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.
The British Rail Class 108 diesel multiple units were built by BR Derby from 1958 to 1961, with a final production quantity of 333 vehicles.
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 114 diesel multiple units were built by BR Derby from September 1956 to July 1957. Forty-nine 2-car units were built, numbered E50001-49 for driving motors and E56001-49 for driving trailers. The units were used in the early days out of 40A Lincoln TMD (LN) on services all over the county, although a small number were transferred to 41A Sheffield (Darnall) during 1959/60.
The British Rail Class 104 diesel multiple units were built by Birmingham Railway Carriage and Wagon Company from 1957 to 1959.
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longest-lived of BR's First Generation DMUs, second in longevity only to the Class 121, with the final five units being withdrawn on 24 December 2003.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 British Rail Class 118 diesel multiple units were built by the Birmingham Railway Carriage & Wagon Company (BRCW) and introduced from 1960. It was a licence-built version of the British Rail Class 116.
The British Rail Class 103 diesel multiple units were built by Park Royal Vehicles with diesel engines by British United Traction (BUT). Ordered in the first half of 1955, 20 of these sets were built by Park Royal at the Crossley Motors works in Stockport of the ACV Group. They consisted of a power car and a driving trailer. Standard BUT equipment was fitted, with 'A' type engines.
The British Rail Class 100 diesel multiple units were built by Gloucester Railway Carriage and Wagon Company Limited from 1956 to 1958, designed and built in collaboration with the Transport Sales Dept. of T.I. Ltd.
The British Rail Class 117 diesel multiple units (DMUs) were built by Pressed Steel from 1959 to 1961. It was a licence-built variant of the British Rail Class 116.
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 107 diesel multiple units were built by the Derby Works of British Railways and were introduced in 1960. The class looked similar to the later Class 108 units, but were heavier - having been built out of steel.
The Class 110 diesel multiple units were built by the Birmingham Railway Carriage and Wagon Company in conjunction with the Drewry Car Co. to operate services on the former Lancashire and Yorkshire main line. They originally entered service uniquely in this region, which earned them the name of the 'Calder Valley' sets. They were an updated version of the Class 104, with more powerful engines, a revised cab design and raised bodyside window frames.
The Class 112 and Class 113 DMUs used the standard Cravens body used on Class 105s but had a single Rolls-Royce C8NFLH engine rated at 238 hp (177 kW) per car, all of which formed into 'power twins' – two car sets with both vehicles powered.
The British Rail Class 115 diesel multiple units were 41 high-density sets which operated the outer-suburban services from Marylebone usually to destinations such as High Wycombe, Aylesbury and Banbury which are on the Chiltern Main Line and Great Central Main Line. Sometimes, these sets used to operate 8- or 12-car-long expresses to Nottingham Victoria in the final years of the GCML. Coincidentally, Class 115 units operated services under Table 115 in the British Rail timetable.
The British Rail Class 210 was a type of diesel-electric multiple unit (DEMU) designed and constructed by British Rail Engineering Limited's Derby Litchurch Lane Works.
The British Rail Class 124 diesel multiple units were built by BR Swindon Works in 1960.
The British Rail Class 123 was a design of diesel multiple unit built for British Rail in 1963. They were the last first generation DMUs built for British Railways and were built at Swindon Works, designed like all Swindon units as inter-city sets. Ten of the four-car sets were built and introduced in 1963. The units bear a visible similarity to the British Rail Class 309; however, there is no 'relation' here as the two types were built by different manufacturers for different markets.
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.
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.
