Articulated Steam Locomotives of North America

We have indeed had a good go at what Chapelon himself, and Gresley's application of his principles, did or didn't achieve for both raw performance and utility to the railways. I was responding specifically to Tom's post about power and speed, which in turn was responding to mine about loco weights.

 

The PO Pacifics introduced in 1910 could produce a maximum ihp of around 1,850. The very large slide valves used for the low pressure cylinders were soon identified as being a significant problem. They could distribute the steam required reasonably well but it took a great deal of power to drive them. It was decided to fit one example with Lentz poppet valves in an attempt to solve the problem but the results were disappointing and it was at this point that Chapelon was given the opportunity to try out his ideas on one locomotive.

Number 3566, nicknamed "Cholera" by the locomotive crews because it was such a poor example of the class, became the guinea pig. Chapelon well understood that the adoption of the Poppet valves alone would not provide the desired improvements. So what did he do? It was important to eliminate steam pressure drop during admission and in order to achieve this the steam chest volume was greatly increased. The steam passages were greatly enlarged in order to reduce pressure loss and also back pressure in a number of parts of the circuit. In order to ensure that the low pressure cylinders were using superheated steam the temperature of the superheated steam was increased by 100 degrees centigrade. Poppet valves were used to allow for maximum port opening at short cutoffs and these were also easier to drive. In order to increase boiler steam production and to minimise the back pressure on the pistons the Kylchap exhaust was provided.

These modifications allowed 3566 to achieve an ihp of 3,000 between 75 and 80 mph and the fuel consumption was reduced by 40 % for a given output. Later the replacement of the Schmidt superheater with the Houlet type increased the output to 3,400 ihp and later again slight changes to the cylinder dimensions improved matters further to 3,700 ihp.

When the movement of the pantographs on the overhead wires was being investigated the electric locomotives involved were propelled at speeds up to 176 km/hr (110 mph) by Chapelon Pacifics.

It was far more than the Kylchap exhaust which delivered the performances achieved by these engines. Some of these improvements did appear in the A4s and if you are going to improve the steam locomotive you have to include every thing at your disposal. No nasty half baked attempts.

If you are wanting to look at a Duplex locomotive take a glance at the 151A built by the P.L.M.

 

“So called Chapelon improvements” were good enough for HNG and the locos so fitted were better performers as a result. If royalty payments weren’t involved I suspect many more locos would have been modified. Thompson must have also also thought them worthwhile as all his Pacifics were so fitted. Your dismissal of them does sound a bit “not invented here”.

 

Would you please, just once, get off your high horse this year and stop misinterpreting what I am saying?

I even singled out the Kylchap for praise, for heavens sake. It’s right there in your quotation of my own post.

It must be an incredibly sad life to lead to wait on an internet forum for someone else to post and then immediately find ways to reinterpret it for the express purpose of trying to denigrate said person.

 

Playing the victim again are we Simon?
Your opinion on Chapelon is just that, an opinion and people are free to agree or disagree.
If you can’t handle the heat then maybe it’s time to get out of the kitchen.

 

Wasn't there a claim of a speed of 112mph by a New York Central 4-4-0 sometime in the 1890s?

 

All sorts of claims of high speed were made by American railroads but there doesn’t seem to be any reliable timings to back them up.

 

Waking up to read this further exasperating post.

Disagreeing with me has always been fine - misrepresenting my views isn’t.

You even quoted me and managed to turn what I said completely on its head.

The ridiculousness of this exchange summed up by a sentence based on something Harry Truman said in the 1940s. Archaic.

There wouldn’t be quite so much heat rather than light if you actually bothered to read what I said in the first place.

Make that your New Year’s resolution. Actually read what I said and instead of throwing out condescending and aggressive misrepresentations, actually put some thinking time into what you say.

For my part, I’m giving my mental health a break for 2023 and you’re going on the ignore list.

Peace and quiet for a change!

 

Perhaps if Gresley had applied more of Chapelon's principles to the P2s they would have been a success. For instance, if their cylinder blocks had been designed in such a way that the incoming steam didn't heat the exhaust! Something that the A1LT have studiously avoided.

 

Something that you're not guilty of? LNER finances?

 

UK Ditto

 

That would have improved their efficiency, but they were rebuilt for other reasons, not because they burnt too much coal for the work they were doing.

 

No, I am not guilty of that.

Perhaps you would like to take up your grievance with me directly and provide some evidence for your statement?

I am fast approaching the point Martin where I may have to have a very serious discussion with the moderators about how certain members (including one moderator) have misrepresented my views and accused me of things I have not done on the open forum.

I have had ten years of this and it only seems to be getting worse of late.

Why should I tolerate someone coming onto a thread, having not taken part in the discussion, to put up a question on my credibility whilst providing no context, evidence, or anything for that matter to back up their claims, while hiding behind a user name?

 

Back to the PLM and the 151A. Built to the design of Ange Parmantier they date from 1932 and could sustain 3,000 dbhp at 47 mph (75 km/h). This was a four cylinder compound design with the low pressure cylinders driving the second driven axle and the high pressure cylinders driving the fifth and the valves were of the poppet type driven by Dabeg rotary cam gear. So what was this successful and trouble free heavy freight design?

On initial inspection it looks like a 2-4-6-2 however it can, and perhaps should, be classified as a 2-10-2 and if that classification was good enough for Chapelon it ought to be good enough for everyone. As to why it is a 2-10-2? It does have inside coupling rods linking the second and third driven axles. From a glance at a photograph you would be unaware that these rods existed and how many have heard of the work of Parmantier anyway?

The French found out the hard way that driven axles need to be coupled. Chapelon Pacifics started better than electric types at the time because the electrics had independently driven axles with no link between them and so steps were taken to create an electrical method of linking the driven axles. Quite what the US engineers were thinking with the Duplex design we might never really know but being aware of the the French designs might have been beneficial to them in many more ways than just the one.

The Pennsylvania would have been better served asking the N & W to build a batch of the J class rather than any Loewy inspired creations from a commercial builder.

US locomotive purchasing is quite strange. Why so many large wheeled locomotives being purchased and used by lines which had little or no high speed requirement? And then you have freight types with too many undriven axles supporting the weight the engine. And yes Allegheny, I am looking at you.

 

The description of T1's slipping at speed sounds more like a suspension problem than an adhesive weight one. The front set of wheels encounters some rough track and slips. Then when it catches again it sends the rear set into a slip. Then the process keeps repeating until you can get both sets to grip together. Sounds like there is some sort of coupling between the two sets of driving wheels that isn't quite understood.

I have noticed something similar when driving Double Fairlies where one end slips, you catch it and the other one immediately does the same. Perhaps something to do with them no longer being in sync. With separate regulators it is much easier to get them both working together again. I expect at 100mph it was quite alarming.

 

Did the LMS and LNER Garratts have this problem?

 

It took a long time for people to understand and apply Chapelon's principles and the day to day work had to continue whilst these lessons were being assimilated. Once this was done they could be applied and taken further by those with sufficient knowledge and understanding to do so. It is argued that these lessons have still not been fully understood and applied

The A4 was a later design than the P2 and though it did not boast of the same tractive effort it did produce higher ihp. Lessons were being applied and they worked. You don't, for example, apply an improved exhaust system and believe that this is the end of the matter. Compared to the A3 the A4 benefited from a number of improvements as designed and well before the Kylchap exhaust was fitted. The valve/piston ratio was improved, the boiler design was modified with shorter tubes, combustion chamber and higher working pressure and the main steam pipe layout was improved and attention was paid to the cylinder castings to remove rough passageways. The A4 produced an improved performance over its predecessors due to the impact of the sum of a number of changes.

 

And as I pointed out to you at the time on the Gresley thread, I disagreed with your suggestion that it could explain the impoverishment of the LNER and to suggest it as a cause was wrong.

There is nothing wrong with the statement I made there. I have nothing to answer for.

I will not be responding further to your antagonism.

I understand the point you are making but my counterpoint would be that the improvements to the A4s you have highlighted there are not down to Chapelon, but down to Gresley.

He was always trying to improve those aspects of his steam locomotives and arguably class A4 was the culmination of all his work from his role as GNR CME through to being LNER CME.

There is no doubt that the fitting of the double kylchap improved his Pacifics and the Mikados ability. That we should credit Chapelon and Kylala with. Ignoring Kyosti Kylala’s contribution is just as wrong as ignoring Chapelons, of course.

Chapelons principles may not have been applied fully but there remain questions about the viability of all his design ethos when applied to a working fleet - and even then, when these could have been applied is when diesel and electric locomotives were in the ascendency.

Do you develop and experiment with steam or do you build good enough steam to get you through to diesels or full blown electrification?

Ironically this thread is talking about the PRR T1, primarily, and as we know from the history of American steam, was withdrawn early compared to European steam (1952 - scrapped by 1956) because the Americans rightly recognised the power of the diesel engine and electrification where possible.