Compound locomotive

For the principles and other applications of the compound steam engine, see compound steam engine and compound engine.

A compound locomotive is a steam locomotive which is powered by a compound engine, a type of steam engine where steam is expanded in two or more stages.[1][2] The locomotive was only one application of compounding. Two and three stages were used in ships, for example.[3]

Compounding became popular for railway locomotives from the early 1880s and by the 1890s were becoming common. Large numbers were constructed, mostly two- and four-cylinder compounds, in Germany, Austria, Hungary, and the United States. It declined in popularity due to a perceived increased maintenance requirement. Nonetheless, compound Mallets were built by the Norfolk and Western Railway up to 1952 and more importantly, Compound locomotives continued to be designed and built in France until the end of steam in the 1970's. French compounding of railway engines became so highly developed, eventually incorporating reheaters between the high and low pressure stages as well as the initial use of superheaters, that France achieved the highest power to weight ratio and the highest horsepower to fire grate-area ratio of any steam locomotives ever built.

  1. ^ van Riemsdijk, John T. (1970). "The Compound locomotive, Parts 1, 2, 3". Transactions of the Newcomen Society (2).
  2. ^ Van Riemsdijk 1994, pp. 4–9.
  3. ^ "The Pictorial History of Steam Power", J.T.Van Riemsdijk and Kenneth Brown, 1980 Octopus Books Limited, ISBN 0-7064 0976-0, p.101