Wheel generator

[AJC]

Steph
That's news to me. I'd taken this book as gospel. I'd rather not have to pay for a set of drawings of the wheel - if they exist - where would you look to find such critical info? Please don't think I'm being churlish, I just wouldn't know where to go from here.
Anyway, thanks for the heads up.

Stay safe

Mike
PS. I'll give Wikipeda a miss.

For a 15xx? Bridgnorth!

Adam

 

[Steph Dale]

PS. I'll give Wikipeda a miss.

Hehe, yeah; me too!

I'd start with photos; you'll relatively easily be able to count spokes and see whether the crank is in-line or between spokes. So that's a start. Similarly, you'll be able to see the rim shape (if there is one).

Dimensions I'd take from a prototype drawing such as an FA or GA. At a push, something that's published for modellers and comes with some form of provenance (so not Skinley!). You can make a reasonable estimate of wheel diameter from other dimensions, like buffer height or wheelbase. Don't forget to make allowance for flanges too; even P4 wheels have larger than scale flanges.

For outside cylinder locos, the crank tends to be (but isn't always) half the piston stroke (there is such a beast as an eccentric crankpin - they were common on GNR-derived locos, including LNER and LBSCR). But, that doesn't work for inside-cylinder locos where the piston stroke has no mechanical linkage to the wheel crank other than through the axle (e.g. 26" stroke on a LSWR T9, with a 9" wheel crank throw).

It's just a case of being careful/cynical when using the data in the book and try to get some independent confirmation of the data within.

Steph

 

[Dog Star]

For an engine design from the GWR then look in the Great Western Railway Journal on-line index to see if the required class has featured in the magasine. When a loco class is featured in the magasine then there is often an official drawing or two, generally a Frame Plan.

 

[SimonT]

The 'standard' tank engine wheel is 4'7", 14 spoke, Pin Between (PB) and a 10" stroke to match the inside cylinders which stroked at 24".

The answer may be found in Russel, vol.2. Page 228 has the Swindon weight diagram and this specifies 4' 7 1/2" wheels. The cylinders are specified at 17 1/2" x 24", so max of 24" available for stroke. On page 229 there is a photo of the valve gear which shows the leading wheel with a pin In Line (IL) and I think 14 spokes. So far, good for Sharman.

However, Sharman lists the 15xx as a 1949 design by Churchward! It was, of course a Hawksworth loco, with drawings listed in 1944 and 1948 and took a lot of the design from the 94XX. The 94XX is listed in Sharman as having wheel attributes simsilar to the 'standard' tank engine. I find the Sharman listing of a 24" stroke for the 15XX strange as there is no previous 4'7" wheel with that attribute. This implies that at a time of finiancial squeeze that there was money to design and build a new wheel. To back the 24" stroke arguement, the weight diagram in Russell is supposedly scale at 4mm and the wheel stroke matches 24".

To further complicate things the 94 is listed as PB but there are photos of 94s with IL wheels.

So, I would say 4'7 1/2" wheels, 14 spokes, stroke as available in model form and a photo of the loco being modelled to check for PB or IL. Or there is Rule 1, it is your model!

Did I say the answer could be found? Stupid boy!

Simon
PS. There is a Swindon GA listed at on the Swindon Drawings list at York. No 124595 on film.

 

[Steph Dale]

Simon,

Perfect example of using other available sources to verify the wheel data and very timely for our 94xx.

Steph

 

[Mike Garwood]

Thanks Simon, thats very comprehensive. Appreciate the time you took to dig those details out.

Mike
(Looking forward to Bachmanns 94xx - even though most of it will go in the bin or fleabay)

 

[SimonT]

Mike,
I'm sorry it's not an exact answer, but then it's part of why we model the GWR!

Steph,
done ages ago. The S7 Group wheels will do me very nicely and I would recommend them to all builders of the kit

Simon

 

[Dog Star]

The S7 Group wheels will do me very nicely and I would recommend them to all builders of the kit.

Thank you for recommending the S7 driving wheels from the S7 Group. Here is a link to the relevant bit of the Scaleseven Group website where one can find details of S7 wheels and the associated crank pins, axles, gauges and tyre profile tooling,