123 / | HD | INTERNAL-COMBUSTION ENGINES |
51 R | DF | MULTIPLE PISTON, COMMON NONRESTRICTIVE COMBUSTION CHAMBER {2} |
51 B | .~ Two-cycle {4} | |
51 BA | DF | .~.~> Two-cycle separate crankshaft for piston |
51 BB | DF | .~.~> Piston offset from crankshaft |
51 BC | DF | .~.~> Plural combustion chamber and plural piston |
51 BD | DF | .~.~> Inlet or exhaust ports in two or more planes |