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.