British Rail Class 46

class of 56 (1Co)(Co1) 2500hp diesel-electric locomotives

The British Rail Class 46 is a class of diesel locomotive. They were built from 1961–1963 at British Railways' Derby Works and were initially numbered D138-D193. With the arrival of TOPS computer system they were renumbered to Class 46. Fifty-six locomotives were built. The first was withdrawn in 1977 and all of them were withdrawn by 1984.

Derby Type 4
British Rail Class 46
Class 46
Type and origin
Power typeDiesel-electric
BuilderBritish RailwaysDerby Works
Build date1961–1963
Total produced56
 • Whyte1Co-Co1
 • UIC(1Co)'(Co1)'
Wheel diameter3 ft 9 in (1.143 m)
Minimum curve3.5 chains (70 m)
Wheelbase59 ft 8 in (18.19 m)
Length67 ft 11 in (20.70 m)
Width8 ft 10+12 in (2.71 m)
Height12 ft 10 in (3.91 m)
Loco weight138 long tons (140 t)
Fuel capacity790 imp gal (3,600 L; 950 US gal)
Prime moverSulzer 12LDA28-B
MU working Blue Star
Train heatingSteam generator
Train brakesVacuum
Performance figures
Top speed90 mph (145 km/h)
Power outputEngine: 2,500 bhp (1,864 kW)
At rail: 1,962 hp (1,463 kW)
Tractive effortMaximum: 55,000 lbf (245 kN)
Brakeforce63 long tons-force (628 kN)
Railroad(s)British Railways
NumberD138–D193; later 46001–46056
Axle load classRoute availability 7

The Class 46 design was structurally the same as the earlier Class 45 build, and had the same Sulzer engine. It differed in the fitment of a Brush generator and traction motors, in place of the Crompton Parkinson equipment fitted to the Class 45.