This is an unusual engine in that there are no cranks or connecting rods. The cylinders and pistons with their wrist pins are still there but in place of the crank is a double lobed cam. The cam is fixed to the stationery outer housing and the cylinders with their pistons spin around the cam. There is a roller follower on each wrist pin which rides the cam. So as the cylinders make one revolution around the cam, each piston sees two top dead centers and two bottom dead centers and thus we have all four strokes taking place in one revolution. This then allows us to substitute ports in the outer housing in place of the usual poppet valve gear, greatly simplifying the engine. Another neat thing about this configuration is that opposite pistons move in and out together which eliminates all inertial out of balance without the use of counterbalance weights. There are restraining links between adjacent wrist pins which keep the pistons from flying o! ff the cam. I know this all sounds very complicated but its really quite simple when you see it work. Main advantages over the normal radial piston engine are: potential for much higher power to weight ratio; very low vibration level; very low cost to produce; and small frontal area.
