Initially the Central London Railway (CLR) purchased 168 carriages from
Ashbury Railway Carriage & Iron Co. and
Brush. Made in 1900–1901 and weighing 14 tons, these seated 48 passengers, 32 on longitudinal seating with 16 on transverse seating in the centre. The cars were high and wide, to run in tubes with a diameter of . The wooden carriage bodies were long on underframes, with wide platforms at each end. Sliding doors at the ends of the carriage led to these platforms that had lattice gates either side. Gatesman rode on the platforms between the cars and operated the gates. The
Board of Trade refused to allow trains with an
electric locomotive at the head and tail as this would require power lines the length of the train so thirty-two larger locomotives were ordered, although the CLR only received 28. These were camel-backed with four motors mounted on two bogies. Manned in the centre cab by a driver and second man, who would uncouple and couple the locomotive at the end of each journey, the locomotives took power from a positive centre rail at 500–550 V
DC. Soon after opening, the company received complaints that vibration was felt in the buildings above the route. The
Board of Trade appointed an investigating committee in January 1901, which reported in May that the problem was due to the large unsprung mass of the 44-ton locomotives, and the track. An experiment in August showed the vibrations could be reduced by rebuilding locomotives to reduce the unsprung mass to tons. The following month, after four of the carriages had been converted into motor cars and fitted with
British Thomson-Houston control equipment that had been invented by
Frank J. Sprague in Chicago, an electric multiple unit was tested. ==Electric multiple units==