Steam Locomotives of a More Leisurely Era
London & South Western Railway
720 as running in 1921
The third type of four-cylinder engine to appear in 1897 was Dugald Drummond’s first express engine for the LSWR. It was an experimental machine with two independent pairs of single driving wheels, the two inside cylinders driving the front pair and the outside ones the rear. This arrangement had been used by F.W.Webb on the LNWR, but whereas the Webb engines were compound, the new South Western was a simple expansion machine. Amongst other features it embodied for the first time Drummond’s firebox water tubes, as depicted by the rectangular casing alongside the firebox. This was applied to all of Drummond’s tender engines from 1900 onwards, but they were eventually removed by Urie in later days. No.720 was at first fitted with a 4’ 5” diameter boiler similar to Class T9, and a further five very similar engines, Nos. 369-73 were built in 1901. In 1907, No.720 received a larger boiler of 4’ 10¾” diameter, but the other five were never so rebuilt, although all eventually lost their water tubes.
As the driving wheels were uncoupled the engines suffered to some extent from the defect of all single wheelers, tending to slipping with a heavy load on a wet rail, and for this reason they were not greatly popular. They were capable of good performances at times, but were latterly only used in times of heavy traffic when there was a shortage of engines. All six were broken up in 1926-7, No.720 was classified T7 and Nos.369-75 E10.
Driving wheels – 6’ 7”, Bogie wheels – 3’ 7”, Cylinders (4) 14”x 26”, Pressure 175 lb., LSWR & SR power classification I