Width of Gresley Bogies

andrew jukes
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Width of Gresley Bogies

Postby andrew jukes » Mon Apr 08, 2013 6:49 pm

Golden Age Models are finalising their soon to be released LNER trains - Coronation, Silver Jubilee and 1938 Flying Scotsman - and I'm discussing with them the running gear for P4 versions. I think the wheelsets will be satisfactory but they are planning to widen the bogies to accommodate the P4 wheelsets and I am trying to establish what the overall width of the resulting bogies will be.

I have suggested a width over axleboxes of 31mm should not be exceeded, but this is based on extrapolating from other designs as I can't lay my hands on a Gresley bogie drawing. Can anyone help with this dimension, please?

I don't know if any other Society members are interested in any of these trains. If so, Golden Age are trying to estimate the number of P4 bogies they will need (there will only be one batch) - so best to tell them now.

Andrew Jukes

Crepello
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Re: Width of Gresley Bogies

Postby Crepello » Tue Apr 09, 2013 10:42 am

andrew jukes wrote:Golden Age Models are finalising their soon to be released LNER trains - Coronation, Silver Jubilee and 1938 Flying Scotsman - and I'm discussing with them the running gear for P4 versions. I think the wheelsets will be satisfactory but they are planning to widen the bogies to accommodate the P4 wheelsets and I am trying to establish what the overall width of the resulting bogies will be.

I have suggested a width over axleboxes of 31mm should not be exceeded, but this is based on extrapolating from other designs as I can't lay my hands on a Gresley bogie drawing. Can anyone help with this dimension, please?

I don't know if any other Society members are interested in any of these trains. If so, Golden Age are trying to estimate the number of P4 bogies they will need (there will only be one batch) - so best to tell them now.


There's absolutely no need to make Gresley coach bogies overwidth, unless you're Hornby trying to disguise a lack of tumblehome!

The 8'0" wheelbase version for articulated suburban sets is 7' 2" between inside faces of the solebars. With a 9/16" plate thickness and 3" inward flange along the lower edges, this gives 6' 9 1/8" between flanges. The journal centres are the standard 6' 6". I imagine these are pretty constant dimensions among the whole family of related bogies.

Golden Age... Love the build and finish quality, but did they even look at a real A4? There should be a bow across the front of the nose, their interpretation was straight when I looked - but Martin Finney got it right!

Given the conversation you've had with Golden Age Models, it sounds like they are committed to these coach sets without having seen a prime source drawing either. Not the approach which is going to win an expression of interest from me!

Hope the info helps,
Crepello

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grovenor-2685
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Re: Width of Gresley Bogies

Postby grovenor-2685 » Tue Apr 09, 2013 11:03 am

but they are planning to widen the bogies to accommodate the P4 wheelsets
As Crepello says there should be no need whatsoever for this unless they are making them underwidth for 00, and why would they do that when 00 generally uses the same length axles? The only item needing adjusting should be the brake shoe position.
Width over axleboxes should be the same as any other coach bogie since journal centres are 6'6", most journals 10" long so allowing for a bit of clearance between axle end and box cover the width over axleboxes should be 7'6" or 30mm, a bit more if the coach had heavy duty journals.
Keith

John Palmer
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Re: Width of Gresley Bogies

Postby John Palmer » Tue Apr 09, 2013 12:29 pm

I would have thought it would pay Golden Age Models to check the availability of relevant drawings at the NRM. The Museum's C&W drawing list for Doncaster includes dwg 831N for a 10' WB compound bolster bogie, which looks as though it may well be for the Silver Jubilee set replacements, even though the drawing number doesn't exactly correspond with that given for these bogies in Harris. I happened upon this information after the briefest of searches, so some serious digging may well yield better dividends. The relevant NRM URL is http://www.nrm.org.uk/ResearchAndArchive/archiveandlibrarycollections/RailwayCoWorks.aspx - go to the PDF indices of drawings from there.

andrew jukes
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Re: Width of Gresley Bogies

Postby andrew jukes » Tue Apr 09, 2013 2:15 pm

Thanks for the responses.

With a drawing showing 7’ 7” as the over-axlebox dimension for a BR Mk 1 bogie, I thought it unlikely a Gresley bogie would need to be wider unless the position of the primary springs made this necessary. Nobody seems to be suggesting that, so 30.33mm might be a reasonable guess and my ‘no more than 31mm’ sounds like a probably acceptable upper limit.

Just to put this in context - a model of the ECML in the late-1930s has to have the streamliners and the quality and finish of the Golden Age Models’ bodyshells make these look like the best source. My discussions with Golden Age started when they produced their Pullmans and did a P4 version - but with flanges that might have suited Martin Goodall but which were some way from a proper P4 profile. So having expressed interest in the streamliners, I said - please can they have P4 profile wheels - and supplied them with appropriate drawings. Given that I’m probably a niche of a niche in sales terms, they have responded well on the wheels but have left me worried about the bogie width. They may well have used original drawings in designing the 00 version of the bogie but obviously want to avoid a complete redesign just for me (and maybe a handful of others).

It would be nice for once to have a P4 train that is ready to run, but this may end up with me fitting bogies to their bodyshells, if their P4 bogies end up too wide.

As for the A4, I agree there are far better starting points for a P4 A4 than the Golden Age version.

Andrew

andrew jukes
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Re: Width of Gresley Bogies

Postby andrew jukes » Wed Apr 30, 2014 11:28 am

Here is an amusing twist to this earlier concern of mine.

The Coronation has been running on my layout, with no problems at all from the very nice Golden Age P4 wheelsets (train seen at Welwyn North in shot 4 on the C&L homepage). The appearance and finish of the train are excellent and the only real problem (but quite a big problem!) is that the weight of the train and the use of plain bearings make its operation on a layout with a ruling gradient of 1 in 100 very difficult. As well as the obvious Pacifics, the train (as empty stock) must be able to be hauled up 1 in 100 by an N2. There is only so much weight you can put in an N2, so thoughts turned to what can be done to make the train easier to haul.

Weight reduction would be a horrible job as inevitably it would involve wrecking some parts of a rather nice model, so the obvious step is to replace the plain bearings with pinpoints. On the face of it, this looks quite straightforward. The bogies can be dismantled with a screwdriver and the existing plain bearings sit in a 2mmØ recess in the axleboxes. Deepening the recess and dropping in a pinpoint bearing (with its flange removed) was the obvious way to do it.

But, with the maximum deepening of the recess and the maximum reduction in length of the outer end of the pinpoint bearing (so much reduced that you can see a pinpoint of light through the bearing!), it was impossible consistently to produce a bogie with free-running wheelsets. it seemed as though the point of the pinpoint had to be on the front face of the axlebox.

Having toiled for what feels like days and only produced one perfect bogie and a few reasonably OK ones, last evening I gave up that approach. There had to be a better way. Shorter axles, perhaps? Finally, I did the obvious and measured the over-axleboxes dimension of the Golden Age bogies. Turns out it's 28.6mm, fully 2mm less than would be reasonable baed on the earlier discussion here.

Now this conversion will switch to being mostly about modifying the bogies so they can be reassembled with each sideframe moved out 1.0mm. There will still be some work to enable the pin point bearings to be fitted, but far less than what I was facing.

So much for worrying about the bogies being too wide! And the train will look better with bogies that are the right width. The ultimate test, of course, will only come when an N2 hauling the train tackles a 1 in 100 gradient - but I'm hopeful I'll have made enough difference.

I plan to use the Golden Age wheelsets and bearings to convert Hornby Gresley coaches.

Andrew Jukes

ps A Golden Age Coronation twin weighs in at 565gm, so the complete train (including observation car) totals around 2.5kg.

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grovenor-2685
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Re: Width of Gresley Bogies

Postby grovenor-2685 » Wed Apr 30, 2014 12:43 pm

ps A Golden Age Coronation twin weighs in at 565gm,

Wow, what are they making it with?
Keith

andrew jukes
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Re: Width of Gresley Bogies

Postby andrew jukes » Wed Apr 30, 2014 3:05 pm

Interestingly, ten Golden Age wheelsets weigh 35gm, whilst ten Exactoscale wheelsets weigh just under 15gm. With 28 wheelsets in the train, I'm around 56gm better off already!

Just like the real thing, there can be a surprising amount of weight to be saved in wheelsets.

Andrew

Trevor Grout
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Re: Width of Gresley Bogies

Postby Trevor Grout » Wed Apr 30, 2014 5:12 pm

grovenor-2685 wrote:
ps A Golden Age Coronation twin weighs in at 565gm,

Wow, what are they making it with?
Keith

Depleated uranium !

regards

zr2498
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Re: Width of Gresley Bogies

Postby zr2498 » Thu Jun 06, 2019 7:31 pm

Andrew
A long time since this thread but I am just getting to sorting the GAM coronation set out. Issues with the A4 being able to haul the set, even on the level. So where did you get to with the modification. Did the conversion to pin point bearings give a noticeable improvement?
It would seem that the spring holding the bogies (with shouldered screw) is far too tight as well so I might modify that. Any other ideas would be welcome.
Regards
Dave


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