British Rail Class 29

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.

British Railways Class 29
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D6121
Power type	Diesel-electric
Builder	North British Locomotive Company
Build date	1958–1960 Rebuilt: 1963, 1965–1967
Total production	20
Configuration	Bo-Bo
UIC classification	Bo'Bo'
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)
Locomotive 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
Multiple working	● Red Circle
Top speed	75 mph (121 km/h)
Power output	Engine: 1,350 hp (1,010 kW)
Tractive effort	Maximum:
Train heating	Steam generator
Locomotive brakeforce
Train brakes	Vacuum
Career	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

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 D6108 was withdrawn in May 1969 and scrapped by McWilliams of Shettleston in 1971, while the other 19 were withdrawn between April and December 1971 and scrapped at BR's Glasgow Works in 1971–72.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.