US Patent 7360511 Opposed piston engine

A two-cycle, opposed piston engine with side-mounted crankshafts and cylinders isolated from mechanical stresses of the engine includes tailored cooling of cylinders and symmetrical cooling of the interior surfaces of piston crowns. Each opposed piston includes a compliant member that permits movement of an axially-centered rod mounted in the piston in order to maintain axial alignment with the bore of a cylinder in which the piston is disposed during engine operation. A single wristpin is disposed externally of the piston to connect the piston with connecting rods that run between the piston and the crankshafts.