Patent ID: 7100333

Claim:
A reversibly expandable loop assembly comprising a four bar linkage defined by four links, each of said links being pivotally connected to two other of said links; wherein two of the said four links are defined as three pivot links having at least a pair of base end pivots and an apex pivot which together define vertices of an isosceles triangle; wherein said three pivot links are pivotally connected to one another at a first connecting pivot; wherein said apex pivot of each of said three pivot links is pivotally connected to one of the remaining two links; wherein each of the remaining two links are pivotally connected to one another at a second connecting pivot; wherein said four bar linkage is constructed such that the three pivot link base end pivots located away from said first connecting pivot and said second connecting pivot of the remaining two links together define a pair of lines which form an angle that remains constant for any relative rotational position of the linkage.