The Burnbake and Woodyhyde Railway

[Graeme Dunbar]

Possibly twisting a bit may help  (left-right rather than tilting fore-aft) as you suggest It need not be much (possibly just the thickness of the metal). The twist would have to be the same for stock or loop clash will occur again.

[B.Meldon]

Years ago now (I see it was almost two whole years!) I mentioned Greenwich couplings, so perhaps it's time to pick up the thread again.

(pretty good, eh? although I say it myself). There's just one problem - the dreaded Loop Clash:

3a by clayliner, on Flickr

Of course, when you stop to think about it, it's pretty inevitable, if you take care to mount them all at exactly the same height... You could bend all the loops down a bit, I suppose, or even bend them all up - but that's not going to solve the problem. Maybe bend some up and some down? At least you might have a 50% (overall) chance of successful engagement. Skew them in the horizontal plane?

Clearly others have found the solution, so I'm asking for the forum's combined wisdom for the best way to solve the problem. Any help appreciated.

David

P.S. We do have some lovely sunrises down here!

I have found that loop clash with the Bemo/Egger/Roco/Liliput couplings can be reduced to virtually zero if the loops are all adjusted to be exactly horizontal to the rails and if they are absolutely flat. Any slight curve in the loop or having them set slightly off the horizontal can cause loop clash problems.
However I do not use the Greenwich loops so this may not apply to them.

Brian Meldon

[Elmgate]

The/an answer is to have loops on one end of the stock only, but this assumes that you will never turn your stock around (and that locos also have a loop at one end - as some do not by original design).

[JulienW]

As a suggestion you could try running a file along the edges of the loops to change their profile.

As they are chemically etched the process leaves a 'cusp'. As the acid cuts the into the metal it does so in all directions, so the width of the cut is wider at the outside of the metal and narrows as it goes into the thinckness of the metal, and this narrowing is curved not straight. If one were to magnify the profile imagine that the square section had had the top & bottom corners cut off with a hole punch leaving a point sticking out halfway through the thickness.

When the loops meet the "points" come together and the loops are pushed upwards where the next set opt points - where the curved cut off corners meet the faces on the original sheet. This gives two points of contact and "locks" the loops.

If one was to file the edge of the loop to give it a more circular profile then as the two 'bars' met one has to go over the other. I suppose as an alternative one could file the cusp off to give a flat edge to the loop then solde rsome fine wire along the cut edge.

One reason why I went over to using DG couplings as these use loops made from wire, so they can't lock...

[paul ludlow]

coupling loop clash, not a problem on my layout. As i seem to be totally incompetent at getting all my stock with identical coupling heights, so it is extremely rare for two wagons/coaches to meet at the same height!! Maybe my incompetence has led to reliable coupling!?!? As one loop always seems to have the ability to ride over or under the other. perhaps some people are just too accurate?? (makes me feel quite good about my poor standards)

[B.Meldon]

coupling loop clash, not a problem on my layout. As i seem to be totally incompetent at getting all my stock with identical coupling heights, so it is extremely rare for two wagons/coaches to meet at the same height!! Maybe my incompetence has led to reliable coupling!?!? As one loop always seems to have the ability to ride over or under the other. perhaps some people are just too accurate?? (makes me feel quite good about my poor standards)

Clearly this is a successful approach for you and it obviously works.

However on layouts like my ones with extensive shunting and marshalling of wagons and with locos that need to run round every train all without the use of the great hand from above or a coupling hook the only way to make this work reliably to an exhibition standard is to have the couplings all at the same height for all items.

If one coupling height is wrong we have found that the vehicles will not automatically couple up or even uncouple properly with the uncoupling ramps we use they also can come uncoupled when not required as well.

It is each to their own, if it works for you than that is great!

Brian Meldon

[paul ludlow]

Brian, your comments taken on board, i understand that for a hands free shunting layout at exhibitions, then accuracy is king. my layout in the garage is purely for my own entertainment and yes i use an un-coupling stick (made from an old paint brush handle and wire). for me this means i can uncouple at any point in any siding without the use of magnets or ramps or clever use of delayed couplers. as you quite rightly say, if it works for you and you are happy, then great. as i am operating the great hand from the sky, i dont tend to notice it!

[clayliner]

Thanks to all for replies and suggestions so far.

Graeme's suggestion of a slight twist seems reasonable but is the opposite of Brian's experience where perfect horizontality and flatness is the aim - though to me that would be counter-intuitive as it would appear to be taking accuracy in fitting and alignment - which is apparently the cause of the problem! - even further. But I'm not disputing that it works for him. As for re-profiling, certainly worth a try, but tricky once the things are installed and best done prior to fitting (as would be twisting).

Removing the loops on locos would appear to be a common practice - I know the estimable John Thorne does that - and would certainly reduce problems. Removing loops from one end of all rolling stock is likely to lead to further problems, especially on a layout where there is a reversing triangle!

My natural sympathies lie with Paul, as a subtle degree of inaccuracy - or natural variation, if you prefer - would seem to be the best remedy. Normally I might have expected to have achieved this without much difficulty myself, but for once I seem to have tried just a little too hard and come unstuck as a result. So much for the pursuit of perfection!

David.

[Hugh Norwood]

As they are chemically etched the process leaves a 'cusp'. As the acid cuts the into the metal it does so in all directions, so the width of the cut is wider at the outside of the metal and narrows as it goes into the thinckness of the metal, and this narrowing is curved not straight. If one were to magnify the profile imagine that the square section had had the top & bottom corners cut off with a hole punch leaving a point sticking out halfway through the thickness.

My experience of recent batches of Greenwich couplings is that they are no longer blackened, but painted, as the black just comes off when the  etches are folded. And no, it's not me being heavy-handed, I did have some of the blackend type and they were fine.

[paul ludlow]

i thought it was just me that knocked the blackening off the greenwich couplings, glad to here that i'm not alone. when i said previously that all my couplings were of different heights, i don't mean by miles, they usually are only out by the thickness of the loop, which means they couple and un-couple quite well. i do have the occasional problems, but as i don't have members of the public watching it isn't a problem.

[clayliner]

Agreed - the black (whatever it is) does come off quite easily and they often need touching up after assembly.

The answers seem to be:

(1) Don't take too much care when setting the coupling heights   and

(2) Make sure no-one else is watching during coupling / uncoupling.

Then everything seems just fine!

David.

[JulienW]

My experience of recent batches of Greenwich couplings is that they are no longer blackened, but painted, as the black just comes off when the  etches are folded. And no, it's not me being heavy-handed, I did have some of the blackend type and they were fine.

i thought it was just me that knocked the blackening off the greenwich couplings, glad to here that i'm not alone. when i said previously that all my couplings were of different heights, i don't mean by miles, they usually are only out by the thickness of the loop, which means they couple and un-couple quite well. i do have the occasional problems, but as i don't have members of the public watching it isn't a problem.

Having done some of my own chemical blackening (both with stuff from Carrs and my home made solution of copper carbonate and 0.880 SG ammonia) if you get too much coating on the brass then it will flake off.

[Graeme Dunbar]

Sorry if this is going further off topic, but as we are discussing Greenwich couplings - is there a way to remove the coating?

It is may seem a bit OCD, but I would quite like to reinforce the bends with a touch of solder.

Something I did learn for making up a few of them is that you get one shot at bending. The bend does seem to work harden the material (if that is the correct term) and the scope for adjusting a bend is very limited before you end up with at least two little bits.

[paul ludlow]

graemeD, i think you are right, you get one go at bending the couplings or they are likely to snap. Makes you think twice and concentrate a bit more on getting it right first time, i have successfully tweaked them a little bit and am now quite good at doing them (i've now made about thirty!). i have found that an old blunt screwdriver is all that is needed to scrape the black off and a touch of matt black enamel does a good job of restoring the finish, hope this helps, Paul.

[clayliner]

Thanks for all the foregoing suggestions and advice on Greenwich couplings.

Now something of a more general nature which has been floating around in my head for a while:

Many of us are familiar with Minitrains chassis and it seems generally agreed that they are sweet-running and very desirable, and lots of people have used them for a variety of projects. If I have one reservation it's about the intrusiveness of the motor into the cab space (the flywheel is actually largely out of sight, hard up against the cab roof as it is). I know there are ways to get round this