Chapelon and related Matters

It wasn't my assessment. I haven't even read the book!

 

Slightly unusually, it's in the heading to the article, above the cover illustration on the web page. It reads:

 

Fourth Line of the Review, beneath the ISBN code.

 

Thanks both!

 

Thanks for that. Although AFAIK Cantlie was Technical adviser to the Chinese National Railways
perhaps his involvement was only with the KF 4-8-4s because they were for use in the Guangdong
Province, and his families past connections with Hong Kong and Canton ?

Or did he perhaps speak Cantonese and not Mandarin?

Regarding the USSR Maillet is brief and tentative.
QUOTE “ U.R.S.S. Il a “transpire “ que des “Prairie” type 131 de la serie Su , qui constituent le
fond du parc des locomotives a vapeur a grande vitesse, auraient recu des ameliorations
conformes aux principles mis en oeuvre par Andre CHAPELON “ END QUOTE.

Michael Rowe

 

Of all the locomotives that Chapelon was responsible for, No 160A1 is probably of greatest interest. In 1936 Chapelon started design work on the rebuilding of a Class 6000 150 as a 160. His aim was to produce a locomotive with great tractive effort and with the ability to run economically at low speed. A steam locomotive is normally much less efficient at low speed because of the greater cooling effect of the cylinder walls and leakages. These two effects militate against expansion at low speed and therefore lead to loss of efficiency.

The trials of 240.700 had shown that even with very high superheat the HP cylinder diagram showed considerable condensation during expansion at short cut-offs when running slowly. The desirability of heating the cylinder walls gave Chapelon the idea of using steam jackets, thereby making the superheated steam do some work before and after entering the cylinders, both HP and LP. Because the latter would be re-superheated it would be possible to achieve this without having the HP temperature higher than the castings and oil could withstand. Chrome steel was used for the cylinder sleeves to reduce wear on the piston rings and subsequent leakage.

To obtain a large expansion combined with a high tractive effort, it was essential to have cylinders of the largest possible volume. But two LP cylinders of the required volume would have been too large. Chapelon therefore decided on a sis-cylinder engine with two HP cylinders and four LP cylinders. The two HP cylinders were towards the middle of the engine, between the second and third and inside the frames. Two of the LP cylinders were inside the frames and of the same diameter as the HP cylinders. Two LP were on the outside, in line with the two inside LP cylinders but larger in diameter and in front of the first coupled axle. The HP cylinders drove the fourth coupled axle while the inside drove the second and the outside the third.

Re-superheating was applied to the LP cylinders. The HP superheater was of the Houlet type to obtain the maximum efficiency from the minimum number of elements. A considerable number of superheater elements had to be reserved for the LP superheater which had to have the maximum number of elements to reduce the loss of pressure in the transition from HP to LP. This also had to be of reduced efficacy so as not to produce excessive temperature; less efficient Schmidt elements were selected. The boiler tubes were mainly flue tubes with just a few small tubes around the periphery of the tube plates.

To increase the efficiency of thermal exchange between gas and water in the boiler, the barrel was separated into two parts by an intermediate tube-plate which was 2m from the smokebox tube-plate. The front part of the boiler was always full of water and the feed water was fed into it by an ACFI pump driven by exhaust steam, with an injector as stand-by. From the pre-heater, water was fed to the boiler proper by a simple overflow. There was a second reserve injector to supply water to the boiler in an emergency.

The locomotive had a double Kylchap exhaust and steam passages with large cross-sectional area. At starting live steam was admitted into the LP cylinders at 10barg. The frames of the engine were considerably reinforced to give it sufficient rigidity. Special arrangements were necessary to allow easy entry into curves. Only three of the driven axles were fixed – the second, third and fourth and these had thin flanges. The leading coupled axle had a lateral movement of 20mm, the fifth 10mm and the sixth axle 30mm. The locomotive rolled easily out of the Tours works over track that had reputation of being difficult for locomtives with a shorter wheelbase.

160A1 was completed in June 1940, just as the Germans were advancing southwards. It was despatched to Brive via Limoges where it picked up 1,200ton train which it had to haul to Brive without any running-in or assistance. 160A1 was secreted away at Brive until the end of the war.

The arrangement of the cranks is of interest. Those of the two inside HP cylinders were placed at 90deg from each other. The cranks of the inside LP cylinders were set at 180deg apart and those of the outside LP cylinders were at 120deg apart from each other and from the joint thrust of the inside LP cylinders. The effect of this arrangement was that the LP group acted as a three cylinder engine with six exhaust beats for each turn of the wheels – note that there are four LP cylinders but the two inside cylinders are smaller but exhausting at the same time, so balance is maintained.

The advantage of the pre-heater was that water could be replenished without any appreciable loss of boiler pressure. It was of greater importance though that no fall in thermal efficiency at slow speeds was observed. Unlike other similar locomotives, the consumption per horsepower at the tender drawbar continued to fall with speed. Trials were carried out at St. Etienne first with complete superheat and re-superheat, secondly with HP superheat reduced by one-third, thirdly without any HP superheat, and finally without any superheat. The results were interesting, to say the least. Without HP superheat, 160A1 consumed only 1.5% more at 50kmh and 3% more at 20kmh. Running with saturated steam only, it consumed 6% more at 50kmh and 13% more at 20kmh. The last figure is explained by the throttling of saturated steam, even at low speeds.

For a similar cut-off in the HP and LP cylinders, and the same speeds, the locomotive, running with saturated steam only, registered an average of 93% of the indicated horsepower achieved in superheated and re-superheated conditions throughout the whole power scale. These trials thus brought to light an aspect of the functioning of a compound locomotive which had previously been unknown. By applying superheat only to the LP steam and by having steam jackets in the HP cylinders, the same efficiency could be obtained from a locomotive as by superheating the HP steam to a very high temperature. This discovery arose from the use of steam jackets, which Chapelon had introduced for quite a different reason. Its principal value is that it was no longer necessary to use very high temperatures which are injurious to castings, oil, piston rings and general maintenance of a locomotive. Because this discovery was only applicable to compound locomotives, it would make these far cheaper to operate and maintain than simple expansion locomotives of similar power.

 

Thanks Michael. I thought Cantlie worked for the Ministry of Railways - see e.g. the attached obituary (which I suspect was issued by the China Society). This is also stated in the booklet Cantlie wrote "The Railways of China", published by the China Society in 1981. Cantlie was based in Nanjing when he worked for the ministry, which was the seat of government at that time. I cannot recall seeing anything which mentions his language abilities. My sense is that apart from the locos purchased from the UK (which were financed by the remission of the Boxer Indemnity - i.e. the Chinese could have it back but only if they use the money to buy British kit), Cantlie was not involved but that does not explain his absence from the other British-built locos specification process. Perhaps they were either too small or too standard to warrant his involvement or any comment? I think a lot of his work was on general railway standards.

The standard English language work on Russan Steam Locos by Le Fleming and Price makes no mention of Chapelon in the section on the Su although I would not read anything into that. The Su was developed from the S and was first produced in 1925 and production finally ceased in 1951 by when 3,750 had been built (although this total may include the S class locos) so they were presumably pretty capable machines. They seem to have experimented with a number of mods. I cannot see any mention of Chapelon in Rakov or in the only other Soviet textbook I have which mentions them (using Google translate on my 'phone - Chapelon would presumably come up as a phonetic), but I cannot be 100% certain.

 

Very interesting and where can I read about it,and see drawings?
I read french.
The water cage at front end of boiler is a no go I think.
It is a pre water heater working by lowering exhaust gas temperatur even more than boiler itself.
Franco- Crosti in other clothes.
If boiler exhaust is cooled under dewpoint of H2SO4 nasty corosion happens.
I dream of a two cylinder compound LNER K1 with Zara truck up front,steam jacket HP cylinder,intermidiate superheat and able to pass where a L1 can go loading gauge wise.
If feed water is preheated with exhaust steam to 99 degree C,pressure raised and then use a little intermidiate steam to get temperature to say 150 degree most of water hardness has solified before entring boiler.
9f boiler plate pressings and wheels

 

Col. Rogers' book, Chapelon's as well (but expensive) - fortunately I have both.
Also, https://fr.wikipedia.org/wiki/160_A_1
As for sulphuric acid, it is only corrosive in liquid form so probably wouldn't be a problem unless it is present when the boiler cools but that's the same for any boiler. The dewpoint of sulphuric acid is about 138degC. Remember that the pre-heater is only 2m long.
If you look here: https://www.martynbane.co.uk/2003Trips/Brienzetc/museum4.htm
there are some photos of a model of 160A1's LP cylinder block at Mulhouse.



https://static1.squarespace.com/static/55e5ef3fe4b0d3b9ddaa5954/t/55e6373fe4b04afd122b821d/1441150783767/#+DOMS-1_Chapelon.pdf

https://www.ebay.co.uk/itm/400827279296

https://www.spur1info.com/en/newsreader/sncf-160a1-as-gauge-1-model-from-proform.html

Below is a photo of a PO 150 from which 160A1 was rebuilt:



This locomotive was originally intended for display at Mulhouse. However, its tender was lost to corrosion (!) and it is now displayed on a roundabout near Perigueux. It has since gained a replica tender. It has been restored and maintained by a local group of railwaymen and enthusiasts. It was originally placed on the roundabout in full rust livery. I remember climbing on to it many years ago, wondering why it was located there!

 

H2So4 dewpoint is a function of temperature,concentration and humidity and varies between 120 and 160 degree.

The water in the front boiler inlet cage have varied between 80 and 200 degree celcius .
Smokebox and exhaust system corroded much more than normal

This Corosion was the given reason for ending Franco Crosti testing in Germany around 1958

 

But the heat exchanger on 160A1 was much shorter than a Crosti and also most of the tubes were flue tubes, so the flue gas at the smokebox end would be hotter than in a Crosti. The only smoke tubes were around the periphery of the tube plates where there was insufficient space for a flue tube. I suppose it also depends on what coal you use. Also the superheater elements passed through it, so superheating would have nullified if the temperature had been too low.

 

Prof Nordmann mentioned in oct 41 that the cylinders of the 05 ( that ran faster and longer unharmed on level track than Mallard going down the drain) was constructed with special care after reading Chapelons describtion of results from testing of 4-8-0 in revue general de chemin de fer feb 1935.

Borsig did not get it below 6.25 kg per ihph and whole Germany felt humiliated but comparing Gresley to Chapelon is very british indeed.

In 1932 Borsig had constructed the small mogul Baureihe 24 069 as a two cylinder compound with 25 bar boiler pressure and that used 4.9 kg steam but boiler could not stand the pressure for long.This can have been influenced by Chapelons feats with the Pacifics in 1929

 

Excuse me but the timeline was: first Holcroft invented his conjugation at Swindon and showed it to Churchward who suggested it should be patented, second convalescing during World War I he prepared and presented a paper on it to the Institution of Locomotive
Engineers and also he made an extant model as a 4-4-0 to demonstrate it. Gresley knew of the presentation but was unable to attend, he had already been interested in conjugated gear driving the valves for three sets of cylinders from two sets of valve and built a 2-8-0 - but not with Holcroft's two to one levers, all cylinders were inclined together at the same angle, and the driving cranks were set symetrically at 120 degrees He met with Holcroft at this time, tried to get him to work for him on the Great Northern Railway and Holcroft proposed to Gresley that you could have the cylinders at different angles to the driving axle if you offset the angles of the cranks. Then Gresley used the Holcroft gear.

"Gresley/Holcroft" was a known term. Never automatic it waned away but I remark on it when I come across it.
Advocating three cylinder locomotives in principal, building them in practice, as well as being a big man over and beyond his position the Gresley's came to be applied to the conjugating levers The same thing happened to the Spencer Moulton carriage bogie. Morally Holcroft's name should have had greater prominence but Gresley it came to be and Gresley genuinely had an eye for a good thing when the saw it.

 

Most of that seems true.

Actually, he did not. I have Gresley’s original patent reproduced in my book and it is abundantly clear he did not take Holcroft’s suggestions forward. In fact, his original patent is much closer to the final layout of his conjugated valve gear than has been given credit for, and within the body of the accompanying text he in fact describes what became his final overall valve gear layout. This was prior to his meeting with Holcroft.

Yes, and I am advocating that it be dropped going forward. Whether it will, or not, will be dependent on how people look at the primary evidence including Gresley’s patent going forward.

My view based on the primary evidence is that morally, it’s Gresley conjugated valve gear, and Holcroft had his own interpretation of it. Applying Holcroft’s name to valve gear he actually had no hand in is historically dishonest, in my view, and attempts to give credit to someone other than the person actually responsible.

 

Unfortunately for Holcroft, he had allowed the patent on his valve gear to lapse in 1913. Gresley was informed of this by his patent agents in 1916.

 

If we are being pedantic there were at least two Gresley conjugated gears, and at least three Holcroft conjugated gears, although only one was built on full size steam locomotives.

I have to disagree with you I'm afraid. I've read through Gresley's patent carefully, and I can find no mention of the two key changes that Holcroft mentions as having suggested to Gresley in their meeting. These changes weren't sufficient to invalidate or even extend Gresley's patent, but they did make the gear as installed on the A3s and successors possible.

The part of Gresley's patent which concerns the A3 installation is the long 2:1 lever which works with the centre valve mounted to one side of the centre line. This was quite different to Holcroft's earlier patent, which was for a symmetrical layout with the valve on the centreline, and there seems no doubt that this was entirely Gresley. A weakness of this layout, though, is a requirement for all the valve rods to be on the same plane. Once you have cylinders and valves at different inclinations this gear will not work. That, AIUI, is why the first Gresley installation, on the 2-8-0, did not use the simple 2:1 lever, but the second arrangement in the patent, using various rockers.

AIUI what Holcroft suggested to Gresley was a small enhancement to the patent design. All three valves /valve rods were to be put on the same plane, even though the centre cylinder was left inclined at a different angle to the others, and then the centre crank angle was adjusted to correct the timing. This, then, if I understand it correctly, as the Gresley/Holcroft gear, with the centre cylinder inclined at a different angle to the outside ones, and the crank angle adjusted to suit. A layout with all three cylinders on the same plane and 120 degree crank angles would be pure Gresley.

 

Hi Jim,

We did discuss this some time ago but I will again respectfully disagree, I think the diagrams in conjunction with the full patent wording show that Gresley was already on the lines Holcroft suggested, the significant wording (for me) being:

In any event, by the time Gresley and Holcroft had had their meeting, Gresley's K3 was under development and it was that version of the Gresley conjugated valve gear which then informed the production O2s, as opposed to No.461 which was virtually the patent verbatim. Note that it had the steeply inclined centre cylinder.

Unless Holcroft had made contact with Gresley earlier than the original K3 plans which had been drawn up earlier than the meeting in 1919, we can't say fairly that Holcroft influenced Gresley here.

I think it would be fairer to say that Gresley in future made alterations in line with Holcroft's suggestions that confirmed his own thoughts.

Gresley went ahead and built another 1000+ locomotives on this principle, without deviating enormously from his original patents. Holcroft was never given any such credit by Gresley or the LNER on the level some secondary sources have given him. I think that in itself is telling, particularly as Gresley was very careful around patents throughout his working life.

Other views are available, but I am not convinced that Holcroft's suggestions were not already being acted on by Gresley, and the timing of the different developments suggests strongly that Gresley was a few steps ahead of him in any event.

(Also of note: the K3s when they emerged had what would be recognisable as long travel valves, somewhat ahead of the GWR/LNER exchange trials and ahead of this being an issue on the Pacifics. Food for thought!)

 

I'm supposed to be studying mid 19thC GWR 2-4-0s today, not Holcroft and 3 cylinders!

Its very tricky to exactly pin down who was first. We know that Gresley was working on the 2-6-0 from 1917, but unless there's a series of dated drawings it's hard to know when the exact cylinder and valve gear configuration was settled on. Holcroft had outlined his concept for enhancing the Gresley gear in a letter in response to a feature on the 2-8-0 published July 26th 1918

I found an on line copy of Holcroft's iLocE paper of November 1918.
https://zenodo.org/records/1523701

and a further discussion, including a large contribution from Gresley.
https://zenodo.org/records/1543200

I also found Gresley's letter to Holcroft setting up their January Meeting:
https://coimages.sciencemuseumgroup.org.uk/images/275/210/medium_DS170422.jpg

It appears that the meeting was more wide ranging than conjugated gears. This letter suggests that Gresley was interested in the subtleties of the GWR 4 cylinder valve gear, which has carefully angled rockers so that the inside valves are not exactly 180 degrees out of phase with the inside. This is a subtlety, incidentally, that was quite lost on the LMS when they designed the Duchess valve gear.

It must surely have been rather unusual for Gresley to set up a meeting with a relatively junior employee of another line.

 

Not sure about 1918, but during my working life not unusual for a CEO or senior officer to
make such an approach if you were attempting to poach talent

Michael Rowe