LSWR L12 class

LSWR/SR L12

30415 at Eastleigh, 1950

Type and origin Power type Steam Designer Dugald Drummond Builder LSWR Nine Elms Works Build date 1904–1905 Total produced 20

Specifications Configuration 4-4-0 Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Leading dia. 3 ft 7 in (1.092 m) Driver dia. 6 ft 7 in (2.007 m) Length 63 ft 9 in (19.43 m) Loco weight 54 long tons 4 cwt (121,400 lb or 55.1 t) (orig); 55 long tons 5 cwt (123,800 lb or 56.1 t) (superheated) Fuel type Coal Boiler pressure 175 psi (1.21 MPa) Cylinders Two, inside Cylinder size 19 in × 26 in (483 mm × 660 mm)

Performance figures Tractive effort 17,673 lbf (78.61 kN)

Career Operators London and South Western Railway, Southern Railway (Great Britain), Southern Region of British Railways Class LSWR / SR: L12 BR: 2P, later 3P Locale Great Britain Retired 1951–1955 Disposition All scrapped

The London and South Western Railway L12 class was a class of 20 4-4-0 steam locomotives designed for express passenger work by Dugald Drummond. They were introduced to the London and South Western Railway network in 1904. Despite the class being an unremarkable continuation of the Drummond lineage, one member was involved in the infamous Salisbury rail crash in June 1906. None of the class survived into preservation after their brief career in British Railways ownership.

In 1904, the LSWR Locomotive Superintendent, Dugald Drummond, was tasked by his superiors to analyse the possibility of an updated version of his successful T9 class 4-4-0. With open competition against the Great Western Railway in earning revenue from ocean-going traffic in the south-west of England at Plymouth, there was a need for a new design of powerful locomotive capable of hauling heavy loads at high speeds. This furthermore provided Drummond with the chance to take advantage of various advances in locomotive technology that had accumulated in the five years since the release of the T9.

The last in an unbroken lineage of Drummond 4-4-0s stretching back to his unsuccessful C8 Class of 1898, the L12 continued the tradition of solid construction and robust operation.

Drummond took the decision to construct a further new class of 20 4-4-0s as part of the competition between the LSWR and GWR regarding boat trains to Plymouth harbour. Once again, the L12 followed the example of the Class S11 in incorporating the same frames as the T9. The major design difference between this and the Class S11 was the fact that the 6-foot-7-inch (2.007 m) driving wheels seen on the T9 were reinstated for fast running on the LSWR main line.

The boiler was also similar to that of the T9s, capped off with a dome and stovepipe chimney, though the smokebox was of a smaller design in comparison due to the initial lack of superheating. The locomotive was fitted with cross-water tubes fitted into the firebox, as featured on the T9 Class. This was an attempt to increase the heat surface area of the water, which was achieved, though at a cost in boiler complexity. The new locomotive had a higher centre of gravity than the earlier T9 class, which would cause the locomotive to become unbalanced on curves at speed, and this would have fatal consequences later on.