B&B couplings - one loop or two?

[009 micro modeller]

Hopefully the title is reasonably self-explanatory. I’m looking at using B&B couplings for my new shunting layout. In the past in 009 I’ve used manual uncoupling and subsequently ramps (the standard 009 ‘Bemo’-type couplings, as also used by Peco, Minitrains, Eggerbahn etc. in both cases). However, I would now like to get some form of delayed uncoupling so am going to give B&Bs a go - on a shunting layout it is advantageous to have delayed uncoupling as it doesn’t require the whole layout to be filled with magnets or ramps in all possible locations; instead I can just have one at the entrance to the sidings.

 

My previous experience with ramp-activated Bemo/Minitrains couplings (not to mention other people’s experience with magnetically-operated Greenwich) suggests that only having the loops on one end of each vehicle is better as it avoids conflicts between the adjacent loops. From what I’ve read about B&B (and similar, compatible DG) couplings, some people do the same with these, but on the other hand it can create issues, with wagons becoming loose if the coupling heights are not absolutely perfect and level. I’m just wondering if this is more of an issue with B&Bs than it is with more standard 009 coupling types and if anyone had any opinions on this? I’m not sure if having built-in delay and magnetic operation would make this more of an issue.

 

With my previous Minitrains wagons uncoupled by ramps, one of the problems (especially with very short wagons) was that with two adjacent coupler loops to lift the ramp ideally needs to be lifted in two very slightly different positions, which obviously it can’t be, so reliability and accuracy was vastly improved by only having one loop to lift each time. I’m assuming this won’t be quite the same for magnetically-triggered B&Bs, because in theory they will just run over the magnet without stopping and lift the loops onto the delay latches/tongues, where they will sit until the wagon is dropped off. At this stage I’m not hugely concerned with the issue of operating stock that can only be used one way round.

[Andrew1974]

I’ve not used them in 009 but in 00 they work well for me with loops on both ends of the wagons.

 

I have omitted the loop from the loco in the past due to not being appropriate staff under the buffer beam for the counter balance and they have worked OK as well.

 

I suspect they will work fine with a single loop of with two, depending on the exactness of the set up.

[nickwood]

I use DG’s very successfully on my layout both for home use and over 30 exhibitions. If your layout is end to end and you are happy not to turn your stock then I can see no point in having loops at both ends of the stock.  The loops in one direction would not be in tension in any case.

 

I accept that there is the possibility of uncoupling if the track level is uneven or the coupling heights vary. Both of these situations would be better addressed at source rather than trying to overcome it with adjustments or unnecessary additions to the couplings. I have found that DG’s are generally tolerant of small variations in height. I have no direct experience of B&B’’s but as they are very similar, I assume that their performance would be similar.

[009 micro modeller]

38 minutes ago, Andrew1974 said:

I’ve not used them in 009 but in 00 they work well for me with loops on both ends of the wagons.

 

I have omitted the loop from the loco in the past due to not being appropriate staff under the buffer beam for the counter balance and they have worked OK as well.

 

I suspect they will work fine with a single loop of with two, depending on the exactness of the set up.

Interestingly, it’s suggested here (even in 7mm) to only use loops on one end for end to end layouts: https://www.gaugeoguild.com/manual/04_D4_2_1_8.pdf

 

Given the nature of my planned layout (intensive shunting but no appreciable gradients) I’m wondering if I’d be better off with loops on only one end, giving easier uncoupling but slightly at the expense of securely coupling together when on the move.

 

The final post here is interesting because of the point about the magnet needing to be strong enough to push up both loops, which I wasn’t sure about but I suppose makes some difference. In 009 I would be using 3mm scale B&Bs as others have done, so slightly smaller than the 00 ones.

 

I might not be following the logic of how they work properly, but presumably if you only fit loops to one end of each vehicle then the end with the loops would not need delay latches and vice versa? As far as I understand it the loop rests on the delay latch of the opposing/adjacent wagon, so if you only had loops on one end you would only need delay latches on one end as well (but the opposite one from the loops). Or am I missing something?

 

Of course, if one end doesn’t have the latch then it does open up the possibility of using a Greenwich coupling, or even an RTR Bemo-style coupling, on that end, although I would probably still be tempted to use a B&B to ensure compatibility. But can they even be built without the latches?

[009 micro modeller]

16 minutes ago, nickwood said:

I accept that there is the possibility of uncoupling if the track level is uneven or the coupling heights vary.

I should be able to avoid uneven track on this because it’s mostly going to be straight and level with one point of very generous radius. One solution to height imperfections that I’ve seen suggested elsewhere is to make the couplings without loops ever so slightly higher than the loop-fitted ones, enough to retain the loops but not so much that re-coupling becomes difficult. It seems like this would work in theory but I slightly doubt my ability to be this precise.

 

16 minutes ago, nickwood said:

If your layout is end to end and you are happy not to turn your stock then I can see no point in having loops at both ends of the stock.  The loops in one direction would not be in tension in any case.

In that case, is there any point in fitting the latches on the ends with loops? After all, there will be no loops on the adjacent wagons to rest on them.

 

I think the wagons might need to have a slightly asymmetric design anyway, so the couplings being single-ended won’t be a huge issue.

 

If you do have the loops only on one end, is there a preferable way round to have them, in terms of which end has the loop relative to where the end of the siding is?

 

16 minutes ago, nickwood said:

I have found that DG’s are generally tolerant of small variations in height. I have no direct experience of B&B’’s but as they are very similar, I assume that their performance would be similar.

I thought the principle on which they work was basically the same. I just think I might get on better with B&Bs during construction, because the loop is etched rather than formed from wire on a jig, as with DGs. I also already have some, whereas I don’t have any DGs.

[nickwood]

21 hours ago, 009 micro modeller said:

I should be able to avoid uneven track on this because it’s mostly going to be straight and level with one point of very generous radius. One solution to height imperfections that I’ve seen suggested elsewhere is to make the couplings without loops ever so slightly higher than the loop-fitted ones, enough to retain the loops but not so much that re-coupling becomes difficult. It seems like this would work in theory but I slightly doubt my ability to be this precise.

I’ve not come across this theory but in principle it makes some sense, however the difference in height would hardly be different to the tolerance you would expect in trying to make the couplings the same height. Not worth the effort in my view. 
 

21 hours ago, 009 micro modeller said:

In that case, is there any point in fitting the latches on the ends with loops? After all, there will be no loops on the adjacent wagons to rest on them.

 

The latches are not needed on the ends with loops. I do fit them though when making up the etches as in my experience the latches are the weak point of the DG design and if one becomes troublesome I can easily swap the loop to the other end, turn the item of stock and continue using it.

 

22 hours ago, 009 micro modeller said:

If you do have the loops only on one end, is there a preferable way round to have them, in terms of which end has the loop relative to where the end of the siding is?

Not that I’ve found. They seem to work well whichever way I choose to face them.

 

22 hours ago, 009 micro modeller said:

 I thought the principle on which they work was basically the same. I just think I might get on better with B&Bs during construction, because the loop is etched rather than formed from wire on a jig, as with DGs. I also already have some, whereas I don’t have any DGs.

At the time I made the decision to go for DG’s, a few years ago now, I couldn’t find a supplier for the B&B’s so my choice was made for me. I do not use DG’s method of making the loops with phosphor bronze wire and a steel dropper soldered to them as the whole loop Assembly and dropper can be easily made from one length of ispring steel wire . I assume with the B&B’s you have to solder a steel dropper to the etched loop?

[009 micro modeller]

11 minutes ago, nickwood said:

I assume with the B&B’s you have to solder a steel dropper to the etched loop?

I haven’t really got started yet but from my research I gather that the dropper is part of the etch, is bent down, and then has a little bit of wire wrapped round it (possibly glued but not necessarily soldered) presumably to make it suitable for magnetic activation. I don’t know whether (or why) DGs would be inherently more reliable than B&Bs (as some people seem to think).

 

15 minutes ago, nickwood said:

The latches are not needed on the ends with loops. I do fit them though when making up the etches as in my experience the latches are the weak point of the DG design and if one becomes troublesome I can easily swap the loop to the other end, turn the item of stock and continue using it.

I’m not sure if this is the case with DGs but I think on B&Bs the latch is cut off the etch and then fitted separately. Your rationale for fitting them anyway makes complete sense but in my case I think the details of the wagon design will preclude the wagons being turned round and used the other way anyway. What is it about the latches that is troublesome, generally speaking?

 

I know people in 009 that use Greenwich (with loop) one end, B&B (without loop) on the other, but while they should be largely compatible I’m not sure I like this idea - if very fine adjustment might be needed it would seem sensible for all the couplings to be the same type.

 

On a more general point, and I’m sure this is the case with a lot of other ‘shunting plank’ type layout plans, not just mine, but it occurs to me that the most appropriate location for a single uncoupling magnet (if using delayed uncoupling) would be just before the points leading to sidings, which would mean it was just off the scenic section. Therefore perhaps I shouldn’t worry so much about the reliability because, in the event that it doesn’t work perfectly every time, I’ll still be able to lift up the loop with an uncoupling hook and place it on the latch entirely off-scene, before using the delay function as intended.

[009 micro modeller]

I’ve started making these now but struggling with the various angles, even if I score it all first. Is the delay latch supposed to be directly above the hook, being pushed up by the loop under it when uncoupling?