British Rail Class 73

British Rail Class 73
A GB Railfreight Class 73/9 at Connel Ferry in 2016
Type and origin Power type Bi-mode (electro-diesel) Builder 73/0: British Railways at Eastleigh Works 73/1: English Electric at Vulcan Foundry Build date 73/0: 1962 73/1: 1965–1967 Total produced 49
Specifications Configuration: ​  • AAR B-B  • UIC Bo'Bo'  • Commonwealth Bo-Bo Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Wheel diameter 3 ft 4 in (1,016 mm) Length 16.36 m (53 ft 8 in) Loco weight 73/0: 76.3 long tons (77.5 t; 85.5 short tons) 73/1: 76.8 long tons (78.0 t; 86.0 short tons) Electric system/s 660–750 V DC Third rail Current pickup(s) Contact shoe Prime mover English Electric 4SRKT Mk II 2 × Cummins QSK19 (73951-2) MTU 8V 4000 R43L (73961-971) Traction motors 73/0: EE 542A 73/1: EE 546/1B MU working 73/9: AAR system (59, 66, 67, 68 008-015, 69, 70, and 73/9) Train heating Electric Train Heating Train brakes Vacuum, Air and Electropneumatic
Performance figures Maximum speed 73/0: 80 mph (129 km/h) 73/1: 90 mph (145 km/h) Power output Electric (continuous): 1,420 hp (1,059 kW) Electric (one-hour): 1,600 hp (1,193 kW) Engine: 600 hp (447 kW) 73/9: 1,600 hp (1,193 kW) Tractive effort 73/0 (electric): 42,000 lbf (186.8 kN) 73/0 (diesel): 34,100 lbf (151.7 kN) 73/1 (electric): 40,000 lbf (177.9 kN) 73/1 (diesel): 36,000 lbf (160.1 kN)
Career Operators British Rail GB Railfreight Network Rail Southern South Western Railway Numbers E6001–E6049 later 73001–73006, 73101–73142 Axle load class Route availability 6 Withdrawn 1972 (1), 1982 (1), 1991–present Disposition 6 preserved, 27 still in service 6 stored, 10 scrapped

The British Rail Class 73 is a British electro-diesel locomotive. This type is unusual in that it can operate on the Southern Region's 650 / 750 V DC third rail power supply, or an onboard diesel engine to allow it to be used on non-electrified routes. This makes it very versatile, although the diesel engine produces less power than is available from the third-rail power supply, so the locomotives are rarely used outside of the former Southern Region of British Rail. It is one of the first bi-mode locomotives ever built. Following the withdrawal and scrapping of the more powerful Class 74 bi-mode locomotives in 1977, the Class 73 was unique on the British railway network until the introduction of the Class 88 bi-mode locomotives in 2017. Ten locomotives have been scrapped.