Structurally rigid collapsible linkage assembly structure

Claim 1

A LINKAGE ASSEMBLY STRUCTURE COMPRISING A PLURALITY OF LINK UNITS WITH EACH LINK UNIT HAVING SPACED SUBSTANTIALLY IDENTICAL SIDE MEMBERS WITH TERMINAL RECESSES AT OPPOSITE ENDS AND FIRST AND SECOND PINS EXTENDING THROUGH SAID SIDE MEMBERS AT OPPOSITE ENDS RESPECTIVELY INWARDLY OF THE TERMINAL RECESSES, THE ENDS OF THE SIDE MEMBERS OF ADJACENT LINK UNITS DISPOSED IN OVERLAPPING RELATION, MEANS PIVOTALLY INTERCONNECTING ADJACENT LINK UNITS OUTWARDLY OF THE RESPECTIVE SIDE MEMBERS, EACH OF SAID INTERCONNECTING MEANS DEFINING A PIN RECEIVING APERTURE AT ONE END AND AT THE OTHER END A LONGITUDINAL SLOT HAVING AN OFFSET PORTION, EACH OF SAID INTERCONNECTING MEANS BEING PIVOTALLY CONNECTED AT SAID PIN RECEIVING APERTURE TO THE FIRST PIN OF ONE OF THE ADJACENT LINK UNITS, AND BEING SHIFTABLY AND PIVOTALLY CONNECTED WITH THE SECOND PIN OF THE OTHER OVERLAPPING ADJACENT LINK UNTIL AT SAID LONGITUDINAL SLOT, ADJACNT LINK UNITS BEING SHIFTABLE AXIALLY TOWARD EACH OTHER TO THEREBY PERMIT SAID TERMINAL RECESSES AT OPPOSITE ENDS OF EACH LINK UNIT TO DISPLACEABLY RECEIVE THE SECOND AND FIRST PINS RESPECTIVELY OF THE NEXT ADJACENT LINK UNITS AT OPPOSITE ENDS THEREOF, AND SAID OFFSET PORTION AT THE LONGITUDINAL SLOT OF EACH INTERCONNECTING MEANS DISPLACEABLY RECEIVING THE SECOND PIN OF THE NEXT ADJACENT LINK UNIT UPON MOVEMENT OF SAID INTERCONNECTING MEANS ABOUT THE PIVOTAL CONNECTION WITH SAID FIRST PIN TO THEREBY LOCK ADJACENT LINK UNITS FROM PIVOTAL MOVEMENT RELATIVE TO EACH OTHER AND MAKE SAID LINKAGE ASSEMBLY STRUCTURE RIGID.