Electro-pneumatic brake system on British railway trains

The Southern Region of British Railways operated a self-contained fleet of electric multiple units for suburban and middle-distance passenger trains.

This was a considerable and successful technical advance, enabling a quicker and more sensitive response to the driver's operation of brake controls.

From the 1920s, the Southern Railway of the UK and its predecessor companies had adopted electrification and multiple-unit train operation as a solution for dense and intensive passenger service requirements.

However it had disadvantages, chiefly: The first Southern units fitted with EP brake could be considered the Bulleid double deck 4-DDs built 1949 (4001 & 4002).

(A small fleet of locomotives were built for the Southern Region and had a brake control system fitted that was compatible for interoperability purposes.)

The Westinghouse brake cylinders and air reservoirs and pumps are used, so that only the means of transmitting the driver's command is changed.

The advantages of the EP system are that: The electrical control system required control cables throughout the length of the train (in addition to the two air pipes for Westinghouse operation) and a jumper cable was provided at each end of every unit for use when two or more units were coupled to run in multiple.

Following on from the original EP stock, the system was developed further on the second generation of Multiple Unit trains built for British Rail in the 1970s such as the Class 313 EMU.

trainwire 13) is fed with a 120 V DC control voltage from the battery and runs in a loop round the train, passing through various governors (air pressure operated electrical switches) in each carriage, finally feeding the power and brake control handle(s) in the driver's desk.