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The LNWR 0-6-0 Coal Engine in 5" Gauge
The Prototype
One of the first locomotives designed when F W Webb came into office in the early 1870’s was the 0-6-0 Goods engine, later known as the Coal Engine. It was introduced in 1873 and had long lived design features adopted by Crewe since well before his predecessor, John Ramsbottom. The engine had inside cylinders of 17" diameter by 24" stroke, with the slide valves between them and operated by Stephenson’s valve gear. The early versions had the usual wooden buffer beams, the sloping smokebox with a horizontally hinged door and were not fitted with brakes. The standard 1500 gallon wooden framed tender, developed under Ramsbottom, was used with the earlier greased axleboxes. Later engines were fitted with round smokebox doors and after a period with wooden brake blocks, the engines had more durable cast iron examples.
More notably however, the locomotive was fitted with an altogether new wheel design, which were variously described as having either ‘I’ or ‘H’ section spokes. They were cast horizontally in one of the first applications of centrifugal iron casting, where the mould was slowly rotated and the molten iron was fed into the centre of the wheel. These wheels were the subject of the lengthy development work undertaken for the Coal Tank design which is also a model supported by Hotspur with drawings, castings and materials. These goods engines were produced in very large numbers and the total of 500 were built between 1873 and 1892. Many of the early versions had no balance weights on the wheels and the finish was plain black; the lined out engines being introduced in the 1890’s. The larger 1800 gallon tenders with oil filled axle boxes were adopted as these became available for other locomotives across the system. Two versions of the prototype are shown here. The tenders used were based on the design originally introduced by John Ramsbottom, beginning with a water capacity of just 1500 gallons and later increased to 1800 gallons. All the tenders at that time had wooden frames. This was not to provide a ‘crumple zone’ in the event of a crash as so many have speculated, but because iron was expensive to produce in those days and wood was cheap, especially as Crewe works was also producing all the necessary rolling stock which was all made from wood at that time |
Here engine No. 3209 has the later round smokebox door and brakes but these are still the early wooden type although it is coupled to the last version of the 1800 gallon tender from around the 1890’s. Here the tender has the standard spoked wheels. The black paintwork has been lined out but the whole locomotive looks in need of a good clean.
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Engine No. 920 is an original Coal engine build with the Ramsbottom smokebox and the Webb chimney and safety valve casing, but without any brakes. They relied entirely on the wooden brakes on the tender which in this case is a 1500 gallon version with grease axleboxes and no coal rails or cab side panel platework. Note the paintwork is just plain black and that the wheel on the locomotive do not have any balance weights. It is also clear that the tender is fitted with the same style of ‘H’ section spoke wheels that are fitted to the engine – these were made for the trailing wheels for the Coal Tank.
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The Model
Although the Coal Tank was introduced after the Coal Engine, the build was simply an extended version leaving the original frame profile and just adding the extra frame for the trailing wheels. This means that the frames for the miniature Coal Engine are already available and all the frame stretcher details are therefore identical. All that is needed is a new drag beam assembly and this has been designed and a prototype chassis is being assembled. In addition the opportunity has been taken to adopt more laser cut parts to speed up the build, where no such assemblies were available before. These comprise the four main coupled axle horns, the simple main stretcher and the two halves of the trailing axle spring housing stretcher. The much more complex motion plate stretcher has been left as a simple bronze casting to allow the additional ribs to be silver soldered in place. The only other axle parts that need special manufacture are the two side cheeks for the trailing coupled wheels but these can be made very easily from stock bar, carefully milled, and silver soldered to reproduce the detailed items in keeping with prototype.
A photograph of the latest progress with the Coal Engine chassis will be included here for those who are interested and it will be shown at exhibitions in due course. A part general arrangement drawing and the necessary detailed drawings are being compiled to complement the Coal Tank information that still applies. The description of the construction of the necessary Coal Engine variants was published in the Engineering in Miniature magazine from March 2016 till August 2017. |
The drawings will also detail other changes needed for this model compared to the Coal Tank. The author's model with the new features of the running boards, chassis brackets and splashers, plus the cab side assembly and reverser.
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phone |
+44 1600 713913
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address
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1 Highmeadow, Wyesham, Monmouth, Monmoutshire NP25 3TB
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Last updated 6th August 2020
