John Tucker

Having been in recent years a relatively poor attendee of Gauge O Guild, Hornby and Bassett- Lowke Society functions, I decided to break the mould during late summer, 2014, and set off for Shipton Oliffe in Gloucestershire, destination Andrew Hurley’s annual Bassett-Lowke event near Cheltenham. In the knowledge that members are encouraged to take something along to run at these gatherings, I took with me an O gauge coarse scale 2-rail electric powered model of Stirling’s Single No 1 which I had scratch-built back in 1999. Although arriving with a product not of Bassett- Lowke origin, I was made most welcome and hoped that the little engine might be given the opportunity to stretch its legs running a circuit or two on John Ingram’s excellent Bassett-Lowke test track.

Also accompanying me were three teak LNER Bing ‘shortie’ bogie passenger coaches. A more appropriate train would have comprised Great Northern sixwheelers but these truncated and lightweight vehicles seemed reasonably suitable, refitted with smooth-running Hornby plastic wheels, providing a fairly authentic-looking ensemble, all of which quietly whizzed along at a steady scale 60 mph with the coaches gently rocking and rolling behind.

The locomotive (full size)

As for the engine, Mr Stirling’s masterpiece, I have always felt it to have been one of the prettiest things ever to have run on rails. It has been described as a true thoroughbred as it embodies the best elements of some of his previous designs and is therefore the perfect result of selective breeding. When it rolled out of the Doncaster shops in 1870, it demonstrated perfection in design excellence, skilful handling of proportion, elegance and a fitness for purpose, a classic example conceived during ‘La Belle Époque’, (no French connection here but the term has a sweeter ring to it than our concurrent ‘Late Victorian/Edwardian period’). It is a product which epitomises the designers’ adage: ‘form follows function’, and yet the engineering principle of only one pair of driving wheels transmitting drive to a rail head seems to defy the laws of physics.

How could such a locomotive draw a fully laden train of between 200 and 250 tons up the 1 in 105 gradient out of King’s Cross and set it well on its way to York, Edinburgh or Aberdeen, albeit with engine changes of the same class en route? It is said that on occasions, an engine which had brought in the empty stock might have assisted in the rear acting as a banker as far as the platform end. Irrespective of such assistance, how much of the colossal 24- spoke driving wheel was in contact with the top of the bullhead steel rail? Not very much, it would seem.

A tangent, we were once taught, is a radius touching a straight line. Therefore, the point of contact is quite small when viewed from the side, although from the front elevation there would appear to be a greater amount of wheel tread, several inches wide in total, sitting on the cross section of the two rails. In spite of the availability of sand to assist with adhesion when needed, it is understandable that Mr Stirling’s colleagues tried to convince him that coupled driving wheels would have worked better, but the Master would have none of it. He had the fullest confidence that a single wheeler with around 17 to 20 tons on that axle and a wheel diameter of eight feet and one inch would create enough friction and perform perfectly well. And so it did!

The aesthetics

A study of the locomotive’s distinctive side elevation shows that lines run in a fluid progression from front to rear, starting with an upward sweep of the top edge of the frames to the smokebox and the cylinder wrapper. Beyond that, it gently lowers and is picked up by the more dramatic flowing line of the footplate up and over the driving wheel axle and is quietly resolved at the rear end by the shapely leading edge of the cab footsteps. The line of the footplate ahead of the axle differs from that to the rear of the axle due to their different heights. But the shaping of the former is determined by the sweep of the connecting rod during its revolution, just clearing the underside of the footplate behind the valance. ‘Form follows function’ again.

When turning slowly, the driving wheel has considerable majesty, a beautiful motion hypnotic to watch. And if you enjoy a touch of slow motion naughty wheel spin, this is the engine to play with. Incidentally, the travel along the rail of a complete revolution of the driving wheel is a remarkable 17.25cm (6¾in), almost the length of the little locomotive less its tender, at full size about 25 feet. Running at any speed, but especially at around 60mph, the machine appears to be striding out in the equivalent of a fifth gear or super-economic overdrive, using steam expansively as it is often described. The model too conveys precisely this impression. One wonders what its braking distance might be at that speed, in effect, bringing a pair of enormous flywheels to a complete stand. Did school physics lessons tell us that a large wheel, good for traction, should be equally good for braking?

Other elegant features include the pierced paddle box splashers. How fortunate we are to have the prototype preserved with this form of splasher, as later versions were filled in, plated behind the slots. Later still, all panels were fitted flush and plain. The tiny boiler too, with its slim length exaggerated by the absence of a dome. The handsome tall tapered chimney at one end, set well apart from the tall, slender and elegantly curved brass safety valve casing at the other end tempts one to run a finger between the two, along the top of the boiler just to confirm that there really is no dome. It is strange that the absence of such a feature can provide more of a sense of beauty than the presence of one, just as a silence in a piece of music can create, or an uncluttered open space in architecture. On a practical note, it is strange also that steam could be collected efficiently through a perforated pipe inside the length of the boiler instead from inside a conventional dome.

Mention should be made of the simple treatment of the cab, although it offers scant protection from the elements for those who had to operate within it. Perhaps it earns a minus point here? In later versions however, greater consideration was to be given to the relative comfort of drivers and firemen.

Finally the front elevation of the engine presents an interesting interplay of shapes with more fluid lines, tracing down from the chimney top and around both sides of the smokebox, then with an outward swing to encompass and cradle the two cylinders. Although this presents a large flat area face on, therefore hardly aerodynamic (a word yet to be introduced to the vocabulary at that time), this is nonetheless an attractive solution to unite the four elements, all set against the simple cab profile further back.

The model

I was astonished to discover that I could find no evidence that a commercial O gauge model of a Stirling Single has ever been produced. Certainly nothing existed in 1999 and, coupled with the unavailability of such a kit, set me on a course of building my own. This position may still be the same today. Furthermore, the only previous Gauge O Guild reference that I can find to a Stirling Single was a colour photograph by Martin Ackroyd of a superb fine scale model of No. 34 appearing on the cover of the Gazette Vol 10 No10, but with no relating article inside. I may have to stand corrected on this but it suggests that there has been no further modelling interest expressed from within our ranks in this class of locomotive for 25 five years. (See note at the conclusion of the article, Ed.)

A possible reason for this could be that it is a bit of a brute to make. If there had been a kit available in 1999, I would probably not have been tempted to go that route because a preference for scratch-building allows me the enjoyment of designing how a model locomotive may be put together. I then construct them to a specification of almost Bassett-Lowke sturdiness, preferring to handle them firmly, with no detail too fragile or vulnerable.

Using moments of spare time, I thought that I would be able to make up this little engine in about a couple of months at the most as it is not much bigger than something from a Hornby OO range. In reality it took, on and off, nearly a year. And yet, the length of the loco is only roughly a hand span or a little more than an octave if you play a piano. So where is the difficulty? I am now certain that had I discussed this subject with likeminded chums prior to getting this far, I would have been well advised not to touch it. It poses difficulties to be sure, examples of which will crop up during the following paragraphs, but I was seduced by its delightfully unadorned simplicity. How very deceptive. I was nevertheless still determined to go all the way.

However, this venture could only proceed if coarse scale driving wheels of eight feet in diameter were commercially available. Surprisingly they were, from JPL Models via Home of O Gauge at that time. Next, could I squeeze in an MSC JH motor? I must have blinkered vision regarding motors as this has always been my preferred means of propulsion, around twenty of which have been installed in all my engines to date, whether an 0-6-0 pannier or an A4 Pacific, and always with a 25:1 gear ratio. I then discovered that it would be possible to accommodate it if it lay horizontally, with a tight fit inside the firebox without its brass flywheel, and therefore with nothing nasty protruding into the cab. This was a considerable relief as I had no desire to power the trailing wheels as the gearbox would have intruded up through the floor well into the cab interior. Also I dislike the principle of a powered tender (another option) pushing a freewheeling locomotive. No lovely wheel spin to observe doing it that way.

By now, I had collected much printed material on the subject, numerous photographs, scale drawings from Skinley, Isinglass and general arrangement works drawings reproduced to 7mm scale plus helpful advice from the library at the National Railway Museum in York. Two books provided all other necessary information: Patrick Stirling’s Locomotives by L T C Rolt and The Stirling Singles by K H Leech and M G Boddy. It was now time to do some rough sketches to establish the most suitable method of construction and assembly of all the envisaged separate components. The greater the number of individual parts, the better, as this helps considerably at the final painting stage. I include a selection of these illustrations which reflect some of my thoughts at the time.

The build

I should have come clean earlier and declared that I am not an engineer and, as I am lathe-less, I am only a partial scratch builder. I buy various items including all wheels, insulated for 2-rail running. For a Stirling Single I also needed two couplings, two plunger pickups, four sprung buffers, four frame stretchers, four wheel bushes, six tender axlebox white metal castings, 18 handrail knobs and a motor with gearbox.

On the subject of turning metal, I used to call upon the services of a good friend and O gauge railway modeller extraordinaire, Ray Powell in Wantage, known to many O gauge enthusiasts in the south but sadly no longer with us. Long ago, he had 2-railed large quantities of Bassett-Lowke and Exley coach wheel sets for me, enabling the conversion from outdoor clockwork and steam to indoor 2-rail electric. For this Stirling Single he fashioned its tall tapered chimney, the lofty brass safety valve and the smokebox door, all of which I believed to be unavailable on the market at that time.

So with everything to hand, I could reach for the hacksaw. First though, I made several photocopies of the scale drawings from which templates were cut and glued to brass sheet. I usually start with the footplate and with this locomotive paid special attention to the accurate reproduction of the subtle shaping above the driving axle. The footplate was made up from four separate pieces: two shaped side pieces, the large plated area at the front end and a smaller cross member at the rear above which the cab floor would sit. The void created in the middle of the assembled parts allowed room for the motor and trailing wheels. The drag beam was then soldered in place and valances soldered to the underside of the footplate.

There are, in effect, two parts to this footplate, the forward shorter and lower part and the remainder at the higher level behind the cylinders. These two components overlap between the cylinders with a central spacer sandwiched in between, all later to be bolted together to form a rigid structure. Then the front buffer beam was added with the two remaining short portions of valance underneath. Consideration had already been given to the position of the cylinders and the drawings show the areas cut away.

The frames were cut out forming the motor chassis, clamped together and pilot holes drilled for the driving and trailing axles in the usual way, and also for the frame stretchers and pickup plungers. My assembly method is orthodox and all parts are eventually nut and bolted together. No taps and dies were used in the construction, but the finished product is robust, built to last and can always be stripped down for whatever purpose in the future.

On this matter of sturdiness, I should add that the boiler was cut from a length of plumber’s standard size copper pipe with a large area cut away underneath around the driving wheels and motor. The copper added some much needed weight amidships and, after introducing lead into the boiler above the motor at a much later stage, the completed smokebox and cylinder unit was pushed onto the front end of the full length boiler to a tight fit and secured.

I had been looking forward especially to making up the large paddle box splashers. This was a real delight, the drilling, cutting and filing out the eleven slots, each different from its neighbour with the edge of the thick brass encompassing bands to be polished after the painting stage. No. 1 was the only class member to have splashers with eleven slots. All the others had ten, the small slot at the leading end having been omitted to reduce the risk of the insertion of a carelessly placed engineman’s foot while the engine was in motion.

From the beginning, this 4-2-2 needed to be treated as a 4-4-0 for current collection via the plunger pickups on the offside driving and trailing wheels. The offside wheels of the tender also collect current through blades of phosphor bronze shim in contact with the inside wheel flanges and transmitted to the drag beam of the engine by an insulated wire and a small plug and socket under the cab fall plate.

The snags

One of the problems relating to the one piece smokebox unit with combined cylinders including all slide bars was how it could be lowered into position with the footplate in the way. Of course it could not. Normally cylinders with slidebars are held in place in slots across the frames, but on this model there was no frame material to use at that location as it had been removed earlier to give clearance for the bogie wheels. Here, an unconventional approach might have been necessary, perhaps one of feeding in some of the components in a horizontal plane from the front end, including the front footplate assembly. In the end I removed the slide bars that were originally attached to the interior of the cylinders and re-introduced them in a modified form serving a more cosmetic role attached to the underside of the footplate. Unconventional and bad practice no doubt, but it works. On its outing to Shipton Oliffe, the train ran nonstop for about three quarters of an hour, covering a distance of approximately 50 yards short of a mile.

The truth is that for we few remaining coarse-scalers, awful compromises sometimes have to be made, and here is another, in this case affecting the front bogie and its ability to negotiate 4ft 6in curves, with all the pitch, roll and yaw that we have to contend with. To this end it was necessary, unfortunately, to select a smaller radius bogie wheel, dispense with, regrettably, most of the shapely and beautiful double bogie wheel splashers, and pare away portions from the inside surfaces of the cylinders in order to gain sufficient running clearances and eliminate short circuits. So admittedly, the little model loses much of its elegant character at its front end. On the prototype the bogie is permitted only three inches of lateral movement which no doubt ScaleSeven modellers can achieve. On this version I have to confess to providing in excess of a scale 18 inches both sides of the centre line.

The paint job

Before applying paint, it was essential to conduct a short test run of the partly assembled, un-oiled and temporarily wired up locomotive, fitted with its bogie. This always proves to be noisier than one might wish, but it confirms that all the moving parts work properly with no short circuits when running through the tightest curves and points, forward and in reverse and with the tender attached.

After dismantling an engine following a satisfactory test run, I always try to do my painting out of doors on warm sunny springtime days. Summer too is ideal as long as there are not too many insects in the air. After cleaning up each component, grey primer from the local motorists shop, or works grey as I prefer to call it, is sprayed on, but thinly as it can clog the detail. This is a time when little defects might show which have previously gone undetected and need attention. It’s well worth the extra time spent dealing with these at this stage.

After some hours to allow the primer to harden, the top coats were applied, several colours in this case: satin black (also from the motorists shop), Doncaster apple green (sometimes referred to as bright or grass green) and a Brunswick or holly green for the tender panel borders, applied by brush, as was the brown paint to the frames. Buffer beams are best undercoated in a matt white paint before applying a slightly toned down vermillion and the same treatment was applied to the injectors. The buffer shanks were painted brown.

I prefer to line out using commercially produced transfers which worked well in this case for the boiler and cab. For the tender, I had to line it by hand using an old school mapping pen. A process not to be hurried, this task should not to be done in outdoor sunshine as the paint will dry before it leaves the pen. A little judicious touching up later made all the difference.

Before applying transfers, the area of polished, splasher brass work had to be exposed by careful scraping with a blade. With all transfers in place, the assembled loco body, tender body and separate tender underframe were sprayed with a satin varnish, but this was done in warm sunshine which dries it quickly, leaving an even overall finish.

The assembly

The motor chassis was assembled and excess paint removed from the inside surfaces and faces of the wheel bushes. Then the driving axle (with wheels quartered), trailing wheels and motor were fitted into the chassis and wired up followed by another test run of the chassis alone, just for further reassurance. The brake gear was then attached to the chassis from below and clearances checked. The chassis was next installed into the footplate, after which the boiler with smokebox and cab attached was secured onto the footplate.

The brass safety valve had to be fitted on to the boiler and then the piston rods were fed into brass tubes inside the cylinders with crossheads and connecting rods already attached. Other items included handrail knobs and rails, buffers, couplings, cab fall plate, back plate and other cab interior details. Fitting the bogie and securing the polished steel connecting rods to the driving wheels with crank pins completed the assembly. Lastly, a driver and fireman took up their positions in the cab.

The driving test

Compared with other models in my locomotive shed which are straightforward enough to drive, the Stirling Single does require a little skill at the control of the faithful Hammant and Morgan. When done properly from a standing start, without wheel spin, it is immensely rewarding. I well remember my driving instructor back in the mid-fifties advising me to gently squeeze in the clutch to get the Morris Minor off to a smooth start. The same light touch applies here, but with a sensitive hand instead, to get the driving wheels to respond and bite onto the rails, drawing away the train with a satisfying gentle acceleration. Once mastered, you feel that you have passed the test. Despite my earlier flippant schoolboy comments regarding spinning the wheels, to do so, as we all acknowledge, is bad practice, self-defeating and simply polishes the wheel treads and rail.

Reflections

Having taken the photographs to accompany these words, I have noticed some matters of detail which could be improved upon. I am aware, for example, that Mr Stirling, during his term of office, would not have approved of my fitting a vacuum brake pipe to the front buffer beam. Perhaps I should remove it out of a sense of respect as he could see no reason why these engines should ever need to be doubleheaded. In fact it was forbidden during his lifetime. Double-heading only became common practice after his death in 1895 with the introduction of heavier trains.

The tender has escaped comment, only because its construction was straightforward. Coal rails are a little tricky to make but an enjoyable task. Real coal set into Polyfilla applied and keyed to a loose fitting base and sprayed satin black brought the tender to life.

Now back to that which pleases the eye, I would have no difficulty in compiling a list of a dozen or so British locomotives that score equally highly on aesthetic grounds, but to choose an outright winner, I would place Patrick Stirling’s diminutive Single No. 1 at the top. Over time I have made examples of most of these locomotives, an irresistible little venture, or perhaps a lengthy journey. Well thought out beautiful objects have always appealed to me as I was an industrial designer in a previous life. On the basis that one should always plan to be well occupied with future projects (especially in retirement), there are two or three more handsome locomotives on my list still to be tackled, if I have the time.

As for the day out, it turned out to be terrific fun, great camaraderie with jolly banter. I resolved to do this more often and in future abandon my somewhat reclusive way of life as a sole operator. It was certainly good for the soul, and body too it should be added, as the mesmerising effect of watching trains go by, running at carefully considered realistic scale speeds in the relaxing company of others, assuredly has a calming influence upon the human frame, slowing down most effectively the heart rate.

Editor’s note; John’s model was built in 1999. Since then, I believe two etched brass kits for this prototype have been introduced, one from the Swanage Model Company and the other is an Ace Locomotive Kits version.

Laurie Loveless hopes to produce a ready-to-run example.