The main generator supplies current to the four traction motors whilst the shunt-wound auxiliary generator, controlled by an automatic voltage regulator, supplies current at 110V for the excitation of the main generator, control circuits, blower and exhauster motors, locomotive lighting and battery charging. Two axle-hung, nose suspended traction motors are mounted on the outer axles of each bogie. They are series wound, six-pole, forced-ventilated machines, and two stages of automatic field weakening are provided by diverter resistances to enable constant wheel tread horse-power to be obtained throughout the required speed range. The traction motors are permanently connected in two parallel groups of two motors in series. The drive to the axles is through single-reduction spur gearing. Auxiliary machines comprise two motor-driven exhausters, two traction motor blowers and one mechanically driven compressor. Both exhausters operate simultaneously, and may be run at high speed when rapid release of the brakes required. A traction motor blower is mounted at each end of the locomotive, for the adjacent bogie. The compressor, which has a swept volume of /min. at 850 r.p.m., is driven direct from the engine through a splined shaft. The compressor supplies air required for operating control gear, horns and sanding equipment. Radiators are mounted on both sides of the locomotive, each having oil and water elements. A roof mounted fan draws air through the radiators and expels it through the roof. It also ventilates the engine room. It is mechanically driven, via a centrifugal clutch, from free end of the engine through a right angle gearbox. An additional output shaft from the same gearbox continues into the rear compartment and drives the compressor. All air required for the engine, electrical machines and auxiliaries is drawn in through oil-wetted filters. Most of the control equipment is housed in a control frame mounted across the locomotive, adjacent to the driving cab. This frame contains the electro-pneumatic contactors and reverser together with the associated relays. At each driving position a master switch, control handle and brake valve are provided, together with an instrument panel and indicator lights. Engine starting is effected by moving the master switch to the “engine only" position, and then pressing a starting button. In this switch position, the engine can be run at varying speeds by moving the control handle, without moving the locomotive. To move the locomotive, the master switch is moved away from the "engine only" position to the appropriate direction of motion.