British Rail Class 120

The Class 120 was a cross-country DMU in three-car formation, built at the British Rail Swindon Works.

British Rail Class 120
Swindon 3-car Cross-country sets
In service1958–1989
ManufacturerBritish Railways
Order no.
  • 30334 (50647-50695)
  • 30335 (50696-50744)
  • 30336 (59255-59301)
  • 30515 (51573-51581)
  • 30516 (51582-51590)
  • 30517 (59579-59588)
  • 30559 (51781-51787)
  • 30560 (51788-51794)
  • 30561 (59679-59685)[1]
Built atBR Swindon Works
Family nameFirst generation
ReplacedSteam locomotives and carriages
Constructed1957–1960[2]
Number built194 cars
Number preserved1 car (a TSLRB)
Number scrapped193 cars
Formation3 car sets: DMSL-TSL[RB]-DMBC
Diagram
  • DP204 or BR586
  • DP205 or BR637
  • DQ101 or BR587
  • DQ303 or BR587
  • DQ304 or BR636
  • DT210 or BR572
  • DT217 or BR561[1][3]
Fleet numbers
  • 51573-51581, 51781-51787, 53696-53744 (DMBC)
  • 59255-59301, 59579-59588, 59679-59685 (TSLRB)
  • 50647-50695, 51582-51590, 51788-51794 (DMSL)[1][2]
Capacity
  • DMC: 18 first class and 16 second class seats
  • DMSL: 68 second class seats
  • TSLRB: 60 second class seats
  • TSL: 68 second class seats
Operator(s)British Rail
Depot(s)
Specifications
Car body constructionSteel[3]
Car length
  • 64 ft 7 7⁄16 in (19.70 m) (DP205, DQ304, over body)
  • 64 ft 6 1⁄8 in (19.66 m) (others, over body)[3]
Width9 ft 3 in (2.82 m) (overall)[3]
Height12 ft 9 1⁄2 in (3.90 m) (overall)[3]
DoorsSlam[2]
Wheelbase
  • 46 ft 6 in (14.17 m) (bogie centres)
  • 8 ft 6 in (2.59 m) (bogies)[3]
Maximum speed70 mph (113 km/h)[2]
Weight
  • Dia 586: 36.50 long tons (37.09 t; 40.88 short tons)
  • Dia 587: 36.35 long tons (36.93 t; 40.71 short tons)
  • Dia 561: 30.60 long tons (31.09 t; 34.27 short tons)
  • Dia 636: 36.95 long tons (37.54 t; 41.38 short tons)
  • Dia 637: 37.05 long tons (37.64 t; 41.50 short tons)
  • Dia 572: 30.15 long tons (30.63 t; 33.77 short tons)
Prime mover(s)Two BUT (AEC) of 150 hp (110 kW) per power car
Power output600 hp (447 kW) per 3-car set
TransmissionStandard mechanical
Train heatingOil burning air heater[3]
Bogies
  • DD1 mk1 and mk2 (one of each)
  • DD2 mk1 and mk2 (one of each)
  • DT3 mk1 and mk2 (one of each)[3]
Braking system(s)Vacuum[3]
Safety system(s)AWS[3]
Coupling systemScrew[3]
Multiple working■ Blue Square
Track gauge4 ft 8 1⁄2 in (1,435 mm)

History

Totalling 194 cars, three batches were built:

  • 1958 - 49 sets for the Western Region
  • 1959 - 7 sets for the Scottish Region
  • 1961 - a further 9 sets for the Western Region

British Railways placed the order with British United Traction in summer 1956 for the equipment required for the 98 power cars and 47 trailers of the first batch. The order, along with equipment ordered by Cravens for 66 power cars and the 3 parcels cars, was valued at £830,000. The first batch was ordered for the WR's West Country dieselisation scheme, which it hoped to complete by the end of 1959. The sets were expected to work between Bristol & South Devon. Their general reliability and good braking characteristics made them popular with drivers.

1970 at Inverness

In February 1959, the BTC placed an order with BUT for the equipment for the seven ScR sets, along with equipment for Class 108s and 127s being built at Derby. These 120s were to work mainly on the Aberdeen to Inverness line although appearances at Oban were not unknown. Otherwise the cars worked mainly in the Western and Midland Regions.

Some cars had a trial refurbishment but this was found to be too expensive, meaning an early withdrawal for most of the class. Some of the London Midland Region's units were transferred to Scotland in the mid-1980s, mainly finding use on local services from Edinburgh (notably to North Berwick). The final vehicles survived until 1989.

Preservation

One trailer car survives at the Great Central Railway: 59276 (TSLRB).

Fleet details
Lot No.TypeDiagramQtyFleet numbersNotes
30334Driving Motor Second with lavatory (DMSL)5864950647–50695
30335Driving Motor Brake Composite (DMBC)5874950696–50744
30336Trailer Second Buffet (TSLRB)5614759255–59301
30515Driving Motor Brake Composite (DMBC)636951573–51581
30516Driving Motor Second with lavatory (DMSL)637951582–51590
30517Trailer Second with lavatory (TSL)5721059579–59588
30559Driving Motor Brake Composite (DMBC)587751781–51787
30560Driving Motor Second with lavatory (DMSL)586751788–51794
30561Trailer Second Buffet (TSLRB)561759679–59685

Accidents and incidents
  • On 12 May 1978, the unit containing 51793-59684-51794, struck a lorry at Oyne and the front two cars were derailed. The unit was on the 07:43 Aberdeen to Inverness. Out of the 54 passengers on board, only 5 people suffered minor injuries.[5]

Other technical details

References
  1. "Class 120 Swindon 3-car DMUs: Numbering". Railcar.co.uk. Retrieved 24 February 2016.
  2. "Class 120, 179". The Railway Centre. Archived from the original on 9 March 2005. Retrieved 24 February 2016.
  3. Vehicle Diagram Book No. 220 for Diesel Multiple Unit Trains (Railcars) (PDF). Barrowmore MRG. Derby: British Railways Board. 1982. DP204, DP205, DQ101, DQ303, DQ304, DT210, DT217.
  4. Fox 1987, pp. 10–11, 26, 33
  5. Rail Express, May 2018, Page 33.

Sources
  • Fox, Peter (1987). Multiple Unit Pocket Book. British Railways Pocket Book No.2 (Summer/Autumn 1987 ed.). Platform 5 Publishing Ltd. ISBN 0906579740. OCLC 613347580.
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