Amongst E.T. Lane’s many sketches and drawings, there are some of various tenders that were used with the early broad gauge engines. These sketches provide a window into a world that would otherwise have been completely lost.

 

 

 

These Tenders do make a rather weird collection of styles – some being adaptations of standard-gauge bodies, with the wheels mounted outside.

 

I have previously modelled the tender ascribed to Aeolus and adapted one of the designs to suit my model of Eagle . I suspect that, in the face of the fickle nature of the early engines, tenders were probably swapped around to suit whatever engine happened to be in working order on a particular day.

 

One of Lane’s drawings is described as ‘old tender of the Viper’ so I guess this indicates that the sketch shows the tender that was originally supplied by the manufacturer. It has a number of unusual features that made it an interesting prototype from which to create a model. Some people like Sudoku puzzles, whereas I enjoy working out how to reproduce the various features of a prototype by means of the tools provided in Autodesk ‘Fusion’. Although I’ve now been using this software for a few years, I still keep discovering features that simplify various modelling tasks!

 

The first unusual feature of the Viper tender is the use of solid disc wheels. It was easy enough to model the basic wheel but then I had to add the ring of rivets just inside the rim. ‘Fusion’ made this a simple task by mean of the ‘circular pattern’ tool. I created a single rivet and then applied the ‘pattern’ tool - and there were all the rivets in a ring!  Of course, replicating the first wheel was equally easy. I have no doubt that computer modelling makes it very much easier to generate these repetitive features and it ensures that the patterns are perfectly regular (although I must doubt whether this necessarily applied to the Victorian prototypes!)

 

I must now confess that I originally built most of my model as a mirror-image, owing to an error when I imported the sketch as a ‘canvas’ into ‘Fusion’. I’m still surprised that the break gear and operating lever were on the right-hand side, as most GWR engines had the brake handle on the fireman’s (left hand side). Perhaps this convention did not apply to the earliest engines. Fortunately, when I discovered my mistake, it was simply a case of applying the ‘mirror’ tool in ‘Fusion’.

 

Creating the Tender Body

 

I used familiar techniques to create the outside frames and main body of the tender. The rivet detail was quickly added by using the ‘rectangular pattern’ tool.

 

Next, I had to tackle the rather elaborate moulding around the upper rim of the tender sides. This took some thought but the method I adopted was first to make a sketch of the end profile of the moulding, as shown in the Lane sketch, I could then extrude this profile along the length of the tender side. To tackle the corners, where the sides meet the back of the tender, I used the ‘revolve’ tool in ‘Fusion’, to rotate the profile through a 90 degree turn about a vertical axis. My method is illustrated below:

 

 

Creating the Upper-side Mouldings

 

By this stage, I had completed the main body of the tender, the outside frame and the wheels. I added the splashers by using the methods I have described previously for several of my other broad-gauge models.

 

 

Basic Components of Viper’s Tender

 

 

Creating the ‘Break’ Gear

 

Now I was faced with a more difficult challenge, as I had to interpret the working of the break gear from the rather ‘wavy’ sketches that Lane produced. In fact, this was a new departure for me as modelling brake gear is something I have neglected in most of my previous models.

 

Sketch by E.T.Lane showing brake gear

 

 

The functions of some of the roughly sketched components were not immediately obvious to me but I gradually worked out that there were two pull rods running along the sides, outside the wheels. One moved to the right when the break was applied and the other to the left. These rods were attached to either the leading or trailing shoes, as appropriate for the direction of movement.

 

These two rods were driven by a rocking lever set on a central pivot between the rods. Another lever on the shaft from this pivot was attached, via further levers, to the operating handle at the footplate end of the tender.

 

The following diagram shows how the rods were supported by guides which which were bored to allow the rods to move freely in the horizontal direction. The rocking lever and its linkage to the operating lever are also shown.

 

 

M y overall layout of the brake operating system

 

Creating these rods looked as though it could be tricky, especially as they have ‘kinks’ to allow them to clear the axle boxes for the wheels. Fortunately, ‘Fusion’ provides the very versatile ‘Create Pipe’ tool, which simplifies the task considerably. All that was needed was a line drawing of the path to be followed by one of the rods. The ‘pipe’ tool then automatically creates either a rod or hollow pipe, which follows the drawn path. The tool also allows for circular, square, or triangular cross-sections, according to the application. Once I had created one rod in this way, it was easy to create the other by means of the ‘mirror’ tool, applied across a horizontal plane.

 

I created each component of the linkage separately as a simple ‘bar’. I then used ‘trial and error’ to determine a plausible arrangement of the individual parts.

 

 

3D model of Brake operating mechanism

 

It was one of those jobs that looks obvious once it’s done but which took me quite a while to puzzle out from the Lane sketch!

 

There’s one other unusual feature, which is the rod linking the two axle-boxes. I turned again to some of Fusion’s tools – ‘create Torus’ and ‘create Pipe’ - to make this item, as shown below:

 

3D model of link bar between axle boxes

 

After solving all those puzzles, the rest of the detailing was ‘plain sailing’. I copied springs, buffers, and side struts from components I had made earlier. The ‘strouters’ that supported the back panel of the tender were similar to ones I have previous created for various wagons .

 

After ‘rendering’, my final 3D model is shown below:

 

 

My 3D model of an ‘old tender for Viper’

 

I think it is a rather lovely example of early Victorian engineering.

 

I still have a puzzle though:

 

 

My 3D models of Viper and tender

 

When I couple this tender up to my model of Viper, it doesn’t seem to match ‘stylistically’. The outside frames and, especially, those solid-plate wheels look far more like the wheels of the engine ‘Ajax’, built by Mather, Dixon & co. - but that leads to another story …

 

Mike