Built by English Electric between 1957-1968, the 1,000 horsepower Bo’Bo’ diesel-electric BR Class 20 (English Electric Type 1) diesel-electric locomotive entered service on many regions around the British Rail network, and boasted unmatched performance and reliability in any task.
In the late forties, prior to nationalisation, the “big 4” railways of Britain experimented with the advantages of implementing diesel traction into their fleets, however, the railways were strapped for cash after the war, and could not implement the new technology in a mainline diesel. After the war, many steam locomotives were in service with the railways, and with many being built prior to the grouping era, and some being from the nineteenth century, modern power was needed. Nationalisation began a new era in railway engineering, as the newly formed British Railways needed to enact cost savings, as steam traction was becoming outdated and too expensive to maintain.
In the height of British Rail’s modernisation efforts, the agency sought for a reliable and powerful type 1 locomotive, developed primarily for freight services. Motivations to implement diesel traction had been prevalent since the days of the “big 4”, however, these motivations were advanced when nationalisation was implemented in 1948, as a few years later, the modernisation plan of 1955 was discussed, with the need to modernise the railways and make them competitive with other types of transportation was prevalent. However, in their efforts, many different classes of diesel locomotives were built called “Pilot Locomotives”, of which were built to test the designs before implementation.
The type 1 prototype, originally named the Type A, was introduced in 1957, and numbered in the D8000 series. The pilot program was unsuccessful, as British Rail decided to mass produce the pilot scheme locomotives, instead of testing them in small batches as was anticipated. Nonetheless, the English Electric type 1 locomotives were produced in an initial order of twenty, along with other type 1 locomotives built by British Thomson Houston, and North British Locomotive Works. In all, fourteen manufacturers were given the opportunity to create the definitive type 1, however, the most successful was the reliable Class 20. The Class 20 was the most successful type 1, as it featured a trusted prime mover, and better cab visibility, as other type 1’s featured offset cabs, meaning there was a bonnet at either end.
The Class 20s were built both at English Electric’s Vulcan Foundry, and Robert Stephenson, and Hawthorns in Darlington. Production was split between two locations, as English Electric was building the Class 40 and 55 during this time frame. The initial order of Class 20’s were numbered D8000-19, and uncommon of British practice, featured just one cab, which was the locomotive’s one major drawback. However, two crew members were present in the cab in daily operations, and the long bonnet of the locomotive was shorter than that of a steam locomotive. However, most crews preferred running the locomotive cab first, as it had uninterrupted views of the track ahead of them. When the locomotive was first introduced, running bonnet first was not an issue due to the crew’s familiarity of steam locomotive operation. Additionally, unions were ever present in the fifties, which prevented the implementation of one person crews. Additionally, the locomotives were built during the implementation of head code boxes, as locomotives built prior to 1960 were manufactured with head code disks, and post 1960, with headcode boxes in the front and rear.
Even though locomotive crews preferred to operate the locomotive cab first, diesel locomotive’s were still easier to operate and maintain than steam engines. To ready a steam locomotive for service, a few hours would be needed, as a diesel locomotive can be started and begin operations almost immediately. Another advantage to the Class 20 was the ability for multiple working, meaning that multiple locomotives could be operated by a single driver, as this would have never been feasible in a steam locomotive. Additionally, the Class 20 was cleaner than steam locomotives, and more efficient.
Because of the crew’s preference to operate the locomotive cab first, they were often seen working in pairs coupled bonnet first. This was convenient for the railway as together they generated 2,000 hp, and could be considered a viable type 4, and in some instances, even more powerful than one type 4 locomotive. This was especially convenient during the Beeching era, as many shorter freights were abolished, and longer freights implemented throughout the system.
The Class 20’s could be seen operating anywhere on the system, and were one of the railways most successful designs. Even today, the Class 20 remains in various mainline duties, as well as being preserved at various heritage railways. Being more than sixty years since the introduction of the type, this stands as a true testament to the reliability and maintainability of English Electric products. Another attribution to the success of the class was its ability for multiple working, as other type 1s from other manufacturers did not include these capabilities, which further hindered its competition in the type 1 class of locomotives.
After British Rail, the locomotives were employed in the construction of the channel tunnel and High Speed One (HS1). Additionally, some units traveled abroad to work for French operators for various purposes. Also, Direct Rail Services (DRS) employed many of the type on their nuclear flask trains. Later, Harry Needle Railroad Company acquired some of the DRS locomotives, and were used to haul new subway trains for the London Underground.
The Class 20 was powered by the reliable English Electric 8 CSVT prime mover, capable of producing up to 1,000 horsepower at 850rpm. The cylinders in the prime mover were allocated in a V-shape, and positioned at a 45 degree angle. These locomotives were nicknamed “chopper” by many rail enthusiasts due to their unique sound. The locomotive was designed quite differently from the others of its time, as it included a single cab and a non-monococque body, which improved its ease of maintenance and availability. The locomotive’s No. 2 end included the cab end, and the No.1 end the bonnet. The locomotive was constructed using a heavy duty steel frame, which contributed to the locomotive’s reliability.
According to Pip Dunn’s book “British Rail Class 20 Locomotives”, he describes the locations of the various mechanisms inside the locomotive. Starting at the bonnet end, the locomotive housed the traction motor blowers and compressors, as well as exhausters and header tank. Next in line was the radiator and fan system responsible for cooling the locomotive, along with the gearbox and popshaft which was connected to the engine. Then, the 8 cylinder 8 CSVT prime mover, which took up most of the space inside the hood, nearby was the EE819-3C main generator, and the EE 911-2B auxiliary generator. Between the generators and the cab was another traction motor blower for the other bogey. The traction motors on the locomotive were axle-hung. Between the bogeys was the 390 gallon fuel tank and batteries.
The class was primarily relegated to freight traffic, as they lacked steam heat generators, although, they included a steam heat pipe passing through the locomotive in its entirety, enabling the class to work with other classes that did include steam heating. However, even without this feature, the locomotives saw passenger traffic during the busy summer months, when heat was not required.
|Wheel Diameter||3 ft 7in|
|Wheelbase||32 ft 6 in|
|Length||46 ft 9 ¼ in|
|Width||8 ft 9 in|
|Height||12 ft 7 5/8 in|
|Fuel Capacity||380 imp gals|
|Prime Mover||English Electric 8 SVT|
|Traction Motors||D8000-8049: EE 526/5D|
|Cylinder Size||10 in|
|Max Speed||75 mph|
|Tractive Effort||Max: 42,000lbf|
|Brakeforce||35 long tons|
|20/0||As built from the factory|
|20/3 (modified by BR)||Modified 20/0 for use moving heavy aggregate trains.|
|20/3 (modified by Direct Rail Services)||Included a complete refurbishment, with the addition of various electrical equipment, and other modern technology.|
|20/9||Modified for remote control operations.|
In addition to the locomotives in mainline service, there are many examples on various heritage railways throughout the country, including the National Railway Museum in York, that houses the original D8000 class leader.
Owned by Class 20 Locomotive Society
|20007||Great Central Railway (Nottingham)|
|20020||Bo’ness and Kinneil Railway|
|20031||Keighly & Worth Valley Railway|
|20035||Gloucestershire Warwickshire Railway|
|20050 (D8000)||National Railway Museum|
|20057||Churnet Valley Railway|
|20059||Chinnor and Princes Risborough Railway|
|20098||Great Central Railway|
|20137||Gloucestershire Warwickshire Railway|
|20154||Great Central Railway (Nottingham)|
|20188||Chinnor and Princes Risborough Railway|
|20214||Lakeside and Haverthwaite Railway|
|20227||North Norfolk Railway|
|20228||Vale of Glamorgan Railway|