"S-RAM" stands for "Sanderson Rocker Arm Mechanism", and is an elegantly simple new drive mechanism to convert reciprocating to rotary motion and vice versa without the energy-robbing side forces on the pistons or crosshead common to crankshaft, swash plate or wobble plate systems.  The S-RAM can vary the piston stroke while maintaining a constant head clearance.  The S-RAM can also be configured with opposed pistons resulting in incredible power density.