tell me more about the latter
It is a heat engine that performs mechanical work using steam as its working fluid.
Steam engine
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. 
what is nsb el 9? It is a retired class of three electric locomotives. who built it? Thune. who is he? They are a Norwegian manufacturing company. when was it founded? 1815. who were its founders? Anders Paulsen Thune. what can you tell about their history? Started in Drammen, produces agricultural machinery and steam engines. The factory expanded to Skøyen in Aker in 1901.
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Steam engine [SEP] Introduction
A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a cylinder. This pushing force is transformed, by a connecting rod and flywheel, into rotational force for work. The term "steam engine" is generally applied only to reciprocating engines as just described, not to the steam turbine. Steam engines are external combustion engines, where the working fluid is separated from the combustion products. The ideal thermodynamic cycle used to analyze this process is called the Rankine cycle.