.G.C.R. locomotive specifications help required

[GCR11F]

Reading through Dow's Great Central Volume 3 I came upon a reference to an unbuilt 1911 Pacific proposal. Being intriqued I looked through my collection to see if I could find out anything more eventually coming across the below technical drawing in both, "East Coast Pacific's at Work" and, "J. G. Robinson A Lifetime's Work" and tried to draw up a technical specifications table, also below.
As can be seen certain technical details were missing from the descriptions I was able to find, (denoted by a ?) and embarassingly while I am a life long railway enthusiast, (the .G.N.R. and .G.C.R. inparticular) my grasp of the technical aspects isn't strong, so require help filling in these gaps.




For clarity I'm specifically looking for:
Cylinders: 3 or 4?
Valves.
Flues.
Tractiion effort, (at 85% boiler pressure).
Maximum axle load.

[Atlantic 3279]

I would suggest, as a non-expert in the most technical matters, that;

The valves would undoubtedly be piston valves at that date on the GCR, where slide valves had been dropped and anything else would be too experimental / unconventional.

Although four cylinders would be typical for a post WW1 Robinson big engine, four at 22" x 26" working at 180 Psi would produce a tractive effort massively in excess of any 1920s UK Pacific, probably too much for the available adhesion and for the steam raising ability of the boiler if employed to the full for any length of time. Robinson had not had notable success with air supplies to grates in his large 4-6-0 express locos, and the illustrated position of the firebox astride an axle wouldn't make things easy for this Pacific either, so high steam demand would not be met for long. On the other side of the coin, only two 22" x 26" cylinders would make the loco no stronger than a Sam Fay or a re-cylindered B4, so it looks like three-cylinders-simple may have been on the cards - something Robinson had only used in the Wath Daisy hump-shunting locos and a single Atlantic (disregarding the compounds).

The diagram appears to show 18 ton projected max axle load.

Don't know about the "wet" heating surface of the flues - sorry.

[Hatfield Shed]

I am afraid the diagram provokes an 'urgh'. At one stroke we have a combination of the disadvantages of the 4-6-0 and pacific formats for an express passenger locomotive, with neither of the principal benefits each format bestows. I will poke around at a few diagrams to guesstimate the missing dimensions, but cannot get around to this until Tuesday. The IHP estimate is inconsistent with the cylinder volume, if it is multi-cylinder as the provision of valve gear for inside and outside cylinders implies. Perhaps this was a sketch that was bever fully thought through?

[Atlantic 3279]

Thinking about this one again, I realise two things; I hadn't originally noticed the reference to both inside and "outside" valve gears, so I have to ask whether there is a clear and definite source for that information. External Stephenson's valve gear would be highly unusual, and certainly frowned upon by Robinson who had a keen sense of aesthetics. If it was a case of valve gear inside for outside cylinders, then we need to know with certainty whether any inside cylinders were also proposed. That brings me to my second belated realization, that the tractive effort and the demand for steam even with three 22" x 26" cylinders, 180 psi and 6'6" coupled wheels would be in excess of that of either the original A1s or the Raven A2s, with no certainty that the boiler (or more particularly the grate) would be up to the job. Perhaps therefore a "mere" two cylinder Pacific was proposed, despite Robinson's evident fascination at the time with four cylinders, but in that case what would be the point (other than looks and publicity) to such a large, heavy, complicated and expensive loco with little more ability than existing cheaper and simpler types with greater route avilability?

[GCR11F]

The valves would undoubtedly be piston valves at that date on the GCR, where slide valves had been dropped and anything else would be too experimental / unconventional.
The diagram appears to show 18 ton projected max axle load.

Thankyou.

I hadn't originally noticed the reference to both inside and "outside" valve gears, so I have to ask whether there is a clear and definite source for that information. External Stephenson's valve gear would be highly unusual, and certainly frowned upon by Robinson who had a keen sense of aesthetics. If it was a case of valve gear inside for outside cylinders, then we need to know with certainty whether any inside cylinders were also proposed.

Sorry I used someone else's pre existing technial specifications table as a template and filled in in without thinking or checking it. The Stephenson valve gear was a guess given the Atlantics and the presence of a step between the first two wheel splashes. Wikipedia on 1090, "These cylinders had their Stephenson valve gear replaced with Walschaerts valve gear, which was the only application of this valve gear, excluding railcars, on a GCR locomotive".
I've unfortunately been unable to find anymore information about the design.

Perhaps this was a sketch that was bever fully thought through?

That might be the case as:
"It was fairly common occurrence for the .C.M.E. to ask his Drawing Office to produce outline drawings of certain types embodying, were possible, existing standards regarding boiler, cylinders, tender and so forth, and introducing, where necessary, up to date improvements”, Dow G., 1965, P.326.

If it was a simple drawing office outline, (rather then designed by Robinson himself) intended as a starting point, (similiar to the, "A0" plans) then the technical problems of such, "hodge podging" of features, (such as: 4 cylinders, small firebox and boiler, and inconsistent .I.H.P.) would make sense.

but in that case what would be the point (other than looks and publicity) to such a large, heavy, complicated and expensive loco with little more ability than existing cheaper and simpler types with greater route avilability?

Personally it seems like something that Fay would do for publicity purposes, (perhaps inspired by the .P.R. of .G.W.R.'s Great Bear?) and presumably Gorton wouldn't have minded/cared so that leaves Robinson known for being a strict disciplinarian and conservative locomotive designer. Could Fay have ordered the outline made without him knowing?

[Hatfield Shed]

For a start it is a two cylinder design. (The statement of cylinder dimensions on the drawing is in that D.O.'s style for 2 cylinder machines.)
With two cylinders the T.E. estimate at 85% of B.P. is 24,684lb; and that is sensible relative to both the grate and superheater areas; the latter because at speed it will need that relatively high superheater ratio to maintain steam supply.

It has quite a lot in common with the 8N (LNER B6) which was relatively successful for a Robinson 4-6-0 (but not the design built in reasonable numbers as a mixed traffic machine). Nine 4-6-0 designs, and none of them candidates for sainthood or stardom...

[Atlantic 3279]

I had also deduced that this was almost certainly a two cylinder proposal, and notwithstanding the exceptional diameter of the outside cylinders the tractive effort as Hatfield Shed has pointed out would not even quite match that of Robinson's Lord Faringdon type four-cylinder 4-6-0 express locos. Even if more of the mixed traffic variant of the four cylinder type were ordered at the very end of the GCR's existence (or by the newly formed LNER, which must at least have confirmed the order) does the outline Pacific proposal indicate some recognition at least by GC management that Gorton's approach to the four-cylinder type had not given results to justify the cost and complication?
Those 3 locos that became class B6 are said to have been regarded by some as the best 4-6-0s that the GCR had, and both the size and layout of their two cylinders had been much more widely tested (and proven successful?) on the huge number of eight-coupled locos to GC design, the Atlantics, the B4s, the B1s and right back to the original fish engines.
Given that the 21" cylinders on the 2-8-0s barred them from some routes, and led to the LSWR fairly quickly getting rid of the RODs that were loaned to it even when locos were sorely needed, the route availability of the 4-6-2 with 22" cylinders would have to be considered very carefully.

[Pyewipe Junction]

Given that the 21" cylinders on the 2-8-0s barred them from some routes, and led to the LSWR fairly quickly getting rid of the RODs that were loaned to it even when locos were sorely needed.

I don't understand this. Why would Robinson, who was designing for the GC, worry about the LSW loading gauge? What were the routes from which the RODs were barred?

[Atlantic 3279]

I doubt that Robinson worried at all about LSWR loading gauge. My thoughts were mainly centred on wider use of locos, for instance after the grouping. 21" diameter was large for outside cylinders on UK locos, some types thus equipped having flattened casings over the cylinders to gain a little more structure clearance. Larger cylinders still might have restricted the use of the projected Pacific somewhat, that's all I meant.

[Pyewipe Junction]

AFAIK O4s/RODs weren't particularly restricted anywhere on the LNER and were even used on the Fife coalfield lines for some time. RODs were also purchased by the GWR, and LMS for use on ex-LNWR lines.

[GCR11F]

Sorry for the late reply and thankyou for all of the information.



That just leaves the piston size, (inches) and the Flues value.