The realisation that ‘Old Father Time’ is standing at the score board, poised to bring the score to 70 at the end of this year, has made me realise that if I don’t do something now, I probably never will! As I hope to be able to enjoy driving it for many years to come, this would have to be a ‘fast track’ project!

By happy coincidence, I was given the book “Garden Railways”, by Peter Jones, last Christmas which has an illustration of a kit built 5”G battery electric Bulleid Pacific, which I subsequently learnt had been featured in an article in the “Model Engineer”. Noel Whiting kindly loaned me the articles and the ‘die’ was cast! Here was a robust, complete rolling chassis, with a fibreglass body, that had potential and was also my favourite locomotive!

A phone call to Robin Neighbour, of MEP, confirmed that as the original intention was to drive the driving axle, (motors now in the tender) the coupling rods were adequate for purpose, so the only possible problem was the effect of heat on the fibreglass body shell, which was quite thin as with the diesel loco bodies. This could be minimised by ventilation cut outs and lining it with a special heat resisting lining that I have now sourced.

As a result of all this promising potential, I produced a detailed preliminary analysis of what form a live steam version could take. Being rather lengthy, I have given a brief summary of it just to outline the main features.

Locomotive and Tender

1. Complete the Locomotive rolling chassis (Southern Locomotives) with water pumps (double acting hand and variable stroke - driven by geared electric motor), ash hopper and grate.

2. Two cylinder ‘steam motor’ with gear drive (2:1) to driving axle. To be ‘nose mounted’, with frame extension at pinion end resting on axle boxes and located with spring loaded pivot pins.

3. Semi-flash steam boiler, including smoke box.

4. Complete body shell (fibreglass).

5. Complete Tender rolling chassis (Southern Locomotives) with batteries (for electric motor driving blower fan to ash hopper and variable stroke water pump), water tank and removable coal bunker (over batteries), and removable body shell (fibreglass).

A locomotive based on this design could be successful if correctly designed in detail. As it is designed to be easily broken down into manageable components for one person to handle, this gives it an advantage over a conventional model, in addition to being easier to build.

From a handling aspect, the heaviest single item will be the locomotive chassis, fabricated from 10mm thick laser cut components!- presumably to give extra weight when the drive was to the driving wheels as originally intended - with tab assembly and MIG welding, which may require special handling facilities for loading into a car boot without assistance. Loading into an estate car should be straightforward.

Since producing this analysis, variations have had to be made in the light of more detailed information becoming available concerning the locomotive chassis, which I will deal with next.

The ‘Steam Motor’

Suffering from an incurable case of ‘Oscillitis’, all my ‘O’ gauge live steam locomotives have oscillating cylinders, my first choice was to use two double acting oscillating cylinders to reduce the overall length. As with the full size ‘Filer & Stowell’ logging locomotives, the pivot would be in front of the cylinder and incorporate a curved ‘slide valve’ controlling admission only, with ’Uniflow’ exhaust, actuated by Hackworth valve gear.

As I wanted to use 1 1/4”(32) bore cylinders and I had been advised that the width between the frames was only about 3 ¾” maximum, I was confronted with the problem of getting steam into the rear of the cylinder from the valve at the front! This would be further aggravated by the decision to use a ’Uniflow’ exhaust, resulting in a marked drop in pressure as the steam ’wheezed’ into the cylinder!! Using some lateral thinking, why not use a central telescopic steam pipe I thought, taking advantage of the elongated piston needed with this form of exhaust control? Here my sanity began to suffer, with ’nightmares’ about Heath Robinson and Roland Emmet!! Then I was spared, when at the TME Exhibition Robin informed me that the actual width between the frames was only 3 1/2”. No way could I use oscillating cylinders!

Plan ’B’ - I always think it advisable to have this, and also possibly ’C’ and ’D’ as well! This precaution is fully justified in an exercise of this sort. This plan is to use a horizontally opposed single acting steam motor, with a ’Scotch Crank’ for compactness, with the ‘dieblock’ replaced by a roller bearing to reduce friction and wear. As the two pairs of cylinders will fill the space between the frames, how do we get the drive to the driving axle? In true Bulleid fashion a chain drive will be used! Thanks to the driving wheel diameter, a relatively large split sprocket can be used, allowing a large enough drive sprocket on the steam motor to give sufficient clearance above and below the cylinders for the chain drive, including allowance for axle movement.

At the moment this is all conjectural, as I have not yet started to draw it up, and ,yes, Plan ’C’ is to mount the steam motor above the frames! This will mean that the crankshaft will have to move with the axle, with extended slides to the ‘Scotch Crank’ to accommodate this ----------**

The Boiler

Why does the titling remind me of “Monty Python’s Flying Circus”, with the large digit (finger!) pointing at said item in an animated fashion? Surely it’s not because this article is in a similar vein!

Here we definitely have both Plan ‘A’ and ‘B’, Plan ‘A’ being a flash steam boiler and Plan ‘B’ a conventional boiler. This is because the flash steam boiler will be quicker and easier for me to build and cheaper! As this is in a relatively untried territory, it seemed prudent to allow for it to be replaced by a normal boiler from the start, that could readily be substituted using the same smoke box unit, and grate/ash hopper. This way, should I be successful in my quest and others may be rash enough to follow, they know that a conventional boiler can be substituted.

Knowing that a flash steam boiler can be contained in the same space, I proceeded straight to Plan ’B’. As it will have to fit in the casing with plenty of space for air gaps and insulation, my first thought was to use the LBSC ’ Hielan’ Lassie’ boiler with its combustion chamber and water tubes to promote rapid steaming and an efficient feed water heater to compensate for its size, in line with Porta’s principles. However, the rake to the backhead and grate, and its width, were not ideal.

Then I remembered a series of articles in the ‘Model Engineer’ for building a 3 ½” G narrow gauge 0-4-0T called “Hackfly”, which was ‘severely criticised’ by LBSC, to put it politely, in his usual fashion! One item was the boiler, for which he proposed an improved version clearly based on the ‘H.L.’ boiler which was ideal for the purpose. To increase the grate/firebox size, I have added 5/8” to the length, an additional row of stays effectively.

When I made my initial enquiries, I was told by Robin that the frames were based on the profile of the full size ones and, having enlarged drawings that I had to ½ full-size , I superimposed the lengthened boiler onto them, with the 7” (175) extension tube to the smoke box housing the feed water heater. It all fitted in nicely. Then came a ‘slight’ problem!

When I showed my drawing to Robin, at the TME Exhibition, he told me that actually the top of the frames at the rear were level, which made sense in the battery electric locomotive as it made a platform for the batteries, but he thought that they could probably be cut away to suit. He would send me their laser cut drawings. These duly arrived and a major problem became apparent!

When designing this locomotive, to give it the maximum market appeal, it was designed on the lines of the ‘tinplate’ locomotive by providing full clearance cut outs in the frames for the bogie and trailing truck wheels. This would make it ideal for operating on small ground level garden tracks with smaller radius curves than would be used on club tracks. Whilst the bogie cut outs are no problem with dummy outside cylinders, the cut out for the trailing truck would result in the rear of the chassis being completely detached when making the cut out for the firebox!

Back to the drawing board! The solution appeared to be to weld in 1”(25 ) by ¼”(6) bars inside the frames with the top in line with the top of the cut out and a 3/16”(4.5) horizontal stretcher plate welded in between them on final assembly. Was that Heath Robinson poking his head around the door?

It would be relatively straight forward to do this before assembly, and I have sent them my drawing asking them if they can do this. If not, it would mean getting it done professionally as the completed chassis would have to be stripped down, the bars and stretcher plate welded in and the chassis clamped onto a horizontal miller and the section milled out, remembering that the frame plates are 10mm thick! I await their reply.

The trailing truck would have to be supplied in component form to allow for modification to suit the chassis alteration. As the wheels will have 10mm side play, the thickness of the frames, I would hope that this will be sufficient on our club track. If I go ahead with the project, we will only know by trying it out. Plan ’B’ would be to do the same as on my ’O’ gauge Bulleid Pacific, namely to remove the wheelset and support the rear of the truck by a link to the front of the tender to allow it to pivot round the curves!

The final disappointment is that when I got a quote from one of our local professional boiler makers I had a price of nearly £2,000 and delivery time of about 45 weeks! Definitely it’s Plan ’A’, and if that fails, I will have to try and make one myself with some help!