British Rail Derby Lightweight


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.
Body framing was extruded and riveted together. Panelling was welded into continuous sheets and riveted to the frame. Luggage racks were light alloy. The floors had 2 layers of flameproof hardboard, covered with linoleum. To reduce noise and condensation, the inside structure and undersides were sprayed with asbestos. Lighting was by 60-watt, 24-volt lamps charged by belt driven dynamos. Heating was oil fired. Standard mild steel bogies ran on Timken roller bearings.
Contemporaneous with these units was the unique Battery Electric Multiple Unit.

Operations

The first units were introduced on services around the West Riding of Yorkshire, namely Leeds to Bradford and Harrogate services from 14 June 1954. Subsequent units were introduced onto services in West Cumbria, Lincolnshire, Norfolk, Newcastle to Middlesbrough, Edinburgh to Glasgow and, later, 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. Initially they also attracted many more passengers. Between February and October 1956 on the London Midland, they carried 800,000 more passengers than steam in the same period of 1955. The largest increase was 434% on the Buckingham-Banbury line, followed by Birmingham-Lichfield 178%, Bury-Bacup 152%, Llandudno-Blaenau Ffestiniog 39% and Manchester-Buxton 38%. 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 The last units were withdrawn from normal traffic in 1969.
Lot No.TypeDiagramQtyFleet numbersNotes
30084Driving Motor Brake Second 5018E79000–79007ER Power Twin sets
30085Driving Motor Composite with lavatory 5078E79500–79507ER Power Twin sets
30123Driving Motor Brake Second 50313M79008–79020LMR Power-Trailer sets
30124Driving Trailer Composite with lavatory 50913M79600–79612LMR Power-Trailer sets
30126Driving Motor Brake Second 50413M79021–79033LMR Power-Trailer sets
30127Driving Trailer Composite with lavatory 50513M79613–79625LMR Power-Trailer sets
30177Driving Motor Brake Second 50413M79034–79046LMR Power-Trailer sets
30178Driving Trailer Composite with lavatory 50513M79250–79262LMR Power-Trailer sets
30192Driving Motor Composite 5025E79508–79512ER 4-car sets
30193Driving Motor Second 5085E79150–79154ER 4-car sets
30194Trailer Brake Second with lavatory 5175E79325–79329ER 4-car sets
30195Trailer Second with lavatory 5185E79400–79404ER 4-car sets
30201Driving Motor Brake Second 6337M79143–79149LMR Power-Trailer sets
30202Driving Trailer Composite with lavatory 6427M79663–79669LMR Power-Trailer sets
30235Driving Motor Brake Second 6339M79118–79126LMR Power-Trailer sets
30236Driving Trailer Composite with lavatory 5099M79639–79674LMR Power-Trailer sets
30240Driving Motor Brake Second 63310M79127–79136LMR Power-Trailer sets
30241Driving Trailer Composite with lavatory 50910M79648–79657LMR Power-Trailer sets
30240Driving Motor Brake Second 5274E79137–79140ER Power-Trailer sets
30241Driving Trailer Composite with lavatory 6314E79658–79661ER Power-Trailer sets
30246Driving Motor Brake Second 6332M79141–79142LMR Power-Trailer sets
30247Driving Trailer Composite with lavatory 6421M79662LMR Power-Trailer sets
30321Driving Motor Brake Second 63313M79169–79181LMR Power-Trailer sets
30322Driving Trailer Composite with lavatory 51115M79670–79684LMR Power-Trailer sets
30324Driving Motor Brake Second 6335M79184–79188LMR Power Twin sets
30325Driving Motor Composite with lavatory 5095M79189–79193LMR Power Twin sets
30380Driving Motor Brake Second 5141M79900Single car unit; 61 seats
30387Driving Motor Brake Second 5151M79901Single car unit; 52 seats

Formations

Four different sorts of formation were created from the 217 cars built of this type, as follows:

Power Twins

Power Trailers

Four Car Units

Single Car Units

79683 was left over as a spare DTCL, and took the place of 79649 in 1957, when this was converted into a special saloon on diagram 565. 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.

Powertrain

Power Twins 79000+79500 to 79007+79507

A number of cars from these units were subsequently transferred to departmental use after withdrawal from normal service:
Thanks to their extended life in departmental service, one 2-car unit and a single car unit survive in preservation on the Ecclesbourne Valley Railway, the former following a high-profile campaign.