Compounds ex time machine thread

You could fit a Krauss-Helmholz truck to a 9F but it would be a complete waste of time, effort, and money. To keep within our restricted UK load gauge side play on the coupled axles is minimal to avoid things like crankpins fouling crossheads etc., so such a truck is pointless.

On, for example, a DR Class 52 2-10-0 which is much wider over the cylinders things can be spread out more. Hence the 52 has + and - 25mm side play on the 1st and 5th coupled axles which with the K-H truck turns the truck and 1st coupled axle into a bogie.

I'm afraid doing that in the UK is just not practical or beneficial within our load gauge.

 

Present 9F has two 20 inch outside cylindes sitting 6 feet 8 apart.
If I put two 15 inch cylindes 6 feet ten apart my Krauss coupled axle can move one inch either way before crosshead-crankpin collision.
Cylinder group will still be three inch narrower total width.

 

That you can do it with your 9F design is not disputed, but you've yet to actually build it.

 

But.....................

What exactly were the needs of UK railways in the days of steam??

As the 9F demonstrated, it was a loco ahead of its time in terms of the ppower that the steam age railway needed - or could use.

 

The needs of railways was always less mass of train doing more work for less fuel.
Is valid today even on mainline steam excursions.
The Webb three cylinder Compound scheme could have made all british steam 12% ligther and 12%more frugal.
The Webb scheme is only usefull in England,Scotland and Wales and a Webb-improved Barry 9F
will better A1,Duke ,MNs and give P2 a good match to 75 mph for little money

 

Apologies if I've missed any reference to it, but the NER had one of a class of simple 4-4-0s that was built to basically the same system as the Midland Compounds, for direct comparison. The designer of the compound system for both the Midland and NER locomotives was, of course, W.M. Smith. As I understand it, sadly he had died by the time that the NER Board decided that his system was A Good Thing and wished to build more, and his family couldn't agree royalty fees for his system, so no more were built. I can see why compounding would work well on the ECML between York and Berwick - plenty of steady and fast running was possible, with little in the way of serious speed restrictions, other than through the Newcastle area (but a stop would be happening anyway) and Morpeth.

 

I think that's vastly over simplified. The need was is and always will be lower TCO (in modern terms) to run the required services. Fuel was never the only factor. Lubricants were a major part of the running costs, to the extent that on the GWR at least they were notified to the board alongside coal expenditure, and the cost of the general overhauls was also a major contributor. There's no point in saving fuel if the saving is swallowed up in extra expenditure elsewhere.

 

According to some analysts compounds maintained their mechanical condition better than simples and they used less lubricants too.

 

Slightly more complicated than that. Loco 1619 was originally a two-cylinder Wordsell-von Borries compound of class M. There were some simples built in class M1 (later just M). But 1619 was rebuilt by Smith as a three cylinder compound of class 3CC his new system (which was originally devised in France by Sauvage).
Johnson of the Midland was a friend of Smith from previous working together, and was so impressed by 1619 that be built his own compounds to Smith's system.
Smith's later compound Atlantics on the NER were four-cylinder compounds of class 4CC.
Robinson built some 3-cylinder Smith compound Atlantics on the GCR, while Glover of the Irish GNR got a class of 3-cylinder Smith compound 4-4-0 built by BP.
Raven of the NER based this three cylinder simple designs on 1619, in part, while Gresley's owed something to Webb.

 

I would expect a compound to have less stress in the frames, compared with a comparable simple.

 

Exactly.If I knew a copyrigth safe place on the web I would put a picture of page 9 from van Riemsdijks book.
An A2/2 like picture of a von Borries/Golsdorf two cylinder compound would have bettered all british pacifics.
https://i.imgur.com/ZQjgKpG.jpg

 

Unfortunately none of the compounds would have significantly reduced the amount of personnel required, which is the real reason diesel and electric inevitably replaced steam in the UK.