LNER Thompson Class A2/1

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Disambiguation: LNER Thompson Class A2
LNER Thompson Class A2/1
New Southgate locomotive derailment geograph-2261880-by-Ben-Brooksbank.jpg
No. 60508 Duke of Rothesay lying on its side, July 1948
Type and origin
Power type Steam
Designer Edward Thompson
Builder Darlington Works
Build date 1944
Total produced 4
Specifications
Configuration 4-6-2
Gauge 4 ft 8 12 in (1,435 mm)
Driver dia. 6 ft 2 in (1.880 m)
Loco weight 98 long tons (100 t)
Boiler pressure 225 psi (1.55 MPa)
Cylinders Three
Cylinder size 19 in × 26 in (483 mm × 660 mm)
Performance figures
Tractive effort 36,385 lbf (161.85 kN)
Career
Operators London and North Eastern Railway
British Railways
Class A2/1
Power class 7P6F
Numbers LNER 507-510
BR 60507-60510
Disposition All Scrapped

The London and North Eastern Railway (LNER) Thompson Class A2/1 was a class of 4-6-2 steam locomotives built at Darlington locomotive works during 1944. They were originally ordered as Class V2 locomotives, as designed by Sir Nigel Gresley, but were revised during construction into a 4-6-2 'Pacific' arrangement under the instruction of Edward Thompson.

Background[edit]

At the time Edward Thompson succeeded Sir Nigel Gresley as Chief Mechanical Engineer of the LNER in April 1941, Darlington works was busy building Class V2 mixed traffic locomotives. Although the V2 class were competent and powerful locomotives, Thompson did not like this design as it required more servicing than his own mixed traffic B1 class 4-6-0. He also envisaged a time when the V2s would be replaced by his own design of 'Pacific' locomotives, but would not receive authority to build a new class during the war.[1] He therefore decided to build the final four V2 already authorised as experimental 'Pacific' locomotives along similar lines to his recently rebuilt A2/2 class. The revised design was authorised in August 1943 and the new locomotives built between May 199 and January 1945.[2]

Design[edit]

The pony truck of the V2 class was replaced by Thompson's own design of bogie and they had an extended smokebox. They retained the same boiler as the V2 class although the pressure was increased to 225psi, giving an increased tractive effort of 36,390 lbf (161.87 kN). The firebox was also the same as the V2 although these were the first LNER locomotives to be fitted with a rocking grate and ashpan. Rather than have all three cylinders driving a single axle Thompson adopted divided drive with the middle cylinder driving the first pair of driving wheels and the outside cylinders the middle pair. Thompson also abandoned the Gresley conjugated valve gear and instead fitted independent sets of Walschaerts valve gear to each cylinder.

Performance[edit]

The four locomotives of this design performed adequately but proved to be under-boilered for their size and lacked adhesion. They were less problematic than the A2/2 class, but did not distinguish themselves.[3]

Accidents and incidents[edit]

On 17 July 1948. locomotive No. 60508 Duke of Rothesay was hauling a passenger train when it became derailed inside Barnet Tunnel, Hertfordshire due to a combination of faulty track and excessive speed. The whole train was subsequently derailed on points at New Southgate, London. One person was killed.[4]

Withdrawal[edit]

All four locomotives were withdrawn from stock in 1960/1.

Stock list[edit]

Original No.[5] LNER No. BR No. Name Entered stock Withdrawn
3696
507
60507
Highland Chieftain May 1944 December 1960
3697
508
60508
Duke of Rothesay June 1944 February 1961
3698
509
60509
Waverley November 1944 August 1960
3699
510
60510
Robert the Bruce January 1945 November 1960

Models[edit]

Apple Green Engines produce a ready-to-run model of the A2/1 in 4 mm scale. PDK, Nucast, and DJH also produce 4 mm scale kits of the A2/1. Crownline have produced a 4 mm kit in the past, but this is no longer available.

References[edit]

  1. ^ Boddy, Neve, & Yeadon, (1973). p. 143.
  2. ^ Boddy, Neve, & Yeadon, (1973). p. 156.
  3. ^ Allen (1962), p.99.
  4. ^ Hoole, Ken (1982). Trains in Trouble: Vol. 3. Redruth: Atlantic Books. p. 39. ISBN 0-906899-05-2. 
  5. ^ The ABC of L.N.E.R. LOCOMOTIVES (Renumbering Edition), Ian Allan, 1946
  • Allen, Cecil J. (1962). British Pacific Locomotives. London: Ian Allan. 
  • 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, Willie (1991). Yeadon's Register of LNER Locomotives, volume 3: Raven, Thompson & Peppercorn Pacifics. Irwell Press. 

External links[edit]