Anatole Mallet

Jules T. Anatole Mallet (23 May 1837 - 10 October 1919) was a Swiss mechanical engineer, who was the inventor of the first successful compound system for a railway steam locomotive, introducing in 1876 a series of small 2-cylinder compound 0-4-2 tanks for the Bayonne-Anglet-Biarritz Railway in France. He subsequently designed an articulated compound system with a rigid chassis at the rear carrying two high-pressure cylinders plus two low-pressure ones mounted on an articulated front driving truck; this was first used for a series of RailGauge|600mm narrow gauge locomotives specially built by the Decauville Company for the Paris Exposition of 1889. This arrangement became known as the Mallet locomotive.

USA

From 1904 onwards, this arrangement was much used in the United States as it enabled considerable increase in locomotive size and power. At first the compound system was universally employed, but most later American "Mallets" had a similar articulated front chassis but used simple expansion; however the name has stuck, even if not strictly valid.