Abstract: A unitary, “hollow out” piston is molded or forged with only two tools, which move along a single parting direction, with a pair of arcuate side walls that provide maximal outer surface area with minimal thickness and weight. The thin walls are internally fortified by a cruciform support structure that is molded integrally by the same tools. No post forming machining steps are needed to reduce weight.

Abstract: A torque limiting device features spring arms that extend resiliently and spirally from a drive member to distal ends rotatably supporting cam followers that engage cam posts on a driven member to transmit rotation from the driven member to the drive member. In response to a predetermined reactive force, the spring arms are resilient and move radially, and the cam followers rotate to allow the distal ends to spring past the cam posts in response to a predetermined reactive force.