Thompson A2/1 Pacifics

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LNER P2 2-8-2
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Thompson A2/1 Pacifics

Post by neildimmer » Sun Sep 01, 2019 10:19 am

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.
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. 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 1944 and January 1945
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.
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
All four locomotives were withdrawn from stock in 1960/1.

Original LNER era Numbers

3696 later renumbered 507 & named Highland Chieftain ... /i-KR23tdF
3696 (works photo) later renumbered 507 & named Highland Chieftain ... /i-2SK8qfQ
3699 unknown location ... /i-Xq4TqwZ

Final LNER era numbers

507 Highland Chieftain ... /i-dGwmJvr
508 Duke of Rothesay Kings Cross shed 21st April 1947 ... /i-ptS36sF
508 Duke of Rothsey ... /i-bV5ZVmG
509 (later named Waverley) Gateshead 18th August 1948 ... /i-t5wWjzL

BR era

60507 Highland Chieftain Haymarket June 1958 ... /i-BPXWBsd
60507 Highland Chieftain 'The Night Scotsman' ... /i-phcHPbC
60507 Highland Chieftain with the 2.15pm Edin burghWaverley to Aberdeen service 22nd June 1954 ... /i-4b6xW2W

60508 Duke of Rothesay New England shed 19th August 1957 ... /i-mKnPZnC
60508 Duke of Rothesay ... /i-DBv7GGw
60509 Waverley passing Princess St Gardens with the 6.05am Aberdeen to Edinburgh service 8th June 1951 Thompson A2-1 ... /i-SVV5qkH
60509 Waverley Dundee shed 20th August 1958 ... /i-h3Pvqnb
60509 Waverley Eastfield July 1957 ... /i-DMJhdvb
60509 Waverley Haymarket shed 16th April 1949 ... /i-VwZvNnK
60510 Robert the Bruce 'The Heart of the Midlothian' Edinburgh ... /i-PsHXwtS
60510 Robert the Bruce Eastfield c1958 ... /i-Nqc6hfh ... /i-PC3qwRz
60510 Robert the Bruce Haymarket June 1959 ... /i-qLcWDdD


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