Foldable extension ladder

Claim 1

A FOLDABLE EXTENSION LADDER COMPRISING A PLURALITY OF SUBSTANTIALLY RIGID, RELATIVELY ADJOINING LADDER-FORMING SECTIONS, EACH OF SAID SECTIONS INCLUDING A PAIR OF RELATIVELY SPACED APART, LONGITUDINALLY EXTENDING SIDE RAILS AND AT LEAST ONE STEP-FORMING MEMBER EXTENDING TRANSVERSELY BETWEEN SAID SIDE RAILS, MEANS ROTATIVELY CONNECTING THE SIDE RAILS OF EACH OF SAID SECTIONS TO THE STEPFORMING MEMBERS THEREOF AND PROVIDING FOR AXIAL TURNING MOVEMENT ONLY OF SAID SIDE RAILS WITH RESPECT TO SAID STEP-FORMING MEMBERS; AND HINGE MEANS CONNECTING THE SIDE RAILS OF ONE OF SAID SECTIONS TO THE SIDE RAILS OF AN ADJOINING SECTION, SAID HINGE MEANS INCLUDING LINEAL HINGE AXES DISPOSED IN PERPENDICULAR RELATION TO THE LONGITUDINAL AXES OF SAID SIDE RAILS, AND SAID HINGE MEANS BEING TURNABLE BODILY WITH SAID SIDE RAILS BETWEEN A FIRST POSITION IN WHICH THE HINGE AXES OF SAID HINGE MEANS ARE DISPOSED IN PARALLEL RELATION TO THE LONGITUDINAL AXES OF SAID STEPFORMING MEMBERS TO PERMIT SAID SECTIONS TO BE FOLDED WITH RESPECT TO ONE ANOTHER AND A SECOND POSITION IN WHICH SAID HINGE AXES ARE DISPOSED IN PERPENDICULAR RELATION TO THE LONGITUDINAL AXES OF THE SAID STEP-FORMING MEMBERS TO THEREBY LOCK SAID SECTIONS AGAINST RELATIVE FOLDING MOVEMENT.