In 1919, ‘The Engineer’ carried a short reference in its January 13th issue to experiments in using ‘coal dust’ in locomotive fireboxes, describing them as powdered fuel engines:
Of the Great Central powdered fuel engine we can at the moment say no mote than that we hope before long to place a complete description before our readers. We dealt in our issues of Aug. 23rd and 30th, with the device employed on American locomotives for coal-dust burning, and we may note now that, whilst the general principles followed by Mr. Robinson are naturally not very different, the arrangement of the parts has been worked out afresh. The Great Central experiments are being watched with interest, and in view of the present desire to economise fuel, and the now proved fact that coal-dust can be used satisfactorily in locomotive fire-box, we shall not be surprised to see other engineers following Mr Robinson’s lead.
To be honest, I’d not considered the idea of pulverised fuel as a source for steam locomotives before, considering the availability of considerable quantities of black coal from mines in the UK. There were perhaps other countries where good steam coal was not so readily available – the USA, Italy, Germany, and Australia – at least in some areas can be considered in that category. Aside from the efficiency, the complexity or otherwise, of burning, handling and distributing pulverised fuel, the economic conditions might well have a part to play in its use.
Take the Great Central example above, that was in the immediate post First World War era, so along with compounding, it was seen as a way of improving the efficiency of motive power through the use of a wider range of fuels. Primarily though, a combination of increased fuel cost and poorer quality coal led to J.G. Robinson’s experiments in using coal-dust, or pulverised fuel. In addition to economics, there was a belief that this would increase the level of combustion, and hence operating performance and efficiency.
The first trials took place with four 8K Class 2-8-0 freight locomotives (later Class O5 in LNER days), between 1917 and 1924. The 2-8-0s were fitted with a bogie tender, housing a container holding the coal-dust, which was then fed to the locomotive’s grate, through pipes. The conventional fire grate and ash pan had been replaced by firebricks, and the fuel blown into the front of the firebox, using a system of fans, driven initially by a petrol engine, and later by a small steam turbine. The coal-dust used in these trials was recovered from colliery screens, and then dried before use on the locomotive, where it was mixed with air for combustion. Amongst the downsides to the use of this arrangement was getting the air to coal-dust mixture right, and the design and layout of the firebox, and even mixing the coal dust with oil (colloidal fuel) proved equally problematic.
The following is an extract from a book entitled “Brown Coal”, published by Australia’s Victoria State Electricity Commission in 1952 gives some insight into Robinson’s experiments on the Great Central.
“The Great Central Railway Company had fitted two locomotives for burning, respectively, pulverised black coal and colloidal fuel, the latter a mixture of about 60 parts of pulverised coal and 40 parts of oil. The pulverised fuel locomotive was in regular service on one of the heaviest runs in England, between Gorton near Manchester and Dunford, a distance of nearly 18 miles; it had to take, its place with a 500-ton load among similar trains; half a dozen of these were following trains, all of which were likely to be held up if the pulverised fuel locomotive failed. All this indicated the confidence of the Railways officials in the reliability of the pulverised fuel locomotive under everyday working conditions. During August 1921 the author had a run on the footplate of the pulverised fuel locomotive on a day when the general traffic conditions were as described above. Running, tests had bees made previously with the two converted locomotives and with another using lump coal; for maintenance of steam pressure and rate of travel on the heaviest portions of the run, colloidal fuel showed best and pulverised coal next best. Two separate engines on the tender, which was specially built for this service, drove the feed screw for the coal and the blower fan. Technically these experiments appear to have been quite successful, but the official view of the company was that there would be no commercial gain in pulverising its high-grade black coal.”
These experiments with alternative fuels were not uncommon on a number of railways in the early years of the 20th Century, as William Holden’s oil-fired examples on the Great Eastern Railway testify. However, in the UK at least, the likelihood of more ‘coal-dust fired’ locomotives was unlikely to grow, and indeed it did not, and remains a curiosity.
It wasn’t just the Great Central that was experimenting with pulverised, the Southern Railway carried out some work in the 1920s, based on those developments in the USA. In 1916, The New York Central converted a 4-6-2 to burn pulverised coal, and although not leading to great numbers of similarly fuelled steam types, these experiments were important in looking in detail at the performance, and efficiency of a steam locomotive over a wider range of fuel types. Brown coal and lignites were relatively common in European countries, such as Italy and Germany, where perhaps they were more fully developed.
In Germany, six of the Prussian “G12” Class 2-10-0swere converted to ‘coal-dust burning’ in 1930, but because of the considerable deposits of lignite/brown coal, a much softer coal with a high water content, new ‘coal-dust burning’ locomotives were being built in the 1950s. In the former East Germany, the state railway Deutches Reichsbahn (DR), constructed a pair of 2-8-0s in 1954/5 – the DR Class 25.10. The second of these was designed and fitted for coal-dust firing, and intended for both heavy passenger and goods workings.
The initiative started in the early 1920s in Germany, when the state railway organisation brought together the loco builders and the coal industry, and established a business to conduct research on the use of pulverised fuel for firing steam locomotives. This organisation – SLUG (Studiengesellschaft) – introduced the ‘Stug’ system, working with Henschel & Sohn, and at the same time a parallel development was being trialled by AEG. In both cases, the initial work was for stationary boilers. In later years, the system used in East Germany, was ascribed to the GDR’s Hans Wendler, and unsurprisingly known as the Wendler coal-dust firing system, which is the system used on the later DRG 2-10-0s.
During the 1950s, coal-dust fired steam locomotives continued to work in Germany, and in East Germany, the DRG converted 20 of the Class 44 2-10-0 heavy freight locomotives, of which almost 2,000 had been built since the 1920s. The system was ultimately replaced – largely due to the complexity of the fuelling system needed – by oil-fired locomotives, which were still in use in Germany in the mid to late 1970s, up until the end of steam traction.
The Southern Railway had built a new class of 2-6-0 locomotives, under its then CME, Richard Maunsell, for passenger duties, with two outside cylinders, weighing in at 110 tons, and developing some 23,000lbs of tractive effort. These new “U” Class moguls included number A629, built in 1928, and fitted with the German design of pulverized fuel system, supplied by AEG. The idea, unsurprisingly, given this was taking place during the great depression of the 1920s and 1930s, was to improve the operating efficiency of the steam engine. The trials took place on the London to Brighton line, and were used as a means of deciding whether it was more economical to convert to the poorer grade of fuels for steam traction, or implement widespread electrification. It was a short lived experiment, and brought to an end following a minor explosion that occurred when the coal dust came into contact with the hot sparks being ejected through the chimney. It was subsequently found that the blast of the steam engine in normal operation was drawing more coal dust/pulverised fuel through the boiler, without being burned.
The locomotive itself was returned to normal coal burning in 1935, and renumbered 1629, and survived to BR days, and finally withdrawn from service in 1964, as BR No. 31629, and of course the Southern Railway embarked on major electrification schemes.
Another intriguing attempt at using ‘cheaper’ fuel, was to mix the coal dust/pulverised fuel with oil, and described as “colloidal fuel” in some quarters. In fact this too wasn’t a new idea, and had been used in ships during the First World War, when fuel supplies were becoming low. The idea seems to have been useful only where the mixture of oil and pulverised coal could be injected into boiler furnaces through an atomising burner, and the complexities of using such an arrangement on a steam locomotive footplate can only be imagined. Well on Britain’s railways in the 1920s and 1930s perhaps, since normal bituminous coal was readily available.
Curiously, the idea was raised again towards the end of the Second World War, in the UK’s parliament, when this observation was made in Hansard:
But, in the end, even the UK’s experiments with oil-firing steam traction was not a success, and the increased march and takeover by diesel and electric traction was the death knell for this idea. But, elsewhere, trials and developments continued, including ‘down under’.
Australia – too little too late? As mentioned earlier, a study carried out on behalf of the State Electricity Authority of Victoria looked in great depths at the use of brown coal/lignites for boilers, and including steam locomotives. The work began in the immediate Post Second World War period, and was driven by industrial action on the New South Wales coalfields, and dwindling supplies of hard, black coal, and the coalfields in Victoria were exhausted. To combat this, for the railways, a large number of locomotives were converted to oil-firing, and the experiments with pulverised brown coal began by fitting the 2-8-2 freight locomotive X32 with the necessary ‘Stug’ equipment from Germany.
This experiment was a success, and in 1951, the remaining 28 members of the class were converted to coal-dust, or pulverised fuel firing, and even one of the prestigious ‘R Class’ 4-6-4 passenger types – No. R707 was converted. The “R Class” was built by the North British Locomotive Co. in Glasgow, and worked some of Victoria’s prestige, express passenger services.
Whilst the experiments – and indeed operational running with the “X Class” and R707 was a success, time was not on the side of this technology, since dieselisation of Victoria’s rail system was rapidly gaining ground, and in 1957, the decision to abandon ‘coal-dust fired’ steam locomotives was taken. R707 was returned to normal lump coal as fuel, and was rescued and fully restored to operations as a preserved example of a fine class of steam locomotive.