Gresley G.N.R. A1 1470 (4470)& 1471(4471)

The London and North Eastern Railway LNER Gresley Classes A1 and A3 locomotives represented two distinct stages in the history of the British 4-6-2 "Pacific" steam locomotives designed by Nigel Gresley. They were designed for main line passenger services, initially on the Great Northern Railway (GNR), a constituent company of the London and North Eastern Railway after the amalgamation of 1923, for which they became a standard design. The change in class designation to A3 reflected the fitting to the same chassis of a higher pressure boiler with a greater superheating surface and a small reduction in cylinder diameter, leading to an increase in locomotive weight. Eventually all of the A1 locomotives were rebuilt, most to A3 specifications, but no. 4470 was completely rebuilt as Class A1/1.
The names for the locomotives came from a variety of sources. The first, Great Northern, was named after its parent company. Others were given the names of high-ranking railway officials, but most were given the names of famous racehorses. One was named after the company's most famous long-distance passenger train
The new Pacific locomotives were built at the Doncaster "Plant" in 1922 to the design of Nigel Gresley, who had become Chief Mechanical Engineer of the GNR in 1911. The intention was to produce an engine able to handle, without assistance, mainline express services that were reaching the limits of the capacity of the Ivatt large-boilered Atlantics.
Gresley's initial Pacific project of 1915 was for an elongated version of the Ivatt Atlantic design with four cylinders. Finally realising that he was in a design impasse, he took as a model the new American Pennsylvania Railroad class K4 Pacific of 1914. This in turn had been updated from a series of prototypes scientifically developed in 1910 under Francis J. Cole, Alco's Chief Consulting Engineer at Schenectady and the Pennsylvania's K29 Alco prototype of 1911, also designed by Cole. Descriptions of those locomotives appeared in the British technical press at the time and gave Gresley the elements necessary to design a thoroughly up-to-date locomotive.
The first two GNR Pacifics, 1470 Great Northern and 1471 Sir Frederick Banbury were introduced in 1922. The Great Northern board ordered a further ten '1470-class' locomotives, which were under construction at Doncaster at the time of the formation of the LNER in 1923. in line with the philosophy behind Cole's Alco prototypes, the Gresley Pacifics were built to the maximum limits of the LNER loading gauge with a large boiler and wide firebox giving a large grate area. The firebox was set low and rested on the trailing carrying axle. However, unlike the Pennsylvania K4, the firebox was not of the flat-topped Belpaire variety, but a round-topped one that was in line with Great Northern tradition. Features in common with the American types were the downward profile towards the back of the firebox and the boiler tapering towards the front. Heat transfer and the flow of gases were helped by use of a combustion chamber extending forward from the firebox space into the boiler barrel, along with a boiler tube length limited to 19 feet (5.8 m), features inherited from the K4 type but not present on the earlier Cole Prototypes. The boiler pressure was rated at 180 pounds per square inch (1.24 MPa).
The 1470-class Pacific was the third Great Northern locomotive type to incorporate Gresley's universal 3-cylinder layout. All three cylinders drove the middle coupled axle. The outside cranks were set at 120°, with the inside crank displaced by about 7 degrees to allow for the 1:8 inclination of the inside cylinder. Gresley conjugated valve gear derived the motion of the inside valve spindle from the two outside valve spindles: this eliminated an inaccessible middle set of valve gear between the frames. A feature of the K4 that had soon been abandoned by the Pennsylvania Railroad was an unusual three-bar version of the Laird slide-bar. However, Gresley adopted this type of slide-bar for all his locomotives and it was later taken up by Bulleid for his Pacifics and by Riddles for the British Railways standard designs



I have added a new photo I have acquired of 4470 Great Northern (sorry about quality)

4470 Great Northern 1st run to Kings Cross Langley 4th April 1922


https://railway-photography.smugmug.com/LNERSteam/Gresley-Locomotives/Gresley-A1A3/4470-4471-60102-Built-GMR-1922/1470447014714471-Gresley-A1/i-DJRfBmQ

1470(4470)/1471(4471) Gresley A1 (4471 Rebuilt to A3) Built 1922 - Railway-Photography
railway-photography.smugmug.com
railway photographs from the last 100 years


1471 un-named in GNR livery photo dated August-November 1922 as it was named 9th November 1922 Gresley A1

https://railway-photography.smugmug.com/LNERSteam/Gresley-Locomotives/Gresley-A1A3/4470-4471-60102-Built-GMR-1922/1470447014714471-Gresley-A1/i-QBFsC9b

1471 un-named in GNR livery photo dated August-November 1922 as it was named 9th November 1922 Gresley A1
railway-photography.smugmug.com
railway photographs from the last 100 years

Last but not least, what Thompson did to Great Northern



https://railway-photography.smugmug.com/LNERSteam/Thompson-Locomotives/Thompson-A11-Rebuild/60113-Great-Northern/i-qz7bkv5

60113 Great Northern - Railway-Photography
railway-photography.smugmug.com
railway photographs from the last 100 years



https://railway-photography.smugmug.com/LNERSteam/Thompson-Locomotives/Thompson-A11-Rebuild/60113-Great-Northern/i-r6mrvgf

60113 Great Northern - Railway-Photography
railway-photography.smugmug.com
railway photographs from the last 100 years


Neil