British Rail Class 24

British Railways Type 2
British Rail Class 24

Class 24, no. 24065 at Motherwell depot, May 1976

Type and origin Power type Diesel-electric Builder British Railways’ Derby Works, Darlington Works and Crewe Works Build date 1958–1961 Total produced 151

Specifications Configuration: ​  • Whyte Bo-Bo  • UIC Bo-Bo Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Wheel diameter 3 ft 9 in (1.143 m) Minimum curve 4.5 chains (91 m) Wheelbase 36 ft 6 in (11.13 m) Length 50 ft 6 in (15.39 m) Width 8 ft 10 in (2.69 m) Height 12 ft 8 in (3.86 m) Loco weight Class 24/0: 79 long tons (80.3 t; 88.5 short tons) Class 24/1: 73 long tons (74.2 t; 81.8 short tons) Fuel capacity Class 24/0: 546 imp gal (2,480 l; 656 US gal) Class 24/1: 500 imp gal (2,300 l; 600 US gal) Prime mover Sulzer 6LDA28 Generator BTH RTB15656 DC Traction motors BTH 137BY, DC, 4 off Transmission Diesel electric MU working ★ Blue Star Train heating Steam Train brakes Vacuum

Performance figures Maximum speed 75 mph (121 km/h) Power output Engine: 1,160 hp (865 kW) At rail: 843 hp (629 kW) Tractive effort Maximum: 42,000 lbf (186.8 kN) Continuous: 21,300 lbf (94.7 kN) Brakeforce 38 long tons-force (380 kN)

Career Operators British Railways Numbers D5000–D5150; later 24001–24047, 24051–24141 Axle load class Class 24/0: RA 7 (6 from 1969) Class 24/1: RA 6 (5 from 1959) Retired 1967–1980 Preserved Four (list)

The British Rail Class 24 diesel locomotives, also known as the Sulzer Type 2, were built from 1958 to 1961. One hundred and fifty-one of these locomotives were built at Derby, Crewe and Darlington, the first twenty of them as part of the British Rail 1955 Modernisation Plan. This class was used as the basis for the development of the Class 25 locomotives.

The final survivor, no. 24081, was withdrawn from Crewe depot in 1980.

The main power for the Class 24 was the Sulzer 6LDA28 diesel engine - denoting 6 cylinders; Locomotive use; Direct fuel injection; (turbo-charged); 28 cm (11 in) bore cylinders. This was effectively an off-the-shelf purchase with small changes to bearings, injectors and some other minor items. The same engine was used in the CIE 101 Class locomotives in Ireland.

The diesel engine powered another off-the-shelf product, the British Thomson-Houston (BTH) RTB15656 main generator which, in the Class 24, was rated at 735 kW (986 hp), 750/525 V and 980/1400 A at 750 rpm. Traction motors, one per axle, were also by BTH being the type 137BY rated at 222 hp (166 kW), 525 V, 350 A at 560 rpm connected to the axle via a 16:81 gear stepdown ratio, each force ventilated by an AEI 12.2 hp (9.1 kW) electric motor.