Stirling-Cycle Engine!

By Staff
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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.

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