The British Rail Class 84 was a 25 kV AC electric locomotive that operated on the West Coast Main Line (WCML) 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 type Electric Builder North British Locomotive Company Order number L91[1] Build date 1960–1961 Total produced 10
Specifications Configuration: ​  • AAR B-B  • UIC Bo′Bo′  • Commonwealth Bo-Bo Gauge 4 ft 8+1⁄2 in (1,435 mm) standard gauge Wheel diameter 4 ft 0 in (1.219 m)[2] Wheelbase 39 ft 6 in (12.04 m)[2] Length: ​  • Over beams 53 ft 6+1⁄2 in (16.32 m)[2] Width 8 ft 8+1⁄4 in (2.648 m)[2] Height: ​  • Pantograph 13 ft 0+9⁄16 in (3.977 m)[2]  • Body height 12 ft 4+1⁄4 in (3.766 m)[2] Loco weight 76.60 long tons (77.83 t; 85.79 short tons) Electric system/s 25 kV AC Catenary Current pickup(s) Pantograph Traction motors 4 × GEC WT501[3] Gear ratio 25:74[3] Train heating Electric Train Heating Train brakes Vacuum; Dual from 1972[1]
Performance figures Maximum speed 100 mph (160 km/h) Power output: ​  • 1 hour 4 × 890 hp (660 kW)[3]  • Continuous 4 × 750 hp (560 kW)[3] Tractive effort 50,000 lbf (220 kN) Brakeforce 65.5 long tons-force (653 kN)
Career Operators British Rail Numbers E3036–E3045; later 84001–84010 Axle load class Route availability 6 Retired 1979–1980 Disposition One preserved, remainder scrapped

The ten strong class was one of five prototype classes of electric locomotives built in the early stages of WCML electrification. Built between 1960 and 1961, the type was not a success, as they were beset by technical problems, and after several lengthy periods of storage, and unsuccessful attempts at resolving these problems, British Rail decided to withdraw the entire fleet between 1977 and 1980.

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 by the North British Locomotive Company in Springburn, Glasgow, to a design by GEC.[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.

Second rebuild 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.

Withdrawal

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

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.

Fleet details

References

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.

External links

Wikimedia Commons has media related to British Rail Class 84.

• "The AC Locomotive Group (caring for Class 84 84001)"