Schmidt, Wilhelm

SUBJECT AREA: Railways and locomotives, Steam and internal combustion engines

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b. 18 February 1858 Wegeleben, Saxony, Germany

d. 16 February 1924 Bethel, Westphalia, Germany

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German engineer, inventor of an effective means of superheating steam in locomotive boilers.

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Schmidt was educated at Dresden Technical High School and worked as an assistant to a locksmith. He experimented with steam engines worked at extremely high pressures and developed ideas for using superheated steam. Two early types of locomotive superheater that he designed were tried out in Prussia in the late 1890s, but his firetube type, which was eventually successful, was first used in Belgium in 1901. Within ten years of its introduction, superheating using Schmidt-type superheaters was standard practice on large locomotives worldwide.

In the superheater, steam from the boiler is passed through tubular elements within the firetubes before passing to the cylinders. This raises the steam's temperature without increasing its pressure: advantages of doing so include increasing the volume of steam produced and reducing condensation in the cylinders, with consequent economies of fuel and water. Schmidt superheaters were first used in Britain in 1906 by George Hughes, Locomotive Superintendent of the Lancashire \& Yorkshire Railway, on two goods locomotives, and then by D.Earle Marsh on the London Brighton \& South Coast Railway; hefitted them to 4–4–2 express tank locomotives in 1908. These were conspicuously successful in comparative trials with equivalent non-superheated locomotives from the London \& North Western Railway.

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Further Reading

J.Marshall, 1978, A Biographical Dictionary of Railway Engineers, Newton Abbot: David \& Charles.

P.Ransome-Wallis (ed.), 1959, The Concise Encyclopaedia of World Railway Locomotives, London: Hutchinson, p. 501 (with references to superheaters, pp. 286, 392–4).

C.Hamilton Ellis, 1959, British Railway History, Vol. II: 1877–1947, George Allen \& Unwin, pp. 268–71 (for the introduction of superheating to Britain).

PJGR