Overhead electrification and wiring question

[009 micro modeller]

For my new project I’m building what is basically an 009 shunting puzzle, with the interesting addition of transporter wagons, on and off which motorised standard gauge wagons will run onto a dock. The technique of motorising the standard gauge wagons themselves individually is one I’ve seen used before, and there’s a few reasons why I’ve chosen to use this method. The main decision now is how to supply power to the rails used by the standard gauge wagons on top of the transporter wagon; previously I’ve seen this done by simply fitting wiper contacts to the end of the transporter, but I’m not sure if this will be reliable enough. Another option is to use the narrow gauge rails to supply power to the standard gauge wagon, via pickups on the wheels of the transporter that are then connected to the rails on top of it. I like this option, though it would mean that the narrow gauge locos could not be powered using conventional two rail; even if the section where the transporters are unloaded is electrically isolated from the rest of the layout, once they are hauled out of this section the standard gauge wagons will draw the power intended for the narrow gauge loco and run off the transporters. There are probably ways of avoiding this problem using DCC, although for now I don’t really want to go down that route. I have seriously considered radio control as a potential solution; a further factor in this is that the layout is likely to include a 3 way point (to save a bit of length compared to two normal points), which would be somewhat challenging to wire.

 

However, a further option is to electrify the narrow gauge line using working live overhead line. I’ve always been interested in quirky old electric railways, including narrow gauge and industrial ones, and in this case it would actually provide a pretty good solution to my problem. With power through the overhead line and return via one of the running rails (with the other running rail being dead) I could avoid inadvertently powering up the wagons on top of the transporters, and the wiring for the point would become very easy as the same parts would always be live.

 

However…

 

 

The yellow highlighted rails would form one side of the circuit, with the overhead forming the other. This is fine, but the frogs (circled in red) are obviously crossed by the dead rails as well. This would create a short as the transporter plus standard gauge wagon (effectively wired for normal 2 rail operation, but out of the section that has this) will end up being supplied with the same polarity from both rails (this is also why I can’t just use both rails as the return, as I think tramway modellers do). Does this mean that I still need to make the frogs switchable (or, as a less good alternative, permanently dead) even though this isn’t necessary for the overhead wire locomotive?
 

On a slightly separate note, if I do go down the working overhead wire route, is there much equipment available for this in 4mm? I know there is some for tramways but I’m not sure how suitable it will be for a narrow gauge layout using bow collectors rather than trolley poles. I also haven’t yet looked into how far off the ground the wire would need to be to clear the transporters and the wagons on top of them, it may turn out to be unreasonably high just from a visual perspective.

[Nearholmer]

If you do decide to install OLE, you’d be far better off commoning the whole of the running rails for return purposes, to minimise the chances of loss of contact.

 

For the unloading siding, you could install a gap in one rail and a switch to connect that rail to either common return or traction supply, the latter only being selected when needed for unloading/unloading purposes.

 

Now the “but”. My instinct is that you will struggle to get reliable contact between a model OLE and a model now-collector, or pantograph, or even worse trolley-pole at 4mm/ft scale. Before going too far, it would be worth rigging-up a test section to allow experimentation around contact pressure, rigidity of OLE etc. On the real thing the collector will lift the wire, appreciably in some cases, but I don’t think you’d want to try that at this tiny scale.

 

I do hope it works, because NG electric railways are a subject too neglected in this country.

 

Maybe as an alternative to transporters you could try those bi-modal carts that the Bessbrook & Newry used.

Edited September 27, 2022 by Nearholmer

[009 micro modeller]

7 minutes ago, Nearholmer said:

If you do decide to install OLE, you’d be far better off commoning the whole of the running rails for return purposes, to minimise the chances of loss of contact.

 

For the unloading siding, you could install a gap in one rail and a switch to connect that rail to either common return or traction supply, the latter only being selected when needed for unloading/unloading purposes.

Thanks for your suggestions. I probably wasn’t very clear originally but the idea is that the end of the unloading siding (so only the bit of track underneath the wagon that is being unloaded) will be wired for conventional 2 rail, but as a continuation of the standard gauge track on the dock in order to supply power to the standard gauge wagon on top of the transporter. This will be permanently electrically isolated from the rest of the narrow gauge system (the wagons are long enough that the couplings will be able to reach over the end of the isolated section). Although I’d like to I don’t think I can common both running rails on the OLE section because under some circumstances they will then be feeding positive current to both the positive and negative terminals on the standard gauge wagon’s motor (via the pickups on the transporter wagon). I was under the impression that this would create a short and possibly damage the motors on the standard gauge wagons.

 

18 minutes ago, Nearholmer said:

Now the “but”. My instinct is that you will struggle to get reliable contact between a model OLE and a model now-collector, or pantograph, or even worse trolley-pole at 4mm/ft scale. Before going too far, it would be worth rigging-up a test section to allow experimentation around contact pressure, rigidity of OLE etc. On the real thing the collector will lift the wire, appreciably in some cases, but I don’t think you’d want to try that at this tiny scale.

It won’t be a trolley pole, partly because they generally have to be reversed at the end of the line. It would probably be some sort of bow collector. I was slightly worried about this aspect of it but tram layouts with live overhead often seem to operate fairly reliably so would this be that different?

[Nearholmer]

19 minutes ago, 009 micro modeller said:

was under the impression that this would create a short and possibly damage the motors on the standard gauge wagons.

No. A short circuit is a zero/low resistance connection between the two poles of the supply (supply and return, positive and negative, call them what you will). Whereas, if you common all the running rails (except in that siding), your motorised wagon riding on its transporter will have both its terminals connected to the same potential (it matters not what that potential is in relation to anything else), there will be no potential difference across it, no current flow through it, and no harm will be done to anyone or anything.

 

For an extreme example, think of birds perching on a 400kV line. Both of their feet are at the same potential, so no current flows through their body, and they don’t disappear in a puff of smoke. Yet, they are themselves at 400kV above earth potential. 

 

19 minutes ago, 009 micro modeller said:

tram layouts with live overhead often seem to operate fairly reliably

In 4mm scale? If so, hats off to the builders, because I think it must take a lot of care to get right.

Edited September 27, 2022 by Nearholmer

[009 micro modeller]

7 minutes ago, Nearholmer said:

No. A short circuit is a zero/low resistance connection between the two poles of the supply (supply and return, positive and negative, call them what you will). Whereas, if you common all the running rails (except in that siding), your motorised wagon riding on its transporter will have both its terminals connected to the same potential (it matters not what that potential is in relation to anything else), there will be no potential difference across it, no current flow through it, and no harm will be done to anyone or anything.

 

For an extreme example, think of birds perching on a 400kV line. Both of their feet are at the same potential, so no current flows through their body, and they don’t disappear in a puff of smoke. Yet, they are themselves at 400kV above earth potential. 

 

In 4mm scale? If so, hats off to the builders, because I think it must take a lot of care to get right.

I did know about the birds on power lines (and it’s the example we were always shown in Physics at school to illustrate this point). For some reason I didn’t make the connection here, probably because of the apparent complexity of the project overall. I think I’ve already solved the problem of inadvertently powering up the standard gauge wagons when not on the unloading siding, but if I can common both rails on the OLE section does this also mean my concerns about the point frogs are unfounded?

 

If I’ve understood correctly, this would mean the entire 3 way point could be live at all times, and (unlike with 2 rail) the narrow gauge system of 3 sidings and a headshunt would be the same electrically as it would be if it was a single straight line (I don’t need any isolating sections for the shunting I want to do so the overhead would be ‘all live’ as well). The switching of the point itself would only be mechanical, to route the trains (not the electricity supply).

 

On the other hand, perhaps I should be less confident about the reliability of something like this in 4mm scale (especially as I am going to be the one building it, having not done anything quite like this before). There is at least one 009 layout (Lochsanda, featured here) that uses working live overhead but I’m not sure how reliable it is. I also wonder whether mine will be less reliable because it’s a shunting layout (Lochsanda and most tramway layouts are continuous run, or at least a fairly long end to end shuttle).

[Nearholmer]

If you common the running rails, no need to worry about switching frog polarity or any of that. What you would be doing is wiring exactly as a real tramway. If you need isolating sections to park locos or whatever, just have isolated sections of OLE, again just like a real tramway.

 

Its all very similar to three-rail electrification, although in model form that has quirks around how the collectors cross running rails at points, which OLE doesn’t.

 

Are you envisaging short locos, or long cars? If the latter, stick two bow collectors on each to improve current collection.

 

Allround, it sounds to me as if you need to consult a tramway modeller, or their forum, to get advice on current collectors.

[Michael Hodgson]

You can do it using overhead, although wiring over the loading siding and a wagon length beyond may look rather odd.  Obviously all the vehicles loaded then need their bow collector(s) or pantograph, and you still need to provide a return path through the transporter wagon(s).   I agree with others above who think that getting reliability may be problematic.  If you end up have to resort to finger-poking to get it to start whilst unloading, you will quickly lose your audience - much more so than when it's necessary at some random spot on an exhibition layout.

 

I think this approach would give you the most reliable electrical connections and has the desirable feature that you can only move the loaded vehicle whilst the transporter is in dock.  However the contacts are very obvious and arguably spoil the image

https://www.ebay.co.uk/itm/265684171932 

 

But if I were doing it, I think I would prefer the option you've already mentioned, pickups on the transporter wagon wheels (all wheels for reliability) feeding the rails on the deck.

 

But whatever system you use, I would suggest that the risk of unreliabilty in starting is double what you would expect with an ordinary loco/track situation - you've still got that usual risk of wheel contact not working, but you also have the risk that the feeder contacts don't make properly.  Of course that's not to say it won't work if everything is well engineered.

 

 

[009 micro modeller]

2 hours ago, Michael Hodgson said:

You can do it using overhead, although wiring over the loading siding and a wagon length beyond may look rather odd.  Obviously all the vehicles loaded then need their bow collector(s) or pantograph, and you still need to provide a return path through the transporter wagon(s).   I agree with others above who think that getting reliability may be problematic.  If you end up have to resort to finger-poking to get it to start whilst unloading, you will quickly lose your audience - much more so than when it's necessary at some random spot on an exhibition layout.

 

I think this approach would give you the most reliable electrical connections and has the desirable feature that you can only move the loaded vehicle whilst the transporter is in dock.  However the contacts are very obvious and arguably spoil the image

https://www.ebay.co.uk/itm/265684171932 

 

But if I were doing it, I think I would prefer the option you've already mentioned, pickups on the transporter wagon wheels (all wheels for reliability) feeding the rails on the deck.

 

But whatever system you use, I would suggest that the risk of unreliabilty in starting is double what you would expect with an ordinary loco/track situation - you've still got that usual risk of wheel contact not working, but you also have the risk that the feeder contacts don't make properly.  Of course that's not to say it won't work if everything is well engineered.

 

 

My thought process with this was a bit convoluted but here goes. The idea I have in mind is basically to use the narrow gauge running rails on the unloading siding (in conventional 2 rail DC fashion) to supply power to the standard gauge track on the transporter wagons (they are sort of Leek & Manifold style) parked in that section, via pickups on the transporter wagon wheels. This will then allow the motorised standard gauge wagons to run on and off the transporters. Again the standard gauge wagons and track will all be normal 2 rail DC, they won’t have anything to do with the overhead line. The reason for doing it like this is that I think it will likely be more reliable and better looking than supplying power for the SG rails via wiper contacts or big contact plates on the ends of the transporters.

 

However, this then leaves me with a problem in that I can’t also use the NG rails to supply current to the NG loco in the normal 2 rail way, even outside the isolated unloading siding. If I did then I’d also end up energising the SG rails on the transporters, causing the motorised wagons to drive off the end.

 

So I need another way to power the NG loco. One solution is battery powered radio control (i.e. eliminating the need for any conductors to supply power to the loco). An alternative solution is overhead wire (i.e. providing an extra conductor to supply power). An additional benefit in both cases is the ability to simplify the wiring for the 3 way point I will probably have to include; for radio control all rails are dead so there is no wiring at all, for overhead wire all rails are simultaneously live so the wiring is very simple. As it’s going to be a shunting puzzle operated by one locomotive at a time I don’t need any further isolating sections. There are things I like about the radio control option but other aspects that I’m less keen on. Meanwhile, I’ve always wanted to have a go at a narrow gauge electric railway but in other circumstances I’d probably be building it as a 2 rail system with cosmetic overhead line. In this case though it seems as though using a real working OLE system would help me to overcome other issues and make the layout as a whole better and more reliable, while the electric locos will add an extra element of interest. The 009 News article on Lochsanda states that it is very reliable and good at maintaining contact as the sprung pantograph helps to push the loco onto the track, while simultaneously pushing up against the overhead wire, although I’m not sure this would be quite as reliable on a shunting layout as opposed to a continuous run.

 

4 hours ago, Nearholmer said:

Are you envisaging short locos, or long cars? If the latter, stick two bow collectors on each to improve current collection.

 

Allround, it sounds to me as if you need to consult a tramway modeller, or their forum, to get advice on current collectors.

Medium sized shunting locos. I agree, I think it would be useful also to speak to more than one person who has done something similar. Has anyone done anything like this on a shunting layout before?

[Nearholmer]

Reading what you’ve said in the above does make me wonder whether battery and radio control for the SG motor-wagons might avoid a having to make the NG unusual. Another option is to use fine thread to move the SG wagons, a miniature rope and capstan system. But, I do like NG electric railways, so please don’t do either. 
 

Loco wise, your best prototype might be MER No.23 in original form, or maybe the ‘electric sheds’ used at Kinlochleven. Ted Polet built a model of me of the latter for his 009 layout Rae Bridge and put two Hopkinson pre-bow collectors on it - the real locos initially had a bizarre double-headed pantograph thing.

 

 

 

 

Edited September 27, 2022 by Nearholmer

[009 micro modeller]

7 hours ago, Nearholmer said:

Reading what you’ve said in the above does make me wonder whether battery and radio control for the SG motor-wagons might avoid a having to make the NG unusual.

For radio control, the better option for me is to make the narrow gauge loco radio control. Then I only have to fit radio control to one or two locos, not eight or nine motorised SG wagons. Meanwhile, the three way point hopefully becomes less complicated and more reliable, whereas the SG line is only a very short section of straight track anyway. There’s a similar issue if I used a DCC solution (not that I’ve really looked into that or am particularly interested) - I gather that everything motorised would need to be chipped, which is a minimum of nine vehicles (eight SG wagons plus one NG loco) despite it being a very small layout.

 

Space inside the loco would not be an issue as a relatively large NG loco will be needed anyway, to shunt the big transporter wagons. Motorising the SG wagons (rather than hauling them with locos/string/chain/push rods etc.) removes the need to have any locos or working couplings on the SG (in particular this avoids the need to uncouple while on the transporters) and being motorised will mean they are not free running when power to them is switched off, so will more easily stay on the transporters when away from the loading dock.

 

However, there’s something quite appealing about the overhead electric idea. As well as solving a couple of practical problems (in much the same way that RC would) it also provides a further interesting and quirky element to the layout and is something I’ve always wanted to try. My main concern is still the wire height that will be required to clear the tops of the standard gauge wagons (even if taller van wagons are banned from the layout) and whether this will just look wrong. If it doesn’t work the overhead wire might then be something I try on another layout in future, rather than trying to add it to a project that is already pretty complicated because of the transporter wagons themselves. But I do think it provides a neat solution here, not only to the issues of powering the SG wagons without conflicting with the NG loco, but also in terms of operating the three way point.

[009 micro modeller]

As a more tangential aspect to this, is using an electromagnet for uncoupling likely to create any more issues with something like this than it would on a comparable 2 rail layout? I’m pretty sure it should be fine but was just wondering if anyone had any thoughts.

[Nearholmer]

It’ll be fine.

[009 micro modeller]

1 minute ago, Nearholmer said:

It’ll be fine.

I thought so. I did think though that most tramway layouts that use a similar electrical system probably don’t have to have uncoupling, so if there were any issues that appear in practice they wouldn’t necessarily have been picked up.

[uax6]

How about having the overhead line as a model of one of the early 3 phase AC ones? That way you have two contact wires and two pans on the roof. Something like this : https://www.rhune.com/fr/  (this is a wonderful rack railway, the locos are over a century old and make a wonderful grinding and whirring noise, well worth a visit!). Then you have the complete path for that section of railway independent from all the rails.

 

3 phase is more common that you think, it wasn't used much here, but around the world it was.

 

AndyG

Edited September 29, 2022 by uax6
correct web address.

[Nearholmer]

Not a bad idea as a way of creating better contact.

 

In reality it was a devilish system in pre-power electronic days for anything other than steep-grade railways, but that needn’t worry anyone in 4mm/ft scale!

[009 micro modeller]

22 hours ago, uax6 said:

Then you have the complete path for that section of railway independent from all the rails.

There were also industrial systems that used two wires with two collectors (like a trolley bus). I’m just wondering if there is any particular advantage, in this case, to keeping it completely independent of the rails. Otherwise it seems as though it could actually be more complicated to wire than a single overhead wire with return through both rails (more similar to normal 2 rail?).

[Nearholmer]

Direct current with both poles well-separated from earth was used where it was difficult to guarantee the quality of the return circuit via the rails (dirt, corrosion etc) and/or where there were worries about damage or interference being caused by return currents straying through earth. In the early years, Siemens and Halske adopted a system with both poles well-insulated, using tubular conductors, current collection being via a trolley (literally a little trolley) running on the tubes, after their attempt at running rail return on an exhibition line in Paris went awry due to dirt getting on the rails. A common late survivor of well-insulated systems was to supply travelling cranes, where nobody wanted return current straying into and corroding structural steelwork.

 

I must confess that when UAX suggested mock 3-phase, I envisaged commoning both overhead wires, and commoning all the running rails, to create something like a dodgem-car track, rather than trying to create a trolley-bus type system, which sounds like a nightmare in 4mm/ft.

 

You could make it really, really complicated for yourself by using real 3-phase, which one German toy train maker, Distler, actually did (it was a clever, but short-lived idea!).

[Engineer]

Just an example of a 2mm scale/7mm gauge model tramway with live overhead and common rail return, with sectioning for automatic stops.  Overhead poles from springy wire and a tiny, grooved brass shoe.  Very simple, worked well.

 

http://www.2mm.org.uk/layouts/the_broadway/index.html

[009 micro modeller]

1 hour ago, Nearholmer said:

Direct current with both poles well-separated from earth was used where it was difficult to guarantee the quality of the return circuit via the rails (dirt, corrosion etc) and/or where there were worries about damage or interference being caused by return currents straying through earth.

That’s what I’d assumed, as I think everywhere I’ve heard of that used this sort of system was an industrial railway in a quarry or similar, not really the place for nicely bonded, clean and neat track.

 

1 hour ago, Nearholmer said:

I must confess that when UAX suggested mock 3-phase, I envisaged commoning both overhead wires, and commoning all the running rails, to create something like a dodgem-car track, rather than trying to create a trolley-bus type system, which sounds like a nightmare in 4mm/ft.

Yes, I imagine it’s the same reason for using both rails as the return (if available) rather than just one. A genuine 2 wire system would have to be wired the same way as normal 2 rail I think, with wires crossing and switchable sections etc. I think though for the appearance I want a single wire (representing DC overhead) with return through both rails is likely to work best.

 

1 hour ago, Engineer said:

Just an example of a 2mm scale/7mm gauge model tramway with live overhead and common rail return, with sectioning for automatic stops.  Overhead poles from springy wire and a tiny, grooved brass shoe.  Very simple, worked well.

 

http://www.2mm.org.uk/layouts/the_broadway/index.html

I think I’ve seen that at an exhibition. Good to confirm though that it runs well, and of course in 009 I should be able to make everything a bit bigger.

[009 micro modeller]

Kearsley is the sort of system I had in mind in terms of the electrification (although mine will be narrow gauge and more of a common carrier). Tramway style fairly lightweight electrification but with diamond pantographs or bow collectors (though I think Kearsley was able to be used by trolley pole stock as well, so possibly the overhead wiring is a bit more complex). I’m trying to find a really good clear photo of what the wire looks like where two tracks diverge from each other, though it doesn’t have to be from Kearsley.

 

Although not in the UK, this also looks interesting: https://m.youtube.com/watch?v=2OrAzWHd-hI

 

Modern main line electrification seems to have a second wire a little bit above the actual contact wire but neither of these railways seem to have this. Am I right in thinking it’s something that’s only really needed on higher speed overhead wire systems?

 

[Nearholmer]

Yes, the catenary wire is there to give support to the contact wire in such a way that it’s position is very tightly controlled, allowing high-speed operation of trains. Simple OLE typically shows noticeable sag between supports, and creates a sort of wave if the collector moves along it quickly.
 

If you look at some early examples of OLE for relatively high-speed use, the LB&SCR system for instance, you will see that the support arrangements were fearsomely complex before nice simple systems were devised.

 

What you are observing are the differences between what are loosely known as ‘tramway’ OLE, low-voltage and low speed, and ‘railway’ OLE, typically higher voltages and speeds, although there is a lot of crossover between applications.

 

Systems that can accept trolley poles heads usually have ‘frogs’ at the junctions or crossings of wires, which are easy to spot in photos. https://www.bathtram.org/tfb/tEars.htm

 

 

Edited October 1, 2022 by Nearholmer

[009 micro modeller]

37 minutes ago, Nearholmer said:

What you are observing are the differences between what are loosely known as ‘tramway’ OLE, low-voltage and low speed, and ‘railway’ OLE, typically higher voltages and speeds, although there is a lot of crossover between applications.

I assume a tramway style would be fine for a narrow gauge light railway, with the low maximum speeds that implies?

[Nearholmer]

Very much so, but I bet there were LR’s here or elsewhere that used catenary systems; as I say, lots of crossover of practice, so the terms are loose shorthand.

 

BTW, are you aware that quite a few UK ‘electric tramways’ were technically Light Railways, some of them 3ft 6in gauge? This occurred because once the 1896 LR Act was in place, it was simpler and cheaper to use that’s a the enabling legislation, rather than the earlier tramways acts.

[009 micro modeller]

48 minutes ago, Nearholmer said:

BTW, are you aware that quite a few UK ‘electric tramways’ were technically Light Railways, some of them 3ft 6in gauge?

Yes. York, several in the Midlands and some in East Anglia were 3’ 6”, among others (if I remember correctly). My ‘backstory’ to make my electrified layout slightly more plausible is that it’s the terminus of a 2’ 6” (so slightly narrower) gauge roadside tramway, originally steam (see Alford and Sutton/Wolverton/Glyn Valley) that also has a slightly more urban (or possibly coastal, à la Volks, Colwyn Bay etc.) section at the other end, but now the section modelled is on its last legs and only handling freight traffic (with the transporter wagons).

[009 micro modeller]

4 hours ago, Nearholmer said:

Yes, the catenary wire is there to give support to the contact wire in such a way that it’s position is very tightly controlled, allowing high-speed operation of trains. Simple OLE typically shows noticeable sag between supports, and creates a sort of wave if the collector moves along it quickly.
 

If you look at some early examples of OLE for relatively high-speed use, the LB&SCR system for instance, you will see that the support arrangements were fearsomely complex before nice simple systems were devised.

 

What you are observing are the differences between what are loosely known as ‘tramway’ OLE, low-voltage and low speed, and ‘railway’ OLE, typically higher voltages and speeds, although there is a lot of crossover between applications.

 

Systems that can accept trolley poles heads usually have ‘frogs’ at the junctions or crossings of wires, which are easy to spot in photos. https://www.bathtram.org/tfb/tEars.htm

 

 

Should it also always have the parallel wire at the mast side, well away from the contact wire? A lot of model systems (whether the overhead is live or just scenic) don’t seem to have this but would it look better to include it?