Steam locomotive

Railway locomotive powered by a steam engine

A steam locomotive, also known as an iron horse, is a type of locomotive that provides the force to move itself and other vehicles by means of the expansion of steam. It is fuelled by burning combustible material (usually coal, coke, oil or, rarely, wood) to heat water in the locomotive's boiler to the point where it becomes gaseous and its volume increases 1,600 to 1,700 times. Functionally, it is a self-propelled steam engine on wheels.

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