Development of the Class 151 commenced during 1983 in response to a specification issued by BR calling for a new generation of DMU with which to equip its fleet. Both Metro Cammell and British Rail Engineering Limited (BREL) were selected to produce prototypes of their design submissions. Accordingly, a pair of 3-car units were constructed, which entered trial service with BR during 1985. If it had emerged successful, the Class 151 would have likely become the basis of Sprinter family of DMUs that were produced during the 1980s. However, following a competitive evaluation against the rival Class 150, the type did not secure a production contract, having lost out to its BREL-built rival. Both units were withdrawn during 1989 and, despite multiple vendors planning to restore them for service, they were ultimately scrapped.
Background
By the beginning of the 1980s, British Rail (BR) operated a large fleet of first generation DMUs, which had been constructed in prior decades to various designs.[6] While formulating its long-term strategy for this sector of its operations, British Rail planners recognised that there would be considerable costs incurred by undertaking refurbishment programmes necessary for the continued use of these aging multiple units, particularly due to the necessity of handling and removing hazardous materials such as asbestos. In light of the high costs involved in retention, planners examined the prospects for the development and introduction of a new generation of DMUs to succeed the first generation.[7]
In the concept stage, two separate approaches were devised, one involving a so-called railbus that prioritised the minimisation of both initial (procurement) and ongoing (maintenance & operational) costs, while the second was a more substantial DMU that could deliver superior performance than the existing fleet, particularly when it came to long-distance services.[7] The initial specification developed for the latter type was relatively ambitious for the era, calling for a maximum speed of 90 MPH (145 km/h), a rate of acceleration compatible to contemporary EMUs, the ability to couple/work in multiple with existing EMUs, facilitate through-access for passengers, feature pressure ventilation, the ability to assist another failed unit, and to comprise either a three or four-car consist.[7]
This specification led to the development of the experimental British Rail Class 210diesel-electric multiple unit. However, to deliver the performance specified, it was found that relatively expensive equipment had to be used, particularly to provide sufficient speed, acceleration, and through-passenger access; it also had maintainability problems due to space limitations. Despite these shortcomings, it was recognised that a production fleet that was assembled from proven components would possess both a greater reliability level and lower maintenance costs; it was forecast to achieve an availability rate of 85 per cent.[7] As such, the type had sufficiently demonstrated a promising reduction in maintenance costs was achievable, especially once initial teething problems were dealt with, as well as the wider value represented by a new generation of DMUs in the reduction of ongoing costs for BR.[7]
By 1983, experiences with the Class 210 had influenced planners to favour the procurement of a new generation of DMUs, but to also adopt a new set of specifications that were somewhat less demanding than the prior set.[7] Specifically, it was decided to drop the top speed from 90 MPH to 75 MPH, as testing had revealed the higher rate to deliver no perceivable improvement in journey times due to the typically short spacing of the stations the type was intended to serve. Furthermore, it was determined that a propulsion system delivering 7 hp per tonne would deliver sufficient acceleration.[7] The requests for compatibility with other rolling stock were eliminated, although auto-coupling and auto-connecting functionality was added. In addition to a good ride quality, the specification included a sound level of 90 dB when at full speed, an operational range of 1,000 miles, and an interval between major overhauls of five years or 350,000 miles.[7]
In comparison to the prior generation of DMUs, which typically used a pair of engines for each power car, the new generation DMU would only use a single engine per car; sufficient cooling was also provided that even with one failed engine, a two-car unit could continue to perform typical services without incurring a major performance deficient.[7] For an operational perspective, it was intended that the DMU could be assembled akin to building blocks, comprising between two and four cars that may or may not be outfitted with various passenger amenities such as toilets and luggage spaces.[7]
Initially formalised as a business specification, these requirements were transferred into a relatively broad technical specification that avoided any specifics other than those that were deemed essential for compatibility purposes. Thereafter, it was issued to various rolling stock manufacturers for a competitive tender.[7] As a part of this process, these manufacturers submitted bids to construct an initial series of three-car prototypes as demonstration units. A relatively constrained timetable of only 18 months between the date of order to delivery of these prototypes was also specified; this has been attributed as having restricted manufacturers to overwhelming lean towards existing industrial practices for their submissions.[7]
In response to the specification, several submissions were received by BR. The railway engineering company Metro-Cammell opted to bid its own design to meet the requirement. A rival bid was also submitted by British Rail Engineering Limited (BREL) that was heavily based on its successful Class 455 EMU, sharing its body and the majority of its running gear. BR officials quickly opted to proceed with a pair of prototypes from both BREL and Metro-Cammell, issuing orders to these manufacturers henceforth.[7]
Design
The Class 151 comprised an aluminium-body that was principally rivetted together; this feature was attributed as enabling a meaningful reduction in weight of 3.7 tonnes over conventional construction methods.[7] The type was designed to achieve a maximum speed of 75mph (120km/h), and was capable of attaining a relatively high rate of acceleration, being aided in this latter aspect by their lightweight construction.[2]
Each car was furnished with a single Cummins NT855-R5 turbo-diesel engine that produced 213kW (285hp).[1] Each engine drove a hot-shift Twin Disctransmission, which in turn powered the axles of one bogie on each car via a Cardan shaft and Gmeinder final drive units.[2] Gear changes were controlled by a microprocessor, the software of which being adjustable to change or improve its behaviour and characteristics. Unusually, the torque converter was attached to the engine rather than the gearbox itself.[7] Overall, the transmission system was observed to be particularly unique for the time.[7] During testing, the gearboxes proved to have some issues, with the clutch itself being identified as being the primary source of these issues. While the performance was greatly improved with modifications, particularly the installation of a clutch composed of different materials, the noticeably rough gearshift process was never entirely resolved.[7]
Other uncommon features of the Class 151 include its use of hydraulically-driven alternators and cooling fans. The main cooler group and radiators were fitted in a pod on the roof of each vehicle.[7] The bogies were of a non-standard design; they exhibited a relatively high pitch frequency of 12 Hz, which opposed the BR convention of lower bogie frequencies and higher body frequencies, causing concern amongst BR staff.[7] As a consequence of their non-standard nature, it was difficult to acquire support and spares for the bogies and several other unique features present on the units, a factor which allegedly heavily contributed to their withdrawal in 1989. There were proposals to fit standard Class 150 bogies; however, this refit ultimately proved to be impractical.[citation needed]
Operations
In accordance with BR's order, a pair of 3-car units were constructed and entered trial service with the operator during 1985.[8][9] These trials were not an isolated affair but performed as a competitive evaluation against the rival BREL-built Class 150; this evaluation was particularly important to the future of either type as whichever proved to possess superior qualities would therefore be likely receive a production contract.[7]
During the trial, members of the public praised the Class 151 for its favourable ride quality; although some vibration was experienced on older sections of jointed track.[7] The noise levels of both the Class 151 and its Class 150 rival were determined to be adequate for its intended service sector, but noted to likely pose an issue if directed towards the higher end of the market. Concerns regarding the body bending frequency of the Class 151 did not prove to have major substance to them throughout the trials.[7] One shortcoming that was observed of the type was the frequent occurrence of rough/jerky shifts by the transmission, which often sent violent shocks throughout the train. While some modifications were made to improve the gearbox, the shifting issue were not fully rectified until a modified version of the transmission appeared some years later on the Class 154; however, interest in the Class 151 or the hot-shift gearbox had evaporated by that point.[2]
Ultimately, the production contract was awarded to the rival Class 150, which accordingly went into quantity production throughout the mid-1980s. Both of the Class 151 prototypes continued in revenue service with BR for a number of years before being permanently withdrawn during 1989.[10] For a time, these units were temporarily stored at Llandudno Junction carriage sheds until they were both purchased by Railtest (later Serco Railtest) who had planned to convert them into test units. However, for the same reasons which saw their withdrawal from service, Railtest did not go ahead with any conversions and the units were again stored out in the open in the sidings of the Railway Technical Centre, Derby.[citation needed]
In March 2000, the units were acquired by a company called Endeavour Rail, who planned to refurbish both for spot hire to train operating companies.[11][12] They were transferred to LNWR at Crewe, but again the proposed refurbishment did not happen and the units remained in the open next to the West Coast Main Line where they would remain until scrapped on site in 2004, by which point their condition had rapidly degenerated in part due to vandalism.[13]
Formation
Unit Number
DMSL (68S seats)
MS (84S seats)
DMS (80S seats)
151001 (151003)
55202
55402
55302
151002 (151004)
55203
55403
55303
Related Research Articles
A diesel multiple unit or DMU is a multiple-unit train powered by on-board diesel engines. A DMU requires no separate locomotive, as the engines are incorporated into one or more of the carriages. Diesel-powered single-unit railcars are also generally classed as DMUs. Diesel-powered units may be further classified by their transmission type: diesel–mechanical DMMU, diesel–hydraulic DHMU, or diesel–electric DEMU.
Pacer was the operational name of the British Rail Classes 140, 141, 142, 143 and 144 diesel multiple unit railbuses built between 1980 and 1987. They were inexpensively developed using a passenger body based on the Leyland National bus on top of a chassis based on the HSFV1 research vehicle. The railbuses were intended as a short-term solution to a shortage of rolling stock, with a lifespan of no more than twenty years. As modernised replacements were lacking, the Pacer fleet remained in service on some lines until 2021, 37 years after their 1984 introduction.
British Rail Engineering Limited (BREL) was the rolling stock manufacturing and maintenance subsidiary of British Rail.
The British Rail Class 156 Super Sprinter is a diesel multiple unit passenger train. A total of 114 sets were built between 1987 and 1989 for British Rail by Metro-Cammell's Washwood Heath works. They were built to replace elderly first-generation DMUs and locomotive-hauled passenger trains.
The British Rail Class 158 Express Sprinter is a diesel multiple unit (DMU) passenger train. It is a member of the Sprinter series of regional trains, produced as a replacement for British Rail's first generation of DMUs; of the other members, the Class 159 is almost identical to the Class 158, having been converted from Class 158 to Class 159 in two batches to operate express services from London Waterloo to the West of England.
Regional Railways was one of the three passenger sectors of British Rail created in 1982 that existed until 1997, two years after Privatisation of British Rail. The sector was originally called Provincial.
The British Rail Class 116 diesel multiple units were built by BR Derby from 1957 to 1961. Introduced as part of the British Railways Modernisation Plan in the mid 1950s, as with other first generation DMUs the 116 was intended to replace steam trains and reduce costs across the rail network. Alongside Metro-Cammell, BR Derby had prior experience with DMUs, having developed a Lightweight Unit, and so was awarded a contract for a new design.
British Rail produced a variety of railbuses, both as a means of acquiring new rolling stock cheaply, and to provide economical services on lightly used lines.
The British Rail Classes 101 and 102 diesel-mechanical multiple units were built by Metro-Cammell at Washwood Heath in Birmingham, England, from 1956 to 1959, following construction of a series of prototype units. These classes proved to be some of the most successful and longest-lived of BR's First Generation DMUs, second in longevity only to the Class 121, with the final five units being withdrawn on 24 December 2003. The oldest set was, by then, just over 47 years old.
The Bombardier Turbostar is a family of diesel multiple unit (DMU) passenger trains that was built by ADtranz and later Bombardier Transportation at Derby Litchurch Lane Works in the United Kingdom between 1997 and 2011. The Turbostar was the first new train type to be introduced after the privatisation of British Rail. The first units were ordered by Chiltern Railways in 1996 and were designated Class 168. Since then the family has grown with the addition of the Class 170, Class 171, and the Class 172.
The British Rail Class 150 Sprinter is a class of diesel multiple-unit passenger trains, developed and built by British Rail Engineering Limited at York Carriage Works between 1984 and 1987 for use on regional services across Great Britain. The type is a second-generation design, built to more modern standards and based on BR's Mark 3 body design for longer-distance services. It was developed alongside the lower-cost Pacers, which were built using bus parts, for use on short-distance services. Two prototype units were built, followed by 135 production units in two batches. Subsequently, further members of the Sprinter family were developed and introduced to service, including the Class 155, Class 156, Class 158 and Class 159.
The British Rail Class 144Pacer is a diesel multiple unit (DMU) passenger train built at Derby between 1986 and 1987. British Rail, seeking to procure improved derivatives of the earlier Class 141, placed an order with the manufacturers British Rail Engineering Limited (BREL) and Walter Alexander to construct their own variant, the Class 144. A total of 23 units were constructed. All units have now retired from mainline service, though the majority of the units have been acquired for preservation on heritage railways and in other uses. As of December 2022, 19 out of the 23 units have been purchased following withdrawal for this purpose, of which 14 units are in operational condition.
The British Rail Class 142 Pacer are diesel multiple-unit passenger trains built for British Rail (BR) from 1985 to 1987. They were built with a high level of commonality with the widely used Leyland National bus. They are part of the Pacer family of railbuses. The last set was withdrawn from service in 2020.
The British Rail Class 143 is a diesel multiple-unit railbus, part of the Pacer family of passenger trains introduced between 1985 and 1986.
The British Rail Class 155 is a diesel multiple unit passenger train. These DMUs were built by Leyland Bus at Workington between 1987 and 1988 as part of BR's replacement of its ageing first-generation diesel fleet. 42 units were originally built, of which only 7 remain; the other 35 units were converted to Class 153 railcars.
The British Rail Class 210 was a type of diesel-electric multiple unit (DEMU) passenger train designed and constructed by British Rail Engineering Limited's Derby Litchurch Lane Works.
The British Rail Class 140 was the prototype of the Pacer diesel multiple unit.
The British RailClass 141 is the first production model of the Pacer diesel multiple unit (DMU) railbus.
The Sprinter is a family of diesel multiple unit trains in use on the British railway system. They were built in the 1980s and early-1990s by British Rail Engineering Limited (BREL), Metro-Cammell and Leyland. Sprinters operate in almost every part of Great Britain, from rural branch lines to commuter expresses into major cities.
The Tyne and Wear Metrocars are a fleet of light rail vehicles manufactured by Metro-Cammell for the Tyne and Wear Metro in North East England between 1978 and 1981. For operation on Network Rail controlled tracks between Pelaw Junction and Sunderland, they are designated on TOPS as the Class 599. Most were refurbished between 2010 and 2015 by Wabtec Rail at Doncaster Works and are scheduled to be replaced by Class 555 rolling stock from 2024.
References
1 2 3 4 5 6 7 8 Fox, Peter (1987). British Railways Pocket Book No. 2: Multiple Units (Summer–Autumn 1987ed.). Sheffield: Platform 5 Publishing. p.44. ISBN978-0-906579-74-9.
1 2 3 4 5 "Met Cam's new DMU". Modern Railways. Vol.42, no.440. Ian Allan Publishing. May 1985. Side Elevation of DMS Vehicle. ISSN0026-8356. Archived from the original(JPEG) on 18 March 2016. Retrieved 9 December 2022.
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
