Class 42_6Tintin is on his adventure to the British Isle. He had somehow escaped from Dr Muller and a burning house. In my last post Tintin had boarded a train – though unconventionally by jumping onto the roof from the foot over bridge – pulled by a Class 27 diesel-electric locomotive. Once onboard, he encountered Dr Muller again, who was onboard the same train. There was a chase across the length of the train, but Muller and his accomplice were able to the disconnect the train locomotive, leaving Tintin behind. Tintin and Snowy boarded a freight train going in the same direction. There is a scene showing the freight train  locomotive where the freight train drivers see the Class 27 locomotive stranded on the track. The locomotive which was pulling this freight train was a Class 42 diesel-hydraulic locomotive.

Class 42_1The Class 42 were conceived and manufactured for the Western Region (WR) of the British Rail. The geography of this areas was interspersed with steep inclines and British Rail wanted to replace the steam locomotives in service with light and powerful diesel locomotives. As diesel-electric were considered to be too heavy, it was decided to go for diesel-hydraulic transmission. A diesel-hydraulic locomotive has one or more diesel engines as the prime mover and the power and torque is transmitted to the driving axle through a torque converter and gearbox, a la an automatic car. These locomotives were lighter because they did not have to carry the extra weight of electric motors to drive the axles. For example, while the Class 44 diesel-electric locomotives weighed 140 tons, the Class 42 weighed only 80 tons.

Class 42_4The Class 42 was based on the design of the German V200 locomotives. However, they were scaled down to meet the requirements of the British gauge. These locomotives were manufactured at Swindon between 1958 and 1961, under license. They were powered by Maybach MD650 Engines coupled with Mekydro hydraulic drives. Technology of the late fifties did not allow hydraulic drives which could handle more than 2000 BHP. As a result, these locomotives were installed with two Maybach engines and two drives. Though the design was German, the engines were manufactured in Britain. Later, locomotives installed with Paxman Ventura engines and Voith hydraulic drives were also introduced. A sister Class 43 was manufactured by the North British Locomotive Company.

Class 42_5A total of 38 locomotives were manufactured. They were configured as B-B, that is two bogies with driving axles. These locomotives ran on the standard gauge, 4′-8-1/2″(1,435 mm). The driving; in fact all wheels; had a diameter of 3′ 3-1/2″ (1,003 mm). They were 60′ (18.29 m) long, 8′ 10″ (2.69 m ) wide and 12′ 1/2″ (3.670 m) tall. The two 64.5 Litre (3,940 cu-inch) V-12 4 stroke Maybach diesel engines produced 2,270 BHP and a maximum tractive effort of 48,200 lb-ft (214 KN). These locomotives could achieve a top speed of 90 mph (145 km/h) due to the limitation of the chassis. During trials they had achieved speeds up to 102 mph (164 km/h). These were versatile locomotives. Though they were introduced mainly for passenger service, they were frequently employed to pull freight trains also.

Class 42_2Though these locomotives met the requirements of light and powerful locomotives, they could not be upgraded or modernised due to lack of space onboard. As a result, air compressors could not be installed and hence once the vacuum assisted braking system was introduced, these locomotives could not pull the new coaches. Similarly, they could not be upgraded for electric heating due to lack of space and continued to use steam heating for coaches. In addition, there was a bias against diesel-hydraulics in the British Rail. All these factors contributed to the early retirement of these locomotives between 1968 and 1972 after serving for between 10 to 14 years.

To hear and feel these locomotives I suggest watching the following video by “Classic Traction”.