London Underground Battery-electric Locomotives

London Underground Battery-electric Locomotives

London Underground Battery-electric locomotives, most commonly known as battery locomotives are used for hauling engineers' trains, as they can operate when the electric traction current is switched off. The first two locomotives were built in 1905 for the construction of the Great Northern, Piccadilly and Brompton Railway, and their success prompted the Metropolitan District Railway to buy two more in 1909, which were the only ones built to the loading gauge of the subsurface lines. Following this, a number of battery vehicles were built by converting redundant motor cars, with the batteries placed in the unused passenger compartment. One exception to this was made by the City and South London Railway, who used a trailer car to hold the batteries, and wired them to a separate locomotive.

From 1936, battery locomotives were built as new vehicles, although in most cases, some components, particularly the bogies and motors, were refurbished from withdrawn passenger cars. The batch of 9 vehicles supplied by Gloucester Railway Carriage and Wagon Company between 1936 and 1938 set the standard for subsequent builds. Including this batch, 52 machines had been built by 1986, in six batches from four manufacturers, with one built at London Transport's Acton Works. Each new batch included some improvements, but most used electro-pneumatic traction control equipment made by GEC, and so could be operated together. The exception were three from the 1936 batch, which used an experimental Metadyne system, and the final batch of six, built in 1985, which used controllers manufactured by Kiepe.

Improvements since manufacture have included the replacement of low-level Ward couplers by buckeye couplers, which has resulted in less damage from shunting accidents, and the fitting of draught excluders and cab heaters for use in winter when the locomotives operate on sections of line above ground. A number of the machines were fitted with Automatic Train Operation (ATO) equipment to enable them to work on the newly-opened Victoria line. Subsequently, some have been fitted with Automatic Train Protection (ATP) equipment, compatible with the system used on the Central line, and some with ATP equipment which enables them to work with the replacement Distance-to-Go Radio (DTG-R) system on the upgraded Victoria line.