Living History: Building The Baldwin Gas Mechanical

Building a 16mm Baldwin Gas Mechanical (BGM) can help to bring history to life. There are many reasons why we should get to know this extraordinary locomotive a bit better.It was a First World War locomotive which was then repurposed for peace so touches on many other stories. Malcolm and I admit that this old rogue of an engine inspires love and fascination. Many others have agreed. 

Wrightscale 16mm model of a Baldwin Gas Mechanical 50hp

Here we are, still producing them after thirty years. A batch is under way.

The Baldwin Locomotive Works of Philadelphia were first approached in 1916 by the French Army. They were looking for an engine which did not emit a pillar of fire by night and of smoke by day, giving itself away to enemy gunners. Motor vehicle technology fitted this bill. The USA was a world leader in MVT, the Philadelphia-Michigan area a leader within the USA. Henry Ford and many others were just up the road at the time.

Although not yet officially a combatant nation, the USA was definitely open for business. The Baldwin Works were able to offer the French a design with possibilities – the Russian Army had been there first. Rodney Weaver wrote an instructive article in the Industrial Railway Record 1977 Issue 71 pp 45 to 47. With a few alterations to existing designs, the company came up with a locomotive that suited.

The French ordered the 50 h.p. version, six hundred in all, bearing the Maker’s Numbers 1001 to 1600.

On April 2, 1917, President Wilson went before a special joint session of Congress and asked for a declaration of war against Germany, stating: “The world must be made safe for democracy.” On April 4, the Senate voted 82 to 6 to declare war. ... In early 1917, the U.S. Army had just 133,000 members. Numbers quickly rose into the millions.

The American Expeditionary Force AEF were now looking for a locomotive suitable for trench warfare. They also liked the BGM and ordered Maker’s Nos 7000 to 7126. They also ordered a 35 h.p. variant, numbered 8001 to 8065.

Under the bonnet of a Wrightscale 16mm BGM Photo courtesy MD Wright

Building the model brings some of the style and experience of building the original. A few compromises have been made - unlike the prototype, the model runs on battery power or 12 volt AC.

Baldwin had a huge erecting shop where large numbers of locomotives were built at one time – unlike the cramped little sheds of Britain and France. When Malcolm batch-builds, a large number of components will be on the bench at one time. They are interchangeable – at least to begin with.

One of the works halls of the Baldwin Locomotive Works of Philadelphia. Photo courtesy of Raymond PECHOT

Baldwin were looking for economy in design. Rather than a chassis on to which was built a superstructure, the frames would do for both. Hence the massive frames which to some seem weird and to others quite unorthodox. The frame which appears below is laser cut from steel; cutting the original was done without the benefit of computerand laser-technology. All the same, many methods are similar. 

Just like the workers of that factory in Philadelphia, Malcolm breaks down the job into sub-assemblies. First come the frames and the frames feature throughout the build. Central and essential to the build, the frames must be fitted squarely or all goes wrong afterwards. In other locomotives  chassis and superstructure could be assembled separately. This meant that, in theory at least, the superstructure and plate-work could be square and satisfactory. Less remedial action would have to be taken …. Well, that’s the theory.

A frame and two sorts of connecting rod, laser ct form steel. A pair of each are necessary for each BGM. Photo courtesy MD Wright

Rest the frames on a flat surface at the correct distance apart. Now raise them on blocks, still keeping them parallel. Now fit the buffer beams. It is most convenient to make jigs – prepared blocks which hold the frames at a suitable height. On the model, the buffer beams have to be marked, predrilled and countersunk before final fit. We suspect that this would have been the case on the prototype. They could not trust the parts to have been made with millimetre accuracy. Now turn the assembly over so that the frames are resting on their upper surface. Check again that the assembly is square. Any faults will start to show up; now and not later is the time to adjust!

    If all is well, solder in a cross-tie.  Again, a scaled-up version would have been fitted to the prototype. Only then could the chassis be considered rigid and square.

The next job is fitting the axle-boxes. Making sure that these small parts are in place and running smoothly is essential and fitting this early is the best policy. First job – turn the frame so that the wheel-slots are facing upwards. Second job is to clean up the axle-box castings. You are aiming for an easy running-fit between axle-box and the cut-out on the frame. Fit the four axle-boxes.

Cranks and axle-box castings. There are four of them, viewed from different angles

Now push a spare axle-rod through the front two axle boxes. It should fit squarely. Any compensatory work should be done now and not later! Check the back two in a similar way.

In the prototype, springing was fitted between the axle boxes and the frame, hence the castings. Personally speaking, I love these chunky white metal cylindrical springs on the model, all part of the character of the locomotive. These springs are added at a later stage which Malcolm calls ‘detailing’. He dryly adds ‘with a lot of effort, working springs could be made to fit’. In theory, they could improve the running of the loco on a model track. He has designed in a rare compromise on the model.  On a 21^st century layout, heroic compensation is not needed. In the conditions of World War One, it was essential. One side of the track might disappear into a shell-hole at any point. The one comfort for the driver and crew was ‘Oh well, if it hadn’t landed near us, it might have been on top of us’  

At the detailing stage, other non-working items are added – the brakes. They are not actually needed on an electrically driven model. ‘Stop’ means ‘Stop’.

But I digress. We have reached the point when one pair of gear boxes is in its appointed place on the frames. Repeat with the other pair, making sure that the temporary axle runs smoothly. If an axle box jams, once again, rub it gently up and down the steel until the white metal has been polished to a smooth-running fit. In the presence of steel, white-metal becomes, very slightly, a lubricant. Make use of this phenomenon sparingly!

A prototype Baldwin Gas Mechanical, only partly restored, on the rack at Apedale, Staffs. The axle-box niches can be clearly seen. Photo courtesy Jim Hawkesworth

Now the wheel-sets can be fitted. Again, you may need to lightly polish the working areas, this time with an abrasive pad. Your aim is to have both wheel-sets in, rotating freely.

In the model, Loctite or similar engineering glue are used to keep the axle-boxes in place. On the prototype, of course, the axle boxes were sprung.

The integrated chassis-cum-superstructure is taking shape. In addition, you are entering into that Yankee ‘can-do’ mind-set. You think about what you are going to make and then you bash theory about a little until it fits!

Try to get hold of Rich Dunn’s ‘Narrow Gauge To No-man’s Land’ Benchmark Press and

Dr Christian Cénac’s  ‘La voie de 60’ Auto-édition