US2382478A - Portable bridge structure - Google Patents

Description

Aug. 14, 1945. J GUTHRlE 2,382,478

PORTABLE BRIDGE STRUCTURE Filed July 27, 1942 Patented Aug. 14, 1945 2,382,478 PORTABLE BRIDGE STRUCTURE James M. Guthrie, Allison Park, Pa., assignor to Reliance Steel Products Company, McKeesport, Pa., a corporation of Pennsylvania Application July 27, 1942, Serial N 0. 452,413

2 Claims.

My invention relates to bridges, particularly to temporary bridges, bridges of the type used by military forces to effect passage across waterways and the like. More particularly, the invention concerns improvements in bridges of the constructions disclosed inv an application for Letters Patent 0f the United States, Serial No. 447,328, filed by one Harold Nagin on June 17, 1942, under the title Porta'ble bridge structure, now Patent No. 2,339,098, issued January 11, 1944, and which is owned in common with the invention of this application.

The bridge structure of the Nagin application is erected of a plurality of identical truss units that are arranged in vertical, laterally spacedapart and parallel planes. The so-arranged t uss units are interconnected and rigidly integrated by means of cross-beams, and on the cross-beams panels of metal grating are borne, providing the floor of the bridge.

In case the span of the bridge to be constructed exceeds the length of the standardized truss unit, two truss units (or three or more, if need be) are interconnected end to end, and these interconnected truss units form in effect the individual trusses that are united by the cross-beams to form the support for the bridge floor. In many installations, it is desirable to reinforce such trusses, so that the bridge will have greater loadsustaining capacity, and this is particularly the case in bridges whose trusses comprise lines of two or more truss units united end to end. Such reinforcement is obtained by securing additional truss units to the trusses that immediately support the floor-sustaining cross-beams. These additional truss units extend in common vertical plane with the trusses the reinforce. If the bridge is of multiple-span construction, that is, if the bridge is constructed of truss units connected end to end, as above mentioned, the reinforcing trusses are arranged to extend across the joints between the so-connected truss units. The lower chords of the upper truss units of such superposed trusses are rigidly secured to the upper chords of the lower trusses.

The object of this invention is to provide means for detachably securing the chords of such superposed truss units in surface-to-surface contact. Advantageously, such means comprise clamps that may be readily applied to and removed from service position.

In the accompanying drawing, in which a, preferred embodiment of the invention is illustrated:

Figure 1 is a diagrammatic view in side elevation of a bridge including reinforcing truss units secured to the main trusses of the structure in accordance with this invention;

Figure 2 is a diagrammatic view. in cross section of the bridge illustrated in Figure 1, the plane of section being indicated at IIII in the latter figure;

Figure 3 is a view to larger scale and in structural detail of the meeting chords of one pair of the superposed truss units of the bridge of Figure 1, in which the struts and diagonals of the truss units are shown fragmentarily in elevation. Said chords of the truss units appear in section on the plane IIIIII of Figure l, with a truss-uniting device of the invention shown in side elevation;

Figure 4 is a view of the truss-uniting device of Figure 3 in front elevati on, as seen on the plane IV-IV of Figure 3, the chords of the truss units united by the device appearing fragment'arily in elevation;

Figure 5 is a view comparable with Figure 4, illustrating a truss-uniting device of modified structure;

Figure 6 is a View of the modified structure as seen on the plane VI-VI of Figur 5.

In the above-identified Nagin application a truss unit is disclosed, and the manner in which various types of military bridges may be constructed of a plurality of such units is described. In the drawingof the present application such truss unit is diagrammatically indicated by the reference character A, and to the extent that an understanding of detailed structure of the truss is desired reference may be had to the Nagin disclosure. Suflice it herein to say that the truss unit comprises upper and lower chords 2 and 3 formed of lengths of metal bar, typically bar of T section, although bars of other cross sections, and metal tubing, are contemplated. The web of the truss unit consists of vertical strut 6, diagonals 4 and 5, and end posts or struts 1 and 8, all formed in this case of lengths of rolled steel of L shape in section. At the opposite ends of the chords 2 and 3 of the truss unit eye-lugs I8 are provided, the lugs at one end of the truss being complementary in shape and position with respect to the lugs at the opposite end, whereby when two truss units are arranged end to end, the lugs on the meeting truss ends register, to receive truss-uniting pins or bolts.

The bridge S shown in Figures 1 and 2 will be understood to be exemplary of the many different bridges that may be constructed of multiples of the truss unit A. The bridge S is twice the length of a single truss unit, and thus the trusses of the bridge, properly considered, consist each of two truss units A, interconnected end to end, by means of pins (not shown) secured in the registered lug I8, [8. In one sense the bridge S consists in two parallel bridge units S and S" (see Figure 2) each constructed of six trusses, each truss including a pair of pin-connected truss units A. Such trusses A, A are supported at their opposite ends upon sills F set on the banks of the waterway to be spanned, and the trusses are laterally spaced as indicated in Figure 2. The parallel trusses of each bridge unit are integrated by means of cross-beams B, which in this case are of steel channel. The union of the crossbeams with the trusses is a' detachable union,

such that the bridge structure may be quickly,

erected and readily taken down. Borne upon the cross-beams are panels of metal grating that form the floors or treads C of the bridge, and at the ends of the bridge, brows or ramps E of metal grating extend from the floors C to the ground or approaches to the bridge. The two bridge units S and S" are spaced apart laterally at proper distance to accommodate the wheels or treads of trucks, tank and other vehicles that are to travel on the floors C.

In many instances the bridges which are constructed of the truss units A will be reinforced, and as herein illustrated, such reinforcement is obtained by the use of additional truss units, A, that are identical with the units A. The reinforcing truss units A are arranged below and in the planes of the trusses A, A, and extend along the trusses and across the joints between the two units A that form each truss. The upper chord 2 of each reinforcing truss unit is positioned against the lower chords 3 of both of the adjoining truss units A, A.

At spaced-apart points in the common extent of the chords 2 and 3, the truss members are united, and it is with the structure and organization of the uniting means that the invention in concerned.

Such uniting means consist in a plurality of devices that clamp the adjacent chords 2 and 3 of the truss members in secure-to-surface contact. The clamping devices R are adapted to be readily applied'and removed. Each clamping device comprises a basal portion or element 42 shaped to embrace the body-the T-shaped body in this case-of one of the chords 2 or 3, and two bell-crank lever or arm portions 13 and I4 that engage the other chord. The arms I3 and H are pivoted to the clamp body 12 at the points l5 and l6. l8 to the distal end of arm I3, while the upper end of the arm I4 is bifucated to receive the body 01 the screw 11, as shown. A nut 19, in threaded engagement with the screw i1, is adapted to be tightened against the arm 14, in such manner that the arms l3 and H are drawn together, thus bringing portions 1.3a and Me of the arms into tight clamping engagement with the chord 2, and locking the chord 2 in surface-to-surface contact with the chord 3. l9 from accidentally moving out of engagement with the arm 14, a lip 19a is provided on the bifurcated end of the arm.

In the use of a plurality of such clampszR, the chords 3 of the main load-sustaining trusses A, A are firmly secured at spaced-apart points tothe chords 2 of the truss units A, and thus the truss members are secured in load-sustaining assembly.

The clamping device may 'be readily applied A clamping screw [1 is pivoted at To prevent the nut i to the chords 2, 3 and removed. By running back the nut IS on the screw IT, the nut may be disengaged from its seat on the arm 14, permitting the screw H to be swung (on its pivot I8) from engagement with the arm [4. Then, the two arms l3 and It may be spread and the clamping device applied to the chords, or removed.

The chords of the truss members are here shown to be of T shape in cross-section, and in the truss assembly described the flanges 2a and 3a that form the cross-arms of the T are positioned back to back, as shown in Figures 3 and 4. The body 12 of the clamping device is fashioned to the form of the T-shaped section of the chords, whereby such clamp body is adapted snugly to engage the chord 3. When the clamp is tightly upon the chords, the portions 13a, Ila of the clamp arms pinch or wedge the flanges 2a and 3a of the T-shaped chords-together, and thus provide maximum security of assembly.

In Figures 5 and 6, a clamping device of modified structure is illustrated. This modified device includes two body portions 20 and 2| that are articulated at their lower ends, by means of an element in the form of a screw 22 extending through a washer 23 and in threaded engagement with a nut 24. A clamping screw 25 and nut 26 are arranged to cooperate with the upper ends of the clamp portions 20 and 2|, after the manner that the screw and nut I1 l9 cooperate with the upper ends of the arms I3 and M of the clamping device first described. The bodies of the clamp portions 20 and 2| are formed with divergent notches 21 that embrace the opposite edges of the meeting flanges of the chords 2 and 3, and when the nut 26 is tightened, drawing the upper ends of the two halves of the clamp together, these notches act with wedging effect on the opposite edges of the abutting flanges, and tightly unite the chords 2 and 3 in surface-to-surface contact.

The washer 23 and nut 24 make ball-andsocket engagements with the lower ends of the clamp portions 20 and 2|, respectively, so that the two halves of the clamp may be readily spread for effective application to the chords, or removal. The normally fixed interval between the lower ends of the clamp body portions may be varied, to adapt the clamp for such variations in the size of the chords as may be found in different trusses.

As indicated in Figure 2 all of the trusses A, A of the bridge may be reinforced by means of truss units A. In order to increase the rigidity of the trusses cross-beams B may be arranged laterally to interconnect, at points spaced longitudinally of the bridge, all of the reinforcing truss units A. In some cases reinforcing truss units may be employed on the outer trusses A, A of the bridge structure, as indicated in dotted lines A in Figures 1 and 2, and these trusses may be interconnected by cross-beams B". However, whether or not the reinforcing truss units be arranged above oar below the main load-sustaining trusses A, A is not of controlling significance herein, since in either case the abutting chords of the truss members will be united by means of the devices described.

The structures herein disclosed are for purposes of illustrating the invention, it being understood that various modifications are permissible within the terms of the appended claims.

I claim as my lnventlonz.

1. A temporary bridge constructed of a plurality of truss assemblies comprising prefabricated portable truss units aligned end to end and provided at the opposite ends of their upper and lower chords with means uniting the truss units in each of said truss assemblies, certain of said truss assemblies including a reinforcing truss extending in common plane with the aligned truss units and in bridging relation with respect to the united ends of the truss units thereof, with a chord of the reinforcing truss extending adjacent to and across the meeting ends of two of the chords of the bridged truss units, and a plurality of clamping devices arranged at spaced-apart points in embracing position upon said adjacent chords, each of said clamping devices comprising two arms that are relatively movable laterally. of both of said adjacent chords, and each arm being effective in clamping both of the chords for securing the chords in surface-to-surface contact and uniting the truss units in load-sustaining assembly.

2. A temporary bridge constructed of a plurality of truss assemblies comprising prefabricated portable truss units aligned end to end and provided at the opposite ends oftheir upper and lower chords with means uniting the truss units in each of said truss assemblies, certain of said truss assemblies including a reinforcing truss extending in common plane with the aligned truss units and in bridging relation with respect to the united ends of the truss units thereof, with a chord of the reinforcing truss extending adjacent to and across the meeting ends of two of the chords of the bridged truss units, and a plurality of clamping devices arranged at spaced-apart points and in embracing position upon said adjacent chords, each of said clamping devices including a body comprising two pivoted arms swingable in a plane extending transversely of the embraced chords, each arm being'eiiective in clamping both of the chords, and means for uniting distal ends of the pivoted arms in chord-securing position.

JAMES M. GUTHRIE.

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