The Great Western Railway (GWR) 9700 Class, or 97xx class, were 0-6-0PT pannier tank steam locomotives that were a direct development of the GWR 5700 Class. The prototype for the class, No. 8700 (later No. 9700), was a rebuilt 5700 Class locomotive that was originally built in 1931 by Beyer, Peacock and Company that was converted into a condensing engine to run on the Metropolitan line to the Smithfield Goods Depot. The pannier tanks of No. 8700 were cut back at the smokebox end to reduce the water capacity from 1,200 to 1,080 gallons. A vertical feed pump was fitted on the right hand side and the characteristic pipes from the smokebox to the tanks were added along with steam vents on the tanks. Test runs through the Metropolitan lines were run to check clearances.
Following the success of the prototype, ten more of these condensing locomotives were built in 1933 by Swindon Works that were numbered 9701 to 9710. They earned the nickname ‘tunnel motors’ by engine crews.
The Great Western Railway wanted to run heavier trains on the Hammersmith & City line between Paddington station and Smithfield Meat Market which resulted in these engines replacing the Metro and 633 class locomotives that were already working on the line at the time.
The eleven locomotives in the class had a condensing apparatus that fed the exhaust steam back into the water tanks. The tanks themselves were shortened to make room for the external exhaust pipes and were extended down to the footplate in front of the cab to increase their capacity. As condensing the steam heated the water, a reciprocating pump (Weir pump) was fitted as a boiler feedwater pump because standard injectors will not work with hot water. The pumps led to (unsuccessful) tests with these locomotives acting as fire engines during World War II.
To work over the electrified underground lines, the 9700 Class locomotives had a special type of Automatic train control (ATC) equipment that lifted clear of the centre rail and had tripcock brake valves that matched the London Transport signalling system.
After the 1955 Modernisation Plan, the United Kingdom embarked on a dieselisation program which slowly reduced the demand for the services of steam engines. Withdrawals of the class commenced in 1959 with the last member of the class, No. 9710, to be withdrawn in October 1964. 16 members of the original 5700 Class managed to survive into preservation but unfortunately no known examples of the 9700 Class were fortunate enough to have been preserved.
Stock List[]
1923 Batch[]
Loco No. | Image | Manufacturer | Build date(s) | Status |
---|---|---|---|---|
9700 | ![]() |
Beyer, Peacock and Company | 1931 | Scrapped |
9701 | ![]() |
Swindon Works | 1933 | Scrapped |
9702 | ![]() |
Swindon Works | 1933 | Scrapped |
9703 | ![]() |
Swindon Works | 1933 | Scrapped |
9704 | ![]() |
Swindon Works | 1933 | Scrapped |
9705 | Swindon Works | 1933 | Scrapped | |
9706 | ![]() |
Swindon Works | 1933 | Scrapped |
9707 | ![]() |
Swindon Works | 1933 | Scrapped |
9708 | ![]() |
Swindon Works | 1933 | Scrapped |
9709 | ![]() |
Swindon Works | 1933 | Scrapped |
9710 | ![]() |
Swindon Works | 1933 | Scrapped |