LNER Class A4 - Definition and Overview

Mallard at York

Sir Nigel Gresley introduced the famous LNER Class A4 locomotives in 1935 to pull a new train called the Silver Jubilee, between London King's Cross and Newcastle, in celebration of King George V's 25th year of reign.

The A4 pacifics (with the 4-6-2 wheel arrangement) were designed for low consumption of coal and water on all kinds of services; passenger and freight. With the introduction of the double-exhaust Kylchap blastpipe, the consumption levels of the above dropped even more, gaining more revenue to their operators.

On July 3 1938 the Mallard, newly fitted with the Kylchap exhaust, set a world speed record of 125 mph (201.2 km/h), pulling six cars plus a dynamometer car. Although the dynamometer car indicated a top speed of 126 mph (202.8 km/h), Sir Nigel Gresley never accepted this speed as the record-breaking maximum. He claimed this speed could only have been attained over a few yards (metres). He was comfortable that the German speed record of 124.5 mph (200.4 km/h) had been surpassed.

The Class A4 locomotives were known to train spotters as "streaks".

External link

• LNER Encyclopedia Page covering the history and development of the LNER A4 Pacifics (http://www.winwaed.com/rail/LNER/locos/A/a4.shtml)
• Detailed list of the names, numbers and production dates of LNER A4 locomotives (http://www.bath.ac.uk/~hssmrg/a4.html)