Animated Engines, Coomber

Coomber Rotary Engine

I first learned of this delightful engine while attending the PRIME show in Oregon. A most prolific modeler, Marlyn Hadley, had one on display. I referred to his excellent book⁶ to create this illustration.

I have not illustrated the valve linkage, as I'm not exactly sure what it looks like! It appears to be a rotary type, incorporated into the main drive shaft. Steam would be admitted to one end of the cylinder at a time, just as in any other double-acting steam engine.

The inner dimension of the stationary ring is not circular, but is slightly elliptical. The main bearing is offset from the center of this ellipse by a one half the stroke length.

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