be required, to give a realistic trial, and Brush already had a suitable one on hand, as a spare from the development of Falcon. This was a Maybach MD655 of 1,400 bhp. The Maybach was also a high-speed diesel engine, running at 1,500 rpm rather than the Paxman's 1,250 rpm. The Paxman was itself considered a high-speed engine, running significantly faster than the English Electric or Sulzer medium-speed (< 1,000 rpm) engines which had been adopted for high-powered British Railways locomotives. The new 100 Hz AC generator was rated at , a conversion efficiency of 91%. The output was at 1,325V / 600A. New AC traction motors were used, with squirrel cage motors supplied by thyristor variable-frequency drives. Brush's experience with AC transmission, gained with Hawk, would be put to use a few years later with the development of the 4,000 bhp single-engined AC transmission HS4000 Kestrel. Hawk was used until 1968, after which its control equipment was becoming irrelevantly obsolete and was superseded by the direct experience from Kestrel. During the 1972 miners' strike the engine and generator were removed as a standby generator for the Brush Falcon works. After this, parts began to be stripped until it was finally scrapped around 1976. References Further reading External links The Railway Raptors 10800 NBL locomotives Brush Traction locomotives Railway locomotives introduced in 1950 Scrapped locomotives Unique locomotives Bo-Bo locomotives Standard gauge locomotives of Great Britain Diesel-electric locomotives of Great Britain Individual locomotives of Great Britain