LSWR G14 Class

The LSWR G14 Class was a series of five four-cylinder 4-6-0 express passenger locomotives designed by Dugald Drummond and introduced at Nine Elms Works from 1908, representing Drummond's attempt to provide the London and South Western Railway with a large and powerful express type capable of working the principal Waterloo–Exeter and Waterloo–Bournemouth expresses. The G14 was one of Drummond's most ambitious designs and one of his most troubled: the four-cylinder layout and the design of the steam passages and valve gear proved mechanically difficult in service, and the class never achieved the performance that its size and power specifications should theoretically have delivered.

Drummond had become persuaded — as several of his contemporaries had, including Webb at the LNWR — that four cylinders offered inherently better balance and smoother power delivery than two. For the G14 he specified two inside high-pressure cylinders and two outside low-pressure cylinders in a layout that differed from the Webb compound in being a simple-expansion design: all four cylinders received steam directly from the boiler rather than using compound re-expansion. The 6 ft 0 in coupled wheels gave adequate speed capability for the Exeter expresses, and the large boiler should have produced ample steam.

In service the G14 Class consistently underperformed expectations. The steam passages and valve events were poorly designed, leading to restricted steam flow that limited the power the locomotives could develop despite the generous boiler. Drummond, characteristically, refused to acknowledge design faults and modified the class repeatedly without addressing the fundamental issue. His successor Robert Urie rebuilt the G14s with his own simplified two-cylinder arrangement from 1915, substantially improving their performance, but by then Drummond's reputation at the LSWR for large, expensive, and disappointing 4-6-0s was thoroughly established. None of the G14 Class was preserved.