GWR Saint Class Loco

Mikemill

Western Thunderer
GWR Saint Class 29xx. Designed by Churchward these elegant engines deserve to be represented in G3.

The chassis have Nylon 3D printed driver wheels, Nick Bains helped to convert my 2D CAD drawings into .stl files for the printer. The axles run in low profile ball bearings mounted in sprung axle boxes.

The motor/gearbox is rated at 400rpm and drives a 3 to 1 bevel gear set to give a very slow through to elegant speed.

Mike
 

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Dog Star

Western Thunderer
The photos show great detail and prompt the question:-

"what period is represented by the model?"

regards, Graham
 

Mikemill

Western Thunderer
Graham

The first true Saints were built 1906 -1907 and were known as Ladies, they had square frames and full length conned boilers.

I am working to the same drawing that Didcot used for their Lady of legend.

I built a G1 curved frame version around ten years ago, so am familiar with these engines.



Mike
 

michael mott

Western Thunderer
The loco looks great overall, is it an optical illusion or is the crosshead tilted down a little toward the centre driver?

Michael
 

Mikemill

Western Thunderer
The Saint is complete, progress over the last couple of months has been slow due to my wife’s illness and then we both had Covid.

I now have G3 examples of engines designed by the GWR’s four most influential CME’s Gooch, Armstrong, Dean and Churchward.

So, Lady Macbeth is done, as its my birthday tomorrow what better present could you wish for but a G3 Saint.



MikeP1010395B.jpgP1010399B.jpgP1010401B.jpg
 

bambuko

Western Thunderer
Thank you for sharing - beautiful model :thumbs:
The first true Saints were built 1906 -1907 and were known as Ladies, they had square frames and full length conned boilers.

I am working to the same drawing that Didcot used for their Lady of legend.

I built a G1 curved frame version around ten years ago, so am familiar with these engines.

As far as I know, early (square frame) versions of both Saints and Counties, had cylinder centreline offset 2 1/2" above wheel centres.
It is only later, curved frames that had cylinders lowered in line with with wheel centres.
I am not entirely sure about Lady of Legend? Is it made to look square, but has later/lower cylinders?

Can anyone help clarify whether all square frames had raised cylinders?

Small detail, but interesting :D
 

simond

Western Thunderer
Interesting question which was touched on some 8 years ago on my Porth Dinllaen thread, with no conclusion other than my 28xx & 47xx have the offset, but my 59xx series Hall does not. All seem to accord with the relevant drawings. I don’t have any understanding why there was an offset on some locos, and not on others, the cylinders were pretty much interchangeable, so unless the loading gauge changed (presumably becoming less restrictive) I have no idea.

as a further observation, my 52xx also has the offset.

Further info; -

Page 62 of Holcroft's "Locomotive Adventure", he talks about his early work after transfer to the DO at Swindon - he was working on a scheme to rebuild the 80 single-wheeler locos into 4-4-0's - "he (Churchward) was prepared to see the cylinder centre lines pass 3 1/2 in. above the driving centre as against 2 1/2 in. in his standard types". This was some time between 1906 when Holcroft transferred from Wolverhampton, and 1908 when they started to scrap the single-wheelers, so presumably, the "standard" was in place before 1906. This would agree with Russell above.

Reading further in the Russell book, there is an interesting reference to the County tanks - page 60 - the final ten (2241-50) of these locos did not have the 2 1/2 inch offset between the axes. These were apparently built to Lot 188 in 1912, and also had the curved drop to the front frames - which apparently was designed by Holcroft. The same change appears to be the case on the County 4-4-0's the later (1912), curved frame, versions appear to have cylinders aligned with wheels, whereas the earlier (1906) versions have an offset.

The first of the 43xx class was designed and produced in 1910, and appears to incorporate the offset - it's certainly there in all the drawings of Moguls, and of their rather larger cousin, the 47xx, in Russell's book. Holcroft merely reports that he used "a No.4 boiler and brought in all the standard parts he could" as instructed by GJC. Holcroft moved to Ashford in 1914.

So, in large-wheeled engines, the offset between the cylinder axis and driving centre was discontinued in new builds after about 1912, but remained, for everything with smaller than 6'6" wheels. Presumably, it worked, and they had all the jigs, and tooling, so perhaps a case of "why change it?"
 
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bambuko

Western Thunderer
@ simond thank you for detailed comments :thumbs:
It's not just Russel book, but also official GWR drawings - of those that I have, all square frames seem to have cylinders offset and later/curved frame versions show cylinders in line.
Having said so... I seem to see a lot of photographs of straight frame locos, where cylinder appears in line with main wheel centres ?
 

SimonT

Western Thunderer
Interesting. However, I'm sure the raised cylinders has nothing to do with curved or straight drop plates. I think that the locos with raised cylinders are pony truck locos and the requirement to get that huge compensation beam in under the cylinders lead to the cylinders being raised. This is based on a limited survey of locos that I have Swindon drawings for - 28, 42, 43, 47, 72, and the bogie 49. The date on the 72 drawings is May/Aug 1934.

The only other pony truck loco for which I have drawings is the Aberdare. It went through three variants of pony truck and complicated compensation. Everything was very low under the inside cylinders. It all got less Victorian Gothic castings and more utilitarian forgings. The logical end point is the Swindon standard under these locos where the only big differences were A frame and ATC gear.
Does DogStar know better from his days at Didcot? Am I up the wrong tree?
 

bambuko

Western Thunderer
Interesting. However, I'm sure the raised cylinders has nothing to do with curved or straight drop plates.
Yes, but it seems that the change from raised/offset cylinders happened at the same time as the change from straight to curved frames.
I think that the locos with raised cylinders are pony truck locos and the requirement to get that huge compensation beam in under the cylinders lead to the cylinders being raised.
No, raised cylinders appear on bogie, not just pony truck locos.
I read somewhere (can't find the source right now) that it was to do with loading gauge.
 

Dog Star

Western Thunderer
... I think that the locos with raised cylinders are pony truck locos and the requirement to get that huge compensation beam in under the cylinders lead to the cylinders being raised.
Simon (@SimonT),

I am not sure that I understand your comment here for the early Saints had the cylinder offset and those engines did not have pony trucks.

Does DogStar know better from his days at Didcot? Am I up the wrong tree?
The question of cylinder offset is particularly interesting in that there appears to be no clear design requirement... or at least to us mere mortals sitting on the outside of SDN DO.

As (possibly) related questions:-

1/ did any four cylinder engines have cylinder offset?
2/ for a class with some members with cylinders and other members with offset centrelines, are there different cylinder castings / front frame forgings? The NRM has registers which record the drawings per class - that might assist in bringing order to chaos.


I recall reading, probably in Holcroft, that Churchward wanted to use one casting for both cylinders and for the joined castings to sit across the frames (on top of the front end forging). I suggest that to simplify the construction of the front-end of the frames the combined cylinders were placed horizontal... and "possibly" that requirement meant that the cylinders had to be offset so as fit within loading gauge. However, if the loading gauge was the reason for the offset, how did the operations department cope with classes which included offset and non-offset examples?

regards, Graham
 
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SimonT

Western Thunderer
Raising the cylinders will have no effect on the loading gauge (unless there was an earlier, more restricting gauge).
Screenshot 2022-11-18 102612.png
This is the Hall GA sections with the loading gauge highlighted in pink. Slightly odd that there is no dimension for the widest part of the loco! I cannot find a loading gauge on an early drawing.

I remembered that I have a 61 GA. Obs, it is a pony truck loco and blow me down, it has offset. It also has a different, more compact, design to the pony truck compensation beam and mounting/pivot.

Most of these locos, other than the 28 and 42 had both square and curved drop plates.
And, I have no idea why the Star had the offset.
 
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