British Rail Class 84

The British Rail Class 84 was a 25 kV AC electric locomotive that operated on the West Coast Main Line of the London Midland Region.

British Railways AL4
British Rail Class 84
Preserved locomotive 84001 on display at Crewe Works open day on 11 September 2005
Type and origin
Power typeElectric
BuilderNorth British Locomotive Company
Order numberL91[1]
Build date1960–1961
Total produced10
Specifications
Configuration:
​
 • AARB-B
 • UICBo'Bo'
 • CommonwealthBo-Bo
Gauge4 ft 8 1⁄2 in (1,435 mm) standard gauge
Wheel diameter4 ft 0 in (1.219 m)[2]
Wheelbase39 ft 6 in (12.04 m)[2]
Length:
​
 • Over beams53 ft 6 1⁄2 in (16.32 m)[2]
Width8 ft 8 1⁄4 in (2.648 m)[2]
Height:
​
 • Pantograph13 ft 0 9⁄16 in (3.977 m)[2]
 • Body height12 ft 4 1⁄4 in (3.766 m)[2]
Loco weight76.60 long tons (77.83 t; 85.79 short tons)
Electric system/s25 kV AC Catenary
Current pickup(s)Pantograph
Traction motors4 × GEC WT501[3]
Gear ratio25:74[3]
Train heatingElectric Train Heating
Train brakesVacuum; Dual from 1972[1]
Performance figures
Maximum speed100 mph (160 km/h)
Power output:
​
 • 1 hour4 × 890 hp (660 kW)[3]
 • Continuous4 × 750 hp (560 kW)[3]
Tractive effort50,000 lbf (220 kN)
Brakeforce65.5 long tons-force (653 kN)
Career
OperatorsBritish Rail
NumbersE3036–E3045; later 84001–84010
Axle load classRoute availability 6
Retired1979–1980
DispositionOne preserved, remainder scrapped

History

As part of the modernisation of the West Coast Main Line, which included electrification, 100 locomotives of five types were acquired from different manufacturers. Ten Class AL4 locomotives numbered E3036 - E3045 were built in 1960 to a design by GEC by the North British Locomotive Company in Springburn, Glasgow.[4]

Locomotive E3040 worked the inaugural AC electric-hauled train from Manchester Piccadilly to Crewe on 12 September 1960.[2]

Power supply

The locomotives always worked on power provided by overhead catenary energised at 25,000 V AC. However, the main transformer, normally operated with the four windings in series, could be operated at 6250V AC with the transformer windings in parallel. This voltage was initially to be used where limited clearances gave concern over use of the higher voltage. Since the clearances were found to be adequate, the lower voltage connections were locked out of use.[5]

Rebuild

Problems with the mercury-arc rectifiers plagued this class and in 1962 E3036 was returned to GEC, the builder of the electrical equipment, in an attempt to find a solution.

Within a year, all ten were out of service for repair. The problems persisted and in 1967 they were once more placed into storage, using the former steam shed at Bury,[6] along with Class AL3.[7] During this time E3043 went to Rugby Testing Centre for trials.[8]

Reprieve

The persistent problems could have been the end of the ten locomotives of Class 84, but the extension of the West Coast Main Line electrification to Glasgow meant that more electric locomotives would be needed. It was therefore decided that the stored Class AL3 and AL4 locomotives would be repaired, which was conducted at Doncaster,[8] and returned to service, with a lower number of Class 87 being built.

Rebuild 2 and renumbering

Between 1971 and 1972, all ten locomotives were rebuilt with silicon rectifiers and dual brakes,[1][9] and were reclassified under TOPS as Class 84, being renumbered 84001 - 84010.

The end

The second rebuild failed to overcome some of the more persistent problems and British Rail decided in 1976 to withdraw them from service. The first to be withdrawn was 84007 in 1977, the last 84003 and 84010 in 1980.

After withdrawal
ADB968021 (ex 84009) load bank tester (1987)

84003 and 84009 passed to the Research Division: 84009 was rebuilt as a load bank tester and 84003 was used as a donor loco. They were given departmental numbers ADB968021 and ADB968022 respectively, although the latter was never applied. In 1995 84009 was broken-up following withdrawal from its load bank duties; one cab of this locomotive was saved together with a quantity of spares.

84002 and 84010 were purchased by GEC for experiments, but scrapped soon afterwards.

84001 was moved to the National Railway Museum in York on long-term loan. The original intention was to eventually swap it for a more representative Class 86, but in 1994 the locomotive was officially claimed for the National Collection. In the intervening years, the 84 had become important to the Museum as the sole-surviving post-steam, main line (i.e. not a small shunting locomotive) example of a North British Locomotive Company product. 84001 remained at the NRM until 2000 when it was loaned to the AC Locomotive Group for an initial period of three years, later extended by five years, in exchange for much-needed cosmetic restoration work being undertaken. It continues to carry BR blue livery, as expensive cosmetic modifications would be required to return to "as built" condition in electric blue livery.

Preservation

One locomotive (84001) has been preserved by the National Railway Museum and is on loan to the Scottish Railway Museum, Bo'ness. Efforts are underway to make this loan permanent and delist the loco from the National Collection.

Fleet details
Key: Preserved Scrapped
Numbers[1] Date Introduced[1] Withdrawn[10][11] Disposal
Pre-TOPS TOPS NBL Works No.
E3036 84001 27793 March 1960 22 January 1979[1] Preserved by the National Railway Museum.
On loan to the Scottish Railway Museum at Bo'ness.
E3037 84002 27794 May 1960 September 1980 Scrapped at Texas Metals
E3038 84003 27795 June 1960 November 1980 To Research Department
Scrapped at Vic Berry, Leicester
E3039 84004 27796 July 1960 12 November 1977[1] Scrapped at Birds, Long Marston
E3040 84005 27797 August 1960 20 April 1977[1] Scrapped at Birds, Long Marston
E3041 84006 27798 October 1960 January 1978 Scrapped by J Cashmore at Crewe Yard
E3042 84007 27799 October 1960 April 1977 Scrapped by J Cashmore at Crewe Yard
E3043 84008 27800 December 1960 October 1979 Scrapped at Crewe Works
E3044 84009 27801 December 1960 3 August 1978[1] To Research Department
Scrapped at Gwent Demolition, Margam
E3045 84010 27802 March 1961 November 1980 Scrapped at Texas Metals

References
  1. Webb & Duncan 1979, p. 59
  2. Webb & Duncan 1979, p. 58
  3. Webb & Duncan 1979, p. 54
  4. Marsden & Fenn 2001, p. 82
  5. Allan 1968, p. 11.
  6. Railway World December 1967, p. 554.
  7. Longhurst 1979, Class AL4–84
  8. Marsden & Fenn 2001, p. 83
  9. Webb & Duncan 1979, p. 55
  10. "The Class 84 Fleet". Rail Blue. Retrieved 11 February 2016.
  11. "Class 84". RAIL. No. 88. EMAP National Publications. January 1989. p. 42. ISSN 0953-4563. OCLC 49953699.

Sources
  • Longhurst, Roly (1979). Electric Locomotives of the West Coast Main Line. Truro: D. Bradford Barton Ltd. ISBN 0851533558. OCLC 16491712.
  • Marsden, Colin J.; Fenn, Graham B. (2001). British Rail Main Line Electric Locomotives (2nd ed.). Oxford Publishing Co. ISBN 9780860935599. OCLC 48532553.
  • Webb, Brian; Duncan, John (1979). AC Electric Locomotives of British Rail. David & Charles. ISBN 9780715376638. OCLC 6916046.
  • "British Railways Motive Power Survey". British Rail Locomotives and other motive power: Combined volume. London: Ian Allan. 1968. ISBN 0-7110-0008-5.

Further reading
  • Derrick, Kevin (2014). Looking back at AC Electric Locomotives. Strathwood. ISBN 9781905276516. OCLC 931820979.
  • McManus, Michael. Ultimate Allocations, British Railways Locomotives 1948 - 1968. Wirral. Michael McManus.
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