US135705A - Improvement in bridges - Google Patents

Description

f3 Sheets--Shget 3. GATES.

Bridges.

Pla-135,705, Patented Felb.11,1873i.

AM moro-urHasn/:Pmc ca Mx (oaamvs's macsss) the truss. of the bridge.

' plates removed.

the same.

UNITED STATES JAMES GATES, on ST. Louis, MISSOURI.

IMPROVEMENT IN BRIDGES.

Specication forming part of Letters Patent No. 135,765, dated February 11, 1873.

' Missouri, have invented a new and useful Improvement in Bridge Construction 5 and I do hereby declare that the following isa full and exact description of the same, reference bef ing had to the accompanying drawing and to the letters of reference marked thereon, in Which- Figure lis a side elevation of a portion o f Fig. 2 is a top view ot' a portion Fig. 3 is a plan of a portion of the upper chord, showing two ot' the top Fig. 4 is a side elevation of Fig. 5 is a top view of a portion ot' the lower chord, showing one of the angleblocks in Section. Fig. 6, is a side elevation of the same. Fig. 7 is a side elevation of an angle-block in the upper chord,showing the vertical rods att-ached. Fig. 8 is an endview of the same. Fig. 9 is a side elevation of an angle-block in the lower chord, showing the vertical rods and lateral pin. Fig. l() is an end view of the same. Fig. l1 is a perspective view of the ends of two tension-bars.

Like letters of like kind refer to like parts.

The invention relates to improvements in bridge construction, the advantages of which are greater strength, integrity, and simplicity, and economy in material, construction, erection, and repair. It consists, first, in the peculiar construction of the lower chord; second, in the employment of an angle-block of peculiar construction; third, in the employinent of packing-blocks with the pins connecting the tension-bars; fourth, in the peculiar joints formed by the tension-bars, pins, and packing-blocks; fifth, in the peculiar construction of the bridge-seat; sixth, in the peculiar construction of the upper chord 5 seventh, in

- the peculiar construction of the angle-blocks ot the upper-chord and the combination of certain elements with them, as will be hereinafter described.

The lower chord A of my bridge is composed of tension-bars a a a a, which are made as follows, viz: A bar of suitable width and thickness, and oi' alength nearly that of a panel, is rolled. Then two otherpieces, a1 al, Fig, 11, 'of about the same thickness, but somewhat wider, and of a length rather more than` the width of the angle-block, are constructed. These last-described pieces are then securely welded under a heavy hammer onto the ends of the. first-described piece. The tension-bar is then at its ends properly drilled to receive two steel pins that pass laterally through the chord. By using two pins, a2 a2, Fig. 6, instead of one, and an an gle-block constructed as is hereinafter described, the chord can be put together Without first inserting the vertical rods B B that connect the upper and lower chords, which would not be practicable were a single pin only used. Further, by using two pins, as described, the chord is laterally materially stiffened. The pins a2 a2 pass laterally through the ends of all the tension-bars in the panel, and are held in place, and in turn serve to hold the tension-bars securely together, by means ot' nuts a3 a3, Figs. 5 and 6, screwed onto the ends. The tension-bars at the ends ofthe chord pass through slots in the bridgeseats, and are attached thereto by pins a4 a4, Figs. 5 and 6, that pass through their ends and bear against a concave surface, d3, in the bridge-seat. To prevent the end brace G from slipping from its position the bridge-seat D is provided at its top with a shoulder, nl. It is also provided with slots d1 d1, Fig. 6, through which the end tension-bars arel inserted. The halfblock cl2, Fig. 6, and bridge-seat are cast in one piece. E E E represent the packingblocks in the lower chord, which are constructed by cutting gas or steam tubing (the diameter of which corresponds to that of the pins a2 a2) into lengths equal to the distances between the tension-rods, to keep them apart. There are two sets ot' packing-blocks at each joint, respectively, placed on the two pins a2 a2. The lower chord being erected, the angle-blocks F F, Figs. 5 and 9, are placed in position. These are provided at their ends with iiangesfff, shown in Figs. 1 and 6, which extend down even with the lower edge and outside of the chord. They are .also provided with flanges f1 f1 f1, of shape shown in Figs. 5, 9, and 10, which extend downward between the tension-bars and tit closely around the packing-blocks E, which encircle the lateralpins a2 a2. They are furtherprovided with tubularshaped projections fzfzfz, extending downward for the purpose of receiving the vertical rods B B. These projections ATENT N QFEICE.

are shown in horizontal cross-section in Fig. 5. The flan ges f 1 f1 fl, arranged as described, provide a hrni support, laterally and longitudinally, for the angle-block.' The upper vfaces fff of` the angle-blocks, instead of being a plain bevel, or a bevel provided with a lip at the lower edge, as is customary, are made slightly concave, as shown, Figs. 1 and 6, to secure a solid bearing for the Vertical braces G G, when there is a tendency to displacement from their original position by the expansion and contraction of the lower chord, or other cause. The ends of the braces G G are shaped to coliform to this concavity.

Heretofore, in the construction of the upper chord ot' bridges of the Howe truss and similar patterns, it has been customary to use pieces of timber of a length sufficient to extend over two, three, or more panels, and arranged in such a way as to bring the joints midway or thereabout in a panel.

By my improvements I am enabled to use timber the length of the panel only, and arranged so that the joints in the chord will coincide with the panels. This construction secures several important advantages: First, in using short pieces of timber, less expense is incurred, as the prices ot' timber in short dimensions are less than that of a similarl quantity in longer form; second, itis easier Iand cheaper to obtain sound timber in shorter lengths; third, the proportions of the pieces ot' timber composing the chord can be readily and exactly adjusted to the strain that each panel is respectively required to meet, thus avoiding any useless expenditure of material and any undue excess of weight; fourth, any piece can be readily replaced without disturbing the position of the remainder; lifth, the system of lateral bracing can be more readily arranged and connected at the joints ot' the chord, and thus secure a simpler and tirmer structure.

The advantages above set forth are mainly obtained by the peculiar construction of the angle-block H, Figs. 7 and 8, which, instead of extending partially into the upper chord, as has heretofore been customary, is made to extend entirely through the chord, both laterally and vertically. The an gle-block H, which is cast in one piece, consists principally of a web, h, Figs. 3 and S, the length and height of which are equal to the width and thickness ot' the chord. The web has tubes h1 h1 ruiming vertically through it to receive the vertical rods B B B, and it is also provided with a lateral tube, h2, to receive the lateral tie-rod I. The web is further provided at its ends with flanges 71,3, Figs. 3, 4, and 7, which inclose the sides of the chord K. Attached to the lower edge is a piece, h4, triangular in cross-section, Aand shown in Figs. 7 and 8, which corresponds to the upper angle-block generally in use in the upper chords of trussbridges. The ends of the chord-pieces rest upon this last-described piece. The anglel lock is further provided at its inner end with a triangular half-block, h5, Fig. 3, against which the lateral top braces abut. It alsomay prove desirable to attach a roof to the block to protect the parts from the weather. .This may be cast in one piece with the rest. 7c 7c k 7c represent the pieces composing the upper chord. L L L represent keys let into the sides yfor the purpose ot4 keeping the chord-pieces ported to thelocality of the bridge. The chordpieces 7c 7c 7c at their ends are framed to t round the lateral and vertical tube projections in the web of the angle-block. After the chord has been erected the top plates m m, which extend over the ends of the chordpieces k, and aid in holding them in place, are put on, the vertical and lateral bracing are inserted, and the lateral and vertical rods screwed up.

The angle-blocks a-nd joints last described aord a solid, continuous iron bearing, both vertically and laterally, throughout the truss. In consequence of this arrangementthe shrinking of the wood in the top chord will not affeet the integrity of the structure. Further, by arranging the lateral bracing at the paneljoints, the truss is strengthened laterally at the points most needing support.

Having described my invention, Wh at I claim as new therein, and desire to secure by Letters Patent, is-

1. Thelower chord, consistingof the tensionbars a a a, the pins a2 a2 the packing-blocks E E E, the bridge-seat D, and the pins a4 a, constructed and arranged substantially as described and shown.

2. The angle block F, provided with the langesff, the tlangesf1 j" f1, and the tubu-l lar projections f2 f2 f2, substantially as described and shown.

3. The packing-blocks E, in combination with the pins a2 c2, constructed and arranged substantially as described and shown.

4. The joints in the lower chord, formed by the tension-bars a, a a, the pins a2, and the packing-blocks E E E, constructed and arranged substantially as described and shown.

5. The bridge-seat D, provided with the shoulder d, the slots d1 d1, and the half-block d2, constructed substantially as described and shown.

6. The upper chord K, consisting of the end angle-block P, the chord-pieces k, the angleblocks H H, the keys L, and the pins N, constructed and arranged substantially as described and shown.

7. The angle-block H, consisting of the web h, provided with the vertical tubes h1, the flanges h3, and the piece h4, substantially as described and shown.

8. In combination with the elements of the angle-block H, constructed as described, the haltblock h5, arranged as described.

9. In combination with the elements of the concave upper surfaces f3 f3, substantially as angie-block H, constructed as described, the described.

short chord-pieces K K, as described. This specification signed and witnessed this 10. The lateral braces O and rods I I, in 15th day of May, 1872.

combination with thev angie-block H, con- JAMES GATES.

structed and arranged substantially as de- Witnesses:

scribed and shown. GHAS. D. MOODY,

11. In an angle-block for a trusslbridge, the F. S. DAVENPORT.

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