These photographs, courtesy of the Churnet Valley Railway, show S160 class 2-8-0 no. 5197 on its home railway, the Churnet Valley Railway, in Staffordshire.

During the 2007 season it was planned that the Gloucestershire Warwickshire Railway was to play host to an unusual locomotive: a wartime American austerity S160 class 2-8-0. Many hundreds of these workmanlike engines were turned out and exported to Europe, several of them spending time on the UK national network.  Sadly the loco didn't come in the end but here is our history of this unique class of locomotive.

During World War 2 the railways of Britain were invaded - by locomotives that shared none of the elegant lines of typical British designs. They were chunky, powerful-looking, robust and - oh, so American. They were the S160 2-8-0s that were constructed in considerable numbers, many shipped to Britain for the D-Day invasion of France in 1944. But while they were being stockpiled, several of them found use on British railways - and the Great Western was the largest user, employing them mainly on coal traffic from South Wales.

The class was designed by Major J W Marsh of the Railway Branch of the US Corps of Engineers, later to become the United States Army Transportation Corps (USATC).  During the 1930s, the US Army adapted a Baldwin 2-8-0 design of World War 1 vintage to create class S159, of which just eight were built in 1941. Major Marsh, in conjunction with the Lima locomotive works in Ohio, undertook a large number of improvements, including details from the 'lease-lend' S200, a 2-8-2 built for the British Army (none of which ever reached Britain), to create the S160 class. The first of them rolled off the production line in 1942. There were variations of the class too: S162 and S166 for Russia (with its broader gauge track) and S161 for Jamaica.

The S160 could hardly be labelled an aesthetic triumph. Instead, it was very much an austerity design intended for fast and economic manufacture, simple maintenance and a relatively short working life. Cast bar frames, greased axleboxes, fabricated rather than cast components and wide tyres contributed to relatively light weight and the ability to cope with the most indifferent of track. The boiler incorporated thermic siphons that supported the brick arch, although these became troublesome in practice and later boilers omitted this feature. The all-steel boiler steamed well, with or without the siphons, while the wide firebox could burn almost anything, including oil. The bogie tender was large by UK standards, carrying 6,500 US gallons (5,400 Imperial gallons) of water and nine US tons (eight long, UK, tons) of coal. The cab was roomy and comfortable with controls easy to reach for both driver and fireman.

Use in the UK

In all, 2,120 S160s were produced, construction being shared between Lima, Alco (American Locomotive Co) and Baldwin. Of these, nearly 800 were shipped to Britain under a lease-lend agreement signed by President Roosevelt and Prime Minister Winston Churchill. The rest were shipped direct to Europe, North Africa and China - no 5197 being one of the Chinese contingent.

The first 398 to arrive were used by the British War Department to supplement depleted locomotive stocks in the UK, although adaptations were carried out in UK works to make them suitable for use here, not least of which was turning the wheel flanges to suit UK track. Even so, they had a tendency to 'snatch' pointwork when running in reverse. Their distribution was as follows:

• 174 - Great Western
• 168 - London & North Eastern
• 50 - London Midland & Scottish
• 6 - Southern

Their use in the UK was relatively short-lived as they were all taken back into USATC stock after D-Day and shipped to mainland Europe.

The locomotives must have been a shock to GWR crews as they were quite unlike anything that had ever run on the system before. But while GWR sensibilities may not have led them to be liked, in practice they proved to be extremely powerful, surprisingly economical and entirely suitable for heavy freight traffic. They also enjoyed rapid acceleration and were also often used for troop trains and, occasionally, ordinary passenger traffic.

However, they did suffer a high failure rate - they tended to develop hot driving axle boxes while those fitted with thermic siphons tended to suffer leaks and tubeplate cracks. The locomotive steam brake was very poor - particularly when working unfitted trains. In the boilers, a major weakness was excessive corrosion and fatigue of the firebox crown bolts, especially if the boiler water level was allowed to fall too low or there was an accumulation of scale on the firebox crown. As a result, there were five incidents of the crown collapsing while in UK use, a disaster for the crew, of course, although only one such explosion resulted in fatality of a fireman. These accidents may also have been contributed to by the unusual gauge frames, which could give a false reading if the valves (which opened the opposite way round to UK gauge frame valves) were not opened properly - in other words, a satisfactory water level could be indicated when the water level was, in fact, dangerously low. Incidentally, the gauge glass was designed to last the life of the locomotive - rather than a tube as in UK practice, the American version was a bored solid square-section block of glass, the light refracting in the glass to make the water appear black.

Post war

After hostilities ceased, the USATC transferred most of the surviving locomotives to countries throughout Europe whose railways were struggling to get back to some kind of normality. After the war, the following countries eventually took members of the class into their own stock:

• 576 to Poland as PKP classes Tr201 and Tr203
• 510 to Hungary as MAV class 411 and CSD class 456 (26 broken up for spares)
• 243 to Italy as FS class 736
• 80 to Yugoslavia as JDZ class 37
• 50 to Turkey as TCDD class 45171
• 30 to Austria as ÖBB class 956
• 27 to Greece as SEK class THg

Several locomotives surplus to USATC requirements were sold direct to other railway systems, notably China, no. 5197 being among those sent there. Some were significantly adapted to suit local conditions and that includes no. 5197, which has air brakes fitted, driven from the smokebox-mounted pump - a significant improvement on the poor steam brake originally fitted. It also has an air-operated reverser which, apparently, is extremely easy to use. The locomotive retains one of its original gauge frames, the other having been replaced by a conventional Klinger-type gauge frame.

Although many only survived for a very short time, a good number continued in use until relatively recently and several survive either preserved or dumped. Six have been imported to the UK, some of which saw service on British railways before D-Day.

Only a small handful ever found their way back to their country of birth.

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