Model of McNaught Type Compound Steam Engine

Model of McNaught Type Compound Steam Engine

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This is a model of an early design for a compound steam engine. A compound steam engine consists of a high pressure cylinder and one or more lower pressure cylinders. The steam exhausted from the high pressure cylinder is used as inlet steam for the next lower pressure cylinder. Each cylinder is sized in proportion to its inlet steam pressure so that each produces the same amount of work. Compounding was introduced in 1845 by John McNaught and widely used in many applications from steamship propulsion to powering large electrical generators.
The model represents McNaught’s original approach for the addition of compounding to standard beam engines. The original low pressure steam cylinder is seen at the right with its piston rod attached to the right end of the beam. McNaught added the smaller, high pressure cylinder just to the right of the crankshaft connecting rod at the left end of the beam. Hundreds of engines had their capacity increased by “McNaughting”, and new engines were built on this principle for many years.
Object Name
Engine, Steam
engine, steam, model
date made
mid 19th century
overall: 22 in x 9 1/2 in x 20 in; 55.88 cm x 24.13 cm x 50.8 cm
overall: 99 in x 36 in x 48 in; 251.46 cm x 91.44 cm x 121.92 cm
ID Number
catalog number
accession number
Credit Line
Gift of Armstrong Technical High School, Washington, D. C.
Steam Engines
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Work and Industry: Mechanical and Civil Engineering
Engineering, Building, and Architecture
Power Machinery
Exhibition Location
National Museum of American History
Data Source
National Museum of American History
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