L&YR Hughes 4-6-0 - drawings

[PenrithBeacon]

2 hours ago, LMS2968 said:

Probably right. The Dreadnoughts had a lot of pull - they needed it against the Pennine gradients - but speed wasn't really their forte.

 

It was said of the L&YR express engines, 'The Highfliers' would run but wouldn't pull, while the dreadnoughts would pull but wouldn't run.' I doubt that either was a hundred percent true, but there's a logic in there.

I have recently bought a 'cab ride' dvd which includes the LYR mainline from Hallroyd Jc to Bradford and there was no chance of fast running,  no chance at all. This is probably the cause of the lubrication issues with the Dreadnoughts because the problem was hidden until they were put on the WCML  where sustained speeds of 60 were expected with top speeds of 75. They weren't up to it. Then they, and the Claughtons,  were tested against Midland Compounds and the Compound was undoubtedly the better engine. Hence it, nominally a less powerful engine, became the LMS standard, but for three years only until the growth of passenger traffic made the design of the Scots essential 

Although I find the LYR passenger engines to look impressive,  the railway was built for the transport of coal and merchandise and loco design was centred around that not passenger traffic. So the passenger types were never going to be the best engines, but the heavy freight 0-8-0 in all its forms could compete with the best.

[PenrithBeacon]

54 minutes ago, rodent279 said:

I've read that it's been said that the GWR 4 cylinder engine could run better than the 2 cyl, but the 2 cyl engine could climb better. Something to do with the Stephenson gear of the 2cyl engine giving them the edge when slogging hard, but the Walschaerts gear of the 4 cyl engine making them freer runners.

It's possible to design the Stephenson gear with negative lead which gives it the advantage at slow speeds over Walchaerts which has a constant lead. Churchward exploited this feature and preservationists find that the GWR 2-6-2T will accelerate faster than the BR4 2-6-4T entirely because of this. Which isn't to say that one engine is better overall than the other.

[LMS2968]

8 hours ago, PenrithBeacon said:

Then they, and the Claughtons,  were tested against Midland Compounds and the Compound was undoubtedly the better engine. Hence it, nominally a less powerful engine, became the LMS standard, but for three years only until the growth of passenger traffic made the design of the Scots essential 

You have to read into these tests. All these early tests were largely conducted, as were these, on ex-Midland lines and arranged by ex-Midland people, who ensured that the Midland design had all the advantages: best possible engine condition, crews well used to the engine and operating over routes they knew, and so on, so the Midland design always came out looking better. There is no doubt that, whatever the test conditions, the Compound would have won hands down; at the time both the L&YR and LNWR 4-6-0s had inbuilt problems with their piston valves, allowing a lot of steam leakage into the exhaust side of the stem chest. How great this superiority would have been ten or so years later after these problems had been identified and eliminated is open to question, but I suspect the Compound would still have returned lower coal figures. But in terms of load shifting it would have been different.

 

The time this sneaky plan didn't work was when the S&DJR 2-8-0 was tested on the Midland coal route to London against the Super D to produce an engine to eliminate the mandatory double heading. The expected victory of the Midland product didn't happen, but instead of accepting this the 2-8-0 was whisked off to Derby to have its valves sorted, then the test repeated. It didn't work and the D again won. The result was the 'Standard' 0-8-0 - the so-called G3 or Austin 7, not a great machine in anyone's eyes. But that's a totally different story!

[rodent279]

9 hours ago, PenrithBeacon said:

It's possible to design the Stephenson gear with negative lead which gives it the advantage at slow speeds over Walchaerts which has a constant lead. Churchward exploited this feature and preservationists find that the GWR 2-6-2T will accelerate faster than the BR4 2-6-4T entirely because of this. Which isn't to say that one engine is better overall than the other.

Thanks. I'm vaguely aware that you are talking about the timing of the admission and exhaust of steam, but could someone explain what negative lead means please, and what it's impact is?

Though this is starting to drift a little from the original post!

[LMS2968]

Lead steam is admitted to the cylinder a bit before the piston reaches the end of its stroke, in the same way that the spark of a petrol engine occurs before the piston reaches Top Dead Centre. This is because steam has inertia and takes time to start to move into the cylinder (in a petrol engine, the fuel takes time to start burning). The introduction of steam early means that there is a 'cushion' of steam between the piston and cylinder cover; and that the steam has already started to flow into the cylinder when the piston reaches the end of its stroke, so there is some pressure for the next stroke as soon as the crank has gone over centre.

 

To return to the petrol engine, the spark is fairly close to TDC at tick over speeds but advances as the rpm rises. It is likewise with lead steam: the faster the engine is going, the earlier the steam should be admitted. Walscheart's gear doesn't allow this as the lead is constant - you get what you've got as it's derived from the (constant) movement of the crosshead - but with Stephenson's it can be arranged that the lead is small, and even negative, at long cut-offs but becomes progressively earlier as the gear is notched up. So at low speed when there is no requirement to cushion the piston's movement and lead steam would try to push the piston back before the crank went over centre, there is little or no lead steam to do this, then as speed rises and cut-off reduces, the lead steam arrives earlier to do its job as already described.

[rodent279]

Thanks, that is about the most clear and concise explanation I have seen!

[kevinlms]

16 hours ago, Gibbo675 said:

 

Ha !

 

When at Riley's in Bury, the standing joke was to tell  the 6201 support group that their big red engine was just a King with a trailing truck.  Too much truth in that one for their liking !

 

To be fair I would suggest that in rebuilt form the L&Y Dreadnought and the Castle class were designed to a similar philosophy with four cylinders actuated by two sets of valve gear using rocking levers, The Castles would have been just fine if modified to burn hard coals.

 

Gibbo.

Big express locos were built with the traffic requirements in mind. The Princess Class needed a bigger firebox, I suspect a King would have a choked firebox by the time it got to Carnforth and then what?

Wasn't a Castle too wide for much of the LMS?

[kevinlms]

11 hours ago, PenrithBeacon said:

I have recently bought a 'cab ride' dvd which includes the LYR mainline from Hallroyd Jc to Bradford and there was no chance of fast running,  no chance at all. This is probably the cause of the lubrication issues with the Dreadnoughts because the problem was hidden until they were put on the WCML  where sustained speeds of 60 were expected with top speeds of 75. They weren't up to it. Then they, and the Claughtons,  were tested against Midland Compounds and the Compound was undoubtedly the better engine. Hence it, nominally a less powerful engine, became the LMS standard, but for three years only until the growth of passenger traffic made the design of the Scots essential 

Although I find the LYR passenger engines to look impressive,  the railway was built for the transport of coal and merchandise and loco design was centred around that not passenger traffic. So the passenger types were never going to be the best engines, but the heavy freight 0-8-0 in all its forms could compete with the best.

The Compound was never a 'better' engine, but it was more economical on coal, which was a key criteria for the Midland management.

Fact was when the Compounds were introduced to the Birmingham '2 hour' expresses they struggled. They were OK if everything worked well, but if things didn't work out on the day, then they couldn't make up any lost time.

The original low superheat Jubilees have much the same trouble, until the superheat was improved, then they did the job well.

 

But we've drifted a long way from Dreadnoughts on the WCML, where they simply weren't designed for long fast runs with heavy trains. No amount of modifications were going to change that.

 

Also remember the LMS under Stamp had determined, that it was cheaper to build new locos, than mess about with major refinements on older locos.

Edited December 26, 2020 by kevinlms
More info

[Compound2632]

28 minutes ago, kevinlms said:

Fact was when the Compounds were introduced to the Birmingham '2 hour' expresses they struggled. They were OK if everything worked well, but if things didn't work out on the day, then they couldn't make up any lost time.

 

That's been a mystery to me. The Euston - Wolverhampton run had much in common with the St Pancras to Leicester, Nottingham, or Derby turns on their home turf in terms of distance, timing, and, I think, loads - very much the inter-city type of service that characterised the Midland. The point of difference I can see is that the gradients were easier, so less call for the engines' hill-climbing abilities. They were very successful engines on the Northern Division, displacing the ex-Caledonian 4-4-0 classes - hill-climbing again? It's well-understood that the combined HP/LP reverser acted as a choke on the steam circuit at high speed - 2632's 92 mph was obtained in its original condition with independent reversers. 

 

The Compounds were undoubtedly the best express passenger engines of their size that the LMS had in the 20s; it's no shame to them that they weren't the right size for working the heavy Anglo-Scottish expresses.

 

38 minutes ago, kevinlms said:

But we've drifted a long way from Dreadnoughts on the WCML, where they simply weren't designed for long fast runs with heavy trains. No amount of modifications were going to change that.

 

Indeed, but it was a question of making the best use of available resources. 

[PenrithBeacon]

1 hour ago, kevinlms said:

The Compound was never a 'better' engine, but it was more economical on coal, which was a key criteria for the Midland management.

Fact was when the Compounds were introduced to the Birmingham '2 hour' expresses they struggled.

...

I think the dynamometer trials do show the Compound to be the better engine in 1924. There is a clear superiority over all its competitors. The issue of the Birmingham expresses simply shows that the LMS didn't have a locomotive that could compete with the best of the contemporary GWR engines as was shown by the trials of a Castle and LMS locos. The Compound was the best LMS engine in 1924 it wasn't the best in the country: the Castle was.

[Compound2632]

12 minutes ago, PenrithBeacon said:

The Compound was the best LMS engine in 1924 it wasn't the best in the country: the Castle was.

 

But of course the two original Smith-Johnson compounds of 1902 outclassed any contemporary Great Western locomotive...

[PenrithBeacon]

57 minutes ago, Compound2632 said:

 

But of course the two original Smith-Johnson compounds of 1902 outclassed any contemporary Great Western locomotive...

A very short lived superiority,  and not only was there not enough them for the superiority to count, but the superiority was thrown away by poor engineering decisions. The Saint was at least as good with much reduced coal & oil consumption. From a business perspective a better engine. 

[Compound2632]

2 hours ago, PenrithBeacon said:

A very short lived superiority,  and not only was there not enough them for the superiority to count, but the superiority was thrown away by poor engineering decisions. The Saint was at least as good with much reduced coal & oil consumption. From a business perspective a better engine. 

 

Well, yes, they had a very brief period as top dog among British express passenger engines. I was thinking one would count the Cities as at least their equal?

 

One could consider it a poor engineering decision to do away with the independent HP and LP reversers but I think one has to remember that engineering has to do with more than just hardware; it's how that hardware is to be used. If it means that the locomotive is going to be easier to use, then the sacrifice of a bit of performance is worth while. How often did an express passenger engine actually need to run at 80+ mph to maintain an average speed of 45 mph - 50 mph? The ability to climb long 1:200 banks without speed dropping much below 40 mph was more to the point. 

 

With a strictly business attitude, Deeley set about removing all the Smith patent features from the design, saving on royalties.

[Gibbo675]

Hi Folks,

 

The largest single variable regarding the operation of steam locomotives of any design is that of the crew. I have had plenty of main line trips where the same locomotive, hauling the same train, burning the same coal, on the same day shewed significantly different performance due to having a change of crew.

 

It is also my experience that both 45407 and 76079 would go just as well, or not, in Scotland and the West Country as they did on the WCML or East Anglia, again dependant upon the crew. I would also say that grid position on the map had no effect upon the locomotives at all, 1:150 with a trailing load of 387 tons is the same wherever you happen to be.

 

Gibbo.

[LMS2968]

Compounds always took a bit of intelligence to get anywhere near to best out of them, and simplifying the driver's tasks could pay dividends in a better average performance at the expense of few very good ones. It was amply demonstrated by the Webb compounds, which many men failed to master.

 

[Compound2632]

24 minutes ago, LMS2968 said:

It was amply demonstrated by the Webb compounds, which many men failed to master.

 

When they were good, they were very, very good*, ...

 

*Adriatic from Euston to Crewe on the record-breaking night of the '95 race to Aberdeen; Jeanie Deans day-in-day-out on the Corridor. One driver one engine of course.

[PenrithBeacon]

2 hours ago, Compound2632 said:

 

Well, yes, they had a very brief period as top dog among British express passenger engines. I was thinking one would count the Cities as at least their equal?

 

One could consider it a poor engineering decision to do away with the independent HP and LP reversers but I think one has to remember that engineering has to do with more than just hardware; it's how that hardware is to be used. If it means that the locomotive is going to be easier to use, then the sacrifice of a bit of performance is worth while. How often did an express passenger engine actually need to run at 80+ mph to maintain an average speed of 45 mph - 50 mph? The ability to climb long 1:200 banks without speed dropping much below 40 mph was more to the point. 

 

With a strictly business attitude, Deeley set about removing all the Smith patent features from the design, saving on royalties.

By Cities I'm assuming you mean the double frame 4-4-0. I would regard these as being very much inferior to the Midland Compounds which I think you would need to compare with such engines as the Precursors and the original Ivatt Atlantic.

I think we're getting well away from the thread's title, so perhaps a return would be welcomed?

[Arun Sharma]

Getting back to the OP's original question, there are drawings and many photographs of the Hughes 4-6-0 Dreadnoughts in Barry C Lane's book, ' Lancashire & Yorkshire Railway Locomotives' published by Pendragon in 2010.