GWR 111 "The Great Bear" and Surrounding Controversies

The later ones tended to be heavier though. Even an original Merchant Navy has 21T on the driving wheels, and the Princess Coronations over 22. Would I be right in thinking a combustion chamber would save some weight in the boiler too?

 

Hi Jim,

I would tend towards the pivot point of these boilers being around the throatplate. Comparing The Bear with a Gresley A1 is difficult as the LNER used flimsier frames and had only 1 middle cylinder. I honestly don't think The Bear had a compromised (i.e. deliberately shortened) rear end. I have an original GA for the Ivatt Atlantics so we can compare. The Bear's reverser was set back quite a bit using standard parts.

Compare the original 47xx cab length to The Bear?

 

(And Jim some of your sources quoted a few days ago are I think wrong but not the content - perhaps deliberately so - to flush us out?!)

 

Here you go. Its a bit misleading though as the Bear's boiler had a sloping backhead so there's even less room than there looks!

I hope not - but its all too easy to make mistakes on a forum: not like writing a book where you need to check formally. Which ones?

 

I seem to remember reading that GWR footplatemen actually disliked having a "proper" cab, once they started being introduced... That said, I would not feel comfortable working on 111's footplate at 70-80mph with such little side protection, and so low a tender front. There's hardly any room to wield a shovel (and a long one at that), taking into account the firebox's intrusion into the "cab".



Richard.

 

To be fair, short cabs were far from unusual. The Midland and LMS 4Fs' drivers' seats - wooden boards - had to be perched above the reverser and had a slot in them through which he could see the pointer to the index scale. Fowler's 'Austin 7s' from as late as 1929 earned the name among firemen of 'Arse roasters'.

 

surely the rebuild of No/ 6399 Fury formed the basis of the 2/2A boilers used on the Scots, Pats,Jubs?

Connaught & Phoenix rebuilt 1942?

 

6399/6170 was the start in that it was fitted with a Class 2 boiler, but the two 5Xs got the first 2As. The Class 2 was not the best steam raiser around, but the 2A was far better. If the 2A hadn't been fitted to the 5Xs, it's doubtful if the weak Class 2 boiler would have replaced the good steaming parallel Scot boiler, the G10 1/4S.

 

There's short, though, and there's short! That cab from The Great Bear looks minuscule. (And accepting @Jimc 's point that the eight wheel tender only added 6" of total length - six inches less tender and and six inches more cab would still have been useful!)

Does anyone have a dimensioned side-by-side comparison of the The Great Bear and a Stanier Princess Royal? Or at leats a comparison in major dimensions, i.e. boiler dimensions and wheel spacing? How similar - and how different - are they? Is there an obvious place where a foot or two is lost and you suddenly get a very truncated cab? (Sloping front to the firebox of the Stanier design is an obvious visual difference, which presumably in turn gives shorter boiler tubes).

Tom

 

The original Class 1 boilers 6200/01 were 20' 9" between tubeplates; the later ones with an elongated combustion camber were 18" shorter. The length of the Lizzies' firebox externally was 8' 6". Running gear dimensions as below.

 

Thanks @LMS2968 Do you have a similar drawing for 111, @Jimc?

It would be interesting to see where the LMS gained length at the back for a longer cab ...

Tom

 

http://www.greatwestern.org.uk/drawings/loco/loco151.jpg
From Greatwestern.org here's a Bear weights diagram.

And here, although I'm not sure how legible it will be, is a line drawing of the Bear in red superimposed on the LMS drawing.

 

Thanks Jim (and @LMS2968). The side by side is interesting, I hadn't appreciated how much longer the Stanier design was. There's 18" extra from rear driver to trailing truck, and an unknown amount extra behind that (the dimension isn't on The Great Bear drawing). (Plus extra length at the front).

The Stanier design has 11'1" between trailing truck axle and leading axle on the tender; The Great Bear has 9'6.5" - 18" less, plus it appears the boiler of The Great Bear protrudes more behind that rear axle. There can't have been much more than four or five feet from shovelling plate to firehole door, which I suspect made firing it ... interesting!

Tom

 

When you come to fire "Beachy Head", you may be pleased that Mr Marsh designed it with a cab a foot or so longer than on a GN Atlantic.

 

Wasn't one of the advantages with pacific designs (in UK service) the capacity of the ash pan for longer journeys, not something that was an issue on London to Bristol runs.
I could be just making this up from misremembering something completely unrelated.

 

Yes, that's just one of the advantages of a wide firebox, but there are others. You have a larger grate area which can better deal with lower energy coal, and the combustion rate can be lower to give out a similar amount of heat.

 

If I'm remembering my Langridge correctly, wasn't one of the thoughts in the LMS drawing office that the Princess was a bit longer than it needed to be? This resulted in the rearranging of the cylinders and shortening of the coupled wheelbase on the Coronation.

 

It was mostly about the spacing of the inside and outside cylinders, the former over the leading bogie axle and the outers over the rear one, same as on the GWR engines. This left a gap in between them, where the frames were subjected to racking stresses which caused loose cylinders and cracking of the frames. In the later Pacifics, the cylinders were brought together so the rear mounting flange of the inners overlapped the front flange of the outers, shortening the distance between them and eliminating that stretch of bare frame. The later engines were all but a foot shorter overall.

 

I came across a further source on this. I must start by saying this is a source I frequently suggest should be treated with caution, Gibson's "Great Western Locomotive Design", but in this case its close to first hand. He says "On the next row of pits to where I was working in 1925 I saw and passed every day the second Star being converted to a Castle... The job was really quite simple. Nearly all the parts, already stamped with the engine number, were used again. Extensions were added by electric arc welding to the back end of the frames, and the only new parts were boiler, cylinders and cab." The Bear conversion wouldn't have been much more complex.

 

Ihave been told that there is some significance to the number 111, anybody able to comment?