LNER Thompson Class A2/2
- Disambiguation: LNER Thompson Class A2
No. 60503 'Lord President' at London King's Cross railway station in 1958
|Type and origin|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
|Driver diameter||6 ft 2 in (1.880 m)|
|Locomotive weight||101.5 long tons (103.1 t)|
|Boiler pressure||225 psi (1.55 MPa)|
|Cylinder size||20 in × 26 in (508 mm × 660 mm)|
|Tractive effort||40,320 lbf (179.35 kN)|
|Operator(s)||London and North Eastern Railway
The London and North Eastern Railway Class A2/2 was a class of 4-6-2 steam locomotives. The A2/2 were former members of Sir Nigel Gresley’s P2 Class of eight-coupled express passenger locomotives. Edward Thompson was appointed on the 28 April 1941 and decided to gain experience by rebuilding the P2 Class, the first of which to be rebuilt was No. 2005, Thane Of Fife in 1943. Thompson changed the wheel arrangement from 2-8-2 to a 4-6-2 'Pacific' configuration and all the other P2s were rebuilt similarly during 1944.
|This section needs additional citations for verification. (October 2015)|
As P2 configuration, the engines had proved to be powerful locomotives, but the long fixed wheelbase made them maintenance intensive, and Thompson saw this is a chance to try out his own thoughts on pacific design. The P2's had been notorious for Crank Axle failure and Thompson believed that the cause of this was placing the drive through just one axle. He believed that divided drive between the front and middle axles should be used, and also that connecting rods should be all of equal length, a theory shared neither by his predecessor or his successor. The great length of the P2 frames were such that they could be changed to a pacific 4-6-2 arrangement, and give Thompson the necessary spacing required for his divided drive layout.
Though the Coupled Wheelbase was shorter than that of any of the Gresley Pacific's (out of the necessity of the original P2 engines needing to space 8 couple wheels as close as possible), the distance between the front axle and the rear axle of the bogie was so great that the locomotives looked something of a misfit. using equal length connecting rods, as well as divided drive moved the centre cylinder correspondingly far forward from the outside cylinders. both the LMS and the GWR had built express engines with divided drive before (LMS Princess Coronation Class, and GWR King Class) but both had taken into account potential frame movement, and using four cylinders spread the power more evenly than three cylinders. the A2/2 and the subsequent A2/3 both suffered badly from frame movement, vibration and loose fittings.
Worst of all was that they could not take over the duties of their predecssors, the P2s, on the harsh Edinburgh to Aberdeen Line, they lacked the adhesion and surefooted-ness of the P2's, and were subsequently moved elsewhere.
Despite their shortcomings, they retained much of the Power of the P2's, and the reduced weight meant they had a high power to weight ratio, and were particularly good at hauling high speed expresses, but reliability ultimately capped them from ever making an impact on the east coast main line.
During their lifetime in steam Earl Marischal was the only A2/2 to cover over one million miles in service, 360,907 as a P2 and 673,947 as an A2/2. The information in the infobox (right) is taken from Ian Allan ABC.
A summary of rebuilding is given in the following table:
The LNER/BR stock list was as follows:
|Original No.||LNER No.
|BR No.||Name||Rebuild Date||Withdrawn|
||Cock o' the North||September 1944||February 1960|
||Earl Marischal||June 1944||July 1961|
||Lord President||December 1944||November 1959|
||Mons Meg||November 1944||January 1961|
||Thane of Fife||January 1943||November 1959|
||Wolf of Badenoch||May 1944||April 1961|
Withdrawals from stock began in 1959 starting with 60505 Thane Of Fife on 10 November 1959. The next A2/2 to be withdrawn was Lord President on 27 November 1959. 60501 Cock o' the North was withdrawn in 1960, while 60504 and 60506 were withdrawn in 1961, with 60502 the last member of the class withdrawn on 3 July 1961.
|This section does not cite any references (sources). (April 2013)|
Apple Green Engines produce a ready-to-run model of the A2/2 in 4 mm scale. PDK, DJH, and Millholme sell 4 mm scale kits of the A2/2. Crownline have also produced a 4 mm scale kit in the past, but this is no longer available.
DJH also sell a kit of the A2/2 for O gauge (7 mm scale).
- Ian Allan ABC of British Railways Locomotives, summer 1961 edition, part 4, page 27
- The ABC of L.N.E.R. LOCOMOTIVES (Renumbering Edition), Ian Allan, 1946
- Boddy, M. G.; Neve, E.; Yeadon, W. B. (April 1973). Fry, E. V., ed. Locomotives of the L.N.E.R., Part 2A: Tender Engines—Classes A1 to A10. Kenilworth: RCTS. ISBN 0-901115-25-8.
- Yeadon, W. B. (1991). Yeadon's Register of LNER Locomotives, volume 3: Raven, Thompson & Peppercorn Pacifics. Irwell Press.