Chapelon and related Matters

It should be stated that the 141Ps were new locomotives, not rebuilds, with 318 being built. They had 35mm thick frames (as per the 141Gs, rebuilt from 141Cs) rather than the 28mm thick frames of the 141C/D/E/F. The 141P were roughly modelled on the PLM 141Cs (not to be confused with Etat 141Cs which are 2-cylinder simples!). They were amongst the finest mixed traffic locomotives built; it's a travesty that none are preserved. 141P82 almost made it but only its Bissel truck survives in Mulhouse. Another Chapelon class not preserved. Just another member of a long list of locomotives to be set aside for Mulhouse that were either cut up or disposed of. One, a 040 (080), preserved at Carnoules in Provence, even had its dome torched to ensure that it never steamed again - this wouldn't be a problem in the UK but in France.......

 

It occurs to me that there is an analogy between Chapelon’s rebuild of the Paris-Orleans Rly Pacifics and Maunsell’s rebuilding of the SECR D/E class 4-4-0s. In both cases, the objective was to get substantially more power out of an existing loco type. The PO Pacifics were of course twice the size of the SECR 4-4-0s and much more complicated, but the principle of the rebuilding was the same. In both cases, the engineers were fortunate in that the original engines had been robustly constructed and were able to absorb the stresses of higher power. Unlike Maunsell, Chapelon was able to add a few tons of extra weight to accommodate extra gadgets plus some extra frame cross-bracing.

Gérard Vuillet (“Railway Reminiscences of Three Continents”) comments on the French locomotive situation in 1929: “Comparatively large locomotives, according to European standards, were in service but, except on the Nord, the lessons of tests made in 1897, following the instructions of Du Bouquet, seem in most cases to have been forgotten.” Locomotives had increased in size, but steam passages had not been scaled up in proportion. The PO Pacifics of Classes 3500 (6ft 5in wheels) and 4500 (6ft 1in wheels) had failed to deliver the expected increase in power over the preceding 4-4-2 and 4-6-0 types.

In 1929, electrification had already started at the Paris end of the PO main-line to Bordeaux, so there would have been reluctance to invest in new steam locos, particularly if that involved scaling up to the 4-8-2 types that had been introduced by the PLM and Est. But loads were increasing, so there was an opening for Chapelon’s ideas on getting more power from the existing engines.

This quote from Gresley seems to confirm the quotes in post #60 from Stanier and Cox, identifying improved steam passages and “internal streamlining” as at the core of Chapelon’s achievement. Chapelon’s work appears to have been well-publicised in the 1930s and so would have come to the attention of engineers around the world, who would have been expected to have taken that into account in their own designs. However, since steam passage details do not affect external appearance or make it into tables of major dimensions, it is difficult to quantify the extent to which designs elsewhere were affected.

Chapelon further boosted performance by features including higher superheat, feed-water heating, poppet valves and multi-jet exhaust systems, but these features may increase overall complexity and potentially attract both royalty payments and extra maintenance costs, so other engineers would have been more wary of adopting them. Other countries were usually more reluctant than France to accept high complexity as the price for optimal performance, and certainly there was no widespread move elsewhere to re-adopt compounding (which had been popular across Continental Europe at the start of the 20th Century but had fallen out of favour in most countries by the 1920s).

From a British perspective, a surprising fact is that Chapelon was actually given the credit for the rebuilds of the (100-plus) PO Pacifics, rather than the CME of the PO. The only British analogy that comes to mind is Walter Smith, Chief Draftsman of the NER under William Worsdell. Smith was allowed to build a 3-cylinder compound 4-4-0 and two 4-cylinder compound 4-4-2s to his own designs. But Smith died shortly after, and his designs did not become NER standards, albeit surviving to become LNER Classes D19 and C8. The D19 did act as the prototype for the Johnson/ Deeley/ Fowler Compound 4-4-0, which totalled 235 engines. Very few other such 3-cylinder compounds were built anywhere (after the demise of the Webb variety), but the model would be adopted by Chapelon in his 242A1.

 

Just to correct myself, the dome and chimney of 040B9 were torched because the locomotive was transferred to its final destination by rail low loader. Why they couldn't be removed in the normal way is not recorded. The locomotive is now a national monument.

 

Probably because the Pacifics were rebuilt using the same principles as those used for 3566. It seems that apart from two persons, the staff at PO were initially very sceptical of Chapelon's 3566 project. One of those two died and the other retired so Chapelon then had to convince his new boss of the value of his work. That's why 3566 took four years to complete. Of course, on completion of 3566, the attitude of the staff towards Chapelon was totally transformed. Maybe guilt played a part?

 

Certainly not the object for redesign Chapelon would ever have wished for: it was not possible to increase the volume of the
valve chests. (This had been clearly included in the paper in which Chapelon proposed the rebuilding of what became the first Chapelon Pacific and larger valve chests were indeed incorporated in incorporated in the completed rebuild.)

 

I just came across an interesting quote. Its from a discussion on the paper 'The development of L.N.E.R. locomotive design by B. Spencer', for the ILocE, https://steamindex.com/jile/jile37.htm
The quote is from one H.G. King, who was apparently ex Great Northern and an LNER employee, presumably on design.
" Gresley was a man who insisted upon all his staff putting a tremendous amount of time in studying every design that was brought out abroad, and many of the suggestions he embodied in his engines were features which he had studied or thought desirable."

I offer no opinions on the development of the W1, but its an interesting observation on human behaviour that when a suggestion is made that a Person A (whom we admire) was influenced by Person B then many of us have a tendency to want to deny it, when actually its something that should be praised!

Incidentally, browsing through old copies of "The Locomotive" yesterday I came across an extended article on the SECR N1 2-6-0, which as most here will know was the very much Holcroft's baby with a version of conjugated valve gear, even though the feature doesn't actually mention Holcroft's name! Anyway one thing that struck me was that the test mentioned conjugated valve gear as used on the continent (think it was continent rather than abroad) and by Gresley with the order suggesting it was more widely used abroad. Now I knew there had been implementations of such gear following Gresley, but this implied a much earlier date. Anyone know?

 

A very fair point Jim. I think though we’re looking at it in perhaps too narrow a frame then. Is it likely Gresley was influenced from developments abroad? Your example suggests yes. Is Chapelon a major influence or a direct influence? I suggest that is less clear.

In relation to the W1 being discussed on the parallel running Gresley thread, I didn’t find any evidence to suggest Gresley had contacted or had been contacted by Chapelon in relation to the W1, neither did William Brown.

Lack of evidence isn’t necessarily evidence it didn’t happen, as I said there.

 

The use of conjugated valve gear in Germany has come up before on another thread, in particular it was applied to large numbers of G12 2-10-0s. The geometric principal was the same as the Gresley/Holcroft gear but it was very differently arranged with the conjugation by transverse rocking shafts back by the second coupled axle.

 

Which one? Gresley gear works quite differently to Holcroft valve gear. There is no such thing as "Gresley/Holcroft" valve gear.

 

I presume Bill2 meant the basic principle of adding anti-phase movements of the left and right valve gear to derive the motion for the centre gear, which must be the same in any implementation of conjugation, whatever the physical form of levers, rocking shafts or whatever.

 

Fair comment.

 

As noted on another thread, this article suggests otherwise: https://www.lner.info/locos/W/w1.php

and here: https://www.sirnigelgresley.org.uk/chime-archive/mob-abofb-11.shtml

 

And as noted on the other thread, the first link is a secondary source with no primary evidence cited.

The second, from the SNGLT is better, but Chapelon is quoted once as follows:

I have rechecked my notes and copies from the W1 file and I cannot see any reference to Chapelon in that time frame. Neither did William Brown in his book on the W1. This quotation gives a reference but there does not appear to be sufficient evidence for this.

 

It is noticeable that in Chapelon’s book, while the Gresley Pacifics get a write-up proportionate to that of all the other classes he covers in his broad survey, the W1 gets a passing mention in an earlier chapter to the effect that: "This was built."

 

On the other hand, if you read Chapelon's account of the 141P in the same book, if you didn't know better, you wouldn't think that he had any input into it!

 

Yes I have noted that down after reading most of it this week - interesting reaction, but I don't know that we can read too much into it.

 

La Locomotive a Vapeur.

QUOTE ( as per the Carpenter translation p.288 ) . It may be mentioned that the LNER high
pressure four cylinder compound 4-6-4 locomotive No.10000 built in 1929 and working at
31.6 atm was rebuilt as a three cylinder simple in 1937 with “ Cock of the North type boiler
working at 17.5 atm ( compared with 15.4 atm. for the latter ). Cylinder dimensions were
508 x 660 mm with Walschaerts gear and Gresley derived motion for the middle valve.
This locomotive streamlined like the A4 Class weighs 111.7 tons with 67.1 tons adhesion
weight. END QUOTE.

This quote is the last paragraph of the 4-6-4 section of the 1952 edition. It does not
appear in the 1938 edition. I suspect the 1937 rebuild was too late for inclusion. The 1938
edition for example includes wrt 2-3-1 the A3s and A4s, but only the Princess Royals on
the LMS ( No Duchess ).

I can only speculate that the ‘Hush hush’ was omitted for that exact reason.

The 1938 copy I have is that formerly owned by OVS Bulleid. It has his signature in
green ink inside the front cover and some axle load calculations ( also in green ink )
on a piece of CIE headed note paper. Does this constitute Chapelon influence ?

Michael Rowe

 

Of course not!!! Copies of the book are expensive anyway but yours.......

 

Plying devils advocate - no, since when he was at CIE was well after his time on the LNER and the Southern Railway.

The books publication is not an indication he was influenced by Chapelon in his work for the LNER.

It may be an indication of his respect for Chapelon, certainly.

It’s a lovely artefact to have Michael, to be sure, but it’s not evidence of influence during his working life.