O4, O5 and B6 cabs (ex GCR 8K, 8M and 8N)

[Atlantic 3279]

The RCTS account says that the cabs of the large boilered O5 2-8-0s were 5" shorter, front to rear, than those of the smaller boiler "standard" O4s, in order to clear the differently arranged fittings on the O5 firebox. The cab of the O5s was of course taller. The height difference is obvious in photos, but I can't decide whether I can see the difference in lengths too. Those of Charles Reddy's drawings that I have, normally convincing to my eyes, depict the 8K(O4), the 8N 4-6-0(derived directly from the 8M), the temporarily unique 6-foot round-top boiler incarnation of the 8K used on pulverised/colloidal fuel tests, but no true 8M.
As the 8M and 8N shared boilers and cylinders/motion (on account of the first 8N being concocted by "adapting" an existing order for an 8M), and the 8Ms were built on the same chassis/platform as the 8Ks, I decided to superimpose the 8K and 8N drawings. This seems to me to show the same overall lengths of frames/loco, and cab on the two locos, with LESS exposed length of firebox on the 8N. If the firebox fittings were in the way of the longer cab on the 8Ms, I'd expect the same on the 8Ns. Am I wrong, or is it the drawings, or even the RCTS details?

[wehf100]

Locomotives of the GCR by EM Johnson concurs with the RCTS account:

" To accommodate the spectacles of a reasonable width the 8M cab was widened by 7'' to 8' 3''. In contrast to the 8Ks, only one spectacle was provided... Although wider and taller, the cab had to be shortened by 5'' to clear the firebox washout plugs. A consequence of this was the steel casing on the right hand side of the cab front to cover the screw reversing gear. Under the cab appeared sandboxes for reverse running, another visual difference from the 8K which housed the boxes in the longer cab."

"In the manner of 9P locomotives, the last five 8Ms, (nos 13,14,15,19,22) had what might be described as the improved cab with two side windows and extended roof."

Hope this helps. A 4mm 8M would be quite a model!

Will

[Saint Johnstoun]

I was going to point Graeme to exactly the same source of information.

Here is my rendering of the O5 - note that the cabs are shorter than the O4.

LNER Class O5.doc

(181 KiB) Downloaded 116 times

[Atlantic 3279]

Thanks Gents. I've now also found some rather better images to substantiate that 5" difference in cab lengths.

[earlswood nob]

Good morning
On my Isinglass drawings; the O5 cab is shown as 7in shorter than that on the corresponding O4/3 cab.
I wonder if the cab of the O4/4 rebuilds is the same length as the O5 cab, but with a single side window.
Comparing the O2 drawing with that of the O5 it seems that the 6in increase in frame length, together with a shorter cab would allow a standard sized O2 boiler to fit. Is this goping to lead to another dream of model conversion?
Earlswood Nob
Ps Haven't got a B6 drawing to compare

[Atlantic 3279]

I think this "problem" is well and truly solved now, In addition to the helpful and gratefully received comments on here, I've had some separate input by e-mail from one or two others (including my extremely helpful acquaintance in Portugal - or sometimes Australia). That, in combination with my brain starting to function a bit better now that the fog of cold/flu/mystery virus is really clearing, led me to realise that I have the reproductions of the 8K and 8N works drawings in the back of vol.2 of E.M. Johnson's "Locomotives of the Great Central Railway" ........

In a nutshell, my faith in the Charles Reddy drawings is now shaken as he appears to have the 8N cab length wrong. The dimensioned works drawings show that the 8K cab roof ought to be virtually 20mm long in 4mm scale, whilst the first 8N cab roof (and I strongly suspect therefore those of the first batch of 8Ms too) should indeed be around 5 scale inches shorter at just a sniff over 18mm. Reddy's drawing has it at about 19.5mm. Even if his 8K is spot-on (??) I'm now glad to remember scratchbuilding my 8K body according to the works drawing.

Resin parts production for an 8M conversion of the Bachmann loco is certainly a possibility that interests me, at the right moment, whenever that is. Fig.43 in the relevant RCTS volume (backed up by comment in the text) showing an 8M apparently in 1935, still showing strong evidence of GC goods lining, over-painted GC script on tender, and LNER number still on the tender rather than the cab, has really taken my fancy! Other things must come first however, such as earning a real living from tedious "proper" work, and finishing off projects already promised for others. A K2 starts to look a more realistic option than I once thought too, and would probably appeal to more of us than would an 8M / O5, so that might come first. I/we shall have to be patient.

[earlswood nob]

Afternoon 'all

I have checked the drawings I have (Isinglass) and there are several sizes of cabs fitted to Robinson locos:

The size of Great Central cabs

B2, B3 4ft10ins
B4, B5 & B9 5ft2ins
B8 4ft8ins
O4/3, /5 & /7 4ft7ins
O5 4ft0ins
Q4 5ft0ins

and I thought they were all the same!!
I look forward to Atlantics next projects
Earlswood Nob

[Horsetan]

.....Resin parts production for an 8M conversion of the Bachmann loco is certainly a possibility that interests me, at the right moment, whenever that is.......

There's still a complete V2 boiler and firebox waiting for you here, for mastering purposes......

[Atlantic 3279]

Ta for the reminder. I will bear that in mind. Plans keep changing at present, as is so often the case when so many things are beyond one's own control.

[Horsetan]

...so many things are beyond one's own control.

Can anyone ever be said to be fully in control?