Engerth locomotive

The Engerth locomotive was a type of early articulated steam locomotive designed by Wilhelm Freiherr von Engerth for use on the Semmering Railway in Austria. The distinctive feature of the Engerth design was an articulated tender as part of the main locomotive frame. Some of the weight of the tender therefore rested on the driving wheels, improving adhesion, while articulation allowed the locomotive to navigate the narrow curves of mountain railways.

Wilhelm von Engerth was born in Pless, Upper Silesia (Now Pszczyna, Poland) on 26 May 1814, the brother of the artist Edouard von Engerth. Initially, he studied architecture, but in 1834 he took up mechanical engineering as a profession. By the late 1850s he was the General Manager of the Imperial Austrian State Railways. Von Engerth was created a Baron (Freiherr) in 1875, and he died on 4 September 1884 in Leesdorf.

Von Engerth first patented his design for an articulated locomotive on 11 December 1852.

The Semmering Railway, opened on 17 July 1854, was one of the first true mountain railways, traversing a section of the Austrian Alps. It was characterized by steep gradients and sharp curves. To work this railway a new design of locomotive was developed.

A competition was held to decide which locomotives would be bought for operation on the Semmering Railway. One stretch of the line had gradients of 1 in 40 (2.5%) and curves with a minimum radius of 190 metres (210 yd) and a maximum radius of 285 metres (312 yd). A speed of 11.5 kilometres per hour (7.1 mph) was required to be maintained and a maximum axle loading of 14 tonnes, with a boiler pressure not exceeding 8.5 kgf/cm² (830 kPa). There were four entrants, Bavaria, built by Maffei; Wiener-Neustadt built by Wiener-Neustadt; Seraing built by Société anonyme John Cockerill in Belgium and Vindobona built by the Glognitz Bahn in Vienna. All four locomotives met the trial conditions, but none proved reliable in practical use. The Semmering Trials led to a number of developments in locomotive design: Fairlie's Patent of 1863, The Meyer locomotive and the Mallet locomotive.

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