LMS 6399 Fury
LMS 6399 Fury was an ambitious British steam locomotive built in 1929 in Glasgow by the North British Locomotive Co. as part of a venture to save fuel with ultra-high-pressure steam from a Schmidt boiler. Fury had a 4-6-0 wheel arrangement and a longer frame than the standard Royal Scot type. It used three cylinders—one high-pressure inside between the frames and two larger low-pressure outside—to form a semi-compound engine.
The boiler was a complex, three-stage Schmidt unit designed to deliver very high-pressure steam (up to about 1,800 psi) to the cylinders, plus a second stage around 900 psi and a small conventional boiler at 250 psi to provide heating if needed. The engine was a combined effort of the LMS, with Henry Fowler as chief mechanical engineer, and the Superheater Company.
In testing, Fury suffered a notorious accident when a high-pressure tube burst near Carstairs in February 1930, killing a worker. After repairs, Fury continued trials at Derby until 1934 but showed limited practical performance and reliability. In 1935, William Stanier rebuilt Fury at Crewe as 6170 British Legion, adopting a more conventional boiler and becoming the first of LMS’s 2 and 2A boilered 4-6-0s. Fury never served revenue trains.
The experiment demonstrated that the promised fuel savings of ultra-high-pressure steam were hard to achieve in practice, mainly due to maintenance demands and water circulation issues in the complex system.
This page was last edited on 2 February 2026, at 10:43 (CET).