GWR four-cylinder arrangement?

I sort of the agree with the comment about keeping your dreams to yourself but there does seem to be a trend on this forum for passive aggressive attempts (from some quarters more than others!) to shut down comments such as yours. This is after all a DISCUSSION forum so aren't people be prepared to give others the chance to opportunity to put their views forward? You don't have to read them!

 

'Best' is a word rather open to interpretation; you need to specify from which point of view they were 'Best'.

As you say the Compounds had their weaknesses and the main one was size - or lack of it. They were more than big enough for the (relatively) short trains on the Midland with its policy of lightweight but frequent trains, but attempts to introduce this system on the West Coast lines failed due to a lack of paths to accommodate the extra trains. As a comparison, a Compound (rated as Class 4) might leave St Pancras with a heavy train made up to 300 tons. A short walk away a LNWR George the Fifth (rated as Class 3) might leave Euston loaded to 400 to 450 tons, and that happened on a daily basis. The Claughtons and Dreadnoughts certainly had their weaknesses too but ultimately had the shear size and steaming capacity (not a Compound's strong point) to shift the heavier loads.

The Dreadnoughts' main problem was that it was never intended for high speed, long distance, non-stop running: that didn't happen on the L&YR. Instead they were intended for shorter runs with intermediate stops and restarts often against severe gradients. However good the Compounds might have been, they would not have done that on a day-in, day-out basis, or possibly at all. The Dreadnoughts' other issues were high coal consumption and mechanical weaknesses, particularly hot boxes. The former was cured, as it was on other LMS classes, by substituting multi-ring valve heads for the original Schmidt single ring and also eliminating the ball valves in the heads intended to give free running. Even Stewart Cox, who hated everything L&YR (he had been a Horwich apprentice!), reckoned they could be made good and reliable both easily and cheaply, but by that time the Stanier era was beginning and Dreadnought withdrawals had already begun.

The Claughtons were designed for the WCML and were fast and powerful - on a good day anyway. But their performances were inconsistent. Their excessive coal consumption was cured by the same multi-ring valve head conversion but their reliability and repair and maintenance costs were terrible, and there was no easy cure. The LMS eventually 'rebuilt' them with three cylinders, known for obvious reasons as 'Baby Scots', although definitely not by officialdom.

The Compound was a good intermediate express engine but nowhere near the answer to the LMS's needs for express power, even in 1923. This is shown by the introduction of the Royal Scots only four years after Grouping, an engine 23 tons 14 hundredweight heavier than a Compound.

 

If that is aimed at me, then I have no problem with discussion, I just happen to think that Mr Hermod should build a loco if he wants to experiment, rather than butchering historical locos.

 

I don't disagree, in terms of butchering a preserved loco but, in reality, he's only talking about his dreams and if he really wants to go ahead I think we all know what reception he'd get! If you thought the idea of using a Castle boiler to kit-build a 47XX was heresy then..........!

 

I have a Roche drawing for a King class and it seems to have straight frame plates with a cut out where aft bogie wheels are.
The distance from front bogie wheels to front drivers are exactly the same as on LNER B16/1.
A better King can be made by putting a single 23inch diameter /28 inch stroke high pressure up front outside beside a 34inchdia/30 inchstroke low pressure between frames.
A more crack resistant frame can be had if is made of four parts sliced around first driver main bearing bloks.
Best french compound used 11.2 lbs steam to make one ihph. Britania used 13.2 lbs and Kings 13.8lbs all after WW2.
Improving outdated technology is more pleasant than wondering where steel from war austerity scrapped herritage locomotives might end up.

 

Due to scaling factors I think compounding should work better on a miniature engine than it does on full size.
Consider a cylinder which is initially hot, the steam expanding will have a cooling effect, and the heat has to be replaced by the next charge of steam. My understanding of compounding is that there is less steam (or should I say heat?) lost due to this effect in a compound because there is less expansion, per cylinder. Now in a miniature engine the mass of metal is greater, when compared with the mass of steam, so the benefit of compounding should be greater than for a larger locomotive.
I hope this all makes sense! Compounding was more common on traction engines, but then again so was steam jacketing, On a traction engine, with the cylinders mounted on top of the boiler, it was easier to arrange for the condensate from the steam jackets to drain directly back into the boiler.

 

I have received a scan of a King GA and can se that outside cylinders (16.5 inches inner dia) are 7 feet 2inches apart.
On GWR mainline running straight forward there can thus be two outside cylinders of 26.5 inches dia 6 feet 4 apart.
(Midland compounds had cylinders 6feet 3 apart and the Adams 4-4-0 was 6 feet 2).
Two King cylinders can be substituted by a single 22.5 times 30 inch cylinder so gauge clearance will be OK.

 

The tonnage is not relevant as it is minimum steam consumption per indicated horsepower hour.
Russia used more than 5000 two cylinder compound 0-8-0 locomotives.
I intend to have an outside frame,inside low pressure cylinder and valve,inside frame and single outside high pressure cylinder.

 

Spot on and explain why four small King cylinders were not as frugal as two from Britania.

 

The problem is that the outside cylinders on a GWR King are positioned in line with the bogie trailing axle and the wheels occupy the small space between the frames and the cylinders, as seen on drawing 82101 section C-C. A cylinder diameter of 16.5" was the maximum that could be fitted in the space available.

This leads into the weight issue for the Kings.

The drawing office at Swindon evidently had considerable problems fitting the cylinders and motion in the space available between the boiler and axles etc. Weight was critical given the size of the boiler adopted whilst still keeping the total wheelbase down to a length that fitted existing turntables and overall height/width inside the loading gauge. The high static axle loads were only tolerated because of the almost zero 'Hammer blow' of the driving/coupled axles as a result of the cranks on each side being 180 degrees out of phase. Any alteration to crank angles or reciprocating masses will negate this advantage.

I suspect that Swindon knew that the dynamic axle loads per wheel, per axle, per side of Churchward standard 18" x 30" two cylinder locomotives were way above what the Civil Engineer would have accepted had the Civil Eng appreciated that hammer blow was an issue, even though is is approximately 5.5 tons per wheel at maximum speed of 6 revolutions per second. If a Hall had a static wheel load of 9.5 tons and a hammer blow of 5.5 tons, total 15 tons then a king with 12.5 tons on the trailing axle wheel would be okay even if this was almost all static load and they declared 11.25 tons (22.5 tons on the axle) to meet the Civil Eng's specification.

The 61xx class, balanced for a smooth ride to suit the 1st class stockbrokers, was the worst I can find. Static axle load per driving axle wheel was 8.8 tons and at 6 rps the hammer blow was 6.16 tons so the wheel load on the rail cycled between 2.64 tons and 14.96 tons at full speed.

I think Swindon met the GWR's specific needs for a certain application for which they only needed a few locomotives, they certainly got their monies worth over 35 years.

Andy.

 

The scheme I have in mind can have lower mass and almost no hammerblow

Bal 1500 by Hermod posted Jun 12, 2021 at 2:18 PM

The single ,outside high pressure cylinder drives first driver inside the coupling rods(3feet2 inches fro mid plane

 

The Kings used ca 20% more coal on a locomotive ca 20% more mass than a state of art locomotive?With fewer parts

Cinderella Starboard by Hermod posted Jul 6, 2018 at 10:16 AM

 

I think it should be borne in mind that a lot of development of the front end of steam engines had taken place since the design of the Kings (which were in any case a development of the Stars and Castles so their lineage goes back a lot further). Much of this development took place in France with lot also taking place in the USA. The Britannias benefitted from this as did the Scots after their rebuild (before the Class 8 Kings got their double chimneys they were very much inferior the the Class 7 rebuilt Scots).
I think the 4-6-0 is much too small a platform for a class 8 locomotive, the 4-6-2, or better yet, the 4-6-4 with a 70 sq/ft firebox, a much better prospect. An enlargement of the DoG is the way to go, but I suppose you could take a look at the proposed GWR 4-6-2 if you must.
Best to move away from Churchward I think and go for a later generation.
A lot of the conversation has been about compounding which is great as long as you have a large budget for maintenance keep it simple.

 

I know you have the Book on Webb's Three-cylinder compounds. Have a look at all the additional pipework in the smokebox which gets in the way of routine maintenance, such as tube replacement and even cleaning. Take the Midland Compounds with their ingenious regulator which delivered steam to the LP cylinders and the balancing side of the HP cylinder only, the HP cylinder only, or a proportion to all three, all controlled by various shut-of or by-pass valves not found or needed on a simple engine. Then there is the valve gear: do you link HP and LP gears together (not ideal); go for independent gears for the two systems; or take the Webb route with a slip eccentric for the LP valves? All extra complication which needs capital expenditure to start with and is a source for additional and potentially costly extra maintenance.

 

You have started an interesting discussion, although it seems to have been more about compounding than about GW 4-cylinder locos. You are right that if you walk under "Caerphilly Castle" in Swindon Museum, the underside looks cluttered and complex. As well as the inside cylinders and valve gear, there is a very large vacuum brake cylinder filling the remaining space in front of the firebox.

The GWR was certainly one of the world's prime users of 4-cylinder simple expansion. It had more than 250 Stars, Castles and Kings. I believe that a larger number of non-compound, non-articulated 4-cylinder engines was found only on the Italian Railways (mostly the Class 685 2-6-2).

The GWR's list of 4-cylinder locos would also include the three French De Glehn Atlantics acquired by Churchward, plus two Dean-built 2-4-0 tandem compounds, which had 4 inside cylinders but only 2 connecting rods (LP cylinders in front of HP cylinders). GWR experts will be able to say more about these Dean oddities.

A number of unusual types of compound loco were built down the years. The book by E L Ahrons draws attention to one British-built example for use in Australia. I quote:

"In 1891-92, Beyer Peacock built for New South Wales fifty 4-6-0 passenger engines, of which two were experimental compounds of a type never used in this country. All three cylinders were 20in diameter and placed outside. The two on the low-pressure side were superimposed somewhat after the manner of Vauclain compounds, but both received steam from the single high-pressure cylinder on the opposite side. The arrangement was equivalent to a two-cylinder compound, in which the low-pressure cylinder was divided."

Maybe the object of this design was to reduce the overall width over outside compound cylinders? Anyway, the two engines worked as compounds for about 10 years before being converted to simples, standard with the rest of the class, later designated C32. Smaller than a GWR Manor, but similar in size and layout to the Highland Rly "Jones Goods" 4-6-0.

https://en.wikipedia.org/wiki/New_South_Wales_C32_class_locomotive

 

There is a compound locomotive still running that nullifies all of Your objections in Austria

https://www.zillertalbahn.at/data.cfm?vpath=technische-details-excel/lok-3

My wildest before sleep dream is sometimes putting a steam jacketed high presure cylinder on and apply superheat to the low pressure steam only.
At other times an IOM 2-4-0 locomotive gets mistreated.

 

I think four cylinder locomotives ,be they simple or compounds ,were silly.
When mentioned in first post,it was to obtain a link to a King GA .
I have been lucky as a very kind reader has sent me a complete GA scan.
My plan was to take a preserved two cylinder GWR 4-6-0 ,of wich there are many,and remove the left cylinder.
And then put in a single big low pressure where the four-cylinder monstrocies had their inside cylinders and drive unto front driver axle.
The need for a King GA drawing is to se how the jungle of cylinders,frames and crosshead was arranged and connected to each other.
Benefit of having this half de Glenn arrangement is to keep the outside ,long connecting rod to the second driver.
Having comitted something worse than blasphemy or child abuse by dreaming of improving GWR locomotives I drop that.
A better solution to the problem of having drivers doing more than five rounds per second is to take a Raven S3/LNER B16 and try a two and a three cylinder compound scheme and then decide from there.

 

Apart from the specifications it says nothing about its operation.

Just out of interest, have you ever done any work in a locomotive workshop?