Patent ID: 7579536

Claim:
A device, comprising: first, second, and third paired-strand levers each configured to receive a pair of tensile strands at locations spaced apart from one another along the paired-strand lever; first, second, and third fulcrums each supporting a corresponding one of the paired-strand levers between the tensile strand receiving locations; a fourth lever linked to the first and second paired-strand levers through the first and second fulcrums, respectively, at secondary lever link locations spaced apart from one another along the fourth lever; a fourth fulcrum supporting the fourth lever between the secondary lever link locations; a fifth lever linked to the third paired-string lever and the fourth lever through the third and fourth fulcrums, respectively, at primary lever link locations spaced apart from one another along the fifth lever; a fifth fulcrum supporting the fifth lever between the primary lever link locations; and an anchor anchoring the fifth lever through an adjustable link to the fifth fulcrum to vary a distance between the anchor and the fifth lever.