Model Hot Air Pumping Engine

CONSTRUCTION TIPS


| October/November 1988



Rider Ericsson engine

1/4 Scale Rider Ericsson engine.

7574 So. 74 Street Franklin, WI 53132

1/4 Scale Rider Ericsson Pumping Engine-The castings for the Rider Ericsson hot air pumping engine are of aluminum alloy and are sold by Meyers Model Engine Works, 15929 Five Point Road, Perrysburg, Ohio 43551.

For those of you who, like me, purchased the castings several years ago from Norbert Keeley, you might want to contact Mr. Meyers, as the furnace and furnace door are now beautiful castings. This is a great improvement over fabricating these parts from sheet and bar stock, and these parts can be purchased separately. I had the castings since 1978 and built both of these engines simultaneously during the past year.

The Rider Ericsson castings were a dream to machine and assemble. There is ample stock for machining and the parts fit together well. Although prints do come with the castings, the complete construction article, including the drawings, was printed in the October, November and December issues of Live Steam Magazine. These articles contain more drawings than do the prints, along with the helpful text, so I chose to work from these articles.

In my engine, I used ball bearings for the crankshaft, instead of the needle bearings that are specified. Use shielded (not sealed) ball bearings of 3/8' shaft size and 7/8' O.D. and soak them in solvent to remove all the grease. Then replace the grease with a light oil-either by soaking, or with an aerosol. This will make the bearings very free rolling. Also, I used 'Oilite' bushings on every moving part, including the sliding fits like displacer rod and pump rod. To seal the water pump flange to the cylinder on both engines, I cut an O-ring groove in the pump flange. This took a 1/16' cross section x ?' I.D. O-ring.

While building this engine, I had the benefit of knowing several people who have built the engine before me and I adopted their changes that have improved the operation of this type of hot air engine. The first change was to use steel for a displacer cylinder, not copper as called for in the prints. Copper conducts the heat right up into the cold end of the cylinder- just where you don't want it. I turned the steel tubing down to .026'-.030' wall thickness for the entire length of the displacer cylinder. A piece of .020'-.031' thick copper was silver soldered to the bottom of the cylinder. Here the thin copper puts the heat right where it is wanted.