Metropolitan - Inner Circle 4-4-0 Locomotives in Great_Britain

Class 1 (Locobase 2144)

Data from Ahrons (1927)

Based on the engines recently built for the Tudela-Bilbao line, these 18 were the first of 120 that London's Metropolitan Underground lines (Inner Circle) and District Lines would operate until electrification in 1905. For the Inner Circle, the orders began with 18 in 1864 (works #412-429); then 5 in 1866 (706-710), 1868, and 1869 (770-774 and 853-857); 6 in 1869 (863-868); 5 in 1870 (893-897).

District engines sported smaller fireboxes (16 sq ft grate area and 90 sq ft of heating surfaces) and two fewer firetubes; see Locobase 9415.

In the tunnels, exhaust steam was diverted into a pipe that returned to the top of the water tank. An smaller-diameter extension pierced the water surface to ensure that while most of the steam heated only the water surface, some would transfer heat into the body of the water itself. Thus the exhaust was kept out of the tunnel itself while being used to preheat (albeit modestly) the water.

Ahrons also notes that the original Bissell bogie truck was replaced in the 1880s by an Adams sliding bogie. He also records that No 1 ran 632,145 miles before her 1887 reboilering, going over 1,000,000 miles before an accident forced her scrapping in 1897.

Class 45 (Locobase 10246)

Data from Alfred Rosling Bennett,"The Early Locomotive History of the Metropolitan Railway," Railway Magazine (June 1908), p. 500-501.

Works numbers for 5 in 1879-1880 (1878-1882); 7 in 1880 (1937-1940, 1944-1946); 5 in 1884 (2979-2983); and 2 in 1885 (2674-2675).

After the Metropolitan had amassed 44 of its suburban tank engines, it paused several years before resuming its purchases. In the interim, the RM article explains, Locomotive Superintendent Tomlinson took a new look at the requirements and modified the design: "He left the cylinders and wheels unaltered, but increased the boiler pressure and bunker and tank capacity, shortened the fire-box and wheel-base, and stiffened the frame behind the buffer beam. The result was a heavier engine with weights adjusted so as to secure 5 tons 17 cwt. extra on the driving and trailing wheels and, consequently, a more powerful machine."