British Rail Class 46

Derby Type 4 British Rail Class 46
Class 46
Type and origin Power type Diesel-electric Builder British Railways’ Derby Works Build date 1961–1963 Total produced 56
Specifications Configuration: ​  • Whyte 1Co-Co1  • UIC (1Co)'(Co1)' Wheel diameter 3 ft 9 in (1.143 m) Minimum curve 3.5 chains (70 m) Wheelbase 59 ft 8 in (18.19 m) Length 67 ft 11 in (20.70 m) Width 8 ft 10+1⁄2 in (2.71 m) Height 12 ft 10 in (3.91 m) Loco weight 138 long tons (140 t) Fuel capacity 790 imp gal (3,600 L; 950 US gal) Prime mover Sulzer 12LDA28-B MU working ★ Blue Star Train heating Steam generator Train brakes Vacuum
Performance figures Top speed 90 mph (145 km/h) Power output Engine: 2,500 bhp (1,864 kW) At rail: 1,962 hp (1,463 kW) Tractive effort Maximum: 55,000 lbf (245 kN) Brakeforce 63 long tons-force (628 kN)
Career Railroad(s) British Railways Number D138–D193; later 46001–46056 Nicknames ‘Peak’ Axle load class Route availability 7

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 The first was withdrawn in 1977 and all of them were withdrawn by 1984.

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.