 'that support the roadway, and whichjare I secured in place bynutsZ Escrowed upon their upper and lower ends. The lines o f clustcrs'voi'. rods, D, tha-t form thcbottom-chord-fof, the bridgc'are connected by horizontal cross-rods,-M, whichl pass through the angleblocks B, and are sccuredinplace bynuts screwed upon their-'ends I claim asl new, and desire to secure`by Letters Patent A bottom-chord, formed of olusters of rods oonnected, as dsoribed, in theA poneis, and cojmlecteflfo each other, through the brac'eblocks, by a. single rod, substantially as', and for. the purpose specified.

2. The'corbina'ton of the oiusrters of rods D, uut-plates E, single rods'G, angie-Hooks B, and nuts H- with eae'n other, with the horizontal cross-rods M, by which the various lines of clusters ure conuected`-toeach other,

und with the vertical rod 1, by which the bottom-hori und superstructure of the bridge are connected together,`

substau-tially as herein shown and described, and for the purpose set forth. Y

, FREDERICK H., SMITH.

-Wituervsezs:

N. SpGARDNm, H. 0. HEUs'rIs.

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