Description
Class F01B : MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES
Subclass 7/06: Machines or engines with two or more pistons reciprocating within same cylinder or within essentially coaxial cylinders (in opposite arrangement relative to main shaft F01B 1/08) with oppositely reciprocating pistons acting on same main shaft using only connecting-rods for conversion of reciprocatory into rotary motion or vice versa