LNER Gresley A4

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60028 Walter K.Whigham awaits departure from Kings Cross with the Heart of Midlothian

60032 Gannet at Kings Cross shed

The LNER's Express Pacific designs were probably the most famous of the LNER locomotives. And of these Pacifics, the A4 is probably the most famous of all. Its distinctive streamlined casing has come to be a symbol of 1930s luxury and fascination with speed. Even today, it is an A4 that holds the world speed record for a steam locomotive.

The concept of a high-speed inter-city train service was inspired by the German State Railways diesel-electric Fliegende Hamburger, and the USA Burlington Zephyr. Gresley calculated that a modified A3 with streamlining should be able to haul trains of eight or nine carriages at similar 100+mph speeds. Trials with the A3 Papyrus and A1 Flying Scotsman confirmed these calculations, and the LNER Board gave the go-ahead to build the "Silver Jubilee" trains.

The "Silver Jubilee" was designed as a complete streamlined train including streamlined coaches that included valvences between the coach bogies. The new A4 locomotives had a wedge-shaped streamlined shape that was refined with the help of the National Physical Laboratory. The A4 also represented an increase in boiler pressure (to 250psi), and was designed to steam more freely than the A3s with the addition of streamlined steam passages and larger piston valves. Later additions included a Kylchap exhaust and Westinghouse QSA Brake Valves.

The first demonstration train ran on 27th September 1935, and touched 112.5mph. The driver actually ran much faster than expected due to the A4's smooth running, but the new coaching stock suffered a rough ride. This was quickly corrected by changing the suspension arrangements, and a continual programme of permanent way upgrades.

The A4s proved to have a reliable and safe record upto World War 2, and participated in a number of high-publicity speed runs and trials that culminated in Mallard's 125.5mph run of 3rd July 1938. This still stands today as the World Speed Record for a Steam Locomotive.

In common with the other Gresley 3-cylinder designs, the A4's suffered from poor wartime maintenance. It would not be until 1948 that attempts were made to re-instate high speed runs.

By the 1950s though, they were being displaced by Peppercorn A1s and then Deltics. In the 1960s, the A4s experienced an 'Indian Summer' in Scotland due a particularly high number of diesel failures.

Six A4s survive in preservation, including two in North America.

This description is based on the [LNER A4] page on the LNER Encyclopedia at http://www.winwaed.com/rail/LNER/locos/A/a4.shtml and was written by the LNER Encyclopedia's Owner.

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