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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.

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.

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).

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.

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

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.

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!

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