The design and development of the Class 91 locomotive

The British Rail Class 91 locomotive is a 25 kV Bo-Bo locomotive with a rated power of 4.54 MW and a design speed of 225 km/h. The locomotive will haul up to 11 Mk IV coaches and a driving trailer on the newly electrified East Coast Main Line from London to Edinburgh. In addition sleeper trains of up to 750 tonnes will be hauled on the West Coast Main Line including the arduous ascents of Shap and Beattock. The contract was placed by British Rail in February 1986. The authors describe the design and development of the power circuit, microprocessor control system and mechanical parts. Particular emphasis is given to the novel aspects of the design