Martin_R Posted July 9, 2012 Share Posted July 9, 2012 Recently there was a good article in the modelling section of Traction Magazine showing modifying Bachmann coach rigid pipe type couplings to magnetic couplings. I have tried it and it works very well but the age old problem of the excessive movement in the sprung close coupling mounts means coaches still have the surging type movement when in motion. I have used the magnetic approach idea in a slightly different way – using magnets to keep coach corridor connections in contact when on relatively straight track but still allowing the close coupling unit to operate as designed on tighter curves. I use a rigid type coupling on fixed rakes of Bachmann coaches and most modern freight stock – Hornby or Roco ‘close type’ or Fleischmann Profi coupler as appropriate. For Bachmann DMU/EMU units with through electrical connection I have always used a home made PCB strip connector in place of the supplied coupling - this gives me more flexibility in getting the unit close coupled. The magnets I have used are 3mm dia x 2mm N42 Neodymium [available from ‘first4magnets’ [usual disclaimer]. These are fitted into a plastic or nylon tube and the complete assembly mounted on the coach buffer beam where the prototype buckeye or hook would be fitted. The assembly is set back slightly so that when the corridor connections or buffers touch there is still about 0.5mm gap between magnets. This prevents the two items of stock locking together and derailing on curves and turnouts. Freight stock with close coupling mounts do need some experimentation in settings especially on buffer fitted stock to ensure no buffer locking takes place on reverse curves. This does mean that coaches and freight stock are handed for this to work correctly but this is not a problem for me – in fact with the 4-CEP it actually helps with correct coach orientation! I use a small spot of paint on the coach or wagon underframe at one end so when making up a rake the spot is always to the loco or leading end of train. The following images hopefully show how the method works on Bachmann MK1's. These show how much movement there can be in the sprung coupling even with tighter coupling offered by the modified magnetic coupling This shows a selection of couplings together with the magnets and nylon tube This shows mounting point for magnet in the nylon tube This shows magnet in position Coaches held close together by magnets Using Hornby close coupling in place of the magnetic couplings Magnets fitted to Bachmann 4-CEP Supplied coupling bar - too far apart PCB coupling bar - closer together Fleischmann Profi coupler used if lighting etc. not required Link to post Share on other sites More sharing options...
Ben Alder Posted July 9, 2012 Share Posted July 9, 2012 I can see the pics now! Food for thought here....... Link to post Share on other sites More sharing options...
Colin parks Posted July 16, 2012 Share Posted July 16, 2012 Hi Martin, Just had a look at your pictures. It is interesting to see that the use of small magnets on the modified Bachmann close-coupling parts did not hold the coaches consistently together. It was what I was going to do with the EMU I am building at the moment - will have to re-think. An idea that comes to mind is to mount the magnets in tubes fitted to the bogies themselves, but it would mean modifying the bogies by adding proper transoms. Colin Link to post Share on other sites More sharing options...
Martin_R Posted July 17, 2012 Author Share Posted July 17, 2012 Hi Colin, I am still working on a few other tweeks at the moment which may get the Bachmann coupling system working better. I have shortened each half of the Bachmann close coupling by another 1mm. This has the effect of pulling the close coupling unit towards the coach end thus taking out all the movement and the gangways now are touching all the time on straight track. On my reverse curved test track the close coupling unit doesn't start to react and open the gap quickly enough and the corridor units initially snag causing a twitch, not quite enough to derail but not what I'm looking for! If you have more generous curves - say not less than 120cm rad and and proper transitions from straight to curve the system works well. I suspect there is some variability in the coupling units on individual coaches so each end of each coach will need a specific length of coupling to get the best out of the system. I am going to try the system with some Keen coupling units and see if this works any better. My next step once I have the various coupling systems sorted is to try and use magnets for vacuum, air and control connections using 1mm dia magnets and some 0.8mm dia very soft and pliable plastic string - I must be mad! I must say having followed your topics on EMU construction I have a long way to go to even come near to your construction skills - absolutely superb and an real inspiration! Martin. Link to post Share on other sites More sharing options...
CWJ Posted July 17, 2012 Share Posted July 17, 2012 I like the PCB connector idea, thanks for the tip! I'll use this for bringing my Class 150 closer together while maintaining the electrical connection I'll be watching the magnetic developments with interest too - there is so much 'play' in close-coupling mechanisms that it would help to be able to pull the cars together. I'd thought of using springs but magnets would be much easier. Cheers, Will Link to post Share on other sites More sharing options...
Martin_R Posted July 18, 2012 Author Share Posted July 18, 2012 Hi Martin, Just had a look at your pictures. It is interesting to see that the use of small magnets on the modified Bachmann close-coupling parts did not hold the coaches consistently together. It was what I was going to do with the EMU I am building at the moment - will have to re-think. An idea that comes to mind is to mount the magnets in tubes fitted to the bogies themselves, but it would mean modifying the bogies by adding proper transoms. Colin Hi Colin, Update on the corridor snagging issue. I found some very small burrs on some of the corridor connectors, a few minutes with some very fine wet and dry and then a rub with a 6B pencil [much cheaper than graphite powder] and now no problems even on a Peco small rad turnout. Running under power through the reverse curves both pulling and pushing 6 coaches showed no issues, added 3 more coaches with normal couplings and magnets still held pulling and no obvious surging - great result! I have just got hold of some of the NEM coupling bars as used on the Bachmann Intermodal wagons and will modify these with magnets for my 4TC set. Hope this helps, Martin. Link to post Share on other sites More sharing options...
James C Posted September 15, 2012 Share Posted September 15, 2012 Recently there was a good article in the modelling section of Traction Magazine showing modifying Bachmann coach rigid pipe type couplings to magnetic couplings. I have tried it and it works very well but the age old problem of the excessive movement in the sprung close coupling mounts means coaches still have the surging type movement when in motion. I have used the magnetic approach idea in a slightly different way – using magnets to keep coach corridor connections in contact when on relatively straight track but still allowing the close coupling unit to operate as designed on tighter curves. I use a rigid type coupling on fixed rakes of Bachmann coaches and most modern freight stock – Hornby or Roco ‘close type’ or Fleischmann Profi coupler as appropriate. For Bachmann DMU/EMU units with through electrical connection I have always used a home made PCB strip connector in place of the supplied coupling - this gives me more flexibility in getting the unit close coupled. The magnets I have used are 3mm dia x 2mm N42 Neodymium [available from ‘first4magnets’ [usual disclaimer]. These are fitted into a plastic or nylon tube and the complete assembly mounted on the coach buffer beam where the prototype buckeye or hook would be fitted. The assembly is set back slightly so that when the corridor connections or buffers touch there is still about 0.5mm gap between magnets. This prevents the two items of stock locking together and derailing on curves and turnouts. Freight stock with close coupling mounts do need some experimentation in settings especially on buffer fitted stock to ensure no buffer locking takes place on reverse curves. This does mean that coaches and freight stock are handed for this to work correctly but this is not a problem for me – in fact with the 4-CEP it actually helps with correct coach orientation! I use a small spot of paint on the coach or wagon underframe at one end so when making up a rake the spot is always to the loco or leading end of train. The following images hopefully show how the method works on Bachmann MK1's. These show how much movement there can be in the sprung coupling even with tighter coupling offered by the modified magnetic coupling This shows a selection of couplings together with the magnets and nylon tube This shows mounting point for magnet in the nylon tube This shows magnet in position Coaches held close together by magnets Using Hornby close coupling in place of the magnetic couplings Magnets fitted to Bachmann 4-CEP Supplied coupling bar - too far apart PCB coupling bar - closer together Fleischmann Profi coupler used if lighting etc. not required Which issue of Traction Magazine was this in? Thanks Link to post Share on other sites More sharing options...
Martin_R Posted September 15, 2012 Author Share Posted September 15, 2012 Hi James - I think it was the July issue that showed the basic method of adapting the Bachmann rigid coach coupling as shown in my first 2 pictures. Cheers, Martin. Link to post Share on other sites More sharing options...
ThaneofFife Posted November 1, 2012 Share Posted November 1, 2012 My article did have the usual caveat - you are free to experiment. Link to post Share on other sites More sharing options...
fungus Posted December 2, 2012 Share Posted December 2, 2012 I have also developed the concept of neodymium magnetic couplings, and carried out some trials of holding strength, both on a test rig and on a garden railway with 12 coaches pulled up a 1 in 50 gradient with reverse curves. My Mk.2 design uses two 2mm x 2mm magnets side by side, so that all couplings will mate with each other without having to worry about polarity. I have also defined a "standard" way round for the two magnets, so that everybody's couplings should work together. A full description of the design and the proving tests are given in http://fungusmodels....-couplings.html and the two following blog posts http://fungusmodels....ing-trials.html and http://fungusmodels....nformation.html. I would be pleased to hear of any comments or suggested improvements to the design. Link to post Share on other sites More sharing options...
cctransuk Posted December 2, 2012 Share Posted December 2, 2012 See post #12 at http://www.rmweb.co.uk/community/index.php?/topic/57741-magnets-for-couplings/page__fromsearch__1 This method has worked fine for me, and can be adapted for coaches that do not have prototypical rubbing bars. Regards, John Isherwood. Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.