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 multiple-unit train is a self-propelled train composed of one or more carriages joined, which if coupled to another multiple unit can be controlled by a single driver, with multiple-unit train control.
The Southern Railway (SR) gave the designations 4-COR, 4-RES, 4-BUF and 4-GRI to the different types of electric multiple unit built to work the route between London Waterloo and Portsmouth Harbour. The 4-COR type units survived long enough in British Rail ownership to be allocated TOPS Class 404. The COR designation had previously been used for the 6-PUL units and was reused by them during World War II when the Pullman car was stored, but this stock was different from the 4-COR units.
The British Rail Class 170 Turbostar is a British diesel-hydraulic multiple unit passenger train designed and built by Adtranz, and later by Bombardier Transportation, at Derby Litchurch Lane Works.
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.
The British Rail Class 121 is a single-car double-ended diesel multiple unit. 16 driving motor vehicles were built from 1960, numbered 55020–55035. These were supplemented by ten single-ended trailer vehicles, numbered 56280–56289. They have a top speed of 70 mph (113 km/h), with slam-doors, and vacuum brakes. The driving motor vehicles were nicknamed "Bubble Cars" by some enthusiasts.
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 309 "Clacton Express" electric multiple units (EMUs) were built by British Rail (BR) York Carriage Works from 1962 to 1963. They were initially classified as Class AM9 before the introduction of TOPS. These units were the first express 25 kV alternating current (AC) units to be built by British Rail and were their first EMUs capable of 100 mph.
The British Rail Class 150 Sprinter is a class of diesel-hydraulic 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 201 six-car diesel-electric multiple units (DEMUs) were built in 1957–1958 at Eastleigh and underframes were built at Ashford.
The British Rail Class 143 are diesel multiple unit passenger trains, part of the Pacer family of passenger trains introduced between 1985 and 1986.
The British Rail Classes 105 and 106 diesel multiple units were built by Cravens Ltd. of Sheffield from 1956 to 1959. The class were built with a side profile identical to British Railways Mark 1 carriage stock, using the same doors and windows. None were selected for refurbishment. The last passenger car was withdrawn from service in 1988.
The British Rail Class 126 diesel multiple unit was built by BR Swindon Works in 1959/60 to work services from Glasgow to Ayrshire and comprised 22 3-car sets and were a development of the earlier Swindon-built trainsets that had been introduced in 1955 to work the Edinburgh Waverley - Glasgow Queen St services. These vehicles formed the first Inter City service to be operated by diesel units in Great Britain.
The British Rail Class 140 was the prototype of the Pacer diesel multiple unit.
The British Rail Class 120 was a cross-country DMU in three-car formation, built at the British Rail Swindon Works.
The British Rail Class 124 diesel multiple units were built by BR Swindon Works in 1960.
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 British Rail Class 172 is a British diesel multiple unit (DMU) passenger train from the Turbostar family, built by Bombardier Transportation's Derby Litchurch Lane Works for use on inner-suburban passenger services. The class is currently operated by West Midlands Railway.
A slam-door train or slammer is a set of diesel multiple units (DMUs) or electric multiple units (EMUs) that were designed before the introduction of automatic doors on railway carriages in the United Kingdom and other countries, which feature manually operated doors. The name came about because of the characteristic noise made by the passengers slamming the doors closed when the train was about to depart.
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 December 2010, 23 percent of the rail passenger cars used on Network Rail are part of a diesel multiple unit.
