Foldable bridge structure

Claim 1

A BRIDGE UNIT COMPRISING A FOLDABLE FRAME COMPOSED OF RELATIVELY ADJOINING FRAME SECTIONS, EACH OF SAID SECTIONS INCLUDING RELATIVELY SPACED-APART, LONGITUDINALLY EXTENDING LOAD-SUPPORTING SIDE RAILS AND AT LEAST ONE LOADSUPPORTING TIE MEMBER EXTENDING TRANSVERSELY BETWEEN SAID RAILS, MEANS ROTATABLY CONNECTING THE SIDE RAILS OF EACH OF SAID SECTIONS TO THE TRANSVERSELY-EXTENDING TIE MEMBER TO PROVIDE FOR AXIAL TURNING MOVEMENT ONLY OF SAID SIDE RAILS ABOUT THEIR LONGITUDINAL AXES WITH RESPECT TO SAID TIE MEMBER, HINGE MEANS CONNECTING THE SIDE RAILS OF ONE OF SAID SECTIONS TO THE SIDE RAILS OF AN ADJOINING SECTION, SAID HINGE MEANS INCLUDING HINGE AXES DISPOSED AT RIGHT ANGLES TO THE LONGITUDINAL AXES OF SAID SIDE RAILS, AND SAID HINGE MEANS BEING TURNABLY BODILY WITH SAID SIDE RAILS BETWEEN A FIRST POSITION IN WHICH THE HINGE AXES OF OPPOSED SIDE RAILS ARE IN AXIAL ALIGNMENT TRANSVERSELY AND PARALLEL TO THE COMMON PLANE OF THE LONGITUDINAL AXES OF SAID SIDE RAILS TO PERMIT SAID SECTIONS TO BE FOLDED WITH RESPECT TO ONE ANOTHER AND A SECOND POSITION IN WHICH SAID HINGE AXES ARE DISPOSED NORMAL TO SAID COMMON PLANE TO THEREBY LOCK SAID SECTIONS AGAINST RELATIVE FOLDING MOVEMENT, AND LOAD-SUPPORTING DECKING CARRIED BY EACH OF SAID SECTIONS AND TERMINATING SHORT OF SAID HINGE MEANS MEANS TO PERMIT RELATIVE FOLDING OF SAID SECTIONS.