Current and Proposed New-Builds

It would look good and it could possibly be made to work properly, if not it would need a Lady of the Lake to help it get started, it was why they were kept well past their use by date. I stand to be corrected but I think the problem was the low pressure engine was reversed by a slip eccentric and if the receiver got choked it wouldn’t reverse resulting in the comical spectacle of an engine trying to get away with the driving wheels revolving in opposite directions. I’m sure Ahrons described this in one of his books.
As far as I know the John Hick’s were not mixed traffic but were built with smaller wheels for the heavily graded Northern Division.
A useless bit of trivia for you. John Hick was an engineer and industrialist later becoming an MP. He was a director of the LNWR and partner in the Bolton Iron and Steel Co that manufactured steam hammers to the design of one Francis Webb, hence the connection.

 

I think one of the reasons that Drummond went for a double single was to get a big firebox in. The coupled wheelbase was 11ft, and at that time there was also a concern about the strength of very long coupling rods. (I think a T9 which is a conventional inside cylinder 4-4-0 has a 10ft wheelbase, and that was considered long). As you say, the resultant 4-2-2-0s weren’t very good, probably a combination of Drummond getting the cylinder dimensions wrong and also choosing two different types of valve gear that have different events. (I think they were Stephenson’s inside gear and Joy outside).

Tom

 

Johnb, don't believe everything Ahrons said, or a lot of other people, for that matter. If the driver did his job right, no steam would reach the low pressure cylinder so the leading drivers would not slip in either direction. They did use a slip eccentric and the problem was that the engine had to move forward half a revolution of the driving wheels to get the LP side into forward gear, and until then it could make no effort in getting the train moving. The HP cylinders meanwhile were acting alone, and were sometimes too small to get the train to move. These compounds had their faults, but fewer than people believe. One was that unless the HP and LP cylinders were in synch - the LP crank at 135 degrees to the two HP cranks, they ran badly and roughly. Some reckoned that they would assume this angle automatically but in practice, drivers would slip the HP wheels to get everything into line. Again, it's down to the drivers knowing how to handle them.

Their main problem was the same as the Jumbos' and the engines of many other railways, come to that: they were too small to handle the massive increase in train weights which came about the turn of the century. Whale overcame this issue by scaling up the Jumbos by about fifty percent.

 

The Webb 3 cylinder compound and use of slip eccentric valve gear for the low pressure cylinder is a little peculiar in that the Dreadnought Class of 1884 are credited with having independently adjustable Joy valve gear for both high pressure and low pressure cylinders. However the type did revert to slip eccentric for the low pressure cylinder and the notion of obtaining automatic reversal is questionable since the original Joy arrangements could be reversed at the same time. Then again, you can read that the crews could manipulate the slip eccentric while the engine was stationary. 3105B built in 1890 worked the same train (the 2.00 pm Scotch dining train) daily from Jan. 1891 until Aug. 1899 and it is credited with nearly always keeping time. This locomotive was the once famous "Jeanie Deans". I believe that we have been lead into to overlooking something here, maybe there is a narrative which needs a level of questioning.

 

Would I like to see a demonstration of that!!! Genuine Mallets, i.e. HP and LP, had exactly the same problem and were only really suitable for low speed slogging, e.g. N&W Y classes. I've never seen this technique used in relation to Mallets! Plenty of trial & (mostly) error, I would imagine.

 

They would almost certainly have been worse if they ran as 4-4-0s. The cylinder / valve gear layout were carried over into the 4-6-0s (Paddleboats [T14] excepted). The difference was the replacement of Joy's gear by Stephenson. I have seen it opined that the different characteristics of Stephenson and Walschaerts prevented them from even coasting without steam on.
How the Drawing Office got the T14 layout past Old Drum heaven only knows (Eric Langridge reckoned the rocking levers were a better design than the LMS Duchesses) but he was going to use it on the 0-8-0 Goods as well. The GA shows it well, and the grate with a fall of 3 inches over 9 ft 6 inches!
Pat

 

Didn't the Caledonian have a small class of 4-6-0s with three cylinders which had different valve gear on the middle engine to the two outside ones, and they were, apparently, pretty much useless. 956 class I think. @LMS2968 will no doubt know

 

I hate to disappoint you, Cartman, but while I had heard of this I knew only vague details. I've had a look in Essery and Jenkinson's 'Illustrated History of LMS Locomotives, not the ideal reference as it's mostly about liveries (so should be mandatory on here!).

We're talking about the Pickersgill 956 Class 4-6-0 introduced in 1921 with three cylinders, Walschaert's outside gear but a derived motion for the middle cylinder. Apparently this latter was very complicated and not too successful, probably, as suggested, to avoid infringing patents. Prior to Grouping, it had been replaced by a Stephenson's gear for the inside cylinder, retaining Walschaert's for the outside.

Whether or not this improved them, I don't know, but there were only four of them and so of no interest to the LMS which withdrew all of them between 1931 and 1934.

 

Thanks 2968. To me, the Caledonian and the South Western, in Drummonds time, were a bit similar, both had decent 4-4-0s, 0-6-0s and 0-4-4 tanks, but when they tried to expand to 4-6-0s, they both came unstuck and ended up with a lot of small classes, none of which were any good. On the South Western, Urie took over and got them right with the H15/N15 correct @Jamessquared ?but the Caley never really got them properly right. The same could be said about the GC too.

 

William Pickersgill and the Caledonian Raiway 956 class Locomotives
ISBN 9781911038054

Constructed same time as NER S3/B16 and just as miserable as they were brilliant.
Book very good with lots of drawings and photos from building.

 

Only Mr Webb himself could give a definitive answer to that question, but there is no record of him doing so.

Webb's first experimental compound in 1879 was a 2-cylinder converted 2-2-2. It presumably had some kind of starting valve to provide HP steam to the LP cylinder to get under way, analogous to those fitted to other 2-cylinder compounds (such as "Aerolite" at the NRM). This little engine worked for a few years on Ashby-Nuneaton local trains.

At an 1879 discussion of the Institution of Mechanical Engineers, Webb aired his thoughts on building a 3-cylinder compound, and is quoted by Ahrons as having said "The boiler steam should be taken into the middle cylinder first, and thence into the outside cylinders" - in other words something like the Midland 4-4-0 and other later 3-cylinder compounds. But he had changed his mind by 1882 when his first 3-cylinder machine appeared.

A couple of possible reasons have already been mentioned, including the loading gauge width limit. Apart from a single experimental type on the LNWR Southern Division (whose cylinders got into arguments with Euston station platform edges), I don't think any engine of LNWR design had outside cylinders larger than 16" diameter. Ahrons quotes a possible influence given (by a Mr Worthington) at another engineers' conference, namely that with a single high-pressure cylinder "some disadvantage would probably arise from uneven pressure in the receiver, which would be replenished only twice, while it would be required to supply steam four times per revolution". That is a theoretical issue, which didn't seem to have any practical effect on the Midland 4-4-0 or other 3-cylinder compounds built that way, but it might have deterred some engineers from 1HP/2LP approach. Certainly, 3-cylinder compounds were never very common on the global scene, with the Midland/LMS 4-4-0 being the world's most numerous example.

Coming back to Webb, his most successful compounds appear to have been his 0-8-0 freight engines, which unlike his 3-cylinder passenger compounds, had coupling rods.

 

When RW Urie took over (as Locomotive Engineer - not CME) he would have been only too aware of the maintenance problems in the Drummond 4-6-0s. Indeed Old Drum himself may have been coming round; the sole engine built to Order F14 (335) was in store only 5 years after building. Looking at drawings of the H15 and comparing them to the later N15 & S15 I get the feeling that the DO was under some pressure to get new engines out quickly. The parallel boiler barrel is one clue (although reusing barrels rolled for aborted Drummond engines must have played a part. The H15 brake gear layout has the brake cylinder under the cab, like the inside cylindered engines. The later classes had them in the empty space behind the front frame stretcher (between the cylinders). I don't think there was time to get another drag box pattern made and they reused the Drummond era one which supported the cylinder. The 4 years until the N15 build started gave ample time to catch up with design refinements.
Pat

 

Someone must have been missing something then, given that the world's most powerful steam locomotive was a 1HP/2LP compound, in terms of grate area, namely Chapelon's 242A1. It produced a continual 4,000hp between 50 and 63mph with a peak of 5,500hp. It also used 20% less coal and 40% less water than a Coronation Scot.

 

The fascinating story of Webb is that he changes to fourcylinder 4-4-0 compounds in 1897.
A lot of autocrats would not have had the spine to do that.
Conjugation springs to mind.
Rumour has it that one Alfred the Great driver had boiler pressure reduced ,after claiming that he could do as well as the new two cylinder Whale things.
Afterthougth is that the frames would have lasted longer as well.

 

France seems to "book-end" the story of the 3-cylinder compound locomotive. The first French example of the 1HP+2LP configuration was a 2-6-0 built for the Nord in 1887. This machine was apparently a success, lasting until 1929, but nevertheless remained a solitary as French engineers preferred the 4-cylinder compound. The 3-cylinder option was then resurrected 60 years later by Chapelon's 242A1.

In the meantime, only Britain and Switzerland had built 3-cylinder compounds in significant numbers.

 

There's a book about them. https://lightmoor.co.uk/books/william-pickersgill-and-the-caledonian-railway-956-class/L8054

 

Not quite a full size working new build of Metropolitan No 1 and a couple of carriages but well worthy of note:



https://www.ianvisits.co.uk/articles/a-marvellous-model-steam-train-has-appeared-in-amersham-49419/

 

Now if we can make it full size and operable

 

What, like this you mean?



(Not my photo).

Tom

 

Nevermind. At least we have an operable E. Wonder what it would take to build a replica F 0-6-2T?