VACUUM ENGINE

By Staff
Published on May 1, 1975
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INTAKE PORT OPEM 10 ADMIT FLAME FROM ALCOHOL LAMP

Box 246, Elfers, Florida 33531

The sketch of this tiny vacuum engine may be of interest to some
of your readers. It is perhaps the simplest engine to build, having
only one cylinder and one slide valve in contrast to a hot air
engine with its displacer cylinder, etc. I have a hot air engine of
1 inch bore, the vacuum engine is also 1 inch-one would expect the
hot air engine to have the most power since there is a push from
the expansion of the hot air as well as the vacuum, but strange to
say the vacuum engine has just as much ‘power’ although
operating on vacuum only. It is fascinating to watch as it pops at
every revolution, sounding like a little gas engine.

It is truly a mystery engine although the principle is that the
hot gases are admitted to the cylinder through an open port on the
outward stroke which is closed by the slide valve at about 95
degrees when the hot gases are supposed to cool, and create a
partial vacuum pulling the piston back on the return of
‘power’ stroke. The mystery is that the hotter the
cylinder, the faster the engine runs! In fact, if one wants to get
a quick start, the cylinder has to be heated. It is also strange
that the transition from hot to cold (in a hot cylinder) can be
rapid enough to cause the engine to run at a high rate of speed,
but it does!

I’ BORE VACUUM ENGINE

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