Two-cycle recompression internal-combustion engines in which the axes of the working and pump cylinders form a single straight line which, if extended, would intersect the main shaft of the engine at right angles, the cylinders abutting and the working piston being prolonged and extended into the pump-cylinder and enlarged therein to form the pumping-piston, thereby forming an annular pumping-chamber which surrounds the extension of the working piston. From the above it follows that the working and pump pistons form a single rigid structure. In engines in this subclass compression of the charge prior to the ignition thereof is effected by the joint action of the pump and motor pistons. The arrangement above defined may be reversed, in which case the cylinder above described as the working cylinder becomes the cylinder of the supply-pump and the annular pumping-chamber becomes the working chamber.
(1) Note. The supply-pump is inseparable from the engine and ordinarily operated upon the whole charge, as in engines in subclass 70.
