British Rail Derby Lightweight
|British Rail Derby Lightweight|
|Manufacturer||BR's Derby Works|
|Number built||219 vehicles|
|Formation||1, 2 & 4 Car Formations|
|Maximum speed||62 mph (100 km/h)|
|Weight||27 tonnes (26.6 long tons; 29.8 short tons) power car|
|Prime mover(s)||Two BUT|
|Power output||(AEC) 125 bhp (93 kW) except BUT (AEC) 150 bhp (110 kW) for single units|
|Multiple working||■ Yellow Diamond|
|Track gauge||1,435 mm (4 ft 8 1⁄2 in) standard gauge|
The British Rail Derby Lightweight diesel multiple units, were the first such trains to be built en-masse for British Railways. The units were built at BR's Derby Works from 1954 to 1955. The units were built in various formations, including 12 power-twin 2-car units, 84 power-trailer 2-car units, and four 4-car units. The two single car units were originally built as a two-car unit and then split two years later when demand came about. Contemporaneous with these units was the unique Battery Electric Multiple Unit.
The first units were introduced on services around the West Riding of Yorkshire, namely Leeds to Bradford services. Subsequent units were introduced onto services in Cumbria, Lincolnshire, Norfolk, and Birmingham to Sutton Coldfield, Bletchley to Buckingham and Banbury, and East London lines services. They were also the last units to run on the Anglesey Central Railway which closed to public traffic in 1964.
These units were an outstanding success, helping to reduce the operating costs of branchlines. As such, British Railways ordered many more DMU vehicles from various builders over the next decade, thus helping to eliminate steam locomotives. However, as these units were non-standard compared to other later DMU vehicles, they were subject to early retirement. The last units were withdrawn from normal traffic in 1969.
Four different sorts of formation were created from the 217 cars built of this type, as follows:
|DMBS + DMCL||DMBS + DMCL|
|79000 + 79500||to||79007 + 79507|
|79184 + 79188||to||79189 + 79193|
|DMBS + DTCL||DMBS + DTCL|
|79008 + 79600||to||79033 + 79625|
|79034 + 79250||to||79046 + 79262|
|79118 + 79639||to||79141 + 79662|
|79142 + 79684|
|79143 + 79663||to||79149 + 79669|
|79169 + 79670||to||79181 + 79682|
Four Car Units
Single Car Units
|79900 and 79901|
79683 was left over as a spare DTCL, and took the place of 79649 in 1957, when this was converted into a special saloon. It was later renumbered 999510 in the departmental saloon series and was eventually scrapped in 1981.
In 1962 three of the power twin units were converted to power trailer units, when 79191-79193 were rebuilt as DTCL vehicles and renumbered 79633-79635.
- Engine: Two BUT (Leyland) 125 bhp
- Transmission: Hydraulic, Lysholm-Smith (Leyland) torque converter
- Coupling code: Red triangle
- Engine: Two BUT (AEC) 150 bhp
- Transmission: Mechanical
- Coupling code: Yellow diamond
A number of cars from these units were subsequently transferred to departmental (non-revenue earning) use after withdrawal from normal service:
- 79018 + 79612 were rebuilt as an ultrasonic test train based at Reading, numbered 975007 + 975008. Replaced by unit 901001.
- 79900 was rebuilt as test coach "Iris", based at Bletchley, numbered 975010. Later transferred to the BR Research Division at the Railway Technical Centre at Derby, for its last few years in traffic, it was repainted into original BR Green livery. Replaced by unit 901002.
- 79185 was taken into departmental use for brake trials, numbered 975012. It was scrapped in 1970.
- 79250 and 79252 were taken into departmental use as staff messrooms, numbered 975013 and 975014. They were scrapped in 1978 and 1982 respectively.
- 79649, the inspection saloon mentioned above, took its place in the departmental series as 999510.
Thanks to their extended life in departmental service, one 2-car unit and a single car unit survive in preservation, the former following a high-profile campaign.
|Vehicle Nos.||Location||Comments||In Service||Departmental Nos.|
|79018||79612||Ecclesbourne Valley Railway||Used as ultrasonic test train.||Part Restored/Not In Service||975007||975008|
|79900||-||Ecclesbourne Valley Railway||Used as test coach "Iris".||Regularly in Passenger Service||975010||-|
|79998||79999||Royal Deeside Railway||fitted with test equipment||operational|
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