Electric Railway Journal · Vol. 57, No. 19 · May 7, 1921 · pp. 855-856.

[Left] RESISTORS, COMPRESSOR, ISOLATING SWITCH, MOTOR-FUSE BOX AND CIRCUIT BREAKER ARRANGED ON UNDERSIDE OF CAR. [Right] MOTORMAN'S CAB ON LEFT-HAND SIDE OF CAR — CONTROLLER COVER OFF.

Equipment and Design Features of Metropolitan District Cars [F Stock]. Improvements Over Cars of Older Design Include Use of 190-Hp. Tapped-Field Motors, Semi-Automatic Acceleration and More Compact Arrangement of Auxiliary Equipment.

An article dealing with the new steel rolling stock received by the three railways operating London's rapid transit lines was printed in the March 5 issue of this paper. This dealt more particularly with their ability to permit rapid transfer of passengers as determined by the number and arrangement of doors. Also some attention was devoted to a general description, which included the layout of the seats, the replacement of straps with handrails and posts and interior fittings. Now more detailed information has been forthcoming relating to the general design and equipment features of the Metropolitan District Railway cars.

The first cars of the order, comprising 100, were put in service in February. During the first few days an eight-car train was stationed for a few hours at one of the busiest stations, with the view of letting the public familiarize itself with the improved rolling stock as a concrete example of how Lord Ashfield was overcoming congestion difficulties in the underground railways. The train aroused a great deal of public and newspaper interest and comment.

The cars are 49 ft. long and 9-1/2 ft. wide. Their height is about 12 ft. The motor cars weigh about 50 tons each, the control trailers 29 tons and the trailer cars 27.5 tons. The wheel base of the motor trucks is 7 ft. 10 in.

Much thought has been put into the electrical design, for that equipment embodies and co-ordinates the most modern apparatus. The motor cars are each equipped with four G. E. 260 motors, which are of the interpole tapped-field self-ventilating type. They are rated at 190 hp. for one hour and 182 amperes continuously. The motors are fitted with twenty-tooth pinions geared to sixty-three-tooth gears. The wheels are 36 in. in diameter. Each pair of motors with its control gear constitutes a complete unit equipment. The normal rate of acceleration will be 1-1/2 m.p.h.p.s.

Substantial improvements have been made in the control apparatus. The contactor tips are provided with arcing horns and a molded arc chute. The interlocks are of the disk type, mounted on the back of the contactor. The contactor box with all its contactors, resistances, etc., is a unit complete with wiring and has its own terminal base. The reverser connected to the motor fields is of the drum type operated by a pair of opposed solenoid coils. The control is non-automatic except that the motor field is weakened automatically by the tapped-field relay when the current decreases as the last parallel point on the controller is reached.

The cars are equipped with Westinghouse clasp brakes of the standard type and are provided with automatic slack adjusters. Hand brakes are fitted to all motor cars and control trailers.

The underframes are constructed entirely of steel, bulb angles form the sole bars and the center longitudinals are rolled steel channels running the whole length of the frame. The cross bearers at the trucks are pressed channel sections. The floor plates are stiffened with short angles and pressings across from the sole bars to the center longitudinals.

The motor car truck side frames are channel sections running the whole length of 13 ft. to the headstocks, but are cut away on the bottom flange to receive the axle boxes. The bolsters are built up of 8 x 3 in. channels 5-1/2 in. apart and stiffened with 5/16-in. plates.

The former arrangement of carrying the draft gear back to the kingpin has been abandoned and a short drawbar fixed to the longitudinal members is substituted. Tight couplings between cars is the result of the use of a central spring buffer through which the drawbar head passes.

Sources

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