Patent ID: 6890278

Claim:
An elongated chain structure, comprising: a plurality of chassis links and movable links alternating with one another along a longitudinal length of the chain, each adjacent pair of said chassis links and said movable links being movably attached to one another for relative rotation of the pair of links on a pivot axis such that each of said chassis links has laterally spaced link plates attached to longitudinally spaced transverse pivot pins, and each of said movable links includes at least one movable link plate that is movable laterally inwardly from a position abutting one of the link plates of the chassis link to a position clear of one of said chassis link plates wherein the movable link plate comprises at least one contact cam protruding laterally from the movable link plate, whereby the movable link plate can be displaced inwardly by causing the contact cam to follow a surface having a decreasing lateral width wherein the chassis link and the movable link plate are relatively rotatable in one of said positions of the movable link plate and fixed against relative rotation in another of said positions; wherein said chassis links and said movable links have longitudinally abutting surfaces that differ from a circular surface around the respective pivot axis, wherein said chassis links and said movable links are prevented from rotating by the longitudinally abutting surface; and wherein at least one of the links of said chassis links and said movable links is displaceable sufficiently to disengage the longitudinally abutting surfaces of adjacent links for relative rotation and to re-engage for rendering the chain rigid.