Folding transportable bridge

Details Folding transportable bridge Folding transportable bridge

1991-04-03

1994-01-11

Dorner, Kenneth J.

Bridges

Transportable

Having launching means

296 375, E01D 1512, B60N 312

Patent

active

052769305

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to the field of folding multi-section bridges and is primarily concerned with the hingeing of the sections.
2. Discussion of Prior Art
It is well known to deploy transportable bridges directly from launch vehicles to enable rapid crossing of obstructions for example rivers and ditches by vehicles such as tanks.
Bridges suitable for this purpose are commonly constructed from two sections that are hinged together in end to end relation. Each section usually comprising a pair of spaced parallel trackways which constitute the upper surfaces of box section girders which are open on-their lower faces. The trackways are spaced by transverse beams welded to the sides of the box section girders which face one another. The spacing between the trackways being chosen to accommodate the track or wheel spacing of the vehicles for which the bridge is designed.
The two bridge sections are joined by hinges each of which extends across the width of a trackway, and permit the bridge to fold from a deployed configuration in which the trackways of two sections are aligned to a folded configuration in which one section lies on top of the other, and the trackways are outermost.
One major disadvantage of the bridges currently in use is that the height occupied by a folded bridge is at least the sum of the section depths. When a bridge is to be transported on a vehicle in the folded configuration, the combined height, length and width of the vehicle and the bridge are subject to limitations such as road bridge height, curvature of minor roads and carriage way width respectively.


Summary of the Invention

It has now been discovered that by partially nesting the folded bridge parts, a number of great advantages can be gained. Partial nesting of the sections allows (a) greater girder depths to be used which in turn allows longer spans to be employed and (b) the possibility of transporting a bridge with three sections nested on top of one another which does not exceed the height limitation when combined with an associated launch vehicle.
Thus according to the invention a folding transportable bridge is provided comprising at least two bridge sections and at least one hinge joining the two bridge sections together end to end, the two bridge sections being rotationally unfoldable between a folded and an unfolded configuration about the hinge wherein the two bridge sections at least partly nest together when the two bridge sections are in the folded configuration.
In order to limit the rotational unfolding of the bridge sections the bridge is preferably provided with at least one extension on one bridge section and at least one stop on an adjacent bridge section, the stop being spaced radially from the hinge on one bridge section, whereby it contacts the extension of the other bridge section when the bridge sections are unfolded.
So that the load on the stops can be reduced the stop is preferably spaced longitudinally from the hinge along the length of the bridge section.
Preferably one of the bridge sections is provided with a cut away which allows the extension of one bridge section to pass through a position in which the two bridge sections are mutually perpendicular.
So as to cut down the weight of the bridge while still permitting vehicles to use it, each bridge section preferably comprises a pair of spaced parallel trackways. Alternatively each section may comprise a single trackway only.
Each trackway preferably constitutes the upper surfaces of a box section girder which section may be open on its lower side.
When the bridge comprises two sections each of which comprises a pair of girders each bridge section preferably comprises an inner girder and an outer girder which are dimensioned to cooperate with an outer girder and an inner girder respectively of the adjacent bridge section. This arrangement has the advantage that both extreme ends of the bridge are identical which facilitates the recovery of the bridge from the opposite end to that whi

REFERENCES:
patent: 4228625 (1980-10-01), Ruffer et al.
patent: 4663793 (1987-05-01), Parramore
patent: 4665577 (1987-05-01), Parramore

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