Kit Building a GWR 2-8-2T

[mobi323]

I am contemplating having a go at making this kit in OO.

I have heard that because it has rather a long wheelbase it has problems with negotiating some radii. I have Hornby second radius and above on my layout. Will this be all right?

I suppose anybody with an 8 wheeled engine RTR or kit built may be able to answer as well.

Thank you in advance as I don't want to spend hours and hours making this model to find that the engine can only run on straights or forth radius curves.

[Sidecar Racer]

I have a 72xx built from I think a Cotswold kit , having done some pre-planning for a layout I think you would be very lucky to

get it round 2nd radius curves , my tests seem to show that 36'' is about the minimum for reliable running and larger would

be better .

 

Hope this helps a bit , it is a monster of a loco but looks superb .

[34theletterbetweenB&D]

The answer is that to get it around second radius curves, means using the compromises that the RTR manufacturers have long employed to get enough flexibility into their chassis. Build the coupled chassis frames rather narrower than is normal kit build practise, and allow the coupled wheels a lot of lateral movement, have the coupling rods as separate pieces crankpin to crankpin. (Take a look at Bach's 9F, four flanged wheelsets on a slightly longer coupled wheelbase than that of the 2-8-2T, they use a 10mm wide chassis block, and the wheelsets have about 1.75mm lateral movement.) Consider using smaller than scale diameter pony truck wheels, and omitting, reshaping or repositioning as appropriate rigid fouling features such as cylinders and steps. (The RTR manufacturers cheerfully 'nibble' in this respect, it is amazing what can be done without too much violence to the finished appearance by taking a millimetre off cylinder diameter and length, and perhaps mounting it a millimetre rearward of where it should be for example.) This will be very much a matter of judgement on your part, as to what can be done without damaging the final look of the model.

 

For sure as Sidecar Racer's post above attests, build it 'right' and you will need much larger radii than any set track curves can provide...

[melmerby]

Bear in mind that the 12"/ft version also tended to protest at tight curves, or so rumour has it.

 

Keith

[Coach bogie]

Could be tricky building the frames narrow if it is the Cotswold kit as the frames are usually the solid brass block.

 

I must admit to having the same problem and having no alternative, fitted flangeless wheels to the second and third axle.

 

Prior to this it would negotiate a peco curved point (2' 6") but not a double slip (2').

 

I tried putting lots of play in the rear axle (as per the prototype) but it was not enough.

 

It is not ideal but it works.

 

I still have a thought of buying the DMR kit which has an etched chassis. There is a lot that can be done here, narrow frames as already suggested. A few other kits to be constructed first though.

 

Mike Wiltshire

[Kenton]

I am contemplating having a go at making this kit in OO.

I hope you have plenty of experience in building kits.

 

The 2-8-2 is probably the most difficult chassis to build and that is when building without compromise.

 

There are tricks to be used to get it round sharper curves but remember that problems are not just confined to curves. Trying to get this beast through commercial OO pointwork, particularly crossings, will also be found.

 

It might look a seriously impressive model but you could find it ends up a static display in a yard.

[bertiedog]

I can speak from current experience with the Cotswold 282, one is on the bench, and experience with making them in the past, and they only like very large curves with the makers own chassis, fit all flanges and it's over 5 feet radius in practical terms. It will manage tighter plain curves, but not point formations.

Flange removal is the only way with the solid chassis, and using set track curves.

Other than that a new frame could be fitted, scratch built or Gibson etc, and the frames narrowed to allow the side movement, but it is not going to gain much, maybe a 3 foot radius reliably, again it could squeeze further , but tight crossovers are going to throw it...and yes, the real thing had the very same issues.

Stephen.

[bike2steam]

I have two 72xx class locos on my layout, both originally K's body kits with partly scratchbuilt chassis using Gibson side frames, with enough play on the driving axles to negotiate 30" minimum radius curves, using Mashima 1628 motors I don't have enough length, on my 20 x 8ft roundy-roundy layout, to find out the maximum they will haul .

[Adrian Wintle]

The Cotswold 72xx that I have was originally built (by a previous owner) with one flangeless wheelset (3rd axle, IIRC). I rewheeled it to have flanged wheels on all four driving axles, but it will not handle anything tighter than about 3' radius plain curves.

 

Adrian

[mobi323]

I'm not arguing with members who know more than me but I wonder how Hornby and Bachmann got round the turning circle problem with their 2-10-0 and 2-8-0 models.

I suppose to partly answer my own question I notice on the kit 2-8-2T the axles are a bit further apart and I suppose that would make the total length of the driving wheels longer. Perhaps these RTR models have more flangeless wheels. Maybe somebody with one of these models can confirm this for me.

I would think the problem was not insurmountable - after all they managed to put a man on the moon.

[34theletterbetweenB&D]

Just take a look at the Bachmann or Hornby 9F on a second radius curve. That's four flanged wheelsets on a slightly longer coupled wheelbase. That will give you an idea of the scale of sideplay required. Alternatively just lay out six wheelsets around the curve, at the spacings for the 2-8-2T (attach them to the track with little dots of blu-tack) the four couled wheels with axles parallel, the end wheelsets with axles radial. That will give you a picture of the lateral displacements. Use a piece of transparent plastic cut out to represent the footplate plan with salient fouling features drawn on in plan: cylinder blocks, footsteps; then you will see where the troubles are. Obviously you could draw this out on paper or in CAD, but this is a quick cheap and dirty look at the challenge.

[Kenton]

I would think the problem was not insurmountable - after all they managed to put a man on the moon.

I don't think anyone is saying it is insurmountable, or that a kit-built 2-8-2 could not be driven round prototypical curves or point-work.

.. just that to use your analogy - they haven't put a man on mars yet

[bertiedog]

Both makers have slimmed the chassis to well narrower than scale chassis width, and they move steps or leave them off, and the 9F has flangeless middle wheelsets anyway. In HO makers have hinged the chassis, or used a sub frame which is hinged, really designs that relate more to RTR trains than scale models. Also the back to back is often set to a figure way from the 14.5mm for 16.5 track, as low as 13mm, which also generates extra play, but the wheel tyres must be wider than recomended to compensate.

 

As tolerances have been tightened up by UK makes, and are nearer so callled scale standards, then it has to be accepted that larger radius track is needed for good smooth running, without risk of de-railment.over point formations of tight opposing curves.

 

On track without points a tighter curve may be possible, but the wheelsets will be rubbing the frame and the lack of working tolerances may cause noise, binds, or jerky running on the tightest parts, even when no de-railment actually occurs.

 

Also where the wheels are allowed to move sideways a lot, electrical pickups become more problematic, the inner is forced hard against the wheel and the outer may not have enough pressure to be in contact properly.

 

With the 282 GWR the steps at the front must be moved or removed, they stop enough swing of the front bogie wheel, and at the rear the frame has to be slimmed to allow the rear wheel to move enough, and this has to be done even with the flangeless driver option to get around set track curves under about 3 foot (36 inch)..

 

There's no magic wand that can be waved to get a large long wheelbase loco over tight curves, but there are tricks, and I think all have been mentioned, don't be put off too much, perhaps using non set track curves will help, flexible track laid to slightly larger curves, with a gentler transition from straight to the curve, and using longer points. Hand made track can help, as gauge expansion can be done on curves to ease the problems.

 

Stephen.

.

[tomparryharry]

I am contemplating having a go at making this kit in OO.

I have heard that because it has rather a long wheelbase it has problems with negotiating some radii. I have Hornby second radius and above on my layout. Will this be all right?

I suppose anybody with an 8 wheeled engine RTR or kit built may be able to answer as well.

Thank you in advance as I don't want to spend hours and hours making this model to find that the engine can only run on straights or forth radius curves.

 

 

Good luck with your 72xx. I have a couple stood by for my project. I look forward to seeing your progress.

 

Regards,

Ian

[RedgateModels]

My 2-8-2 was built to handle 2nd rad curves, there is quite a bit of sideplay in all drive wheels, I even counterbored the final drive gear so that it could slip over the bearing shoulders so that there would be sideplay in that axle too!

 

http://www.rmweb.co.uk/community/index.php/blog/236/entry-4700-2-8-2-visits-summat-colliery-on-test/

 

Not sure if the GWR design is longer though

[tomparryharry]

I do like that 2-8-2. Looking at the photos, I can imagine it as a 4-8-2, but thats probably another story.....

 

Ian

[RedgateModels]

I do like that 2-8-2. Looking at the photos, I can imagine it as a 4-8-2, but thats probably another story.....

 

Ian

 

With the original length smokebox and a longer frame a 4 wheel bogie á la Britannia would fit.

[tomparryharry]

I am contemplating having a go at making this kit in OO.

I have heard that because it has rather a long wheelbase it has problems with negotiating some radii. I have Hornby second radius and above on my layout. Will this be all right?

I suppose anybody with an 8 wheeled engine RTR or kit built may be able to answer as well.

Thank you in advance as I don't want to spend hours and hours making this model to find that the engine can only run on straights or forth radius curves.

 

 

Hello Mobi,

 

I've just got one of my 72xx chassis to turn over quite nicely. It will go thro' medium radius (whatever that is) peco code 75 points, when set up in crossover fashion. All 8 wheels are flanged, with Romford/Markits wheels. The intended motor will be a Romford Bulldog, or equivalent, as the chassis is already set up for it.

 

Regards,

Ian

[3 link]

I am just finishing off a GWR 42XX 2-8-0 in 7mm and that can negotiate 6' radius Peco turnouts smoothly without any problems. On the first axle I kept rigid as there is no clearance because of the cylinder crossheads, 2nd axle has lots of side play, 3rd axle is the drive axle so no side play at all and the last axle has loads of side play. This is a JLTRT kit and the only other part of the kit in my opinion that has helped alot with tight curves is the fact that the coupling rods are jointed and not rigid, I do not hold out much hope with rigid coupling rods fitted.

 

ATB, Martyn. P.S. And just to add that all the drivers are flanged.

[John_Hughes]

Another point to watch is that the cylinders on these marvellous engines went right out to the limit of the (GWR!) loading gauge, so some fouling of pre-positioned structures such as platforms is possible.

[lonesome_whistle]

John, no offence meant but I think it's only fair to point out that the '72s' were not at all liked by the poor blokes that had to use them. I suspect that there would be very few Western enginemen that would have a good word to say about them even today and they certainly wouldn't describe them as marvellous. As was alluded to earlier in the thread, having a model 7200 tank that derails itself would be quite prototypical.

[tomparryharry]

Another point to watch is that the cylinders on these marvellous engines went right out to the limit of the (GWR!) loading gauge, so some fouling of pre-positioned structures such as platforms is possible.

 

 

I think you will find it's 8'11", which is a standard size, shared across the larger Great Western 2 cylinder classes. 28/38xx, Halls, 42/52xx, 68/78xx, 10xx, etc.

 

Regards,

Ian

[Horsetan]

John, no offence meant but I think it's only fair to point out that the '72s' were not at all liked by the poor blokes that had to use them. ...

 

They were banned from a number of sidings due to their length and relative inflexiblity....

[John_Hughes]

John, no offence meant but I think it's only fair to point out that the '72s' were not at all liked by the poor blokes that had to use them. I suspect that there would be very few Western enginemen that would have a good word to say about them even today and they certainly wouldn't describe them as marvellous. As was alluded to earlier in the thread, having a model 7200 tank that derails itself would be quite prototypical.

 

I was thinking of their muscular appearance rather than their performance! Agreed, they could apparently be shy steamers, and I've heard that once going weren't always that keen to stop!

[John_Hughes]

I think you will find it's 8'11", which is a standard size, shared across the larger Great Western 2 cylinder classes. 28/38xx, Halls, 42/52xx, 68/78xx, 10xx, etc.

 

Regards,

Ian

 

Indeed, and thanks for that; I didn't mean to imply that they were the only locos built to that width; but I don't think there was actually anything wider, though I stand to be corrected.