DG couplings

[David Holman]

 Had my first experience exhibiting with these at Tolworth over the weekend and nothing like 13 hours continuous operation to shed light on things. Mostly, they work well, but (as my school reports often said) could be better. So interested to hear about the following:

• The coupling loops can sometimes get in each others' way. Is just having a loop at one end best, or are there ways round this?
• Found that the loops can stay up after uncoupling, because the iron wire dropper has stayed down after the magnet is switched off. I have not fitted loops to any of my locos, so this caused problems at times. Plus see above. Should I try shortening the dropper wire, make the front the loop heavier, or even mount the coupling so it sticks out less and the loop can't go beyond vertical?

 Other things I found were:

• Though nice and discreet, the etches are a bit lightweight, so a thump from a half kilo loco can upset alignment - especially if there is a buffer stop at the other end...
• Several times, a loop came partially out of the etch. Ideas on preventing that welcome.

 2mm and 3mm versions clearly work very well from what I've seen at shows, so it would be good to learn how I might refine my 7mm ones - including how best to set up and test them.

 

[Angus]

Hi David,

As a 2mm scale modeller I've been using DGs for a while now so have experience of my own and those shared by others in conversations amongst other 2mm modellers.

I've never used them in 7mm scale though.

The loops are recognised as a problem, that said, I don't have much of an issue. Some 2mm modellers just put the loop on one end of their stock, which works if your stock always travels in one direction. If not you are going to have problems due to stock with no loops trying to couple (or have to carefully choreograph the moves).

When I first started using DGs I experimented with some soft iron wire for the loops. I thought I was being clever as this meant I could just fold the loop and dropper up out a single piece of wire, no need to solder on a dropper. The wire was thicker though, probably bigger than 0.5mm where the standard 2mm wire is 0.3mm.

I found I had a couple of issues:

Firstly the loops clashed more causing problems when coupling. Changing back to 0.3mm phosphor bronze wire all but removes the issue. I think the slight spring in the phosphor bronze wire also helps.

Secondly the loops didn't drop back as consistently. I suspect this was do to the loop being heavier so the dropper didn't have as much of a counter balance effect bringing the loop down. The wire was also a slightly tighter fit in the mounting hole (but still free to move) so I suspect there was more friction involved. Again, moving back to phosphor bronze wire with an iron dropper resolved this.

I've found the loops do pop out occasionally but only if I'm manhandling the stock, I've never had this issue if they are on the track and my fingers aren't involved.

As your rakes are short might it be worth trying some 0.3 phospher bronze for the loops? It should be strong enough even for 7mm.

 

[Mayner]

I don't know if they are interchangeble but both the DG and B&B couplings (Derek Bunting) appear to be based on the Rivorossi (hook and loop) coupling the B&B using an etched loop rather than the user having to form the loop from wire.

I successfully used B&B couplings under exhibition conditions on a EM gauge layout over 20 years ago, seldom experiencing problems coupling up or magnetic uncoupling, my wagon stock had loops at both ends locos with hooks only, while a friend who used a mixture of B&B, Rivorossi , and Bemo couplings fitted a loop at only one end.

The friend's father (an Irish Railway Clearing House employee) used Rivorossi couplers on his OO gauge GWR layout during the 50s and 60s, his son continuing to model the GWR this time in EM.

Whether B&B couplings are available in S or 7mm is another question.

[David Holman]

Interesting and thank you both.

Looking at the instructions again, they suggest a curved, rather than an angled bend to the dropper might work better.

 Further experimenting certainly required though, including:

• Building a test rig so stock can be pushed back and forth on the work bench
• Try altering the height of the magnet. I use the Dingham ones and on 15v, instead of 12v, as this works better with AJs, so maybe there is an issue there.
• Vary the length of the dropper as the shorter it is, the greater chance for the loop to fall back down on its own weight
• Find some way of ensuring the loops don't go beyond the vertical, as once they do, then there is no way they can fall back again.

 As for loops just at one end, am doing that with some of my trains as it works well with fixed rakes. However, as soon as haunting is involved, it all goes to pot because having a turntable means you soon get a loopless loco with a loopless wagon.

 Overall, I'd happily use three links and the hand from the sky, but for front operated exhibition layouts that is not practical for the paying public.