Gazette - August 2018 (Vol 20 No.8)

The prototype GWR Steam Railmotor 80 - with permission from Steam Picture Library

“Hello, I am GWR Steam Railmotor 80 – no fancy names here, just a number! I was built in 1906 to Diagram Q, one of 8 units, by the Gloucester Wagon Company. Construction of the various designs was performed by the GWR itself but a number like me were contracted to other companies. Unlike other siblings such as No. 93 (Diagram R of a 70 foot length – 74ft over the buffers), which is now preserved, I am only 59.5 feet long (63ft 6in over the buffers). Why I am shorter, I am not sure. Perhaps it was weight saving or cost saving or loading gauge restrictions on some routes. In any event, I remained in service until 1935 when I was withdrawn. Unlike many other steam railmotors I was not converted to an auto-train push-pull coach unit – of which the last was withdrawn in 1958.
The GWR steam railmotor units, despite differing coach designs, were all powered by essentially the same motor design. Soon after initial deployment of the units it became apparent that motor breakdowns required removal of the whole coach from service. And as a result spare power units were introduced and kept available so that in the event of a failure the power unit could be quickly (?) replaced and the coach returned to service – thus continuing its revenue earning capability with the minimum of disruption.
Removing the motor required the whole boiler to be lifted through a panel in the roof to about 23ft and this could only be performed at major service centres where facilities with sufficient lift height were available. Breakdown cranes could also be used. There were, however, several design flaws that probably resulted in the demise of the concept. These include issues with the vertical steam boiler having its tube ends not covered in water as in a conventional design, and this resulted in leaking. The ride of the steam railmotors could also be uncomfortable with vibration occurring under some circumstances.
Why were we, the steam railmotors, built? As early as the mid-1800s designs were being produced for a combined engine and coach and some very interesting and curious designs were developed. However, from the early 1900s railway companies were seriously looking for cost savings in railway operations. The GWR invested more than any other UK railway company in the concept of a steam railmotor with some 99 units constructed. From December 1903 GWR Board approval for construction of the first of these was issued. The last were built in 1908.
The steam railmotor was designed with needs of branch lines in mind where the passenger traffic was light. However, the power of the steam railmotor was low compared to a conventional locomotive and so the lines on which the rail motors could be run were restricted. Inclines were an enemy. The concept was, however, a success and passenger numbers increased. In fact, part of the operation of the units was to enable stopping at intermediate points between stations. Passengers were expected to climb into the coach using the ladder units provided. However, this was quickly realised to be impractical and so the ‘Halt’ was created – a raised platform, typically of just one coach length, just sufficient to allow easy access. Where possible, trailer coaches were deployed to increase capacity. Often these were coaches converted from normal passenger stock, including clerestory units, but with a driver’s cab created at one end to enable double ended operation. The demise started from about 1915 when the utility of the auto-train, often a single coach with a small tank loco fitted for push-pull operations, really started to take effect with its greater capacity for load and expansion in trailer coach attachment.
Now, whilst I may have been withdrawn in 1935 my details, and those of other steam railmotors, have been preserved in various drawings. I am pleased to say, that a number of model manufacturers and kit makers have taken up the challenge to ‘preserve’ me in miniature form. One such kit maker is Scorpio Models who offer both Diagram Q and Diagram R models to be built in 7mm/ft scale.zz The shedding for steam railmotors existed throughout the GWR and in the Cornwall area included St. Blazey servicing the Lostwithiel – Fowey Branch. Was I ever stationed there? That cannot be confirmed but it could well have been the case and it would be a logical choice for the fictitious location of my model.
The following is a report from my model maker…

The model comprises three major components: the non-powered bogie, the steam power bogie, and the coach body plus roof. Construction was tackled in that order.

Soldered construction was required as the kit consists of a combination of brass and nickel-silver etches. There were also copious castings in brass, nickel-silver and white-metal. A resistance soldering unit (RSU) was used in conjunction with solder paste which contains a non-corrosive flux – in my view acid fluxes are something to be avoided if possible.

The design of the trailing bogie followed prototype practice and involved fabricating the complete structure from trusses to brakes. Each axle is free to move in the vertical plane within its horn blocks. There was a certain degree of uncertainty about how well this would actually work. There is neither rocking beam nor springing and the fall of a wheel and adhesion to the track is therefore dependant on gravity. However, even after painting, the wheel The constructed bogie - note the detail. The completed trailing bogie in primer. sets are free to move and running trials have proven the concept.

The prototype coach could be fitted with Dean, Standard or American type of bogie. The kit includes etches for the Standard type. The trailing bogie is designed to allow compensation as each axle can rise and fall freely within the frame. It is quite a detailed unit. This was the first of the major components to be built and it gave a feel for the construction of the motor bogie which also was a very detailed unit to build.

Building the boiler was challenging but satisfying. One of the challenges was that there are two etches that had to be rolled to form the top and bottom of the cone sections. The unit is actually built up from an inner layer formed inside lateral discs which then had the outer layer applied to form the unit.

The chassis is compensated but only on one side i.e. there is a rocking beam on one side that allows the two wheels on that side to rock up and down. The wheels on the other side are rigid. For the compensation to be effective the motor mounting has to be free inside the boiler. At one point during trial running it was found that this freedom was restricted. Once this problem had been corrected the compensation was found to work well.

There is a great deal of detail that can be seen externally not to mention the internal construction with inner boiler. It is by design a vertical unit with the fire at the base (the fire door is open) the tubes run vertically, the smoke box is at the top as is the steam collection. Referring to the pictures at the top of the following page; the steam pipe has to run all the way down to the cylinders from the regulator; the exhaust runs back from the sides of the cylinders; the regulator is in a fairly conventional location and the reverser is the lever painted red.

The design of the prototype was such that the centre line of the boiler of the power bogie provided the point about which the bogie pivoted. The prototype unit was installed with rubbing plates and buffing springs attached to the underframe to maintain this axis. The base of the boiler was also attached to two hefty transverse beams that were slung from the underframe (solebars) by scroll irons. The beams on the model can be seen in the photos together with the ‘sprung’ rods dropping from the bogie side frame to the beams.

The guidance in the instructions was insufficient and incorrect in that it indicated that the scroll irons be mounted forward of the position they now occupy. They were also specified to be located too far apart as compared with the vertical rods. And in the initial position, as per the instructions, there was no clearance for the bogie to swivel as the motion plate fouled on the leading transverse beam. It was only after careful measurement with the model on a flat surface that these issues were deduced. Finally, when the cast white-metal floor was initially installed it pushed the whole bogie forward and the leading axle looked very strange sitting in the air raised above the track! On reflection, these issues may have been caused in part by the chimney and roof not being built with identical overhang at each end – about a 1mm error. This was, of course, my fault. However, some notes in the instructions on the interdependencies of all the related components would have been useful.

The prototype power and trailing bogies wheels were of 4ft diameter. Slaters wheels have been used on the model.

The model is powered by a Mashima motor and a Zimo DCC decoder loaded with sound files of railmotor no. 93 from YouChoos in the UK. A Stay Alive unit from DCC Concepts has also been installed to ensure continuous power and DCC signal as pickups are only installed in the power bogie.

The coach placed over the bogies showing the rough assembly of the whole model.
The coach design was such that a central vestibule serviced two seating compartments. In addition there was a luggage compartment just behind the engine compartment. Driving facilities existed at each end to allow control and travel in both directions.

The coach work was built from brass etches and was fairly conventional. Each side was made up of two panels on either side of the passenger vestibule with detail relief provided by overlays.

The roof had to be rolled from its flat etch and this required some delicate handling as much of the panel was half etched to provide detail for rain gutters etc. The roof was designed such that some of the partitions were duplicated – some attached to the roof helping to form its shape. These partitions would provide a detail face to partners already installed as part of the coach itself. Such false partitions helped provide the shape of the roof but getting the whole length to sit down on top of the coach sides was a challenge. This was eventually achieved in conjunction with securing the base of these partitions through the floor with tabs provided. These tabs were meant to be twisted to retain the roof but this was considered unsatisfactory as the tabs were quite large and risked deforming the partition if twisted. The partitions were secured by drilling through the tabs at the under floor level and inserting split pins to hold the roof in place.

One of the differences between this Diagram (Q) and that for Diagram R of which Railmotor 93 (preserved) is a member is in the hand-rails. Number 80 has far fewer such items. Number 93 has an additional number for access from ground level for the crew.

Clear styrene was used for the windows fixed with G-S Hypo Cement. Windows were cut out from sheet and manoeuvred into place on the end of a sticky stick used by jewellers to position gem stones, etc. This was the first time that this method has been used and it certainly made it easier.

One of the periods of operation for the layout is the early twentieth century. Between 1912 and 1922 the GWR adopted a crimson lake livery. Phoenix Precision sell GWR Coach Lake, but such paints are not available here in Australia. Nor are the usual Halfords spray cans. Consultation then took place with experts in the UK and an automobile colour was recommended.

Preparation consisted of a good going over with a fibreglass pencil followed by a scrub with ‘Bar Tenders Friend’; a thorough wash down with water, and finally, a wash in acrylic thinners. An automotive etch primer was applied by airbrush after allowing time for the model to be completely dry. The power bogie showing the scroll bars and cross members that serve to support the bogie under the coach. The coach was air-brushed using Vauxhall Burgundy Red provided by a local automotive supplier. The roof was painted in Railmatch GWR Roof White, purchased during a UK visit. The underframe was finished in Tamiya Nato Black XF-69, which is actually a shade of grey.

Lining was applied using a Bob Moore pen using a Humbrol gloss bright yellow, number 69, to represent gold lining. Transfers were from a mix of Fox Transfers and HMRS Pressfix.

The various components were then finished in Humbrol Satin Coat.

Single loco lamps have been installed at the front and rear and the DCC facility can be activated to switch colours of the red/white LED installed in each lamp depending on the direction of travel. The lamps were purchased from Modelu in the UK and the LEDs sourced from DCC Concepts. The lamps are 3-D printed in a red plastic to the GWR pattern but have been over-painted red to reduce the glow from the LEDs – red being the correct colour of the lamps prior to 1938/39.

“Well, that is my life story. Was I a truly ‘useful’ engine? I like to think that I was and that my new life, in model form, at Uley Junction will serve my patrons well. And I can rest content that, as the fore runner to the auto-train services, and indeed to the modern day DMUs that ply back and forth across the UK, I was an inspiration to the generations that followed and a credit to my designers and engineers that made me possible.”

The build of this model could not have been completed without input on the painting of the coach. My thanks to Derek Mundy and those that he asked to assist – Alan Brackenborough and Ian Rathbone.

1. An early short video as the unit was being built https://www.youtube.com/watch?v=jFJt5oujRq4
2. The completed model on test track https://www.youtube.com/watch?v=4OnBVExFkIg&t=34s

1. The Steam Railmotors of the Great Western Railway Ken Gibbs – The History Press
2. Wikipedia web page https://en.wikipedia.org/wiki/GWR_steam_rail_motors Note the error in the length of Diagram Q.
3. GWR Modelling web site http://www.gwr.org.uk/index.html - Liveries
4. A Pictorial Record of Great Western Engines – Volume Two: Churchward, Collett and Hawksworth Locomotives J.H. Russell, Oxford Publishing Co., Pg 55
5. A Pictorial Record of Great Western Coaches – Part 2 1903-1948 Including Brown Vehicles - J.H. Russell, Oxford Publishing Co., Pp 27, 33
6. STEAM Picture Library