As can be seen from the accompanyingillustration, this little engine is remarkably simple in appearance. The engine complete, with equipment, weighs at the most but 14 ounces. The cylinders, three in all, are stamped from brass shells for strength and lightness. The pistons are made from ebony fiber. The cylinders have a bore of ⁵⁄₈″, with a piston stroke of ¹⁄₂″. The crank case is built up from a small piece of brass tubing and is drilled out for lightness. The crankshaft is hollow, and is supported at the rear by a special bearing which acts as a rotary valve, admitting the intake through the crankshaft and permitting the exhaust to escape through a specially constructed bearing.
The tank is constructed of 30 gauge sheet bronze, wire wound, and fitted at the ends with spun brass caps. The actual weight of the engine alone is 2¹⁄₂ ounces, the tank and fittings weighing 11¹⁄₂ ounces, making the total weight of the complete power plant 14 ounces.
Another interesting type of compressed air engine that has been developed in America is the Schober four cylinder opposed engine. While this engine is different in appearance from most compressed air engines, it has been made to work satisfactorily and is consistent with the same high class construction that is displayed in most all of Mr. Schober’s engines. The accompanyingdiagram 18illustrates the method of operation of the four cylinder engine.