Ryder-Ericsson hot air engine AS#14

 

This is a Ryder-Ericsson hot air engine, or Sterling engine, invented by Robert Sterling, a 19th century Scottish clergy man.

Sterling wanted a safer engine than steam in response to the many explosions of early boilers.

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It is an external combustion engine, i.e. the combustion (fire) is outside the cylinder. The working fluid is air and generates about 1 hp.

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John Ericsson was a Swedish-American engineer, best known for designing and constructing the USS Monitor, the Union iron clad of Monitor-Merrimack fame. He also designed the propeller system used on ships replacing side wheels or paddlewheels.

Early, or alpha, hot air engines had two pistons (in separate cylinders).

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Ericsson’s contribution, or beta engine, was to combine the power and displacer pistons in a single cylinder. This considerably reduced the size, weight, and cost of the engines.

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Our Ryder Ericsson has a 10” cylinder which was the largest of their engines. You will often see 6” and 8” ones.

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They were very safe, reliable and easy to operate and were primarily used to pump water (point out the water pump) for both commercial and domestic uses.

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Sterling engines are very popular today and are used on most artificial earth satellites and space systems for cooling. Recalling your chemical thermodynamics, if you run a sterling engine backwards, it is a refrigerator!