Stirling-Cycle Engine!

Rider-Ericsson Hot-Air Pumping Engine

Content Tools

2855 San Fernando Road, Atascadero, California 93422-7706

After showing this 1895 Rider-Ericsson hot-air pumping engine at a few of our local shows and getting the reactions that I did, I thought some of you might be interested in seeing a Stirling-Cycle engine. As most other people, I had only heard of Stirling engines and only recently seen a handful of the scale models, including that of an Ericsson. In no way did I ever imagine that I would end up with an actual engine, especially out here on the west coast!

I came across this engine quite by chance, while 'horse trading' some other iron with a long time friend of my dad's. He had been a collector and restorer of the old lungers for quite some time and was peddling off most of them in order to get back into the Model T iron. I admit, I was probably like a kid in a candy shop!

Having already acquired a bit of engine savvy in the short time that I had been in the hobby, I locked onto the sight of a particular curved spoke flywheel off in the corner of this gentleman's barn. I knew it was old, but was dumbfounded when I was told what it actually was. He mentioned that he intended to also sell the Ericsson, but of course at a price somewhat higher than your average Fairbanks or John Deere. It so happened I was still in possession of a near-complete Model T racing engine that he had his eyes on. Needless to say the rest is history. Both of us went home grinning ear to ear with our new toys.

Restoration of this engine was a whole new ballgame compared to the gas engines. The burner (for wood or coal) needed to be relined and the transfer (displacer) piston, a 22 inch long sealed sheet-metal slug, needed to be completely refabricated. Not being real familiar with fire brick and not being fully set up to do heavy sheet-metal work, I hesitated for almost a year to start the restoration. Attending the EDGE&TA National Meet in Grass Valley, California, in '93 and seeing two Ericssons there and running was all it took to get me started with the tools and paint.

The original burner was lined with a very unique set of fire brick, each being a different shape and size complete with their own cast in part numbers. Once the cast iron burner shells were cleaned up, and after making several attempts of pouring a solid liner in each shell, I finally ended up with a good clay mix and good usable burner. The transfer piston was formed by a local sheet-metal shop, after which I heliarced the pieces together. The original piston had been filled with a wood pulp type of insulation which I replaced with fiberglass in the new piston. The piston is capped on top by a bronze casting that is riveted and soldered into place to form an airtight unit.

While removing this casting from the original piston, I drilled the rivets out and used a torch to break the solder loose. Try .hitting 100 year-old wood pulp with a torch and see what happens! That stuff burns better than gasoline! From here all parts were sandblasted and painted, all bearings rebushed, a new leather seal added to the power piston and final assembly done. I was even able to use the original hard rubber valves in the pump. The next hurdle was to figure a viable way to transport and show this top heavy 625 pounder. After much thought, the final product ended up as seen here, on its trailer, but minus miscellaneous tie downs and braces for travel.

I won't go into great detail here on the engine's theory of operation, but generally speaking, the engine consists of one long cylinder with a water jacket at the top (cool) end and a burner around the bottom (hot) end. There are no valves or ports since the air trapped in the cylinder is repeatedly cycled by the transfer piston between each end of the bore. During each cycle, the air is heated and cooled, causing it to expand and contract, thus applying cycling pressures on the power piston. This generates just enough power to operate the engine itself and the water pump the engine's one and only task. Believe me, it took me nearly as long to figure this thing out as it did to restore it!

About six months was required to complete this project, but it was well worth it. Many thanks go to Roy Gregory and Carlton Ekdahl for their advice and expertise.