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33 minutes ago, NCB said:

All very useful. I'm contemplating some 6 wheel stock. I used a Cleminson arrangement on a couple I built a long time ago which worked fine and would go around 12" radius curves in OO, but I was able to stick a massive weight on the middle axle to keep it on track. I'm dithering between a modified Cleminson, not too disimilar to your Slaters milk van, and a bogie arrangement as you have above. This is 3mm/ft and I doubt springing or weighting will work for the middle axle, hence the choices I've narrowed it down to.

 

Nigel

Another way is to fix the centre wheels so they can't rotate, then remove a segment of the flange at the bottom - rather like the old Tri-ang diesel motor bogies...

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12 hours ago, Mikkel said:

Interesting comparison of six-wheeler arrangements, thanks for posting that. How typical that the neatest looking one - milk van - is also the one giving trouble!

To be fair to Slaters, if you get the tracklaying right and the curvature adequate, their sixwheelers shouldn’t give a problem. That happened with the coach once I had sorted the track join. The milk van body is a collection of plastic strips joined by holes, and this makes it very lightweight, with a tendency to “float” when in motion.  I tried it running with some cast resin barrels for a load, and it really does need some weight in it. Allowing the centre wheelset to lift with some springing turns out to be an improvement without being a necessity.

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If you turn back to the picture of the Slaters 6wheeler, you’ve got an example of something very close to the Cleminson principle. There’s a small bright headed screw placed centrally midway between the axles, and this forms a pivot for the outer axles to swing on. The wheelsets are mounted on a flat plate which extends towards the centre and swings on this screw. The Slaters design is very neat in the way the two long flexible wires act as a linkage to respond to sideways displacement, moving the centre wheelset to the opposite side, as this is also on a sliding plate.

i suppose we need a picture of the underside of an ACE 6wheeler now, please, Kevin? Agreed they are excellent runners.

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It’s pretty much exactly the same as the Slaters, except that the pivot-points are on the outer axle centrelines, and everything is cruder, or more robust if you will, so that the radius arm is c2mm rod, rather than wire, for instance. The ‘trick’ appears to be the huge amount of slop in all moving parts, combined with very free sliding surfaces. The slop means that the axles can rock a bit, as well as do their radiating or sliding stuff.

 

The Ace design is an exact copy of a Carette  design from c1909.

 

i wonder if the finescale attitude leads to everything being a bit too finely toleranced/adjusted, when more slop would allow track imprecision to be better tolerated.

Edited by Nearholmer
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I think a lot is in the freely sliding surfaces bit, where you’re being supported on a true flat plane to start with, then just permit some “rock” for track unevenness. Presumably having the pivot placed under the outer wheels so they can swivel allows them to take up a line tangential to the rail at that point, which will reduce the friction. If you’re on a sharp curve using a long wheelbase chassis with the wheels mounted square, the “corners” will have a tendency to be at an angle to the rail and “dig in”. 

My under frame using the bogie mounting is an instance of having too much slop built in it, and it does get a bit ramshackle in the way it flops about, and it’s hell just to land the wheels on the track to start with. One model underframe which is a good performer and worth trying to copy is an ancient job in OO by ? Triang, Hornby? an LMS milk van. I used to have one, but I’ve flogged it off, so can’t offer a picture.

Did any standard gauge line use Cleminson underframes? There must have been some, but I can’t think of where. It appears it was fashionable for narrow guage lines with curves who had aspirations for their passengers beyond “bug boxes” in the 1870- 1880 period., NWNGR (WHR), Manx Northern, the Ballymena lines, Lough Swilly, West Donegal, Clare lines, and the Southwold, who managed to have Cleminson goods wagons, including private owner coal wagons, besides coaches. Talking of which, I do hope you’re following their blog, they’re just about managing, and I’d like to see them succeed. 

https://www.southwoldrailway.co.uk/the-blog-and-the-srt/

Edited by Northroader
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Well I'll throw in my two peneth worth have built quite a few six wheelers for my Caledonian fleet I've a favorit a mix of ideas but as a rule I have one outer axle fixed the other end rocking the center axle is designed to slide from side to side by as much as 1.5mm each way. 

 It's hard to get it all set up so it sits flat with all wheels touching (built and set up on a glass sheet) and I'm finding it hard to get a consistency in production meaning some run realy well and some are pigs.

 With this method all will run on 3rd radius curves and Large Peco points bit it's hit and miss when trying to run on 2nd radius curves and medium points with some going through and some not which I freely admit is more down to my build inconsistency than any thing else.

 

 I've thought of different methods including all the above but am not sure which will give the best overall results. 

 Looking at some of the passenger stock with the springs, axle boxes and step boards it can be hard to actually see the wheel set in detail and I must admit I'm a little bit tempted to try fixing the center wheel set and cutting away the lower part of the flange effectively making the six wheelers four wheelers. It would make for an easier life and would make the whole lot much more trouble free when running and its one of those things that to the causal observer  would not be visual if you didn't actually know about it.

 

 One of my builds in question. All very visable while unpainted but once painted and sat on the track the flange method would become all but invisible.

 This one will run quite happily on large radius points and third radius curves but becomes very indifferent on anything less.

20181010_090035.jpg

Edited by Londontram
Correct spelling mistakes
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Having lifted a picture of ACE 6wheelers off Kevin’s thread, I’m taking the liberty of pinching a picture of a Carette 6wheeler from the same place, my only excuse being to try and keep bits on them all together. Voucher for pint to be left at the Gun Inn, Coldharbour.

4924029E-A6F1-429F-9DF6-06E151D8125A.jpeg.45c87801b16c68f54f0b7b145b3e7168.jpeg

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Just to round this off, here’s a diagram by Edward Beal from his “Modelling the Old Time Railways”,  shewing his recommended way of doing six wheelers. The outer wheelsets are mounted in axle guard sets which can swing on a centre pivot, and the middle wheelset is fixed. When a sixwheeler is standing on a curve, the wheelsets are’nt in line, and sideways displacement needs to be allowed for. Then it’s working out if you use dummy outer axleguards mounted on the solebars with extra inside bearings, or have moving outer axleguards, in both cases extra clearance is needed inside the solebars. The two coarse scale coaches show the outer wheelsets are mounted on a pivot, and the centre wheelset can traverse. This way and Beals method allow the outer sets to take up a more tangential position to the rail, which reduces the rolling resistance, as well as reducing the tendency for flanges to climb the rail.673FFB4F-8594-4829-857D-171072F5D61F.jpeg.6f1157aca82373d1436ae62a89d0c4a5.jpeg

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We clearly need to institute a controlled trial/test of the competing systems, keeping some things (wheel-profile perhaps, vehicle weight, overall wheelbase etc) constant, and including all sorts of "nasties", like sharp reverse curves with no intervening tangent, track-twist, and tight vertical curvature, in the "test course".

 

To make it more interesting, we could "run a book" on the outcome.

 

'The Beal' confuses me slightly, though. Is that pivot in the centre fixed to anything, or does the whole of the long bar/arm down the centre, and the two outer axle cradles, simply flop about; and, how are the two outer cradles loaded by the weight of the body - are there bearing pads?

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OThe centre pivot is a screw which goes up into the wood floor. The two outer wheelsets have a bearer pad as an upper surface, that’s the part that’s arrowed “soldered” and this just slides in an arc on the underside of the coach floor.

i suppose I’m running a book on the success or otherwise every day of running trains on Washbourne, without making the trials more elaborate.

 

 

Never mind, it’s SPRING tomorrow!! Cast aside dull care and frolic!!

 

 

AE28D4EA-73A1-4D1D-AB71-E665347790E1.jpeg

Edited by Northroader
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1 hour ago, Northroader said:

OThe centre pivot is a screw which goes up into the wood floor. The two outer wheelsets have a bearer pad as an upper surface, that’s the part that’s arrowed “soldered” and this just slides in an arc on the underside of the coach floor.

i suppose I’m running a book on the success or otherwise every day of running trains on Washbourne, without making the trials more elaborate.

 

 

Never mind, it’s SPRING tomorrow!! Cast aside dull care and frolic!!

 

 

AE28D4EA-73A1-4D1D-AB71-E665347790E1.jpeg

I think the frogs have got the right idea.

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