Mallet, Jules Théodore Anatole

SUBJECT AREA: Land transport, Railways and locomotives

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b. 1837 Geneva, Switzerland

d. November 1919 Nice, France

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Swiss engineer, inventor of the compound steam locomotive and the Mallet articulated locomotive.

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Mallet's family moved to Normandy while he was still a child. After working as a civil engineer, in 1867 he turned to machinery, particularly to compound steam engines. He designed the first true compound steam locomotives, which were built for the Bayonne- Biarritz Railway in 1876. They were 0–4–2 tank locomotives with one high-pressure and one low-pressure cylinder. A starting valve controlled by the driver admitted high-pressure steam to the low-pressure cylinder while the high-pressure cylinder exhausted to the atmosphere. At that time it was thought impracticable in a narrow-gauge locomotive to have more than three coupled axles in rigid frames. Mallet patented his system of articulation in 1884 and the first locomotives were built to that design in 1888: they were 0–4–4–0 tanks with two sets of frames. The two rear pairs of wheels carried the rear set of frames and were driven by two high-pressure cylinders; the two front pairs, which were driven by the high-pressure cylinders, carried a separate set of frames that was allowed sideplay, with a centre of rotation between the low-pressure cylinders. In contrast to the patent locomotive of Robert Fairlie, no flexible connections were required to carry steam at boiler pressure. The first Mallet articulated locomotives were small, built to 60 cm (23.6 in.) gauge: the first standard-gauge Mallets were built in 1890, for the St Gotthard Railway, and it was only after the type was adopted by American railways in 1904 that large Mallet locomotives were built, with sizes increasing rapidly to culminate in some of the largest steam locomotives ever produced. In the late 1880s Mallet also designed monorail locomotives, which were built for the system developed by C.F.M.-T. Lartigue.

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Bibliography

1884, French patent no. 162,876 (articulated locomotive).

Further Reading

J.T.van Riemsdijk, 1970, "The compound locomotive, Part I", Transactions of the Newcomen Society 43 (describes Mallet's work on compounding).

L.Wiener, 1930, Articulated Locomotives, London: Constable (describes his articulated locomotives).

For the Mallet family, see Historisch-Biographisches Lexikon der Schweiz.

See also: Bousquet, Gaston du; Vauclain, Samuel Matthews; Webb, Francis William

PJGR