also brushless and producing three phase electrical power gave ~500 kW for electrical train heating, and also supplied power to electrical fans etc. in the locomotive. The armatures/rotors for both alternators were electrically energised by DC produced by the rectified output of brushless alternators. Each of the 6 axles was powered by an individual traction motor which was a four pole force ventilated type. Connection of the axle to the motor was via a reduction gear (giving top speed), then through a flexible hollow shaft drive to the axle. The fans (blowers) to cool the traction motors and engine radiators were of the three phase asynchronous type, the motors driving the compressors, pumps, fans for the dynamic (resistive) brake etc. were DC motors. Braking system Locomotive braking was by vacuum, air (high pressure) or dynamic (electrical regenerative resistive braking), the dynamic brakes were preferentially used at high speeds, with the air brake being activated at lower speeds where dynamic braking was less effective; speed sensors automatically determined the braking type to be used. Additionally a hydraulically activated parking brake was fitted. Electronic devices Plug-in solid state modules were used for voltage and power control including monitoring wheelslip and monitoring engine temperature. Superstructure construction A Warren truss body construction with welded, stressed steel skin was used on the sides of the locomotive which supported the transverse load of the main engine entirely. Bogies The bogie side frames were of one piece cast construction with coil spring suspension, connected by 4 transverse members; two internal and two at either end After the Hither Green rail crash, British Rail issued a directive that all locomotives should have an axle weight of no-more than 21 tons. In an attempt to comply with this, Brush fitted the locomotive with modified British Rail Class 47 bogies. The lighter construction and traction motors helped but the attempt was ultimately unsuccessful leaving Kestrel at 22.5 tons per axle. Kestrel continued to be used but the axle-weight problem contributed to the decision to sell the locomotive and prior to this, in March 1971, the original bogies were refitted. Cabs The driver's cab is attached to the frame below by rubber fittings. Driver controls were similar to that of Class 47. Career British Rail Construction of the locomotive (Brush works No. 711 of 1967) started in 1966 and was complete by 1967. However the locomotive was considerably over the 20t