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EspañolLNER CLASS A1/A3
:''Disambiguation: LNER Thompson Class A1/1, LNER Peppercorn Class A1''
The London and North Eastern Railway (LNER) 'Class A1/A3' is a class of 4-6-2 steam locomotives, designed by Nigel Gresley. The 'A3' was a refinement of the earlier 'A1', and the two are often considered together; all surviving A1 locomotives were eventually rebuilt as class A3.
The Great Northern Railway's (GNR) A1 class wa the brainchild of Nigel Gresley, who became Chief Mechanical Engineer of the GNR in 1911. The intention was to produce an engine with ample capacity for mainline express services while being more economical to operate than existing locomotives.
A total of seventy-nine of the class were ordered between 1921 and 1934, the first A1 entering service on the GNR in April 1922. The first ten of the A1 steam locomotives cost an average of ₤8,560 compared to the ₤6,840 for each of the first ten of the GWR's comparable Castle Class.
In the 1923 Grouping, the GNR became part of the newly-formed LNER with Gresley continuing as Chief Mechanical Engineer.
The A1 Pacific steam locomotive had 3 cylinders: 2 on the outside and 1 in the middle connected to the middle driving wheel. Gresley was as much artist as engineer and gave the locomotives an aesthetically pleasing design, decking them out in an attractive livery and giving them evocative names, mostly taken from racehorses of the era.
The A1s set new standards of performance with the heavy expresses on the East Coast Main Line, and the famous No. 4472 ''Flying Scotsman'' was the first British locomotive to officially reach 100 mph (GWR 'City of Truro' is acknowledged to have reached 102mph on 9th May 1904, but records are not verifiable - ref http://www.nrm.org.uk/pressoffice/pressreleases/2004/truro.asp). However the class suffered from a number of engineering problems. They had a stiff "all or nothing" regulator which, combined with the absence of any compensating levers near the rear pony truck and driving wheels, made them liable to slipping. This tendency to "wheel burn" resulted in the rails having to be changed every few weeks at points where the A1s habitually started from rest.Such frequent rail changes were very rare.The A1/A3 and A4 classes had 6'8" driving wheels, similar to most British Pacific locomotives. The competing LMS 'Coronation Scot' Pacifics had 6'9" driving wheels, and coped adequatly with the heavy gradients and loads on this Anglo-Scottish trunk route.On the Waverley route from Carlisle to Edinburgh which closed in 1969, with gradients of 1 in 75 for many miles,and very severe,almost constant curves,saw the fastest journey of a heavy express train hauled by an A4, disproving the claim of the machines inability to tackle steep gradients.They were perfectly capable of handling inclines as any other express passenger locomotive.
Mainly because of weight restrictions, and firebox design Pacific locomotives had less traction on the rear coupled wheels. For this reason the Great Western Railway, with one sole example,would not use Pacifics. Indeed the 'King 'class 4-6-0 was just as poweful as the other three post 1923 grouped UK railways most powerful Pacifics.Toward the end of steam it was realised that an express locomotive with only 6'2" driving wheels, was quite capable of running up to the magic 100m.p.h.with less risk of slipping.Controlling slip was a skill all good drivers had, and except in a few special cases, opening and closing the regulator is not all or nothing.A driver will open the regulator slowly, but if slipping becomes violent, he can slam the regulator shut, thus cutting off the steam supply to the cylinders immediatly.
The A1s had a chronic tendency for the "big end" of the inside connecting rod to run hot; this was partly due to the design of the conjugated valve gear. The problem was largely cured eventually by replacement with a GWR design of big end. There were also such significant faults as broken lubricator pipes, which could only be replaced by lifting the boiler off the frame. However, the clearest proof that improvements were possible came with a comparative test in 1925 against a GWR Castle Class engine, in which the Castle performed better despite being smaller and lighter.
After a preliminary period of disbelief , Gresley began to experiment with modifications to the A1s. A successful result was obtained with No. 2555 ''Centenary'', by reducing the cylinder diameter slightly, changing the valve settings to give freer steam flow, and increasing the boiler pressure from 180 psi to 220 psi with a larger superheater. The results included freer running and conservation of coal, thus reducing the need to change locomotives mid-run. A side-effect of the changes was that the axle load was slightly increased. A new class of locomotives was then built to this design; the class was designated A3 and the first one was outshopped from Doncaster Works 22/08/1928, and the last 09/02/1935, sometimes known as the ''Super Pacifics''. All the original A1 Pacifics were eventually altered to A3 form as they went through the shops, and the 17 that weren't rebuilt by April 1945 were re-classified Class A10.
The A3s were even more successful than the A1s, handling the largest and heaviest expresses on the LNER. On a test run No. 2750 "Papyrus" set a new British rail speed record of 108 mph. This provided the impetus for a further development, the streamlined A4 Class.
As World War II broke out there was a requirement for 24-car freight trains to run on the East Coast Main Line and the A3s' (and the remaining A1s') performance on these freight trains was a vindication of their design, although lower standards of maintenance emphasized their detailed weaknesses.
After the war there were calls to overcome these troubles but they were mostly ignored, as the locomotives' performance was still good. The appearance of the A3 did change slightly when smoke deflectors were fitted to each side of the smokebox, and they performed better with the double chimneys which were fitted in 1958-1960. But even in the 1960s they were easily recognisable as being brethren to the original class A1 Pacifics which saw service 40 years before.
The prototype locomotive (Great Northern) had been rebuilt into what was virtually a new design and one other had been withdrawn in 1959 (Solario), but otherwise the class remained intact until 1962, still on express passenger work. The last to go was No. 60041 ''Salmon Trout'', in December 1965.
No. 4472 ''Flying Scotsman'' is the only survivor of the class. Its activities since being purchased for preservation in 1963 are such trips to USA and Australia have made it one of the best known and widely recognised steam locomotives in the world.
In Thomas the Tank Engine and Friends, one of these locomotives was the basis for Gordon the Big Engine. Flying Scotsman itself also guest stars in the 1968 Railway Series 23rd book "Enterprising Engines", as Gordon's Doncaster brother.
★ LNER Encyclopedia Page covering the history and development of the LNER A1/A3 Pacifics
The London and North Eastern Railway (LNER) 'Class A1/A3' is a class of 4-6-2 steam locomotives, designed by Nigel Gresley. The 'A3' was a refinement of the earlier 'A1', and the two are often considered together; all surviving A1 locomotives were eventually rebuilt as class A3.
| Contents |
| Development of Class A1 |
| Class A3 Super Pacifics |
| In fiction |
| External links |
Development of Class A1
The Great Northern Railway's (GNR) A1 class wa the brainchild of Nigel Gresley, who became Chief Mechanical Engineer of the GNR in 1911. The intention was to produce an engine with ample capacity for mainline express services while being more economical to operate than existing locomotives.
A total of seventy-nine of the class were ordered between 1921 and 1934, the first A1 entering service on the GNR in April 1922. The first ten of the A1 steam locomotives cost an average of ₤8,560 compared to the ₤6,840 for each of the first ten of the GWR's comparable Castle Class.
In the 1923 Grouping, the GNR became part of the newly-formed LNER with Gresley continuing as Chief Mechanical Engineer.
The A1 Pacific steam locomotive had 3 cylinders: 2 on the outside and 1 in the middle connected to the middle driving wheel. Gresley was as much artist as engineer and gave the locomotives an aesthetically pleasing design, decking them out in an attractive livery and giving them evocative names, mostly taken from racehorses of the era.
The A1s set new standards of performance with the heavy expresses on the East Coast Main Line, and the famous No. 4472 ''Flying Scotsman'' was the first British locomotive to officially reach 100 mph (GWR 'City of Truro' is acknowledged to have reached 102mph on 9th May 1904, but records are not verifiable - ref http://www.nrm.org.uk/pressoffice/pressreleases/2004/truro.asp). However the class suffered from a number of engineering problems. They had a stiff "all or nothing" regulator which, combined with the absence of any compensating levers near the rear pony truck and driving wheels, made them liable to slipping. This tendency to "wheel burn" resulted in the rails having to be changed every few weeks at points where the A1s habitually started from rest.Such frequent rail changes were very rare.The A1/A3 and A4 classes had 6'8" driving wheels, similar to most British Pacific locomotives. The competing LMS 'Coronation Scot' Pacifics had 6'9" driving wheels, and coped adequatly with the heavy gradients and loads on this Anglo-Scottish trunk route.On the Waverley route from Carlisle to Edinburgh which closed in 1969, with gradients of 1 in 75 for many miles,and very severe,almost constant curves,saw the fastest journey of a heavy express train hauled by an A4, disproving the claim of the machines inability to tackle steep gradients.They were perfectly capable of handling inclines as any other express passenger locomotive.
Mainly because of weight restrictions, and firebox design Pacific locomotives had less traction on the rear coupled wheels. For this reason the Great Western Railway, with one sole example,would not use Pacifics. Indeed the 'King 'class 4-6-0 was just as poweful as the other three post 1923 grouped UK railways most powerful Pacifics.Toward the end of steam it was realised that an express locomotive with only 6'2" driving wheels, was quite capable of running up to the magic 100m.p.h.with less risk of slipping.Controlling slip was a skill all good drivers had, and except in a few special cases, opening and closing the regulator is not all or nothing.A driver will open the regulator slowly, but if slipping becomes violent, he can slam the regulator shut, thus cutting off the steam supply to the cylinders immediatly.
The A1s had a chronic tendency for the "big end" of the inside connecting rod to run hot; this was partly due to the design of the conjugated valve gear. The problem was largely cured eventually by replacement with a GWR design of big end. There were also such significant faults as broken lubricator pipes, which could only be replaced by lifting the boiler off the frame. However, the clearest proof that improvements were possible came with a comparative test in 1925 against a GWR Castle Class engine, in which the Castle performed better despite being smaller and lighter.
Class A3 Super Pacifics
After a preliminary period of disbelief , Gresley began to experiment with modifications to the A1s. A successful result was obtained with No. 2555 ''Centenary'', by reducing the cylinder diameter slightly, changing the valve settings to give freer steam flow, and increasing the boiler pressure from 180 psi to 220 psi with a larger superheater. The results included freer running and conservation of coal, thus reducing the need to change locomotives mid-run. A side-effect of the changes was that the axle load was slightly increased. A new class of locomotives was then built to this design; the class was designated A3 and the first one was outshopped from Doncaster Works 22/08/1928, and the last 09/02/1935, sometimes known as the ''Super Pacifics''. All the original A1 Pacifics were eventually altered to A3 form as they went through the shops, and the 17 that weren't rebuilt by April 1945 were re-classified Class A10.
The A3s were even more successful than the A1s, handling the largest and heaviest expresses on the LNER. On a test run No. 2750 "Papyrus" set a new British rail speed record of 108 mph. This provided the impetus for a further development, the streamlined A4 Class.
As World War II broke out there was a requirement for 24-car freight trains to run on the East Coast Main Line and the A3s' (and the remaining A1s') performance on these freight trains was a vindication of their design, although lower standards of maintenance emphasized their detailed weaknesses.
After the war there were calls to overcome these troubles but they were mostly ignored, as the locomotives' performance was still good. The appearance of the A3 did change slightly when smoke deflectors were fitted to each side of the smokebox, and they performed better with the double chimneys which were fitted in 1958-1960. But even in the 1960s they were easily recognisable as being brethren to the original class A1 Pacifics which saw service 40 years before.
The prototype locomotive (Great Northern) had been rebuilt into what was virtually a new design and one other had been withdrawn in 1959 (Solario), but otherwise the class remained intact until 1962, still on express passenger work. The last to go was No. 60041 ''Salmon Trout'', in December 1965.
No. 4472 ''Flying Scotsman'' is the only survivor of the class. Its activities since being purchased for preservation in 1963 are such trips to USA and Australia have made it one of the best known and widely recognised steam locomotives in the world.
| LNER Number | British Railways Number | Original Name (Rename(s)) | Entered Service | Rebuilt | Withdrawn |
|---|---|---|---|---|---|
| 4470 | 60113 | Great Northern | 4/1922 | 9/1945 | 16/11/1962 |
| 4471 | 60102 | Sir Frederick Banbury | 7/1922 | 10/1942 | 11/1961 |
| 4472 | 60103 | Flying Scotsman | 2/1923 | 1/1947 | 11/1963 |
| 4473 | 60104 | Solario | 3/1923 | 10/1941 | 11/1959 |
| 4474 | 60105 | Victor Wild | 3/1923 | 10/1942 | 11/1963 |
| 4475 | 60106 | Flying Fox | 4/1923 | 3/1947 | 11/1964 |
| 4476 | 60107 | Royal Lancer | 5/1923 | 10/1946 | 11/1963 |
| 4477 | 60108 | Gay Crusader | 6/1923 | 1/1943 | 11/1963 |
| 4478 | 60109 | Hermit | 7/1923 | 11/1943 | 11/1962 |
| 4479 | 60110 | Robert The Devil | 7/1923 | 8/1942 | 11/1963 |
| 4480 | 60111 | Enterprise | 8/1923 | 7/1927 | 11/1962 |
| 4481 | 60112 | St Simon | 9/1923 | 8/1946 | 11/1964 |
| 2543 | 60044 | Melton | 6/1924 | 9/1947 | 6/1963 |
| 2544 | 60045 | Lemberg | 7/1924 | 12/1927 | 11/1964 |
| 2545 | 60046 | Diamond Jubilee | 8/1924 | 8/1941 | 6/1963 |
| 2546 | 60047 | Donovan | 8/1924 | 1/1948 | 4/1963 |
| 2547 | 60048 | Doncaster | 8/1924 | 5/1946 | 9/1963 |
| 2548 | 60049 | Galtee More | 9/1924 | 10/1945 | 12/1962 |
| 2549 | 60050 | Persimmon | 10/1924 | 12/1943 | 6/1963 |
| 2550 | 60051 | Blink Bonny | 10/1924 | 11/1945 | 11/1964 |
| 2551 | 60052 | Prince Palatine | 11/1924 | 8/1941 | 1/1966 |
| 2552 | 60053 | Sansovino | 11/1924 | 9/1943 | 5/1963 |
| 2553 | 60054 | Manna | 12/1924 | 7/1943 | 6/1964 |
| 2554 | 60055 | Woolwinder | 12/1924 | 6/1942 | 9/1961 |
| 2555 | 60056 | Centenary | 2/1925 | 8/1944 | 5/1963 |
| 2556 | 60057 | Ormonde | 2/1925 | 1/1947 | 10/1963 |
| 2557 | 60058 | Blair Athol | 2/1925 | 12/1945 | 6/1963 |
| 2558 | 60059 | Tracery | 3/1925 | 7/1942 | 12/1962 |
| 2559 | 60060 | The Tetrarch | 4/1925 | 1/1942 | 9/1963 |
| 2560 | 60061 | Pretty Polly | 4/1925 | 5/1944 | 9/1963 |
| 2561 | 60062 | Minoru | 5/1925 | 6/1944 | 12/1964 |
| 2562 | 60063 | Isinglass | 7/1925 | 4/1946 | 6/1964 |
| 2563 | 60064 | William Whitelaw (Tagalie) | 8/1924 | 11/1942 | 9/1961 |
| 2564 | 60065 | Knight Of the Thistle | 8/1924 | 3/1947 | 6/1964 |
| 2565 | 60066 | Merry Hampton | 8/1924 | 12/1945 | 9/1963 |
| 2566 | 60067 | Ladas | 8/1924 | 11/1939 | 12/1962 |
| 2567 | 60068 | Sir Visto | 9/1924 | 12/1948 | 8/1962 |
| 2568 | 60069 | Sceptre | 9/1924 | 5/1942 | 10/1962 |
| 2569 | 60070 | Gladiateur | 9/1924 | 1/1947 | 5/1964 |
| 2570 | 60071 | Tranquil | 9/1924 | 10/1944 | 10/1964 |
| 2571 | 60072 | Sunstar | 9/1924 | 7/1941 | 10/1962 |
| 2572 | 60073 | St Gatien | 10/1924 | 11/1945 | 8/1963 |
| 2573 | 60074 | Harvester | 10/1924 | 4/1928 | 4/1963 |
| 2574 | 60075 | St Frusquin | 10/1924 | 6/1942 | 1/1964 |
| 2575 | 60076 | Galopin | 10/1924 | 6/1941 | 10/1962 |
| 2576 | 60077 | The White Knight | 10/1924 | 7/1943 | 7/1964 |
| 2577 | 60078 | Night Hawk | 10/1924 | 1/1944 | 10/1962 |
| 2578 | 60079 | Bayardo | 10/1924 | 5/1928 | 9/1961 |
| 2579 | 60080 | Dick Turpin | 11/1924 | 11/1942 | 10/1964 |
| 2580 | 60081 | Shotover | 11/1924 | 2/1928 | 10/1962 |
| 2581 | 60082 | Neil Gow | 11/1924 | 1/1943 | 9/1963 |
| 2582 | 60083 | Sir Hugo | 12/1924 | 12/1941 | 5/1964 |
| 2743 | 60089 | Felstead | 8/1928 | 10/1963 | |
| 2744 | 60090 | Grand Parade | 8/1928 | 10/1963 | |
| 2745 | 60091 | Captain Cuttle | 9/1928 | 10/1964 | |
| 2746 | 60092 | Fairway | 11/1928 | 10/1964 | |
| 2747 | 60093 | Coronach | 12/1928 | 4/1962 | |
| 2748 | 60094 | Colorado | 12/1928 | 2/1964 | |
| 2749 | 60095 | Flamingo | 2/1929 | 4/1961 | |
| 2750 | 60096 | Papyrus | 3/1929 | 9/1963 | |
| 2751 | 60097 | Humorist | 4/1929 | 18/1963 | |
| 2752 | 60098 | Spion Kop | 4/1929 | 10/1963 | |
| 2595 | 60084 | Trigo | 2/1930 | 11/1964 | |
| 2596 | 60085 | Manna (Prince of Wales) | 2/1930 | 10/1964 | |
| 2597 | 60086 | Gainsborough | 4/1930 | 11/1963 | |
| 2598 | 60087 | Blenheim | 6/1930 | 10/1963 | |
| 2599 | 60088 | Book Law | 7/1930 | 10/1963 | |
| 2795 | 60099 | Call Boy | 4/1930 | 10/1963 | |
| 2796 | 60100 | Spearmint | 5/1930 | 6/1965 | |
| 2797 | 60101 | Cicero | 6/1930 | 4/1963 | |
| 2500 | 60035 | Windsor Lad | 7/1934 | 9/1961 | |
| 2501 | 60036 | Colombo | 7/1934 | 11/1964 | |
| 2502 | 60037 | Hyperion | 7/1934 | 12/1963 | |
| 2503 | 60038 | Firdaussi | 8/1934 | 11/1963 | |
| 2504 | 60039 | Sandwich | 9/1934 | 3/1963 | |
| 2505 | 60040 | Cameronian | 10/1934 | 7/1964 | |
| 2506 | 60041 | Salmon Trout | 12/1934 | 12/1965 | |
| 2507 | 60042 | Singapore | 12/1934 | 7/1964 | |
| 2508 | 60043 | Jack Brown | 12/1935 | 5/1964 |
In fiction
In Thomas the Tank Engine and Friends, one of these locomotives was the basis for Gordon the Big Engine. Flying Scotsman itself also guest stars in the 1968 Railway Series 23rd book "Enterprising Engines", as Gordon's Doncaster brother.
External links
★ LNER Encyclopedia Page covering the history and development of the LNER A1/A3 Pacifics
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