Schoenner Engine

Three-cycle, Non-compression Flame-ignition Engine


| April/May 2003



Schoenner engine

I found this engine at a local antique shop in the early 1960s, priced at $10. I did some talking and got it for $7. Did I pay too much? It was missing quite a few pieces, but I understand engines and I made the following missing parts: the sideshaft and its gear; the head; intake and exhaust valve cams; and the rocker arm. It's still missing its burner tube, but we'll come back to that. It has a 1-3/8-inch bore, a 2-3/4-inch stroke and the flywheel is 6-1/2-inch in diameter. It has most of its original paint and pin striping. It is, it should be noted, a toy engine, and was never built to actually work for a living.

Dale Nickerson's Schoenner engine, missing many of its pieces when found. Dale made the engine's cylinder head, sideshaft, valve cams and the rocker arm.

Background

In the early 1970s while on my way to a show in Ohio, I made a side trip and stopped at Don Irvin's model shop in Burbank, Ohio. Don had an identical engine (I don't recall how complete it was), and according to Don, Jean Schoenner of Nuremburg, Germany, made my engine some time between 1880 and 1890.

It's a three-cycle, non-compression flame-ignition engine. The engine's operating sequence is thus: On the intake stroke the sideshaft cam opens the fuel intake valve on the side of the cylinder admitting a small amount of gas - at the same time the automatic valve on the front of the cylinder opens, letting in air. When the piston reaches half its stroke the gas valve closes. The piston goes a wee bit more, exposing a port on the side of the cylinder. Flame provided by a burner tube is sucked in causing combustion, followed by a quarter-turn power stroke. At the end of that stroke the exhaust valve on the front of the cylinder head opens, discharging the spent gases.

Looking at the Schoenner from above. The tube at the back of the cylinder is an oiler, the fitting at the front is the air intake valve. The sideshaft gear is just visible on the left side of the crankshaft.

I first tried running it on propane, but with no result - no doubt I had the wrong fuel/air ratio. Next, I made an acetylene generator with two outlets; one supplying gas for the inlet valve, the other supplying gas for the flame. The only problem was, as gas was admitted the flame was pulled out. Following that I made a small, separate reserve tank for the flame's gas supply, but the engine still pulled the flame out.