Jump to content
 

Is the Overhead live...?


298

Live Overhead  

76 members have voted

  1. 1. Is your Overhead.....

    • Live, and used exclusively for current collection
    • Live, but is wired to one of the running rails
    • Dead, but with pantographs or other collectors touching the wire
    • Dead, and with fixed height pans
    • No wires


Recommended Posts

What about the case of operating pantographs on models, be it out the box or homemade? If the loco didn't pick up from the rails, how would this mechanism be powered/controlled?

 

In pre-DCC times, taking power from the overhead allowed some independence of control. Today, it strikes me as adding unnecessary complication unless the modeller was using Märklin's 3 rail system, in which case the overhead and centre rail/studs are common.

 

Here's a superb French layout with OHLE, on which the overhead is NOT live: http://www.dailymotion.com/video/xgklw6_le-reseau-du-club-ferroviaire-de-franche-comte-aiguillages_travel. I can't say as I've noticed any at the last few continental shows I've been to (Faszination Modellbau Friedrichshafen, Hobby Modell Spiel Leipzig, Intermodellbau Dortmund) with overhead in the offscene areas. FREMO, for instance, specifies that overhead should be cosmetic.

Link to post
Share on other sites

Guest jim s-w

I know the advantage of a sliding contact over a rolling one but I can't believe that one sliding contact is more reliable than 4 rolling ones

 

Cheers

 

Jim

Link to post
Share on other sites

I know the advantage of a sliding contact over a rolling one but I can't believe that one sliding contact is more reliable than 4 rolling ones

 

Cheers

 

Jim

 

"High Gill" seemed to manage to run Lima 87's as Overhead only (Gordon H is a great believer in live pantographs), but we never seemed to be able to do it reliably in Deepcar, and that's with two 76's wired together, all four pan heads needed cleaning after a couple of circuits.

 

A while ago I asked the same question on a US HO Traction modelling forum, and the general concensus roughly produced a 50-50 split between Overhead only and 2-rail. The advantages of the former are being able to quickly build really complex junctions without worrying how they'll be wired, and I'm told the continual scraping contact keeps the wire clean, providing the layout is looked after and operated on a regular basis.

 

It seemed people were happy to stick to their preferred and traditional method, that's absolutely fine by me but something like the Bachmann 85 might be accused of challenging the "norm", as I believe every previous RTR model of a British AC electric was able to pick up using it's pantograph and also featured a changeover switch.

Link to post
Share on other sites

What I have seen, and been impressed by, is a DCC loco which could raise and lower its pantographs.

 

Ws

 

One DCC solution to appease the live overhead modellers could be a decoder with a third input (an electric blue wire) from the pantograph, and the decoder uses this with a return through one of the rails, but sensing a loss of supply, switches to the other rail to maintain momentum and hopefully draw a spark when contact is re-made. It sounds complicated and the current draw may still be a problem for scale wires (I've melted a soldered connection in the overhead during a short test on my layout), but might be useful for Tram modellers with trolley poles as it would allow the vehicle to roll to a stop should the pole dewire.

 

While we're at it we could also fit suitable control circuitry and a mechanism for raising and lowering the pantograph, which would of course need a 2-rail supply anyway.

Link to post
Share on other sites

Guest jim s-w

Thats interesting Andy.

 

The continual use thing might be a problem as my layout will only be run twice a year max. From what I remember of High Gill there was no reason for trains to stop and stand on the front. Was that true? (it might make a difference. if something is romping along at a scale 100mph to stopping and starting)

 

Cheers

 

Jim

Link to post
Share on other sites

  • RMweb Gold

What I have seen, and been impressed by, is a DCC loco which could raise and lower its pantographs.

 

Ws

 

RTR stuff or homebrew?

 

AFAIK I am the only one with it in UK locos.

 

Andi

Link to post
Share on other sites

From what I remember of High Gill there was no reason for trains to stop and stand on the front. Was that true? (it might make a difference. if something is romping along at a scale 100mph to stopping and starting)

 

Cheers

 

Jim

 

I think one of the lines had a loop, I'm not too sure having only seen it on a home video and when it was on the BBC Children's programme "Corners".

Link to post
Share on other sites

Jim, I am rather perplexed by your comments.

 

Firstly, BNS is divided up in to many different electrical sections - most probably each platform is a seperate section with one of these Arthur Flury Section Insulators,

 

4--Streckentrenner.jpg

 

or the earlier Brown Boveri type (Flying Duck in the Trade)

 

sib.173134612_std.jpg

 

at either end.

 

They are all fed from the same source however, so initially if something causes a trip the whole lot shuts down, but when the section with the fault is found, this is then isolated from the rest so that you would be able to re-energise everything else and get the trains moving again. There is a RTP working section insulator by Sommerfeldt which out of the box is not too dissimilar to the Brown Boveri type at a glance (although I know it is no where near up to your standards!):

 

somm153.jpg

 

And allows continuous electrical pick up across it as per prototype. As a rule, every set of points or crossovers usually has one of these between or near them in the wiring to provide for the electrical sectioning. On the main line, electrical sectioning is provided at overlaps, where there are two wires running in parallel for a span with a switch between them.

 

Neutral sections are a different kettle of fish entirely for when each section either side is fed from a different feeder station, and since these are often out of phase with each other, on no account must they ever be connected. In this case you have in order Section 1 - insulator - earthed section (the neutral bit) - insulator - Section 2. The reason for the earthed bit is so that in case of insulator failure, or a dodgy train drawing an arc, you still do not get the two sections connected together.

 

Also, unless your running Triang class 81's with one original pan, all model pantographs have at least two points of contact with the OLE, albeit quite close together. However with no frogs to cross, and continuous power when crossing insulators, this should be at least as good as, if not better than two wheels in contact.

 

I have built a test plank with OLE, and never had to clean the pan or OLE - it was always the wheel/rail interface that was the cause of poor running. However, I do believe that the most sensible option is to have dead OLE with pans running along it - the reasons outlined in this thread are valid. I am just doing it live because I can and I want to. It probably helps that my layout does not have fiddle yards mind!

Link to post
Share on other sites

Guest jim s-w

Hi

 

they are Brown Boveri type and I will be modelling them. The problem is to keep the tension either side and I plan to cheat and continue the contact wire through them (and the insulator) I dont see how you could assemble everything with some sort of non metal elements that are glued and keep it all reliable. Plus it means I cant just solder everything together in the gantry (Colins insulators are white metal anyway) the whole thing is just a monumental faff for no visual gain.

 

its this sort of thing that really emphasise the huge difference between third rail and overhead and why you cant really say its just as easy to do one as the other. Even with out the live aspect they are a world apart.

 

Also, unless your running Triang class 81's with one original pan, all model pantographs have at least two points of contact with the OLE, albeit quite close together. However with no frogs to cross, and continuous power when crossing insulators, this should be at least as good as, if not better than two wheels in contact.

 

not sure model pans are sophisticated enough for that to be true. the way the head is controlled means you are more likely to just have one point of contact and the other just below the wire. However on properly built track remember the wheel never leaves the rail - even when crossing the frog its always supported by the wing rails.

 

Cheers

 

Jim

Link to post
Share on other sites

  • RMweb Premium

Lancaster Green Ayre will be dead OHLE with Pantographs and bow collectors touching the wire. I agree with all J S-W's points p[articularly the problem of access in the fiddle yard and the storage space problem. I've ot to fit 27 boards into my garden shed and ahve carefully designed the layout with the OHLE on 12 of the boards and none on the other 15. The fiddle yard pairs are only 300mm thick when paired for storage and the ones with OHLE are some 450mm as each board with OHLE is paired with one without. Those can only have fixed scenery to a maximum of 50mm. However I want the collectors to toch the wire so that some movement of the wires is seen as they move along. Even though no OHLE has yet been built I have been asked the question many times already. Hopefully the test section ,which is a curved removable viaduct section about 1 metre long with 3 gantries on it, will be on display at Warley in the demonstrator section this year.

 

Jamie

Link to post
Share on other sites

  • RMweb Gold

Way back I played with live overhead in order to have seperate control of electric trains, now with DCC there is no benefit and therefore no point in having the equipment as anything but cosmetic. I did wonder whether it would be possible to use small size 1meg resistors as insulators between diferent sections of line but converted to DCC long before I got to experimenting. As Jim plans, my section insulators have a continuous wire through them for strength.

 

Andi

Link to post
Share on other sites

  • 2 weeks later...

I think one of the lines had a loop, I'm not too sure having only seen it on a home video and when it was on the BBC Children's programme "Corners".

 

Not sure how I missed this thread up to now, but anyway...

 

Yes, 'High Gill' was wired throughout, fiddle yard included.

The Outer track was a continuous run on the scenic section, but the Inner track had a passing loop with cripple siding. The basic arrangement was almost an exact mirror image of the track layout of Grayrigg, though that wasn't a particular aim, just a coincidence.

When running, pick up through the various pantograph types was very reliable, often much better than through the wheels on the diesels that ran. If anything, it was only the wheels (and rails) that ever needed cleaning.

A mixture of Sommerfeldt 968's and home made AEI Cross-Arms & Brecknell Willis High-Speeds were used on the various locos.

Freight trains would often be stopped in the passing loop.

 

It is the experience of running the layout this way for 10 years or more that maintains my faith in the viability of working live wires, no matter what others might think.

'Too much trouble', 'What's the point', 'No benefit with DCC' ? Not interested.

It is the principle of using the wires in the way they were intended, and the challenge of making it happen that scores for me every time.

"Dead Wires are for Wimps". ;)

Link to post
Share on other sites

I totally disagree for the reasons I stated earlier. Most continental layouts using overhead are wired throughout; if all the major European manufacturers produce locos with working pantographs why not use them? It seems logical to me. You like dummies I like working models; it's as simple as that.

 

Simon

Simon, I totally agree with you.

 

One DCC solution to appease the live overhead modellers could be a decoder with a third input (an electric blue wire) from the pantograph, and the decoder uses this with a return through one of the rails, but sensing a loss of supply, switches to the other rail to maintain momentum and hopefully draw a spark when contact is re-made. It sounds complicated and the current draw may still be a problem for scale wires (I've melted a soldered connection in the overhead during a short test on my layout), but might be useful for Tram modellers with trolley poles as it would allow the vehicle to roll to a stop should the pole dewire.

 

While we're at it we could also fit suitable control circuitry and a mechanism for raising and lowering the pantograph, which would of course need a 2-rail supply anyway.

Andy,

 

I've suggested this idea previously on other Forums and discussed it with you.

 

Surely, adding additional feeds to the catenary wire would solve the issue of excessive current melting soldered joints.

RTR stuff or homebrew?

 

AFAIK I am the only one with it in UK locos.

 

Andi

Andi,

 

ESU have a DB Class 151 in their "Engineering Edition" range of RTR models that has this feature as standard. I have an Olivia's Class 76 awaiting conversion to have raising and lowering of the pans via linear micro servos once ESU release their new extension board (51970) that allows two servos to be operated from a 21 Pin LokSound or LokPilot decoder. I think they use this same extension board in their 151.

 

I've seen a demonstration of your locos raising and lowering their pans some years ago at DEMU in Burton. Most impressive! Do you use memory wire?

 

 

In this thread reference has been made to using 3rd and 4th rails for current collection, and I've given that much careful consideration. It is much harder to achieve because the clearances between the collector shoes and the running rails when the loco or EMU passes over pointwork is very tight. I'm not sure that my engineering skills are good enough to manage that reliably. So I've ruled out using conductoir rail current collection for powering the locos and EMUs simply on the grounds of practicality. But I am still considering it for independent power to interior lights. That way the lights will go out when the collector shoes lose contact with the conductor rails, copying what happens on LT rolling stock where only the emergency lighting was battery powered.

Link to post
Share on other sites

  • RMweb Gold

Andi,

 

ESU have a DB Class 151 in their "Engineering Edition" range of RTR models that has this feature as standard. I have an Olivia's Class 76 awaiting conversion to have raising and lowering of the pans via linear micro servos once ESU release their new extension board (51970) that allows two servos to be operated from a 21 Pin LokSound or LokPilot decoder. I think they use this same extension board in their 151.

 

I've seen a demonstration of your locos raising and lowering their pans some years ago at DEMU in Burton. Most impressive! Do you use memory wire?

The locos that you would have seen, and that are shown on Youtube are memory wire. I wasn't aware of the micro linear servos! Very useful. Servo decoders are available in the Zimo range, the MX632W looks like the perfect option so I will be revisiting some of my ACs very shortly.

http://www.youtube.com/watch?v=wqV7Q16DiSs

 

In this thread reference has been made to using 3rd and 4th rails for current collection, and I've given that much careful consideration. It is much harder to achieve because the clearances between the collector shoes and the running rails when the loco or EMU passes over pointwork is very tight. I'm not sure that my engineering skills are good enough to manage that reliably. So I've ruled out using conductoir rail current collection for powering the locos and EMUs simply on the grounds of practicality. But I am still considering it for independent power to interior lights. That way the lights will go out when the collector shoes lose contact with the conductor rails, copying what happens on LT rolling stock where only the emergency lighting was battery powered.

The bigger problem with trying to make working third rail pick ups for traction would be gaps, our stock simply cannot have the momentum needed to carry it over gaps in the juice rail, especially given how much we tend to cram pointwork into much tighter spaces than the real thing.

 

Andi

Link to post
Share on other sites

A combination of mass scaling as the cube of length and the use of worms in models means that while a real train can sometimes continue for miles without any power, in the smaller scales at least a model will screech to a halt in a few scale yards.

 

To defeat the exhibition nitpickers, why not just wire the OLE up to an electric fence unit and if they ask whether it is live, invite them to touch it :O

Link to post
Share on other sites

Guest jim s-w

 

 

Not sure how I missed this thread up to now, but anyway...

 

Yes, 'High Gill' was wired throughout, fiddle yard included.

 

 

Was the overhead one section Gordon?

 

Cheers

 

Jim

Link to post
Share on other sites

Guest jim s-w

 

The bigger problem with trying to make working third rail pick ups for traction would be gaps, our stock simply cannot have the momentum needed to carry it over gaps in the juice rail, especially given how much we tend to cram pointwork into much tighter spaces than the real thing.

 

Andi

 

Not really Andi. You could either use dynadrive for a mechanical solution or stay alive decoders for an electrical option.

 

Cheers

 

Jim

Link to post
Share on other sites

RTR stuff or homebrew?

 

I don't know about UK or European models, but in the US, MTH offer a Pennsylvania GG-1 and a Milwaukee Bi-polar with working pans.

 

http://www.mthtrains.com/news/476

 

http://www.mthtrains.com/news/466

 

Even though I have no interest in modelling the MILW, I'm tempted to get a Bi-polar just to play with. All those wheels!

Link to post
Share on other sites

Surely the real reason to build working third rail or OHE is because you want to even if it does make life harder. I've noticed that the larger scale tram modellers almost always do use live overhead.

 

I'm still waiting for someone mad determined enough to build a fully wired three phase system. It was used on main lines in a few countries and remained in northern Italy till the mid 1970s. It's still used on a few rack lines including the Petit train de la Rhune in the French Basque country which is well worth visiting. Apparently on mountain railways the regenerative braking is particularly economical but section breaks are complicated because you can't allow an interruption in a single phase so the pans or collectors at both ends of the loco are up all the time.

Link to post
Share on other sites

Surely the real reason to build working third rail or OHE is because you want to even if it does make life harder..

Quite so. It is the engineering challenge to make this kind of thing work on the smaller scale that is sufficient in itself. Some might say similar things about working in P4.

Any idiot can lay a bit of track and have a train thrash round it. Only accomplished idiots can do the same thing at a scale 200mph or more whilst picking up the power from a near scale overhead wire! :biggrin_mini2:

Was the overhead one section Gordon?

Yes, the wires served as a common return.

In that respect there was no issue whatsoever with voltage drops and current capabilities because all wires including contact, catenary and returns are paralleled together and effectively share the current.

On High Gill (and Carstairs for that matter), there were two common returns, one for track (the inner rail) and the overhead wires.

The outer rail was broken for sectioning and associated track circuiting, which therefore functioned for both overhead and track power.

The hand controllers had an extra switch by which the driver selected either overhead or track return depending on the type of loco. A 1k resistor was included betwen the two returns to provide a limited current path for the track circuits to work with either power source.

There is no particular reason why it wouldn't have worked with DCC, had it been available at the time.

Orientation of locos is an issue which exists no matter what the control system.

Link to post
Share on other sites

Guest jim s-w

 

Any idiot can lay a bit of track and have a train thrash round it. Only accomplished idiots can do the same thing at a scale 200mph or more whilst picking up the power from a near scale overhead wire! :biggrin_mini2:

 

Indeed so but while every approach is valid some strive for realism over technically difficult. ;) Most wont care either way but while someone might look down on people for not energising the OLE just as many people will look on those who do as someone with more time than sense.

 

At the end of the day what you are really saying is, if everything is modelled properly with pans touching the wires and tensioned OLE theres more worth if one is energised over one that isnt. In reality that just means soldering a wire to a mast rather than a rail. Its can be that simple.

 

Cheers

 

Jim

Link to post
Share on other sites

At the end of the day what you are really saying is, if everything is modelled properly with pans touching the wires and tensioned OLE theres more worth if one is energised over one that isnt. In reality that just means soldering a wire to a mast rather than a rail. Its can be that simple.

Quite so. All it needs is one nominated mast per baseboard and one extra wire around the layout to connect them all together. 'Pin 2' on the baseboard connectors, I seem to recall... :smile_mini2:

 

I will never be able to escape from the view that having gone to all that trouble creating mechanically sound and visibly excellent OHLE, it seems a shame not to use it in the way it was intended. Of course, there is little to stop one trying it occasionally when the opportunity presents itself...

Link to post
Share on other sites

Guest jim s-w

it seems a shame not to use it in the way it was intended.

 

I actually agree and its not the electification thats the problem for me - its the size of the fiddleyard and the extra storage space it would take that means its just not worth it. I suppose I could always energise it anyway so that when people ask if its live the answer would be an honest yes!

 

Cheers

 

Jim

Link to post
Share on other sites

I actually agree and its not the electification thats the problem for me - its the size of the fiddleyard and the extra storage space it would take that means its just not worth it. I suppose I could always energise it anyway so that when people ask if its live the answer would be an honest yes!

 

Cheers

 

Jim

 

Quite agree Jim,

 

post-340-0-09270000-1343324246_thumb.jpg

 

It would be a nightmare to get stock on and off in an exhibition time period, and with another 20 feet to build for yours and my layout, it would at least double the amount of space the fiddle yard already takes up in terms of height. But we do like a challenge . . . (starts thinking . . :no: )

 

Cheers

Tim

Link to post
Share on other sites

Archived

This topic is now archived and is closed to further replies.


×
×
  • Create New...