JimC

Found an illustration of the 2-4-0 :-). This is from the same article in the Engineer as the image I linked to earlier. 

There's also some discussion and more images on this thread: 

I've had a first stab at the locomotives in original condition, which I've added at the top. For the vexed question of livery, I've seen mention of dark reddish-brown, and that's my idea of a dark reddish brown. As is my convention I've left off lining.
I'm being naughty by giving it the number 1 - it seems that four of the locomotives carried names, but probably not their numbers, while those that were nameless displayed the numbers. No 1in the stock list was the mis-spelt Treffrey.

Coal - well maybe @MarcD can tell us from the GA drawing. I note, however the diagonal line of rivets towards the back of the tanks, which looks like a watertight partition. I'll speculate, on no more evidence than those rivets, that possibly there might have been a coal supply there. 

The eventual Lynne & Fakenham/Eastern & Midland/M&GNJR version of the locomotives as 2-4-0s with larger driving wheels would be an interesting addition to the page, but rather off my theme. But does anyone have a photo they could upload? There's a photo of one as an 0-6-0 tender locomotive here. https://rogerfarnworth.com/2019/11/16/the-lynn-and-fakenham-railway-part-1/ Interesting to note that at this stage it still retains the side tanks, complete with the original CMR number plate, but has acquired a reasonable cab.

2 hours ago, MarcD said:

I have a GA for the loco in its original form.

That would be interesting and useful to see. Would you be able to share it with me or let me know the source?

https://www.vintagedition.com/1890-cornwall-mineral-railway-1873-locomotive-metamorphosis

This is from an article in "The Engineer" about the other members of the class that were rebuilt as 2-4-0 tender engines somewhere well to the east of Swindon, but the drawing is very helpful. I tend to be suspicious of drawings (and models) as sources, on the grounds that the artist may well not have been any better informed than I am, but that one clarifies a number of smudges I was unsure of in the photo and seems well founded. I was also delighted to spot in the text a dimension for the footplate height, which is rarely documented on the weight diagrams but enormously helpful for getting proportions correct.

The buffers appear to be conventional but short, which is also the case in some other small locomotives of the period I have sketched. Supposedly as pairs they were single manned, and you can see how the cab steps would make transfer between the cabs on the run possible, but surely rather perilous even for 19thC concepts of safety. You'd think a gate in the rear cab sheet would have been far more practical. Maybe though, if they were used in pairs, they tended to run with the driver in one cab and fireman in the other. Also one imagines that speeds on a 19thC mineral railway would have been very low, even compared to the conventional 25mph of unfitted freight on the main line. 

On 10/03/2022 at 15:50, Miss Prism said:

Looking at a CMR map, I'm not sure those engines ever encountered a high-level coaling stage (unless there was one at Newquay?). Probably done with buckets from low-level stages.

According to RCTS a lot of them lived at Swindon.

Here's a thing. I'm just looking at sketching up the as built configuration as per this very useful photo. RCTS states that the frames were lengthened at the back to fit in the bunker, but when I line up this photo with my drawing it seems as if in fact they didn't. Instead the cab entrance was moved forward. At least I'm finding that the cab spectacle plates and wheels only line up with the photo if you assume they didn't extend it. What does the panel think?

And another curiosity- the locomotive is assumed to have been named after Joseph Treffry, a major local land owner and entrepreneur who had built several horse drawn tramways that became parts of the Cornwall Mineral Railway. But if so they spelt his name wrong!

I do wonder how much coal they spilled coaling these from a standard GWR stage.  There were special carts for smaller bunkers as below at Didcot, but even so it must have required some precision. The glazing on that rear mounted spectacle plate must have been awfully vulnerable too.

For interest, these are the two images I made most use of for this sketch.

The numbers shown with 1392 present and 1398 absent presumably date the diagram to between April 1883, when 1398 was sold, and November 1906, when 1392 was withdrawn. My best guess is that the weight diagram is the condition after they were converted to saddle tanks in 1883/4, and the photograph is possibly after the first boiler change which was Jan 1904 for 1396, but it could be any time up to March 1934, by which time it would presumably have had a 1361 boiler (RCTS doesn't mention dates for that change).

Amazingly though, the last one being withdrawn wasn't the end of the story.  See this thread for  the second life of one (or part of one) of the class. https://www.rmweb.co.uk/community/index.php?/topic/156057-identification-of-a-mystery-outside-framed-engine/

Also https://www.flickr.com/photos/14581588@N05/4735888892 and http://www.historywebsite.co.uk/articles/Railway Gazette/OWWR.htm

Its got a nice feel to it. I've been mulling over using an old Triang 2721 chassis for something on the same lines Its a pity Triang chose a prototype with such a long wheelbase.  I'm not entirely sure about the caption though!

7 hours ago, Miss Prism said:

 There is no obvious sign of the long tanktop handrail, 

You're correct, the long rail does seem to have been a GWR addition. Goodness knows where I got that from! I've altered the original post.

I was idly scanning locomotive drawings (as you do) and I was struck by how much this locomotive matched the general style of the Dean 0-4-4s, with short wheelbase and a long gap to a short wheelbase bogie, although it is rather larger. They were built in 1885 by Beyer Peacock for the Mersey Railway, and three ended up with the Great Western via the Alexandra Docks Company.

Well, I've produced the sketches, and altered the first page to include the usual description. I thought it might be more interesting to include the discussion rather than start a new page. 
The other feature of 795 that differs in photos and weight diagram is the forward of the cab hand rails and, I think, the radius of the cab cutout just above it.

Rather randomly, because I came across it while preparing the drawing, I was interested to see a 1924 photo in RCTS (K452) of another ex P&M locomotive, 928, in which as well as the GWR cabside plate the saddle tank is still labelled P & M No 14 with what appears to be a cast plate. 

Here's a first draft which I'll take a good look at later. Feel free to comment.  I was struck, when I was copying standard parts from other drawings and the like, by just how small this locomotive is, so I thought that for now it would be fun to have an outline of a 57xx behind to give an idea of the  relative size.
 

I reckon there's at least two more differences between drawing and GW era photo.
And what about the sanding arrangements? It looks to me as if there's just a single smallish sandbox located between the wheels, instead of two large conventional ones on 942. Don't recall seeing anything like that elsewhere. 

And aren't those buffers unusual, so very short.

One thing about that one which is interesting, but fortunately not my problem is that the balance weights in that photo are completely different to the one I linked to, clearly they - and I presume the wheels - had been changed.

Here is a GWR outline drawing. How many differences can we spot between this and the photograph @Miss Prismlinked?

There's another photo of her in Industrial days here: https://thetransportlibrary.co.uk/index.php?route=product/product&product_id=100626

2 hours ago, Miss Prism said:

I haven't got anything more square on than:

http://www.gwr.org.uk/pannier-pics/795-small.jpg

Shame, but that one looks useful: I haven't seen it. Do you have a large version?

My guess is it depends. 

Weight diagrams for major classes are often very well drawn. Some of the ones for one off absorbed are sketchy in the extreme. 

Something rather interesting - to me at least - passed through my hands recently, which was 4 or 5 weight diagram like drawings of absorbed Welsh classes about 5 inches wide. They'd been drawn by A E 'Dusty' Durrant who was a Swindon Apprentice and draughtsman. What was interesting is that they were dated, and the dates were in the middle of his apprenticeship. Holcroft, Durrant etc are strong on what they did during the day and weak on the evening classes where they were taught draughtsmanship and presumably engineering maths and it now occurs to me that weight diagram like drawings would be an obvious training exercise. 

And I've just realised I have a email contact with an ex Swindon drawing office draughtsman. I had better ask, hadn't I!

Dammit, why didn't I find that? I have a copy of that photo from RCTS, but much worse quality. 

[later] especially as you'd already posted it in this blog!

I've been given some GWR archive material, including a lot of locomotive diagrams, and to my surprise and delight they include weight diagrams of 342, 95/6 and 92. unfortunately the 342 drawing especially has suffered, but I may be able to work up some improvements on my drawings of these little oddities.

An interesting vignette from the GWR Elist. Apparently on ECS workings the 15s didn't ingratiate themselves with the S&T department "because nearly every week it seemed one would take out a shunt signal somewhere between Paddington and OOC - and there was no room to move the signals, so the same ones got clobbered time and time again!"

Thanks for that.

It would be interesting to hear a comparison with the USA/S100 and/or the Riddles Austerity from someone who has relevant experience. 

23 hours ago, Dana Ashdown said:

To my eye the dome over the firebox seems a little too low, relative to the boiler barrel, but thats how it is in the picture, so I wonder how much of the boiler shell was original.

According to RCTS no 15 received new boiler barrels in both the 1866 and 1887 rebuilds, but kept the original domed firebox for her entire life. Apparently new frames were fitted in 1890, which seems a surprising repair on such an oddball locomotive. I did have trouble getting a dome shape that I was happy with. 

@Dana Ashdown found a photograph of number 15 in her 1887 (final) incarnation, which inspired me to see if I could have a go at producing a reasonable sketch from the photo. As I was going to be colouring the new one I thought I would also colour the previous 1866 rebuild sketch.

1866

Very unusual brake setup for the 1866 rebuild, but I'm confident its a reasonable interpretation of what Ahrons drew in the line drawing I worked this up from.

1887

Looking at the photo carefully I decided it was evident that rather than build a new saddle tank in 1887 Wolverhampton had simply extended the original, which considerably simplified the task. Brakes are more conjectural than I would like, but a similar setup was used by Wolverhampton on early 517s. 
Colour wise, well, its intended to give the impression of Wolverhampton green. Who knows. As ever I've left out the lining and anything else difficult! GWW seems to be silent on the colours of the painted numbers, but white edged in black seemed feasible to me. 

I also added these revised images to the original post after the RMweb site image problems in 2022.

39 minutes ago, DonB said:

They had one of their Pacifics over a pit ... I don't recall the experience as being cramped ... 

If the pit under Caerphilly at Swindon is any guide then its far deeper than a working pit would be. In fact it would be quite useless for doing any work on the locomotive!