The Mallard

Max Commercial Speed	*90 mph 145km/h (See Below)
Speed Record	126 mph 202km/h
Introduced	1930
Picture thanks to the A4 preservation society

Introduction

The Mallard was one of many Gresley Class A4 steam engines built by LNER in the 1930s for high speed passenger transport along the East Coast Mainline (London-Edingburgh) shown in blue on the map. It was a rival project to the LMS Silver Link which achieved 114mph (185km/h) earlyer in 1938 on the west coast mainline shown in red. Unlike other steam engines the design incorporated some aerodynamics, even if it was somewhat crude. This engine was used as an express locomotive right into the 60s in the UK until diesels on northern routes.

Service Speeds

Today top commercial speeds are determined by either the condition of the track (called line speeds) or the top designed speed of the engine (whichever is smaller). There was no strict top speed in the 1930s. The steam engine was made to go as fast as the driver and fireman could make it go. (This wouldn’t be possible now because engines today have upper limits much faster than their design speed, the wear and tear would be enourmous). Speeds of over 100mph (160km/h) in service were commonplace, however services were usually timetabled assuming a top speed of 90mph (145km/h). For the 1930s this was an extremely fast rail service

Did the A4s help the mainline?

The East Coast Mainline where the A4s ran was maintained at conditions allowing 90mph travel for large sections in the early-mid 20^th century. As a result the modern inter city 225 trains average a speed of 112mph between London and York, fastest train service in the UK and putting the UK in 6^th place for fastest shedules in each country. This average speed is also better than average speeds along dedicated high speed lines (eg 103mph Firenze -> Rome, Italy). Undoubtedly part of the reason for fast services today is the fact that it was already in fairly fast condition (90-100mph (145km/h - 160km/h)) before high speed trains came along (125mph (200km/h) and now 140mph (225km/h)) so it has been viable to upgrade large quantities of the mainline for fast running. (Note: The Section of line between London to York includes Stoke Summit where the Mallard set the speed record)

The Record Run

Above: This engine is big. Source: A4 Society

The record run of the "Mallard" on July 3rd, 1938 was made with a six car streamline set plus a dynamometer car, with a total tare of 240 tons. The Mallard was chosen because it was one of the four engines with Kylchap exhaust at that time. These engines had freer running qualities and higher speed than standard A4. I believe that the Mallard was the first A4 fitted with Kylchap exhaust and had had about three months of service at the time of the speed run. The run started from Barkston triangle, running southbound. The Mallard pulled the train over Stoke Summit at 75 mph, then accelerated downgrade at a gradient of 1:178 to 1:200 over six miles distance to attain a speed of 114 mph. It eventually reached a speed of 125 mph, with a peak at 126 mph for a few seconds. After that it ran at a speed of at least 120 mph for another three miles. By then the inside big end showed sign of overheating and the engine had to run light back to Doncaster for repair.

The big end is the end of the coupling rod (i.e. the rod that goes from cylinder cross-head to driving wheel - Treibstange in German) that is connected to either the crank pin on the wheel if on an outside cylinder, or the cranked axle if it's on an inside cylinder.

The Class A4s today

A large proportion of the Class A4 steam engines have been preserved by the Class A4 society and according to them are now in better condition than they ever were in the 1930s. As a result a few have suggested trying to set a new steam speed record. Generally speaking most preserved engines are limited to 30mph (45km/h) but the preserved A4s are still allowed to run at up to 80mph (130km/h), for the sight of steam at speed is what makes them worth preserving.

Is this the steam world record?

Although the Mallard was the fastest engine in the UK at the time, questions about whether or not it is officially the fastest train in the world often come up. Textbooks I have consulted assure it is. However a German train did come almost as fast by about half a mph, and some Germans claim they should have the world record since their train was running on level track whereas the Mallard was running on a very slight decline. Some Americans claim too that they had a steam train run at 127mph (203km/h). This could be possible since a lot of high speed runs were done by steam engines in the USA but many of them were unofficial and therefore rejected.