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Author Topic: New coupler development (was Coupling survey)  (Read 30491 times)

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Offline Caz

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Re: Coupling survey
« Reply #210 on: March 13, 2018, 05:40:25 PM »
That is looking good Richard, a question, is the coupling handed as that is why I stopped using the likes of B&B etc.

Offline belstone

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Re: Coupling survey
« Reply #211 on: March 13, 2018, 09:08:21 PM »
That is looking good Richard, a question, is the coupling handed as that is why I stopped using the likes of B&B etc.

Not handed, that has been one of my requirements from the start as it means I can just have plain hooks on locos which saves an awful lot of hassle.

Offline SheldonC

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Re: Coupling survey
« Reply #212 on: March 18, 2018, 06:37:24 PM »
I'm afraid I haven't followed this topic from the beginning, but I have to admire the persistence & ingenuity that have gone into this development; I congratulate you & hope it proves a technical & commercial success.  It's a pity the Rapido became universal at such an early stage.  Incidentally, your mention of aquatic ruminations reminded me that Archimedes did not have his "Eureka!" moment in the shower. :thankyousign:

Offline belstone

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Re: Coupling survey
« Reply #213 on: March 18, 2018, 11:08:55 PM »
A really good test session this evening, getting as close as I think I ever will to total reliability.  I put a coupler on the front of my "Old Faithful" J39 and bashed some wagons around the yard for a good half-hour without being seized by a desire to throw my tiny toy trains out of the window. I have found one new problem though.  I was trying to uncouple a single 16 ton mineral wagon and it would not behave.  There was no obvious cause, but in the end I realised that this particular wagon is unusually free-rolling compared to the others in my test fleet. As I attempted to uncouple it, the magnet was drawing it forward by its drop arm towards the wagon I was trying to uncouple from.

This one is going to need a bit of experimenting with magnet configurations and strength to solve. I suspect that what I might need is two magnets with a gap between them, so that the drop arms on the couplers are only pulled downwards and not drawn along the track.  That will be a lot easier to achieve with permanent magnets than electromagnets.

More to report when my super strong Chinese magnets arrive.

Richard

Offline Black Sheep

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Re: Coupling survey
« Reply #214 on: March 19, 2018, 01:31:40 PM »
would more weight help, or some paint brush bristles sticking up to offer some resistance help?

Offline SheldonC

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Re: Coupling survey
« Reply #215 on: March 19, 2018, 03:31:35 PM »
That is looking good Richard, a question, is the coupling handed as that is why I stopped using the likes of B&B etc.

Not handed, that has been one of my requirements from the start as it means I can just have plain hooks on locos which saves an awful lot of hassle.
One of the advantages of some of the commercially available systems is the availability of couplings of two or three different lengths.  Do you think it's worth considering this as a route to allow those who choose to do so to have a short coupling at one end and a long one at the other, in order to avoid buffer lock on tighter curves than two short ones can cope with?  This "handedness" would be totally at the customer's discretion.

Offline Black Sheep

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Re: Coupling survey
« Reply #216 on: March 20, 2018, 03:34:59 PM »
Stupid question (I'm allowed one a month according to my manager)

if propelling over a fixed magnet (not electromagnet) will the couplings uncouple or would you need to stop, 'kadee shuffle' and propell again?

Likewise, pulling over a fixed magnet

just thinking the electromagnet could be used as normal but with a back up of some fixed magnets in the actual siding incase (or to prevent) re-coupling due to a sharp point.

I'm possibly making sense...

Offline Newportnobby

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Re: Coupling survey
« Reply #217 on: March 20, 2018, 03:58:47 PM »
I think André-NL came up with a great 'now it's there - now it's not' arrangement for magnets.......

http://www.ngaugeforum.co.uk/SMFN/index.php?topic=28831.0

Offline belstone

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Re: Coupling survey
« Reply #218 on: March 20, 2018, 10:26:57 PM »
It is fair to say my solenoid-based uncoupler is not a success.  Pressing the button creates a small earthquake as the armature bangs against its end stop, sufficient to derail any wagons within a foot or so of it.  The solenoid coil draws an alarming current (1.2 amps) and gets hot far too quickly.  I want to try it at a lower voltage but can't lay my hands on a suitable power supply right now.

The permanent magnets themselves are possibly too powerful, I went for big poky N52 magnets in the hope that they would have sufficient range not to need any holes in the baseboard at all. They don't have the range I hoped, and need to be reasonably close to the underside of the sleepers on Peco Code 55 before they do anything.  Slightly closer than that and they do far too much. Magnetic field strength decreases exponentially with distance, so with very powerful magnets the magnet height (relative to the top of the rails) becomes super-critical.  I'm looking for a design which can easily be retrofitted to existing layouts without having to dig up the track, otherwise I would stick with the big round "sucker" electromagnets.

I also remembered something that I had learned with the earlier design but then forgotten, which is that steel wagon weights and mild steel axles are bad news when you are waving magnets around under the track.  One of my cattle wagons had been playing up seemingly at random: I found that it had a mild steel axle on one wheelset, non-magnetic on the other.  (Current Farish wheelsets have non-magnetic axles.)

@newportnobby I saw Andre's post and like the design a lot, but ideally I want something that can be operated via a microswitch on my hand-held controller, so mechanical systems are out.

@Black Sheep Earlier versions of the coupler were designed around fixed permanent magnets but I had major problems with accidental uncoupling of the last one or two wagons in a train.  In the end I had to add so much artificial drag to the wagons (via coil springs slipped over the axle ends) that my J39 would slip to a standstill on an eight wagon train.  At that point I gave up with permanent magnets...

@SheldonC The limiting factor on length is the pivot for the arm.  This needs to be roughly level with the bufferbeam, any further back and the arm cannot lift far enough before it hits the vehicle body.  As long as the buffer bar on the coupler sticks out slightly further than the buffers on the vehicle it will handle very sharp curves no problem. On NEM coupler boxes the dropper needs to clear the front of the coupler box, so NEM-equipped vehicles tend to end up not as close-coupled as those where the coupler is mounted direct to the chassis. NEM coupler boxes are totally pants and there is not much I can do about that.  But for locos (where there is no arm to worry about, just a fixed hook and delay bar) I like your idea and will look into it.  Some locos with NEM pockets have the pocket ridiculously far forward (Dapol class 26 for starters) and a shortened hook assembly would make a lot of sense if it can be done.

Shopping list now includes a couple of brass flap hinges, and I am thinking I might have to learn about servos after all.  I also found an interesting post where someone had made their own uncoupling electromagnet for DG couplers (which have a lot in common with mine) so I might acquire some varnished copper wire and try that as well. Isn't this hobby of ours great?  You never need run out of things to do.

Richard

Offline T-TRAK_Andrew

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Re: Coupling survey
« Reply #219 on: March 21, 2018, 05:03:55 AM »
Always learning, from both wins and losses.
My Model Railway blog: http://ttrakandrew.wordpress.com/
My FlickR Photostream: http://www.flickr.com/photos/85896932@N07/

Offline belstone

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Re: Coupling survey
« Reply #220 on: March 21, 2018, 07:23:20 AM »
My perversion of a `drop away' permanent magnet:

https://www.youtube.com/watch?v=fV8shkYND38

https://www.youtube.com/watch?v=Z-LSPIym5zM

https://www.youtube.com/watch?v=5Q0oHMmv7fA

Cheers, Andrew G.

Neat and ingenious, thank you for sharing that.  I am looking to do something similar, but with an electrical actuator rather than the manual pushrod.  I just ordered a servo and controller from Heathcote Electronics which I think will do the job. The controller is a simple two position device controlled by an on-off switch, which suits my microswitch system perfectly. I think it would be a good idea to have some kind of compensating spring between the servo arm and the hinge flap but there is no need for them to be mechanically linked: as with your design, the  flap will fall downwards under its own weight as the servo arm moves away.

I had a play around late last night to establish the ideal distance between magnet and rail tops, so I just need the servo kit to turn up and I am back in the uncoupling game.

Richard

Offline Black Sheep

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Re: Coupling survey
« Reply #221 on: March 21, 2018, 09:48:06 AM »
would the peco / gaugemaster fixed electromagnet work,

It does require drilling a hole for it to come to the top of the baseboard, but it's only a 5mm pole between the sleepers so easy enough to do and camouflage again

Offline SheldonC

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Re: Coupling survey
« Reply #222 on: March 21, 2018, 01:08:14 PM »
It is fair to say my solenoid-based uncoupler is not a success.  Pressing the button creates a small earthquake as the armature bangs against its end stop, sufficient to derail any wagons within a foot or so of it.  The solenoid coil draws an alarming current (1.2 amps) and gets hot far too quickly.  I want to try it at a lower voltage but can't lay my hands on a suitable power supply right now.

The permanent magnets themselves are possibly too powerful, I went for big poky N52 magnets in the hope that they would have sufficient range not to need any holes in the baseboard at all. They don't have the range I hoped, and need to be reasonably close to the underside of the sleepers on Peco Code 55 before they do anything.  Slightly closer than that and they do far too much. Magnetic field strength decreases exponentially with distance, so with very powerful magnets the magnet height (relative to the top of the rails) becomes super-critical.  I'm looking for a design which can easily be retrofitted to existing layouts without having to dig up the track, otherwise I would stick with the big round "sucker" electromagnets.

I also remembered something that I had learned with the earlier design but then forgotten, which is that steel wagon weights and mild steel axles are bad news when you are waving magnets around under the track.  One of my cattle wagons had been playing up seemingly at random: I found that it had a mild steel axle on one wheelset, non-magnetic on the other.  (Current Farish wheelsets have non-magnetic axles.)

@newportnobby I saw Andre's post and like the design a lot, but ideally I want something that can be operated via a microswitch on my hand-held controller, so mechanical systems are out.

@Black Sheep Earlier versions of the coupler were designed around fixed permanent magnets but I had major problems with accidental uncoupling of the last one or two wagons in a train.  In the end I had to add so much artificial drag to the wagons (via coil springs slipped over the axle ends) that my J39 would slip to a standstill on an eight wagon train.  At that point I gave up with permanent magnets...

@SheldonC The limiting factor on length is the pivot for the arm.  This needs to be roughly level with the bufferbeam, any further back and the arm cannot lift far enough before it hits the vehicle body.  As long as the buffer bar on the coupler sticks out slightly further than the buffers on the vehicle it will handle very sharp curves no problem. On NEM coupler boxes the dropper needs to clear the front of the coupler box, so NEM-equipped vehicles tend to end up not as close-coupled as those where the coupler is mounted direct to the chassis. NEM coupler boxes are totally pants and there is not much I can do about that.  But for locos (where there is no arm to worry about, just a fixed hook and delay bar) I like your idea and will look into it.  Some locos with NEM pockets have the pocket ridiculously far forward (Dapol class 26 for starters) and a shortened hook assembly would make a lot of sense if it can be done.

Shopping list now includes a couple of brass flap hinges, and I am thinking I might have to learn about servos after all.  I also found an interesting post where someone had made their own uncoupling electromagnet for DG couplers (which have a lot in common with mine) so I might acquire some varnished copper wire and try that as well. Isn't this hobby of ours great?  You never need run out of things to do.

Richard

I think it would be possible to overcome the problem of closer coupling by introducing a crank into the lifting arm/loop, provided this did not cause it to foul something else.

Offline belstone

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Re: Coupling survey
« Reply #223 on: March 21, 2018, 03:33:44 PM »
would the peco / gaugemaster fixed electromagnet work,

It does require drilling a hole for it to come to the top of the baseboard, but it's only a 5mm pole between the sleepers so easy enough to do and camouflage again


I tried the Peco electromagnet a while ago but it wasn't powerful enough.  From what I have read, that type of electromagnet with a long bar sticking out is a bit inefficient, my own experiments have tended to bear that out.  The Gaugemaster version might be better but it's a bit expensive for something I'm a bit dubious about.

@SheldonC cranking the loop would allow the coupler to be positioned a little further back, but there isn't really any need on non-NEM vehicles, close coupling on these is as good as it will ever need to be already.  On the NEM version the pivot cannot be positioned any further back than the front of the coupler pocket, and most manufacturers put the front of the pocket level with the bufferbeam for some weird unfathomable reason.  The DJM "Mermaid" is an especially good example of what I am up against trying to achieve NEM compatibility with reasonable close coupling. The Farish horsebox and CCT are the opposite extreme, with long buffers and a coupler pocket set well back, needing a longer than standard coupler to avoid buffer locking.

Basically I think I am going to have to give up with plug-in NEM compatibility on rolling stock and just concentrate on providing it for locos which is where it is most needed.  There are just too many design variables, and most vehicles now seem to have coupler boxes on stalks which flop around all over the place. Coaches usually run in fixed rakes, and fitting a coupler to the outer bogie on each rake is pretty easy, at least on the Farish and Dapol coaches I have looked at, and doesn't involve wholesale butchery of the body or chassis. Wagons are cheap enough that most people will (I think) be content to remove the coupler boxes and attach the new couplers to the underframe with small screws. On most Farish stuff this would be a reversible modification as the coupler boxes just clip on. Cutting chunks out of the chassis to fit my couplers on a brand new £120 loco is a less appealing prospect.

The plain hook and buffer for locos doesn't even have to look the same as the one on the full-function looped coupler, as long as it is compatible.  It is more important to have some easy means of adjusting the height to compensate for variations in NEM coupler box design, and that should be achievable with a bit of thought.

Richard

Offline belstone

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Re: Coupling survey
« Reply #224 on: March 23, 2018, 07:54:08 AM »
I now have a nice simple design for NEM plug-in coupler hooks with easy height adjustment.  The only problem is that it will require soldering - a length of wire soldered at right angles to the coupler, and then the ends snipped off short.  It needs to be soldered to accommodate all the different lengths of coupler that will be needed for NEM equipped locos. Do people think this will be a problem?  I have tried to keep the design soldering-free but I can't see a way around this one. I suppose the pin could be glued, but a round wire on a flat surface doesn't give a lot of contact area, so I am not sure it would really be strong enough, depends on the glue I suppose.  I might try it with thick cyano.

I only have two unmodified locos with NEM coupler pockets, Dapol B1 and Farish A2.  So I made up a rough prototype of my new design and tried fitting it.  To equip these two locos with new couplers front and back I need three different lengths of coupler at two different heights, with two different pin diameters.  So much for the "standard" NEM coupler pocket.

 

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