Diesel multiple units and railcars are trains, usually with passenger accommodation, that do not require a locomotive. Railcars can be single cars, while in multiple units cars are marshalled together with a driving position either end. As of December2010[update], 23 percent of the rail passenger cars used on Network Rail are part of a diesel multiple unit.
Some prototype steam-powered railcars appeared in the mid-19th century, and at the start of the 20th century over 100 were built. Diesel motors became powerful enough for railway use after World War I, and the Great Western Railway built several single cars and multiple units in the 1930s, which lasted until the 1960s. A 1952 report recommended the trialling of lightweight diesel multiple units, followed by plans in the 1955 Modernisation Plan for up to 4,600 diesel railcars. Most of these had a mechanical transmission, but the Southern Region had experience of DC electric multiple units, and diesel electric multiple units were introduced.
In 1960 the Blue Pullman service was introduced using high-speed trainset consisting of coaches sandwiched between two power cars. This arrangement was later used for the InterCity 125 permitting a top speed of 125 miles per hour (201km/h). Initially this train was considered to be a diesel electric multiple unit, but for operational reasons the classification was changed and the power cars became identified as Class 43 locomotives.
Steam railcar Enfield built by William Adams for the Eastern Counties Railway in 1849. Note the raised buffers for use with other rolling stock.
From 1847–1849 William Bridges Adams built a number of steam railcars, vehicles with a steam engine for propulsion and passenger accommodation. These were the Express or Lilliputian, Fairfield and Enfield. Kitson and Company of Leeds built Ariel's Girdle in 1851. However, the next railcars were built in 1902 for the London & South Western Railway for the line from Fratton to East Southsea, although before entering passenger service it was lent to the Great Western Railway (GWR). By 1908 the GWR had purchased or built 99 railcars (or railmotors as they called them), but from 1917 began converting them into autocoaches for use on push-pull trains with a steam locomotive,[1] as these were more reliable and were able to haul additional carriages or goods wagons.[2] Between 1905 and 1911 the Lancashire and Yorkshire Railway (L&YR) purchased or built seventeen steam rail cars, some running into the 1940s.[3]
After trials in 1924, the London & North Western Railway bought three types of steam railcars from Sentinel-Cammell and Claytons.[4]As of 2012[update] a reconstructed GWR 1908 steam railmotor is operational, based at Didcot Railway Centre and an GWR autotrailer is being restored.[5][6]
One of the earlier, more-streamlined GWR diesel railcars, still in British Railways service in May 1956
An early petrol railcar was the 1903 Petrol Electric Autocar built by the North Eastern Railway. In 1914 the London and North Western Railway commissioned a 90hp (67kW) petrol-electric railcar, although this was converted into a driving trailer in 1924. After World War I more powerful diesel engines were available and in 1928 the London Midland & Scottish Railway (LMS) commissioned a four-car diesel-electric multiple unit using a 500hp (370kW)Beardmore engine, similar to that used on the airship R101, placed in a power car that had been used on the Lancashire and Yorkshire Railway's electrified line from Bury to Holcombe Brook.[7] In the early 1930s Armstrong Whitworth built three railcars for the LMS, LNER and Southern Railway. These had a 250hp (190kW) Sulzer engine driving two GEC traction motors and could seat 60 passengers, able to pull trailers or run in multiple.[8]English Electric built a prototype railcar called Bluebird with a 200hp (150kW) engine.[9] In 1938 the LMS built a 3-car articulated multiple unit at Derby, with two 125hp (93kW) motors driving the axles using a torque converter, controlled using an electro-pneumatic system. Seating 162 including 24 first-class it ran in service between Oxford and Cambridge, but was withdrawn in 1940 due to World War II.[10]
Between 1933 and 1942 the GWR received 38 diesel power cars. The first stream-lined car used one AEC120hp (89kW) engine, seating 69 passengers. This was followed by three cars with two engines for a cross country service between Birmingham and Cardiff,[11] then suburban passenger cars and a parcels car. No 18 was designed to pull horse boxes and with electro-pneumatic multiple unit control, followed by twenty more to a similar design. The last four were built with only one driving compartment so as to operate in pairs with a trailer between them.[12]As of 2012[update] a GWR diesel railcar is preserved in running order at the Didcot Railway Centre,[13] one is a static exhibit at the Museum of the Great Western Railway[14] and one is being restored at the Kent and East Sussex Railway.[15]
First generation DMUs
The railways were placed under Government control two days before war was declared on 3 September 1939.[16] After the war, the railways were in a poor financial state, with a maintenance backlog.[17] Government control was relinquished when the Transport Act 1947nationalised most of the railways in the United Kingdom and control passed to the Railway Executive of the British Transport Commission,[18] who inherited 37 diesel railcars.[19] A 1952 report recommended lightweight diesel multiple unit trials, and a memo to the Board suggested diesel railcars could replace push-pull steam trains on 168 routes. After fuel rationing ended, the first order was placed in November 1952 for 21 x 2-car sets built at Derby Works, which became known as Derby lightweights.[20] More were to follow until this class numbered 66 motor cars and 55 trailers.[21] In 1952, British United Traction made numerous 4-wheeled single car railbuses.[22]
A Diesel Multiple Unit in 1983
As part of the 1955 Modernisation Plan of British Railways, plans were made for up to 4,600 diesel railcars.[21] The British Railway workshops at Derby and Swindon did not have the necessary capacity, so private carriage builders such as Metropolitan-Cammell, Gloucester, Birmingham and Cravens received orders.[23] Not all units could work in multiple with each other, but the blue square coupling code covered 84 percent of the cars built, using a four-speed gearbox with gear selection controlled pneumatically.[24] Engines could vary in power output from 150 to 230hp (110 to 170kW) and vacuum brakes were used.[25] Internally the units could be classified as suburban with doors for each seating bay and 3+2 seating in second class, such as Class 118, low density with two doors per vehicle side, 3+2 bus style seating in second class, such as Class 114 and Intercity with interiors to the same standard as locomotive hauled stock, such as Class 124.[26]
In 1963, Richard Beeching's The Reshaping of British Railways report recommending the closure of 5,000 miles (8,000km) of mostly rural branch railways,[27] led to the Beeching cuts and halted the manufacture of new vehicles.[28]
As of 2012[update], about 250 vehicles survive in preservation,[29] and various vehicles (mainly 101s and 121/122s) survive in departmental use.
Diesel electric multiple units
Diesel electric multiple units were introduced on the Southern Region, where there was experience of DC electric multiple units. The Hastings line had special restrictions due to tunnels on the line and special narrow stock was needed. The six car sets had two power cars, each having 500 horsepower (370kW) diesel generator driving two standard Southern Region 250 horsepower (190kW) traction motors.[30] Introduction had been planned for June 1957, but special services were run early following a fire at Cannon Street in London. When the full timetable started 12-car trains divided en route into non-stop and stopping portions.[31] Elsewhere the standard loading gauge could be used and the trailer vehicles were similar to contemporary Southern Region electric multiple units.[32] Two car sets were built for local services on unelectrified lines in Hampshire, followed by three car sets, for which the generator was uprated to 600 horsepower (450kW).[31]
The Blue Pullman was a class of high-speed luxury diesel-electric multiple units introduced in 1960. Six coach sets were used on the London Midland Region, all first class with at seat service served from two kitchen cars. The two power cars had diesel engines connected to a 870hp (650kW) generators, both supplying four 199hp (148kW) traction motors. The Western Region units had two additional second class coaches. All cars were double glazed and air-conditioned, the first on British Railways.[33]
There was a desire in British Railways for faster trains, but none of the main-line diesel locomotives could achieve anything faster than 100mph (160km/h). It had been calculated that 4,000hp (3,000kW) was needed, and after the Paxman Valenta engine with an output of 2,250hp (1,680kW) became available, a prototype train with two Class 41 power cars and standard Mark 3 coaches was built.[34] In 1973 this prototype achieved 143mph (230km/h), and production InterCity 125 trains entered service in October 1976, becoming the first 125mph (201km/h) diesel train service in the world. Initially the rolling stock was considered to be diesel-electric multiple units, with coaches sandwiched between two power cars.[35]
Two prototype Class 210 DMUs were introduced in 1981, based on the Mark 3 coach bodyshell with a diesel engine mounted at the end of one of the driving cars. It was not a success due to complexity and cost.[36]
Second Generation DMUs
The Pacer series grew out of a single car prototype developed for export that used a body designed by Leyland Motors with bus components mounted on a 4-wheeled high-speed freight underframe.[37] Two car production units were introduced into Britain from 1981[38] to 1987.[39]
The Networker Turbo was built for Network SouthEast in the early 1990s. The Class 165 is a two or three coach unit used on local services on Chiltern and Thames routes out of London and was followed by the 90mph (140km/h)Class 166 for long distance services.[43][44]
Privatisation
This section needs to be updated. Please help update this article to reflect recent events or newly available information.(May 2023)
Train manufacturer British Rail Engineering Limited was privatised in 1989,[45] and between 1994 and 1997 the rest of British Rail was privatised.[46] Ownership of the track and infrastructure passed to Railtrack on 1 April 1994; afterwards passenger operations were franchised to individual private-sector operators and the freight services sold outright.[47] Rolling stock is owned by ROSCOs and leased to the train operators; competitive tenders are invited from manufacturers for new trains. During the privatisation process, there was a gap of nearly three years during which no new rolling stock orders were placed. The first new order placed was in June 1996 for four Class 168 Clubman DMUs for Chiltern Railways. These were a development of the Networker Turbo design already in use by Chiltern and other operators.[48]
Bi-mode Class 769s are being converted from Class 319s for Great Western Railway, Northern and Transport for Wales Rail.[55] Diesel-electric and diesel-battery-electric Class 230s are being converted from London Underground D78 Stock for Transport for Wales Rail and West Midlands Trains.[56]
Refuelling
Train manufacturer in the UK and other rail reliant countries that use DMU rail cars must be refuelled at depot stops with diesel. The refuelling process is usually carried out by a qualified operator with knowledge of rail refuelling. The train driver would usually level the train up to the platform to meet the refuelling pipes assigned at measured distances according to the length of the DMU and the refill nozzles. A Rail Refuelling Flyte Coupler[57] is used to connect the DMU to the fuel line. It is a screw in connection with a safety dry break mechanism to stop accidental leaks. The flow of fuel needs to high volume but low pressure to ensure the fuel does not overfill. Usually there is a float arm similar to a toilet cistern that cuts off the refuelling once a predefined level is reached, however if the pressure is too high, this can cause the train tank to overfill and leak fuel.
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.
A railcar is a self-propelled railway vehicle designed to transport passengers. The term "railcar" is usually used in reference to a train consisting of a single coach, with a driver's cab at one or both ends. Some railway companies, such as the Great Western, termed such vehicles "railmotors".
A diesel locomotive is a type of railway locomotive in which the power source is a diesel engine. Several types of diesel locomotives have been developed, differing mainly in the means by which mechanical power is conveyed to the driving wheels. The most common are diesel–electric locomotives and diesel–hydraulic.
A railbus is a lightweight passenger railcar with an automotive engine. It shares many aspects of its construction with a bus, typically having a bus body and four wheels on a fixed base instead of on bogies. Originally designed and developed during the 1930s, railbuses have evolved into larger dimensions with characteristics similar in appearance to a light railcar, with the terms railcar and railbus often used interchangeably. Railbuses designed for use specifically on little-used railway lines were commonly employed in countries such as Germany, Italy, France, the United Kingdom, and Sweden.
The Birmingham Railway Carriage and Wagon Company (BRC&W) was a railway locomotive and carriage builder, founded in Birmingham, England and, for most of its existence, located at nearby Smethwick, with the factory divided by the boundary between the two places. The company was established in 1854.
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.
The British Rail Class 127 diesel multiple units were built by BR Derby in 1959. Thirty 4-car units were built, formed of two outer driving motor vehicles, sandwiching two intermediate trailers which were classified class 186. The technical description of such as 4-car unit was DMBS + TSL + TS + DMBS.
In 1933, the Great Western Railway introduced the first of what was to become a successful series of diesel railcars, which survived in regular use into the 1960s, when they were replaced with the new British Rail "first generation" type diesel multiple units.
The British Rail Class 143 are diesel multiple unit passenger trains, part of the Pacer family of passenger trains introduced between 1985 and 1986.
Push–pull is a configuration for locomotive-hauled trains, allowing them to be driven from either end of the train, whether having a locomotive at each end or not.
The different railway companies in Germany have used various schemes to classify their rolling stock.
The Stadler GTW is an articulated railcar for local transport made by Stadler Rail of Switzerland. GTW stands for Gelenktriebwagen.
The British Rail Class 124 diesel multiple units were built by BR Swindon Works in 1960.
The British Rail Class 128 was a class of diesel multiple unit, built for British Rail. Introduced in 1959, ten of the class were built by Gloucester Railway Carriage and Wagon Company, each with two 230 hp British United Traction - Albion engines. The class was built specifically for parcels, fitted out with parcel racks and bike storage at each end, and did not feature any passenger accommodation. The last members of the class were withdrawn in 1990 and broken up the following year, and none were preserved.
The British Rail Class 125 was a design of three car Diesel Multiple Unit built by BR Derby at Derby Works in 1958. They were almost identical in appearance to the Class 116.
A hybrid train is a locomotive, railcar or train that uses an onboard rechargeable energy storage system (RESS), placed between the power source and the traction transmission system connected to the wheels. Since most diesel locomotives are diesel-electric, they have all the components of a series hybrid transmission except the storage battery, making this a relatively simple prospect.
Exeter Traction Maintenance Depot is a railway Traction Maintenance Depot situated in Exeter, Devon, United Kingdom and is next to the city's main St Davids station. The depot is operated by Great Western Railway and has an allocation of diesel multiple units.
The Rolls-RoyceC range was a series of in-line 4, 6 and 8 cylinder diesel engines used in small locomotives, railcars, construction vehicles, and marine and similar applications. They were manufactured by the Rolls-Royce Oil Engine Division headed by William Arthur Robotham to 1963, initially at Derby and later at Shrewsbury, from the 1950s through to 1970s.
A steam railcar is a rail vehicle that does not require a locomotive as it contains its own steam engine. The first steam railcar was an experimental unit designed and built in 1847 by James Samuel and William Bridges Adams. In 1848, they made the Fairfield steam carriage that they sold to the Bristol and Exeter Railway, who used it for two years on a branch line.
The British Rail Class 769 Flex is a class of bi-mode multiple unit (BMU) converted by Brush Traction, and running in service with Northern Trains. The train is a conversion of the existing Class 319 electric multiple unit (EMU), a conventional unit type which had become surplus to requirements during the 2010s.
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Bosley, Peter (1990). Light Railways in England and Wales. Manchester University Press. ISBN978-0719017582. Online preview available at books.google.co.uk. Retrieved 20 September 2012.
Jenkinson, David (1996). History of British Railway Carriages, 1900–53. Atlantic Transport. ISBN978-1899816033.
Marsden, Colin (2010). HST: The Second Millennium. Ian Allan. ISBN978-0711033894.
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