Coupled engine


May 28, 2022

Coupled engine - a steam engine with multi-stage steam expansion. An engine in which the pressure in diesel cylinders is first reduced, and then the process is repeated in subsequent cylinders with lower and lower pressure. Systems with two, three and four levels of steam expansion have been encountered. Mostly, the steam between the cylinders is heated in secondary superheaters. Compound engines are more efficient than single-stage steam expansion engines, such as twin-cylinder engines, but are more complex. They dominated steamers and ships' propulsion, while they were rarely used in steam locomotives, where lower fuel consumption did not compensate for the complicated construction and operation as well as higher repair costs.

Examples of steam locomotives with a coupled engine

Steam locomotives operated in Poland with a horizontal engine: Oc1, Od2, Od13, Pn12 ATSF 3000 - a Mallet system steam locomotive with two twin engines coupled.


Sołdek - the main engine of the museum ship in Gdańsk, A closed hoisting machine in front of the Queen Louise Mining Open-air Museum in Zabrze, The piston blower of the blast furnace in the Museum of Nature and Technology in Starachowice is out of service.


Paweł Terczyński-Atlas of steam locomotives.

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