Unknown, Curved Cylinder Steam Engine
United Kingdom - Manufacture date: pre 2001
Bore = 3/4", Stroke 3/4", Flywheel diameter = 4"
Style: Double Acting, Curved Cylinder Horizontal

12" length x 9" width x 5 1/2" x height 11"
(includes base)

The Curved Cylinder Engine

his little engine, built by Bob out in Washington state. is quite an  interesting design. Most cylinders one encounters are made using a straight bore. The Curved Cylinder Engine, as it's name implies, uses an unusual cylinder design which has a  curved radius, matching the arc prescribed by the swinging pendulum, mounted in the "A" frame. I'm told the design was of French origin.

This engine, along with the James Booth Rectilinear engine shown in another area of this site, were offered to me when Bob, made the painful choice to begin dismantling his remaining collection of engines. I couldn't resist acquiring an engine such a novel design to add to this growing collection of hand made engines.

The Curved Cylinder Engine arrived in perfect running order and required only a simple wipe down to make it shelf ready. I ran the engine on air immediately after unpacking it and found it to run as smooth as silk. This little engine will run on as little as 10 pounds of air and is a heck of a lot of fun to watch, especially knowing the darned design is so improbable to begin with.

Bob tried to explain to me how he went about machining the interior of the cylinder, but he quickly  lost me somewhere after the part where he said, "I began by building a special little rig that let me..."

Detail View of the Curved Cylinder

View of the "A" Frame

The skills used in creating this little machine are quite amazing. Not only is the process of machining cylinder somewhat of a mystery, but the "A" frame was not created from castings. All of the frame structure was cut and assembled from flat sheet brass. The flanges were all hand cut and fitted before being soldered into position to form a strong rigid structure. Quite a piece of work and an excellent example of Bob's skills and ingenuity.

The back side of the pendulum is available to drive a complete new set of flywheels, doubling the available delivery of usable motive forces. I've been exceptionally lucky to find a few unusual engines over the past few years, but none match this one for pure whimsical practicality of design. This one is going to be a keeper.


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