GWR Small Prairie locos details

[bertiedog]

Assembling a Sayer Chaplin Small prairie GWR Loco, 45xx version with tapering tanks and larger wheels, but having trouble finding drawings.

 

http://www.rmweb.co.uk/community/index.php?/topic/120676-sayer-chaplin-262-gwr-small-prairie-tank-locomotive-kit/

 

I thought there was a Roche GWR 45XX drawing, but I have no copy and can only find the 44xx outline from the net, with the slightly smaller drivers and straight top tanks.

• Is is safe to assume the chassis are identical apart from the wheel diameter?

I have the drawings for the chimney details and the safety valve cover, these were standard items.

All the parts etched by Sayer Chaplin match the photos of the surviving 45XX class very closely indeed, but many smaller parts never supplied by them need to be made, and have to fit in with the etched parts.

• Can anybody with a complete Roche book see if the 45XX is in the drawing collection, before I have to get a new copy!!

Or is there another dedicated class book with decent drawings on the market currently?

 

Stephen

[bertiedog]

Problem solved, found old loose leaf GWR 4500 small prairie drawing by Roche, which must be the one that Sayer Chaplin used themselves as the details match.

Stephen

[OldSutt]

Bags of info/drawings in GW Railway Journal nos 96,97,98 re 45xx etc.

[bertiedog]

It was mainly that I was suspicious, and rightly so it seems, that the wheel base and axle spacing were altered with the bigger tanks and wheels. I am now not sure that the commercial rods and chassis would have matched, but it will be done to the Roche dimensions to be consistent and match the Sayer parts. I think from experience that Sayer Chaplin used the then new Roche drawings themselves, the details match pretty closely.

Anyway I now have the right drawing to work with and the axle positions can be marked on to the new frames for drilling in the mill.

Most of the finer details are covered by photos on the net of the preserved examples of the class.

Stephen

[DCB]

There was a long running argument on this forum re 44XX vs 45 XX  but the bare facts are the wheelbase is different, the centre axle is in the same place on both classes but the other two axles are moved back by 6 " on the 45XX   so 6' and 5'6" on the 44XX and 5'6" and 6' on the 45XX.  The rods are I believe identical just swapped side to side.

I believe when they realised larger wheels would make the small tank more useful they found the motion bracket prevented simply fitting larger leading driving wheels, moving the axle back 6" gave the required clearance and moving the back axle as well allowed the same rods etc to be used, only the mainframes being altered and these only extend to the cylinders. Other people disagree but I'm not sure they realise how frames were made, and how inisitent Churchward was on standardisation of small parts. 

 

  K's used the same chassis for 44XX and 45XX but simply reversed it to change the wheelbase betwee locos.

There was also a 46XX 4-4-2T with the same parts as the 45XX etc but 5'2" wheels.  As the 45XX could do 60 mph the 46XX didn't really offer much so only one was built.

[Il Grifone]

Number 4600 probably suffered from tail wagging at speed and a discrete veil was drawn....

 

Here she is at Birmingham Moor Street   http://www.warwickshirerailways.com/gwr/gwrms1735.htm

 

It can be inferred from the text that all was not well with the design.