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In depth idiot
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Discussion Starter · #1 ·
I have been working on my late BR steam 'fast fitted freight' stock this past winlockterdown, and have made decent progress on sufficient wagons for several sets of proper length to rattle along behind K3, V2 and Doncaster's pacifics.

But thus far I have dodged the significant shortcoming. My loose coupled unfitted freight trains look very well when operated, the Bachmann miniature tension lock repositioned to allow just 2mm between bufferheads when pulled, and buffered up when pushed, produces the correct action. However this simply won't do for fully fitted' at all.

The fixed buffers mean no prospect of buffering up with sprung buffers, so 'The Compromise' will either be: move the bufferheads into the fully compressed position, and use a constant distance coupler so that vehicle spacing is correct in appearance but the bufferheads are not in constant contact; or, use a springy coupling with enough give and flex to allow the vehicles to space out with the inner bufferheads maintaining contact on curves, and closing up to both bufferheads on contact on straight track.

The first compromise is simple and will work, but I prefer the latter idea, just don't know whether it is feasible. This would have to work on trains of circa 40 wagons and enable movement on a 30" minimum radius, and I do want to vary the train make ups, on all but the conflat set.

Anyone?
 

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On flexible, my first thought goes to plastic and then 3D printing and I have seen a few 3D printed NEM based fixed couplings on Shapeways/market place such as this one:
https://www.shapeways.com/product/JZZQYBLQK...;li=marketplace which looks like a sample set but there are sure to be others.

My thinking is that if you could get some flexibility in the E/W direction (taking train motion as being N/S) without compromising the strength it might do what you want?

Of course it doesn't have to be a 3D print but it could be a starting point for other ideas?

David
 

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In depth idiot
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Discussion Starter · #3 ·
Thanks David, an interesting option, I will have to run some searches for what else is out there.
 

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That's an ingenious option presented by DWB - I'm actually surprised that the manufacturers didn't come up with something like that years ago because it seems like a logical progression. It's not perfect, but it's certainly a big step in the right direction for realism. With modification, it could be adjusted and made better - like shortening the links for example.

Personally, I adopted 3 link couplings over 30 years ago on my wagons using mostly Smiths couplings. Can't get more realistic than that, however, as we all suffer from an effect called 'age', 3 link couplings become a challenge with the eyesight. That's when we move to 7mm scale where chain link couplings are double the size and pretty much the accepted norm.
 

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In depth idiot
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Discussion Starter · #5 ·
I considered three link for the loose coupled freight vehicles, but the simpler path of altering the NEM pocket mounting and shortening the 'stem'of the Bachmann design of miniature tension; with the added benefit of the Brian Kirby magnetic uncoupling mod., won the day. Acceptable compromise until some better autocoupler design that more closely represents three links in action and appearance is made available. (Close, but no cigar: Dingham, Spratt and Winkle. Neither could produce the maximum 2mm separation between bufferheads possible with the Bachmann coupler, which enables the wagons to buffer up when propelled, far the best effect as the trainload spacing is correct.)

This is currently applied to many of the fitted vehicles, but it is a compromise to far, for screwlink coupled fitted freight. I want the same action as with the close coupling system on coaches, minimal slack between vehicles so the train moves as a piece. Even the Kadee has too much slack. I may have to settle on something like the Keen 'knuckle' on a pivot or in the NEM pocket, suitably positioned for distance, with bufferheads retracted.
 

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In depth idiot
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Discussion Starter · #6 · (Edited by Moderator)
It has been suggested (independently of this forum) that the magnetic coupling option might be worth a look, and having looked, a thought came to my mind.

THE BUFFERS. If each buffer complete were a magnet with poles appropriately positioned it would be job done. There would always be the inside buffer pair in contact on curves, and on straight track both sets of buffers in contact. This is way too simple for someone not have thought of previously, surely? It may just have required the superior field strength of current formulations to be made a practical reality.
 

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The first thing that sprang (that doesn't happen often) to mind was this: if you're pulling a long train the magnets need to be strong enough not to separate, but when you come to a curve one of them has to do just that, so finding a workable solution to that might be nigh on impossible.
 

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In depth idiot
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Discussion Starter · #8 ·
QUOTE (hoonsou @ 21 May 2021, 01:34) <{POST_SNAPBACK}>The first thing that sprang (that doesn't happen often) to mind was this: if you're pulling a long train the magnets need to be strong enough not to separate, but when you come to a curve one of them has to do just that, so finding a workable solution to that might be nigh on impossible.
You are right, and while thinking some more about this I realised that the bufferheads need to move to stay in contact, and to be linked by an equalising bar pivotted on the rear of the buffer shanks and on a centre line pivot. That way a mean constant spacing is maintained at all times as the bufferheads move.

There would be a 36" minimum radius requirement based on my past experience, no problem for me, but would significantly limit demand. More complex than a central pivotting rigid bar coupling and just pushing the bufferheads into fully compressed position, so sadly probably a non-starter.
 

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Thinking about this, on the second day of reading, I have seen a central magnetic coupler. It certainly looked large enough to pull a good number of items, but I vaguely remember that there were issues, when it came to wanting to join and separate them. {The mental picture of that is rather haunting!} It's a long time since I saw them and it may be that they no longer available. It might be possible to have an electro-magnet, with a decoder and relay, for the power, but the expense would be horrendous.

Julian
 

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QUOTE central magnetic coupler
On the subject of magnetic couplers, these have been getting a lot of attention recently - https://www.westhillwagonworks.co.uk/hunt-couplings-new-c-2/

I have recollection that someone else has introduced a similar product recently but can't quite remember who it was.

David.
 

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In depth idiot
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Discussion Starter · #11 · (Edited)
And the verdict is in. I am going magnetic with the buffers fixed fully retracted for realistic spacing. (And now I know where the 'Edit' facility is, I can add the information I failed to include on first posting.) The slack in the train is negligible, as it should be, so that the train moves as one piece. This naturally generates a little wheelslip on the steam traction, just a half turn or two at dead slow, which is very attractive.

These fitted goods trains will not be shunted, but have vehicles manually substituted as time passes. (I cycle through the seven year transition on BR(ER) from all steam, to diesels dominating, and the stock alters to match: pregroup and the earlier grouping stock steadily disappearing, and the BR design replacements more in evidence. It's quite a big job on 'historical reset day'.)
 
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