Late steam in bigger engines had a series of overfire jets along the side of the firebox. They looked like canisters of some gas, but probably weren't. What were they and how did they work?

Over-fire jets used steam jets to educt extra air through openings in the firebox sides above the fire (same principal as the exhaust up the stack in the smokebox). Some railroads called them "smoke consumers" as they reduced the amount of smoke produced on coal fired engines. The "canisters" you see on some engines were mufflers to try to quiet the noise. Some overfire jets had them; some didn't.

While we're on this subject, has anyone seen a drawing for the actual nozzle for these jets, especially the very small, unmuffled ones that worked through about a 2-1/2-inch tube? I have a notion that the brand name was Viloco. PM 1225 was equipped with these, but the cast-steel nozzles were destroyed by rust before we got the engine, and some had already been replaced by the Pere Marquette with flattend pipe nipples (which may have worked perfectly well, for all I know). These nozzles were a steel casting with a venturi around the opening. The steam orifice was maybe 1/4 inch.

The turret valve for these jets is labeled "smoke consumer" on this engine. We have never restored this system, but in the interest of keeping the neighbors happy it might be a wise project to undertake. It would be interesting just to see if it works.

Aarne:
Illinois Railway Museum has all of the VILOCO drawings and archives. I am not sure if the nozzel drawings are in the collection. I am also uncertain of the location on IRM. They were in the technical library above the air brake room, but may have been transfered to one of the main libraries at IRM. Tom Schnieder or Jim Kehrine will know.
J.David
P.S. I tried out the smoke consumers on former Commonwealth Edison No. 5 (a LARGE 0-6-0) a few times. They were mounted in the cab, above the firedoor and so loud that you could scarcely think (they did work though). JDC