Patent ID: 8336286

Claim:
A motion transmitting drive chain comprised of: a forward end and a rearward end and a plurality of successive, flexibly-connected links between said forward and rearward ends, adjacent links having interlocking, axially-aligned projections for resisting compressive loads; and a spring having first and second ends, the first end of the spring being operatively coupled to the drive chain at a first spring attachment point, proximate the forward end of said spring; whereby the spring and attachment point are configured to apply a compressive force to at least some of the flexibly connected links of the drive chain located between the spring attachment point and the rearward end of the spring, the compressive force causing axially-aligned projections to interlock adjacent links; wherein the links are comprised of pins having central axes of rotation, the pins flexibly connecting adjacent links to each other, the projections and the central axes of the pins being separated from each other by a separation distance wherein the spring and attachment point are selected such that compressive force acts through a geometric line of action located on the projection side of the central axes of the pins, the line of action being substantially orthogonal to said separation distance, whereby links are urged to rotate about said pins to interlock the projections; wherein the attachment point is selected such that the line of action is located outside the links, on the projection side of the axes of rotation; and wherein the spring is a coil having a cross section selected to enable the links to pass through the interior of said coil.