Electric Railway Journal · Vol. 49, No. 19 · May 12, 1917 · pp. 871-873.

LONDON UNDERGROUND EXTENSION — FIVE-CAR SUBWAY TRAIN OPERATING OVER MAIN LINE RAILROAD TRACKS IN SUBURBS.

Extension of London Underground System [Bakerloo Line]. Subway Equipment with Unusual Features of Body Design and Electric Control Is Operated Over an 8-Mile Section of the London & North Western Railway Tracks to Give Through Service Between the Suburbs and the Center of the City.

Recently there has been placed in service an extension of the Bakerloo underground line in London, England, which will open up a large area of new countryside and residential districts, and will directly connect the northern suburbs with the central, west end and southeastern districts of the city. In part, the tracks of the London & North Western Railway are used, and this will give the passengers of this system a choice of some five terminal stations in town connecting with main-line railways. The new extension is about 8 miles in length. It runs above ground for this distance, although the cars to be used upon it are, of course, designed for subway service, since the remainder of the 20-mile route is underneath the surface. Power at 600 volts direct current will be supplied to the extension from the London & North Western power houses at Willesden.

Control Equipment

As the route makes use, in part, of the tracks of different railway systems of which one employs an earth return while the other employs an insulated return consisting of a fourth rail, it has been necessary to modify the equipment of the motor cars accordingly. For this purpose two additional sets of shoes have been fitted on the motor trucks of the cars, one set on either side. On the trailing truck of the motor car insufficient clearance exists below the body to fit shoes for the fourth rail, so that these have had to be arranged on the truck of the adjoining trail car, connection being made to the motor car by means of jumpers.

For the conversion from earth to insulated return negative switches and fuses to the main circuit and to each of the auxiliary circuits have been provided. In doing this, care was taken to reproduce the standard wiring arrangement of the road that uses insulated return, so that, electrically, the difference between the two types of rolling stock is confined to the control equipment.

The control, which is supplied by the British Thomson-Houston Company, is of the relay automatic type, the contactors being picked up in their correct sequence by the current-limiting relays when the controller handle is placed on the operating point. The principle underlying this method of control is that, after a contactor has been picked up, its coil is immediately transferred, by means of interlocks, to another wire. Thus there are essentially two operating wires, the pick-up wire and the retaining wire, although other wires are introduced for forward and reverse, circuit breaker setting, etc. There are no main bus lines through the train, which is composed of a motor car at the front and rear and three trailers between them. Consequently a potential relay is fitted on each motor car, and this drops all contactors on that car when the shoes lose current. This is necessary because, when no current passes through the main coil of the current-limit relay, it ceases to exercise its control over the rate of picking up contactors.

The controller has four forward points and two reverse points, of which Nos. 2 and 4 are running points where all resistance is cut out. A useful provision in the control is that, if in the course of the automatic notching-up the controller handle is brought back to the first or third notch, as the case may be, the automatic closing of contactors is stopped, but those already closed are kept up. Another feature is the operation of the safety button on the controller handle, which may be released except when at off position. But if the handle itself is let go it flies back to off position, instantly cutting off current and applying brakes throughout the train. Another safety device which is now a part of the standard London Electric Railway equipment is the control circuit governor. By interrupting the control circuit, this prevents the train from being moved forward unless the train pipe of the Westinghouse air brake is charged with air and the tripcock is cut in.

Each motor car is fitted with two General Electric 212 motors of 240 hp., mounted on the same truck and geared for a free running speed of 35-40 m.p.h.

Rolling Stock

As mentioned above, each train consists of five cars, two motor cars and three trailers. The latter are standard London Electric Railway cars, while the motor cars were designed for a new extension over the Great Western Railway, whose opening has been postponed for the time being. The motor cars are provided with covered vestibules at the trailing ends, and they have center doors. They were described in the Electric Railway Journal for Feb. 7, 1914, page 298.

This is the first case wherein rolling stock designed for underground service has been run in passenger service on a main line railway, and provision has had to be made for passengers to get on or off at the stations on the London & North Western Railway, which have platforms of the standard main-line height — higher than that obtaining in the underground tubes. This has been accomplished on the trail cars by superimposing short ramps on either side of the existing platforms of these cars. It has been possible to do this without encroaching upon available headroom, owing to the open character of the gangways. But the closed vestibules on the motor cars have prevented any similar provision for this equipment.

The number of seats on each motor car is thirty-two, and on each trailer fifty-two. Third-class accommodations only are provided. The car bodies are constructed of steel, with some wood interior finish. Ventilation is provided by an air duct with perforations which runs for the whole length of the car, and is open to the atmosphere at the ends. The prominent feature of difference from common practice in the United States is the installation of control equipment in a raised section of the body over the motor truck. This is done to save height.

General dimensions and weights of the motor cars are as follows:

Length over all	47 ft. 9 In.
Width over body	9 ft. 8 In.
Total height from rail	9 ft. 3 In.
From center to center of truck	29 ft. 6 in.
Diameter of motor wheels	36 in.
Diameter trailing wheels	29 in.
Weight on motor truck wheels	47,500 lb.
Weight on trailer truck wheels	20,200 lb.
Total weight of car completely equipped	67,800 lb.

The total weight of a five-car train without passengers is approximately 246,000 lb., and the seating capacity is 220 passengers.

LONDON UNDERGROUND EXTENSION — GROUP OF WOMEN GUARDS, OR GATE WOMEN, WHO OPERATE THE NEW SERVICE AND ARE SUBORDINATES OF THE MASCULINE OFFICIAL APPEARING AT THE LEFT OF THE ILLUSTRATION.

LONDON UNDERGROUND EXTENSION — MOTOR CAR WITH CONTROL EQUIPMENT COMPARTMENT ELEVATED TO CLEAR MOTOR TRUCK.

LONDON UNDERGROUND EXTENSION — VIEW OF CAR PLATFORM AND GATE SHOWING RAMPS DESIGNED TO PROVIDE FOR VARIATIONS IN STATION PLATFORM HEIGHT.

Sources

Electric Railway Journal, McGraw Hill Company, Digitized by Microsoft, Americana Collection, archive.org.