British Rail Class 20

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English Electric Type 1
British Rail Class 20
20903 at Doncaster Ron Hann.jpg
Hunslet-Barclay 20903 on a weedkilling train at Doncaster, April 1994
Type and origin
Power typeDiesel-electric
BuilderEnglish Electric at Vulcan Foundry and Robert Stephenson and Hawthorns
Build date1957–1962, 1966–1968
 • WhyteBo-Bo
 • UICBo'Bo'
Gauge4 ft 8 12 in (1,435 mm) standard gauge
Wheel diameter3 ft 7 in (1.092 m)
Minimum curve3.5 chains (70 m)
Wheelbase32 ft 6 in (9.91 m)
Length46 ft 9+12 in (14.262 m)
Width8 ft 9 in (2.67 m)
Height12 ft 8 in (3.86 m)
Loco weight72 long tons (73.2 t)
Fuel capacity380 imp gal (1,700 l; 460 US gal)
Prime moverEnglish Electric 8 SVT Mk.II
Traction motorsD8000–D8049: EE 526/5D
Remainder: EE 526/8D
TransmissionDC generator, DC traction motors
MU working Blue Star
Train heatingNone
Train brakesVacuum
Performance figures
Top speed75 mph (121 km/h)
Power outputEngine: 1,000 hp (746 kW)
Tractive effortMaximum: 42,000 lbf (186.8 kN)
Brakeforce35 long tons-force (349 kN)
Railroad(s)British Railways
NumberD8000–D8199, D8300–D8327; later 20001–20228
Axle load classRoute availability 5

The British Rail Class 20, originally known as an English Electric Type 1, was a class of diesel electric locomotive. 228 locomotives in the class were built by English Electric between 1957 and 1968. The large number was partly to do with the failure of other early designs in the same power range, and reliable locomotives being needed.

The locomotives were originally numbered D8000–D8199 and D8300–D8327. They are known by railway enthusiasts as "Choppers",[1][2] a name taken from the distinctive beat the engine produces under load which resembles the sound of a helicopter.

References[change | change source]

  1. Oakley, Michael (1981). BR Class 20 diesels. Truro: Bradford Barton / D&EG. ISBN 0-85153-419-8.
  2. "'At least 20 20s' for Barrow Hill diesel jubilee". The Railway Magazine: 9. July 2007.