LNER Gresley Classes A1 and A3

The Class A3 of the British London and North Eastern Railway ( LNER ) is an express train steam locomotive with the wheel arrangement 2'C1 ' (Pacific ) and a three-cylinder engine. The first 52 locomotives were originally designated as Class A1, but have been gradually converted into the Class A3. The most famous locomotive of this series is the No. 4472 Flying Scotsman, the (161 km / h) overcame the first British locomotive officially the " 100-mile - per-hour limit".

  • 2.1 weight distribution
  • 2.2 three-cylinder engine
  • 2.3 Tender
  • 2.4 Conversion variants
  • 3.1 non-stop long-distance journeys
  • 3.2 speed records


The first British " Pacifics "

In 1908 the Great Western Railway built the first British locomotive with 1901 already introduced in America Axle "Pacific ", the No 111 The Great Bear. This was initially a single piece, in 1922 Sir Nigel Gresley designed for the Great Northern Railway another Pacific. The built in railway workshop in Doncaster locomotive carried the number 1470 and the name of Great Northern. A little later, the No 1471 Sir Frederick Banbury. The locomotives excited at the trial runs sensation; among other things, put the No 1471 with a 620 -ton train a distance of 170 km in 122 minutes, which equates to an average of 83.5 km / h. It has a top speed of 123 km / h was achieved.

The class A1

Because of successful attempts, the locomotive type A1 over that of Vincent Raven built for the North Eastern Railway Class A2 showed to be the better design. Therefore, ten additional copies have been ordered by this type. In their delivery, the Great Northern Railway and the North Eastern Railway had already been merged into the London and North Eastern Railway. The 1470 and 1471 there had been renumbered in 4470 and 4471, and the new machines were numbered 4472-4481. Until 1924 followed by further 40 locomotives (No. 2543-2582 ).

The new class A3

Between 1928 and 1935, a further 27 locomotives were added, which were designated as Class A3 (No. 2500-2508, 2595-2599, 2743-2752 and 2795-2797 ). Externally these cars differed only minimally from the A1; However, they had to the prior art in accordance with an increase of 12.4 to 15.2 bar pressure and a larger boiler superheater. This also required a broader vapor collection box, which did not fit entirely into the smoke chamber, so this had to be widened laterally with two essays. These covers could Classes A1 and A3 visually different from each other.

Conversions of A1 to A3

The A3 had a more powerful and therefore heavier than the boiler A1 and thus a slightly higher axle load, which prevented their usability on some routes. However, because they had a significantly higher performance while still a lower water and coal consumption, it was decided to rebuild all A1 A3. In most cases, the conversion took place when the boiler had to be replaced anyway.

The conversion of A1 (now referred to as A10) to A3 was completed by the end of 1948; one exception was the first A1, No. 4470, which was in 1945 converted into the Class A1 / 1, an optically not very successful upgrade with an A4 boiler and back staggered outer cylinders in order for the agent cylinder an independent third Walschaerts control be able to accommodate.


As is common in the UK, were all locomotives proper names, which were also mounted on signs at the locomotive. Up to five copies were all named A1 and A3 by known race horses, which is why the names seem to have an unspecified origin. Two locomotives are renamed over time.


The overall design of the A3 was from generalized type as framing steam locomotive with the wheel arrangement 2'C1 '. The kettle was equipped with a superheater for the steam operation, the wheelsets are driven by three steam cylinders, the piston rod of the centrally positioned below the cylinder front chamber flue formed as a crank drive, the first drive axis. The outer cylinder worked on the second drive axle. For the supply of fuel and water, a Tender was carried.

Weight distribution

Although the A3 work from the outer impression tail-heavy, it was able to keep the rest on the rear drive axle weight ( axle load ) low and thus to avoid a weak point of many Pacific locomotives as for example also appeared in the German series 10. In experiments it had been found that highly stressed running axles particularly stressed the track because of their smaller diameter.

In order to shift the weight of the locomotive as far forward as possible, Gresley has provided in the construction of the boiler a steeply raked front firebox transverse wall extending to the boiler center, and not, as usual, ended up at the bottom of the long boiler. It was in the lower half of the boiler rudimentary combustion chamber whereby the heavy pipe wall and thus the focus of the boiler was moved forward.

Even with the trailing axle weight itself was saved by not using a drawbar frame. The axle was mounted in an outer frame, the special shape of the axle bearing not only a lateral displacement, but it is also a movement to a conceptual fulcrum caused (type Cartazzi ).

Three-cylinder engine

As all three cylinder engines by Sir Nigel Gresley the A1 and A3 were fitted with its proprietary control, wherein the movement of the slide of the inner cylinder is discharged through a lying forward of the cylinders rods of the movements of the slide of the outer cylinder, in turn, the normal of a Walschaerts - ( Heusinger ) control were moved.

Gresleys construction, which required only two simple lever, had the advantage of being able to dispense with a poorly accessible third control rod between the wheels, as used for example in the German standard locomotives of the series 1:10, 3:10 and 05. However, it was so great that it was no longer possible, all three cylinders evenly to supply steam because the game -related inaccuracies of the two outer controls and the transmitter rod added with operationally increasing wear of the bearing clearance.


The A1 and A3 were as equipped with a four-axle Tender. This had no bogies, but firmly in the frame -mounted axles. As with the LNER usual, the tender were equipped with a water scoop, the water could be refueled during the trip. The tender of five locomotives were provided with a narrow side passage.

Tag variants

Starting in 1954, some A3 received in a boiler replacement due to something with more efficient boilers of LNER Class A4. 1957 and 1958 were equipped with all A3 Kylchap blowing pipe plant, which had tentatively receive one of the locomotives in 1937.

Because the chimneys of the A1 and A3 were very short because of the narrow British loading gauge, the view of the driver training was hampered by steam and smoke swirls along the boiler. Only in 1960 were mounted on the German model Witte smoke deflectors, so the problem was solved.

Notable trips

Non-stop long-distance journeys

By Nachtankvorrichtung and almost sufficient assessment of the coal is depleted, it was possible to drive through the 632 km long route between London and Edinburgh, without pausing. Because of the long travel time, however, one -stop service to staff turnover was first necessary. To avoid this, the tender of five locomotives were provided with a narrow side passage through which the staff could change from the first car manufactures. The first regularly scheduled non-stop driving on this route took place on 1 May 1928, at that time was a sensation.

Speed records

The building is still under state of A1 No. 4472 Flying Scotsman was driving on 30 November 1934 as the first British locomotive officially 100 mph (161 km / h), a record which was held unofficially from the City of Truro since 1904, a 2 ' B- locomotive of the Great Western Railway. Rebuilt 4472 was the first in 1947.

Even faster drove the A3 No 2750 Papyrus on March 5, 1935. On a long-distance test run between Newcastle and London she reached with a 220 -ton train 174 km / h and 431.7 km at an average speed of 109 km / h Thus, it remained the fastest unfaired steam locomotive in the UK, because faster were only the streamlined locomotives of the LNER Class A4 and the Coronation class of London, Midland & Scottish Railway (LMS).

Exceeded in normal operation the locomotives regular 90 mph (145 km / h).


All 79 A3 locomotives survived the Second World War. The first locomotive was retired in 1959, the others followed 1961-1966.

The only preserved until today locomotive Class A3 is the No. 4472 Flying Scotsman, one of the most famous steam locomotives ever (see pictures). The 1963 decommissioned locomotive that had the number 60103 worn when British Railways was purchased by Alan Pegler and again provided with their characteristic green LNER livery and their old number. She also received a second tender to cover longer distances without water companies can. In this form, many special trips have been made with the locomotive, including in the U.S. and Australia, where she set another record aufstellte in 1989: in 9 hours and 25 minutes, a distance of 422 miles ( 679 km ) was non-stop traveled - the longest ever operated nonstop trip with a steam locomotive.

Other private owners followed, but finally let the state of the engine not to bet more. After the owners could not afford the funds for a restoration, was dismantled for several years and with an uncertain fate in London the Flying Scotsman. 1996 Dr Tony Marchington bought the locomotive, and it was very costly for £ 750,000 restored. Since 1999 the Flying Scotsman is operational again, and in 2004 he was sold to the National Railway Museum in York. The locomotive is still used regularly on special trips, mostly on the railway line York - Scarborough. Currently (2009) it is a radical overhaul.