British Rail Class 29

British Railways Class 29
D6121
Type and origin Power type Diesel-electric Builder North British Locomotive Company Build date 1958–1960 Rebuilt: 1963, 1965–1967 Total produced 20
Specifications Configuration: ​  • Whyte Bo-Bo  • UIC Bo'Bo' Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Wheel diameter 3 ft 7 in (1.092 m) Minimum curve 3.5 chains (70 m) Wheelbase 37 ft 0 in (11.28 m) Length 51 ft 6 in (15.70 m) Width 8 ft 8 in (2.64 m) Height 12 ft 8 in (3.86 m) Loco weight 73 long tons (74 t) Fuel capacity 460 imp gal (2,100 L; 550 US gal) Prime mover Paxman Ventura Transmission DC generator, DC traction motors MU working ● Red Circle Train heating Steam generator Train brakes Vacuum
Performance figures Top speed 75 mph (121 km/h) Power output Engine: 1,350 hp (1,010 kW) Tractive effort Maximum: 45,000 lbf (200 kN) Brakeforce 50 long tons-force (498 kN)
Career Railroad(s) British Railways Number D6100–03/06–08/12–14/16/19, D6121/23/24/29/30/33/34/37 Axle load class Route availability 6 (RA 5 from 1969) Retired 1969–1971

The British Rail Class 29 consisted of 20 diesel locomotives which were rebuilt from the North British Class 21. The original licence-built MAN engines of the Class 21s had proved unreliable, so in 1963 locomotive D6123 was sent to Paxman's Colchester works to receive a new Paxman Ventura V12 engine. A further 19 were re-engined in 1964–1965 at Polmadie Works, with other changes made at the same time. This included the fitting of four-character headcode displays in the nose ends. After rebuilding, they returned to service from Eastfield depot in Glasgow.

Although these offered more power and much improved reliability over the original Class 21s, they did not survive much longer, due to their small class size and the use of a non-standard high-speed diesel engine. D6108 was withdrawn in May 1969 and scrapped by McWilliams of Shettleston in 1971, while the other 19 were withdrawn between April and December 1971 and scrapped at BR's Glasgow Works in 1971–72. No Class 21 or Class 29 locomotives survive today.