Imaginary Locomotives

[Joseph_Pestell]

North British Railway musings on  the theme of the 'H' Atlantic. Perhaps the extension to a Pacific is pretty obvious. Unlike the Atlantic, this one has a wider firebox. Inevitiably there's some resemblance to Raven's NER design, though perhaps not as much as I expected:

 

NBRpacific.jpg

 

More logical perhaps would be to have a six-coupled version fo the Atlantic instead:

 

NBR_4-6-0.jpg

 

Since you have named it "Aberdonian", shouldn't it be a 2-8-2?

 

Seriously, those both look terrific. But I think a 2-8-2 (with smaller wheels) would also work under that Pacific's boiler.

[Compound2632]

North British Railway musings on  the theme of the 'H' Atlantic. Perhaps the extension to a Pacific is pretty obvious. Unlike the Atlantic, this one has a wider firebox. Inevitiably there's some resemblance to Raven's NER design, though perhaps not as much as I expected:

 

NBRpacific.jpg

 

More logical perhaps would be to have a six-coupled version fo the Atlantic instead:

 

NBR_4-6-0.jpg

 

But this overlooks the reasons why Reid went for an atlantic rather than a 4-6-0 in the first place - the tight curves on several of the North British's main lines, particularly the Waverley route.

[BernardTPM]

Interesting, though how much of that was a perceived rather than an actual problem, given that Gresley Pacifics and Thompson B1s were later used on the Waverley route.

[brack]

Interesting, though how much of that was a perceived rather than an actual problem, given that Gresley Pacifics and Thompson B1s were later used on the Waverley route.

Did they ease curves? Change flange/wheel profiles? Or just accept that track and loco maintenance would cost more in return for longer trains and higher capacity?

When the Atlantics did arrive there was a bit of hoo-hah about weight and oscillation from the track dept, which turned out to be unfounded. Perhaps if reid had gone with a six coupled loco as well they'd have thrown a bigger wobbler like the Highland River class debacle, where newlands won his personal battle with Smith and his replacement then built locos with higher axle loading and hammerblow. Hindsight proved that Smith better understood hammerblow than newlands, but sadly being right didn't mean his career wasn't knackered, in spite of his only design having been probably the best 4-6-0 of any LMS constituent.

[scots region]

North British Railway musings on  the theme of the 'H' Atlantic. Perhaps the extension to a Pacific is pretty obvious. Unlike the Atlantic, this one has a wider firebox. Inevitiably there's some resemblance to Raven's NER design, though perhaps not as much as I expected:

 

NBRpacific.jpg

 

More logical perhaps would be to have a six-coupled version fo the Atlantic instead:

 

NBR_4-6-0.jpg

 

Did you paint these yourself Bernard?

[BernardTPM]

Only in parts.

[rockershovel]

I was scratching my head over the Pacific, which looks subtly “wrong” somehow.... if I might make a suggestion, the firebox is the key to it. Look at fireboxes on the Coronation Class, for example; the lower section is conspicuously slopes over the trailing wheels, with the lowest point ahead of the trailing axle. The front of the firebox is further forward on the boiler, the upper front corner more-or-less over the third driving axle.

 

That reduces the length of the boiler barrel by one full band, and makes the whole thing more balanced in appearance. That said, it does have a marked resemblance to Great Bear, which would have been contemporary, so it probably DOES represent quite an accurate image of what a NBR Pacific of that era would have been like

 

 

The GWR certainly built Atlantics with narrow fireboxes

 

 

That said, despite the usual fetish of an elegant appearance, there were some notable donkeys built around that time

 

[BernardTPM]

I was scratching my head over the Pacific, which looks subtly “wrong” somehow.... if I might make a suggestion, the firebox is the key to it. Look at fireboxes on the Coronation Class, for example; the lower section is conspicuously slopes over the trailing wheels, with the lowest point ahead of the trailing axle. The front of the firebox is further forward on the boiler, the upper front corner more-or-less over the third driving axle.

That reduces the length of the boiler barrel by one full band, and makes the whole thing more balanced in appearance. That said, it does have a marked resemblance to Great Bear, which would have been contemporary, so it probably DOES represent quite an accurate image of what a NBR Pacific of that era would have been like

Yes, the comparison with The Great Bear is apt. Also look at the similarly lanky form of the (later) NER Raven Pacifics.

Edited March 16, 2018 by BernardTPM

[rockershovel]

Yes, the comparison with The Great Bear is apt. Also look at the similarly lanky form of the (later) NER Raven Pacifics.

 

I wasn’t aware of these locos, but the point is well made. I note that like Great Bear, these locos were also considered to be adversely affected by excessively long boiler barrels and hence, tubes.

 

The highly successful eight-coupled types developed around the early twentieth century seem to have settled on 15-16’ as the optimum length - the LNER Garratt would be 13’6” - and the Gresley and Stanier Pacifics seem to have been in this range. Great Bear was more than once referred to as “an exercise in boiler design”, after all.

[TheQ]

 

That said, despite the usual fetish of an elegant appearance, there were some notable donkeys built around that time

 

2E421C43-7AD1-4915-9970-A1F0B443A198.jpeg

Donkeys in more ways than just appearance,The highly unsuccessful Kruger class of about 10 locos, the longest any lasted was 7 years,some only 3!!!. Some parts went in to the Aberdare class..

[Satan's Goldfish]

I was scratching my head over the Pacific, which looks subtly “wrong” somehow.... if I might make a suggestion, the firebox is the key to it. Look at fireboxes on the Coronation Class, for example; the lower section is conspicuously slopes over the trailing wheels, with the lowest point ahead of the trailing axle. The front of the firebox is further forward on the boiler, the upper front corner more-or-less over the third driving axle.

 

That reduces the length of the boiler barrel by one full band, and makes the whole thing more balanced in appearance. That said, it does have a marked resemblance to Great Bear, which would have been contemporary, so it probably DOES represent quite an accurate image of what a NBR Pacific of that era would have been like

 

9B9A2833-767C-46C4-9B45-030B653A28ED.jpeg

 

The GWR certainly built Atlantics with narrow fireboxes

 

B84E6E56-61D2-47E5-B415-95DD961E1594.jpeg

 

That said, despite the usual fetish of an elegant appearance, there were some notable donkeys built around that time

 

2E421C43-7AD1-4915-9970-A1F0B443A198.jpeg

Sorry, I have a strange fascination with TGB's tender; looking at the picture, are the bogies very similar in wheel size/spacing to the front pony truck?

[Regularity]

I was scratching my head over the Pacific, which looks subtly “wrong” somehow.... if I might make a suggestion, the firebox is the key to it. Look at fireboxes on the Coronation Class, for example; the lower section is conspicuously slopes over the trailing wheels, with the lowest point ahead of the trailing axle. The front of the firebox is further forward on the boiler, the upper front corner more-or-less over the third driving axle.

 

That part was a combustion chamber.

[TheQ]

Sorry, I have a strange fascination with TGB's tender; looking at the picture, are the bogies very similar in wheel size/spacing to the front pony truck?

According to this http://www.greatwestern.org.uk/drawings/loco/loco151.jpg the Wheels are indeed the same 3ft 2in diameter, the bogies do look very similar. But the loco Bogie has 7ft between the wheels, the tender bogies have 5ft 9inches between the wheels.

[JimC]

The Great Bears tender bogies are indeed assumed to be the locomotive bogie design shortened.

[melmerby]

I was scratching my head over the Pacific, which looks subtly “wrong” somehow.... if I might make a suggestion, the firebox is the key to it. Look at fireboxes on the Coronation Class, for example; the lower section is conspicuously slopes over the trailing wheels, with the lowest point ahead of the trailing axle. The front of the firebox is further forward on the boiler, the upper front corner more-or-less over the third driving axle.

 

That reduces the length of the boiler barrel by one full band, and makes the whole thing more balanced in appearance. That said, it does have a marked resemblance to Great Bear, which would have been contemporary, so it probably DOES represent quite an accurate image of what a NBR Pacific of that era would have been like

 

9B9A2833-767C-46C4-9B45-030B653A28ED.jpeg

 

The GWR certainly built Atlantics with narrow fireboxes

 

B84E6E56-61D2-47E5-B415-95DD961E1594.jpeg

 

That said, despite the usual fetish of an elegant appearance, there were some notable donkeys built around that time

 

2E421C43-7AD1-4915-9970-A1F0B443A198.jpeg

The Great Bear has inside axleboxes on it's trailing truck which affects the design of the firebox/grate somewhat

 

The GWR Atlantics would have been better if the trailing wheels weren't just a "bolt-on" for a 4-6-0 chassis.

Maybe somebody can knock up a mock-up with a wide firebox and a proper trailing truck?

 

The Kruger style did improve a little as it's design evolved when a standard Swindon boiler with a front pony truck version the "Aberdares" arrived:

http://www.swindonviewpoint.com/sites/default/files/GWR%20S%2093%20Locomotive%20No%202652%20a%20lmember%20of%20the%20Aberdare%20class%20one%20of%20the%20less%20graceful%20designs%20named%20this%20as%20they%20were%20to%20haul%20coal%20trains%20from%20South%20Wales.jpg

 

Keith

Edited March 16, 2018 by melmerby

[TheQ]

The Great Bear has inside axleboxes on it's trailing truck which affects the design of the firebox/grate somewhat

 

The GWR Atlantics would have been better if the trailing wheels weren't just a "bolt-on" for a 4-6-0 chassis.

Maybe somebody can knock up a mock-up with a wide firebox and a proper trailing truck?

 

 

 

Keith

Though the Scott series of Atlantics were when Churchward wasn't sure of whether to go for 4-4-2 or 4-6-0, Number 171 Albion was the trial engine against the Frenchmen, which went from a 4-6-0 to a 4-4-2 and back again, hence the narrow fireboxes, within 10 years  all 20 were converted to 4-6-0.

 

Even the Aberdares weren't that pretty, I think the very heavy looking chassis is the problem in asthetics...

Edited March 16, 2018 by TheQ

[JimC]

The GWR Atlantics would have been better if the trailing wheels weren't just a "bolt-on" for a 4-6-0 chassis.

Maybe somebody can knock up a mock-up with a wide firebox and a proper trailing truck?

 

 

2708?

 

http://www.rmweb.co.uk/community/index.php?/topic/14790-imaginary-locomotives/?p=3029554

[scots region]

 

The GWR Atlantics would have been better if the trailing wheels weren't just a "bolt-on" for a 4-6-0 chassis.

 

Good grief you’re right, I never noticed that before.

[Satan's Goldfish]

Cheers guys, sounds an easy enough mod...

[rockershovel]

I’d always understood that the GWR had pretty much decided on the boiler and firebox design, resulting in a series of 4-6-0 designs which distinguished themselves in trials on other lines... but Stanier would develop wide-firebox designs for LMS...

Edited March 16, 2018 by rockershovel

[The Johnster]

Well, Churchward was certainly an innovator in boiler design, and production methods in general, and it was at his instigation that a standard range of boilers, cylinders, wheels, and running gear was introduced out of which a standard range of locos could be easily put together and bits swapped at overhauls.  This predated, just, the comparative trials between the de Glehn atlantics which were the only real reason for producing his own design adapted to atlantic form.  As the trials proved no particular advantage to the atlantic over the 4-6-0, or to compounding over simple 2 and 4 cylinder layouts, those ideas were not taken up at Swindon.  Had they proved advantageous, later GW locos may well have gone down the atlantic/pacific route of the ECML lines, but there is a significant advantage to a 4-6-0 9n the GW, with main lines requiring fast running but with significant gradients in South Devon, the legacy of the atmospheric disaster, and fairly significant ones in South Wales as well; these were better suited to 4-6-0 tractive effort and sure-footedness.

 

As for 4-6-0s distinguishing themselves on other lines, we are mainly talking about 4 cylinder 4-6-0s of Star, Castle, and King classes.  A Star was lent to Camden to be tried on the WCML of the LNWR, without the knowledge of Webb, whose board did not see fit to inform him of the occasion; poisonous internal politics were not confined to the early LMS period and particularly despicable on a railway which considered it's officers to be gentlemen.  Pendennis Castle showed up well in comparative trials against Gresley A1s, arguably prompting their development into A3s, but the LNER never built a 4 cylinder 4-6-0, or pacific, so they couldn't have been that impressed.  The LMS wanted to order 50 Castles which Swindon did not have the capacity to build in a time of similarly despicable internal politics, and they settled for the Lord Nelson based Royal Scot with Derby induced hobbling, a poor steamer.  The de Glehn 4 cylinder layout appeared on the LMS' later pacifics, with the Princess looking like a stretched King, but this about the only GW practice that those engines or the Coronations employed.  The 1948 exchange trials featured a King proving itself on heavy King's Cross-Leeds trains, but made no impact on ER running practices

 

Had Swindon abandoned the 4-6-0 format in favour of atlantics for express running, which would have been viable on the Bristol road, a wider firebox would almost certainly have been used, and probably a different boiler to the no.1 to go with it, but Churchward wanted to test his design against de Glehn's and did not go to the trouble of designing a boiler with a wide firebox more suitable for atlantics.  The Great Bear, of which the best part was the brilliant name, is hardly representative of best practice, and arguably shows a fundamental lack of understanding of atlantic/pacific design principles at the back end of the boiler.  Swindon ran into trouble with bigger than no.1 boilers, only the Castle's no.7 being successful, and the 47xx and King's, while being very good steam producers, took matters too close to loading gauge and axle loading restrictions too be really useful across the entire main line system, as would the Mattingley's had it been built.  The wide cylinder setting of Churchward and Churchward derived locos severely limited their usefulness away from the GW, which counted against them for through working on other railways/BR regions.

 

Churchward is often cited as one of the most influential designers of his time, but his ideas were not largely taken up by other railways.  The greater influence IMHO was Collett's rebuild of Saint Martin with 6' driving wheels, the progenitor of most subsequent British mixed traffic practice and widely adopted everywhere except the Southern, which succumbed to BR standards of this pattern eventually, and anyway already had very good mixed traffic horses in the form of the Maunsell moguls and the excellent Urie 4-6-0s.  One can regard the Black 5 as a Hall to LMS standards and the B1 as one to LNER standards, and the BR standard 5MT as a Hall to BR standard standards.  All of these are narrow fireboxed 4-6-0s and similar in principle to GW practice.  

 

The dichotomy is between a fast, good riding, atlantic or pacific with a wide firebox over the trailing wheels, free steaming and free running, or a similar size 4-6-0 which does not ride as well at high speed, and which needs an excellent boiler (the GW's were pretty good by all accounts) to steam freely and precision construction and frame building to run freely, but performs much better on the banks!  Shap and Beattock are formidable, but not in the way that Dainton or even Skewen, straight off the platform at Neath around a tight curve and two miles of 1 in 90, are.  The Great Bear and the Mattingley pacific are red herrings; one should probably never have been built and the other wasn't anyway!

 

But a modelling project of a Churchward atlantic with a wide firebox and perhaps 7' wheels with a no.1 boiler for Bristol trains would look wonderful, not that I'm volunteering.  I'm a South Wales Valleys man, and engines that go that fast frighten me...

Edited March 17, 2018 by The Johnster

[Compound2632]

As for 4-6-0s distinguishing themselves on other lines, we are mainly talking about 4 cylinder 4-6-0s of Star, Castle, and King classes.  A Star was lent to Camden to be tried on the WCML of the LNWR, without the knowledge of Webb, whose board did not see fit to inform him of the occasion; poisonous internal politics were not confined to the early LMS period and particularly despicable on a railway which considered it's officers to be gentlemen.  , and engines that go that fast frighten me...

 

Point of fact: Webb retired in 1903 and died in 1906; North Star was built in that year as an atlantic. The exchange of 4-6-0s took place in 1910, under George Whale's superintendency, involving an Experiment and a Star. The exchange might have done more credit to Crewe had it taken place a year later using a superheated Prince of Wales 4-6-0. But the operating conditions on the main lines of the two Western railways were so different that comparisons were doomed to be odious, except on the question of coal consumption.

 

I'm ignoring the calumny directed at the Derby drawing office.

[brack]

I'm not sure you can describe the B1 as a hall to LNER standards, it's more a case a convergent evolution. The B1 effectively was a bunch of standard parts put together to give a cheap, robust go anywhere, do anything loco to replace a lot of life expired stuff. It's lineage goes through the B17, and from thence the D49 and B16. It wasn't so much a case of build me a hall or black 5 as build me a B17 without the complications of an extra cylinder and with smaller wheels for mixed traffic work. The fact that however you do it you end up with a 2 cylinder 5MT 4-6-0 with 6'ish drivers is because that is what the majority of work in this country needed, but the Hall was not the first to meet that specification. The black 5 I agree stems from the Hall line, with non-swindon features creeping in. I'm not saying that the hall didn't influence later classes on other lines - nobody is blind to what their counterparts are doing, but that outside of the Swindon tradition people came to a similar form as a solution to a similar problem. Claiming that all later mixed traffic 4-6-0 designs were attempts to copy a Hall are like suggesting that the hall emerged because collet was trying to copy Urie's H15, the Highland's River or Clan or Raven's B15.

[runs as required]

It used to be written that the type of coal readily available to a railway influenced the design of firebox and boiler.

So in retrospect is that so much OS Nock armchair engineering?

 

Are we actually conceding that S Wales anthracite burning Castles would have been equally at home (as some Directors of northern lines once hoped) back in the 1920s shaking narrow fireboxes full of bituminous Markham coals down while bowling north to Newcastle or Lancashire brights forward when slogging over from a standing start at Oxenholme through Tebay up to Shap Wells ?

 

In the US the wide firebox seemed to be dominant from the early 1900s - even for anthracite burners - the Wootton firebox allowed the coal haulier to burn the anthracite slack while profiting from transporting the expensive hards to markets.

Cheapness seemed to win out with plain round top fireboxes/parallel boilers, perhaps incorporating a syphon, compared to tricky Belpaire costly shaping and detailing.

 

So could Churchward have achieved his standard types more expediently staying with his plain transatlantic influences than allowing himself to be seduced by Frenchie fancy ?

 

dh

[Northroader]

Careful, there’s two kinds of coal in South Wales, anthracite was mined in the west around Swansea,being a hard coal which burned quite slowly, popular for furnaces with long processes, like brewing and malting. The central and eastern area, north of Bridgend, Cardiff, and Newport, produced a different kind of coal, generally called steam coal, much softer. When you burnt it, it swelled, became spongy and burnt fiercely, with a fairly low ash content. This was what the GWR used, not the anthracite. Northern coals were similar, but generally not as high bitumen content, and more ash was produced.