Catenary

PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
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612
Tamworth, Staffs.
Not a problem..

Made my brain hurt, trying to explain it? ;)o_O:giggle::giggle:
 
ebay mike

ebay mike

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Norfolk
This has got a bit too technical for me - and it's only one of the questions. Here is what I had in mind. Forget the colour coding of the wires - it has no meaning other than to differentiate one wire from another and show where it comes from and goes to. Track 4 has no planned overhead due to the complexities of the loco storage and servicing facilities. I have installed a SPDT switch as I thought it might be necessary to prevent any compromise between the two central stations. Yes, there are three separate 50110 5amp units.
131804_b245639d0be1d7bb57f30c84c15bb284.jpg
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
23,864
612
Tamworth, Staffs.
So, going back to your first post:

Here goes:
  1. Who runs stuff with the pantos up and actually in contact with the wires?
  2. Who relies on power via the overhead? I saw recently it can be problematic with DCC.
  3. Are there any associated problems with wear on either of the 'bits'?
  4. What about (in particular PIKO) stock that have current collectors made of plastic? Do you replace them with metal ones or adopt a method similar to Nodrog who uses fishing twine to limit vertical movement which would prevent actual contact?
  5. Who uses trolley poles (with wheels) on the LGB brass wires and are they troublesome?
  6. Some of my locos are DCC (Kroks, Taurus, LCEs etc.) but I have a number of analogue LCE sets and trams. Is it feasible to have analogue running at the same time as DCC using one rail as the feed and the overhead as return if the chipped engines are track powered only?
No doubt there are other things I need answers to, but this will do for now.
1. It would appear some have/do do this.

2. Think we have covered this (in great detail! ;) ) overhead analogue - YES, DCC- NO.

3. There will be some wear (obviously) but it should be reasonable.

4. No one has answered this specific point?? I would 'tether' the pants to avoid wear. - I would guess the rate of attrition would be pretty high??

5. Again, not addressed, but there have been threads on tramways and homemade wheels..

6. DCC on track only, and analogue via catenary, should be fine. - So your diagram should work.

Think that sums it up so far? :think:
 
L

LGeoB

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12 Dec 2017
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6
Perth, Western Australia
I don't have the skills to draw diagrams on the computer in a reasonable time-frame, so this will have to be a thought-exercise..


These days, you tend to feed the output of a transformer (or a DC supply) into a 'controller' and the output of the 'controller'' is fed to the track.
'Controller' could be a DCC central station, or an analogue throttle, supplying a variable DC to the track.
Notionally, it would be possible to have a single transformer (could be a switched mode supply) feeding the inputs of both a DCC CS and an analogue controller. - This is the common source I am referring to. If there is a link here, it is possible (not definite) there could be a common path through the two controlling devices. As you say, this could cause some damage somewhere.

Now to the output voltages to the track/catenary:

The DCC signal/voltage is 24v peak-to-peak NOT +24v to -24v. This is a balanced signal, and you measure 'leg-to-leg' and not leg to ground.
The DC voltage will be (maximum) 24v. but again, unless 'we' make one leg 'grounded' it is just a potential between two wires. - It only by convention, we tend to call the negative/black wire 'ground'.
The black wire of the DC controller will only be at 0v. if we define the red wire as +24v. with respect to it. If you use the red wire as your reference, then the black wire is at -24v. with respect to that.
It is only when we either connect a wire to 'ground' / 'earth' / 'frame' or define that as a common-point it becomes 'ground'.

In our track and catenary scenario, we are using ONE rail for one leg of the DC only. - The other leg of the supply is the catenary.
The rail will float to some arbitary potential, but this doe not matter to the DCC system which is only looking between the two rails. The signal/DCC waveform will sit on top of this potential, but the decoder is looking at the difference between the two tracks with respect to each other, this will still be the 24v. DCC signal.

Having read that bacj, I have not explained it to well, but does it help?
When I check the DCC output on my 'scope, it shows an essentially square wave of +18v to -18v on my Lenz system with the PSU I use.

Geoff
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
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St.Neots Cambridgeshire UK
So, going back to your first post:



1. It would appear some have/do do this.

2. Think we have covered this (in great detail! ;) ) overhead analogue - YES, DCC- NO.

3. There will be some wear (obviously) but it should be reasonable.

4. No one has answered this specific point?? I would 'tether' the pants to avoid wear. - I would guess the rate of attrition would be pretty high??

5. Again, not addressed, but there have been threads on tramways and homemade wheels..

6. DCC on track only, and analogue via catenary, should be fine. - So your diagram should work.

Think that sums it up so far? :think:
In answer to No. 4
Re wear on the Pans, the Ruschbahn had them touching the overhead where there was overhead at all times. No specific wear was observed over some 5-6 years of running days. These happened 2 times a Month (April - Sept) and were pretty well all day affairs. The Overhead Yard Pilot would be trundling up and down Shunting pretty well continuously. And other Locomotives would get a fair bit of exposure to the Overhead Wire. However if we had a serious dewirement the attrition to the Pans could be such that a replacement would be necessary.
 
Madman

Madman

Registered
25 Oct 2009
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233
Pennsylvania, USA
Two quick vids from my experimental temporary, "O" gauge, layout.



 
dennishodge

dennishodge

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21 Feb 2018
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Bellevue, WA, USA
When I check the DCC output on my 'scope, it shows an essentially square wave of +18v to -18v on my Lenz system with the PSU I use.

Geoff
Indeed. (I miss my old Tektronix scope!) I think the commentary about safety and potential voltage is to say that at any one point in time, if all you have are the two wires, you can only experience a maximum differential of 18 volts.
 
Melbournesparks

Melbournesparks

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30 Sep 2015
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City of Eltham
Couldn't find a specific section relating to 'overhead' matters and as I've got more than one question I thought I'd put them all in one place. Over the years I've accumulated quite a number of locos, trains and trams with pantographs, bow collectors or trolley poles. To date I've relied on the 'imagine it's there' principle in respect of the overhead wires. Not long ago there was a rather animated discussion in the coffee lounge about the lack of realism when running locos with pans down (or up with no corresponding infrastructure). This got me thinking as I have accumulated a significant stock of related items - enough to do a complete installation on my layout.
Here goes:
  1. Who runs stuff with the pantos up and actually in contact with the wires?
  2. Who relies on power via the overhead? I saw recently it can be problematic with DCC.
  3. Are there any associated problems with wear on either of the 'bits'?
  4. What about (in particular PIKO) stock that have current collectors made of plastic? Do you replace them with metal ones or adopt a method similar to Nodrog who uses fishing twine to limit vertical movement which would prevent actual contact?
  5. Who uses trolley poles (with wheels) on the LGB brass wires and are they troublesome?
  6. Some of my locos are DCC (Kroks, Taurus, LCEs etc.) but I have a number of analogue LCE sets and trams. Is it feasible to have analogue running at the same time as DCC using one rail as the feed and the overhead as return if the chipped engines are track powered only?
No doubt there are other things I need answers to, but this will do for now.

Just as a matter of interest I have several masts with bases. I recently bought some solar powered lights from Poundland which came with two part brackets I did not need for the installation I required. With a small amount of packing/adaptation they look as if they will fill the role at a pound a pop rather than the £5 plus for LGB ones. No promises or guarantees about suitability, but I'm off to the shops to stock up on a few before they all go. For the uninformed the genuine LGB item is the light grey one.
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Late to the thread, but I can answer some of these. I have about 120m of electrified outside track, with overhead for pantographs and trolley poles. The overhead is powered by a constant voltage of 32v DC (less at the far end of the line!) which provides power to on board radio receivers and electronic motor controllers on each tram or motor car.

The contact wire itself is 0.7-1mm copper wire, from old multi core mains wiring. Some LGB locos retain their original pantographs, but I found the brass conductors do notably wear after a while. I've replaced at least one pantograph with a scratchbuilt version that is slightly more robust, and has hard steel conductors. The idea is the wear is spread along the entire length of the trolley wire, but concentrated on the pantograph, so you want the wire to wear with preference to the pantograph. Trolley poles have either steel fixed heads, or brass wheels.

Trolley poles are a bit of a black art on their own, but they certainly can be made to work once you know the requirements. Generally speaking they're very tolerant of loose untensioned wire that is poorly centered over the track, but easily dewired by sharp kinks and badly aligned overhead frogs. If you want a system for both trolley pole and pantograph operation you'd build it for trolley poles, but make sure the wire stays within the track center required by pantographs. I found fixed trolley pole heads are a bit more forgiving of rough and dirty overhead than wheels, but wheels are fun and they let you back up without having to swing the pole around. I don't use the LGB wire so I'm not sure how easily that could be made compatible with trolley poles, but at face value it looks like it might be easier just to scratchbuild?

I found from running outside that the pantograph to wire electrical contact is very reliable, not affected even by several week's buildup of tarnish on the copper. Fixed trolley pole heads can sometimes be vulnerable to collecting crud off the wire because of their small contact area, so you have to wipe them every now and then if it's the first run for a few weeks.

Many people express doubts that an overhead system would be durable enough for outside operation, but it's really far less of a problem than most people assume it to be. There's no shortage of wildlife here ranging in size from possums to feral deer, and breakages are pretty rare. I have a few places where the contact wire is joined in such a way it just comes apart if it's pulled on with any force, so damage to one section is localized. Even so, in several years of operation there's only been a handful of times that damage has occurred, and it's generally quick to repair. Of course it depends on your local environment and geography a bit.

Anyway here's some pictures:

131984_fcd00aafa1847cedd6a396f5feaa5204.jpg


This scene shows some farily typical construction for a tightish curve. The wooden poles are spaced a bit further out from the track center here to allow a bit more room for adjustment. On straight track the overhead wire poles are typically 1.2-1.5m apart.

131986_a4bfbd26687b39b3f4709a80e00f8491.jpg


The birney tram has a small brass trolley wheel. The width of the groove in the trolley wheels has to be consistent across the entire fleet to make the overhead frogs for junctions work reliably.

131988_9192b0efcf2b53209e2380fd8afde3de.jpg


Here we can see a typical overhead frog, made from a bit of copper. Adjusting the frogs so the trolley pole goes the right way at junctions can be tricky, they have to be positioned fairly accurately to work well.

131990_59c97c6560db44b035d8ad63fa92d3d7.jpg



Where the line crosses a pathway above grade, there's a swinging gate. Here we can see how the section of wire attached to the gate (right) meets the fixed wire. At places where the line crosses a pathway at grade, the section of wire above the pathway is made from code 100 nickel silver rail which fits into rail joiners either side so it is easily removable. It also just falls out if someone trips on it, though for new construction I tried to avoid at grade crossings.


131992_5c38822421d9a21ef58e1fe8d6dc9d85.jpg


The little English Electric loco has a large brass trolley wheel. Here we can also see a typical overhead wire pole, made from a moderately straight stick hammered into the ground. For new construction I painted the ends of the sticks that go in the ground so they last a bit longer.

This system developed largely in isolation, so I certainly wouldn't claim any of the above follows best (or even good!) practice, but hopefully it's some good inspiration. Which solutions are best for you depends a lot on your resources, available materials, environment, time etc.
 
dunnyrail

dunnyrail

DOGS, Garden Railways, Steam Trains, Jive Dancing,
25 Oct 2009
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St.Neots Cambridgeshire UK
Good to see more of your super line Mel. Much miss your talk in the Central as you have done some amazing stuff with Trams.
 
JimmyB

JimmyB

Phase 1 complete, roll on Phase 2
23 Feb 2018
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Nice write up and pics, however you mention keeping the wire in the centre, on the prototype the wire never remains in the centre but move from one side to the other, this provides even wear on the panto-graph, where and centre line catenary would quickly cause wear in the panto-graph.
 
ebay mike

ebay mike

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Nice write up and pics, however you mention keeping the wire in the centre, on the prototype the wire never remains in the centre but move from one side to the other, this provides even wear on the panto-graph, where and centre line catenary would quickly cause wear in the panto-graph.
Jim, I think Mel's wording is 'within the track centre needed for pantograph use' in order to provide for both panto/bow and trolley pole. The former have a very limited area above the rails in which they will function correctly, whereas the latter can swing quite dramatically outside the bounds of the roadbed.
 
Perry

Perry

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24 Nov 2017
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Heights of High Wycombe
In olden days (33 years ago), I constructed a catenary system on an OO gauge layout for running two locos simultaneously on the same length of track. The T/C Triang double ended electric loco would double head the T/C diesels on my erstwhile "anything goes/went" indoor layout. That was 6 house moves ago. Technology has moved ahead.
 
Melbournesparks

Melbournesparks

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30 Sep 2015
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City of Eltham
Good to see more of your super line Mel. Much miss your talk in the Central as you have done some amazing stuff with Trams.
Thanks, sorry I have been so lazy in updating the thread and rehosting old images, I really need to get onto that.


Nice write up and pics, however you mention keeping the wire in the centre, on the prototype the wire never remains in the centre but move from one side to the other, this provides even wear on the panto-graph, where and centre line catenary would quickly cause wear in the panto-graph.
Jim, I think Mel's wording is 'within the track centre needed for pantograph use' in order to provide for both panto/bow and trolley pole. The former have a very limited area above the rails in which they will function correctly, whereas the latter can swing quite dramatically outside the bounds of the roadbed.
That's pretty much it Mike, for a pantograph the wire has to stay within the width of the conductor (just between the rails is usually a good rule for 45mm gauge) but a trolley pole is fairly tolerant of a wide range of lateral movement. This can be seen to full effect on trolley buses, which can pull over to the side of the road when the wires are centered above the traffic lane.

I recently learned that LGB actually published a set of standards for overhead. Height above rail between 208mm and 232mm, lateral deviation from track center max 25mm. In reality I think that minimum wire height was specified just to clear LGB's tallest rollingstock, on my line a minimum wire height of 190mm works fine.
 
Ralphmp

Ralphmp

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Herts
Found this a really interesting thread. Catenary is something I've wanted to install for a while but have been put off by 4 things -
  1. logistics of accessing the track to put locos and rolling stock on (I think I've figured out how to deal with this)
  2. physical access to all parts of my layout for maintenance (I am currently able to step over the track with relative ease but the increase in height by adding catenary will present me with a mobility challenge)
  3. cost of using LGB components (I thought the prices shown on various retailer websites for masts were for a box of 12, not for one mast!), and
  4. how to build my own system
My biggest issue with building my own is I can't figure out how to suspend the wire such that the suspension "gubbins" don't foul the pantographs.. I like the way the LGB system uses a double wire with the suspension clips attaching to the top wire, leaving the lower one as a continuous smooth wire. However, I can't work out how to replicate this and whilst the pictures in this thread are very interesting, I can't work out how the various builders managed to achieve the same results with a single "wire" as LGB do with their double wire. If anyone could post close-ups of this or describe how they did it I would be very grateful!
 
Melbournesparks

Melbournesparks

Registered
30 Sep 2015
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City of Eltham
Found this a really interesting thread. Catenary is something I've wanted to install for a while but have been put off by 4 things -
  1. logistics of accessing the track to put locos and rolling stock on (I think I've figured out how to deal with this)
  2. physical access to all parts of my layout for maintenance (I am currently able to step over the track with relative ease but the increase in height by adding catenary will present me with a mobility challenge)
  3. cost of using LGB components (I thought the prices shown on various retailer websites for masts were for a box of 12, not for one mast!), and
  4. how to build my own system
My biggest issue with building my own is I can't figure out how to suspend the wire such that the suspension "gubbins" don't foul the pantographs.. I like the way the LGB system uses a double wire with the suspension clips attaching to the top wire, leaving the lower one as a continuous smooth wire. However, I can't work out how to replicate this and whilst the pictures in this thread are very interesting, I can't work out how the various builders managed to achieve the same results with a single "wire" as LGB do with their double wire. If anyone could post close-ups of this or describe how they did it I would be very grateful!
The first one isn't really a problem unless your rollingstock is so heavy it's awkward to lift any other way than straight up. With a wire height of 230mm there's plenty of room to reach underneath.

I can see how access could certainly be tricky for some people, it comes down a lot to how your railway is designed. Mine was an electrified line from day one, so I always had a pretty clear demarcation between areas for walking and areas that are railway/garden. There are a few places where a path crosses the rails on the level, but they're designated locations with removable sections of overhead. Having said that it sort of became habit to just leave it up all the time and step over.

Depending on the traction system you use, a potential option could be a permanent gap in the overhead. This is actually done on some full size electrified railways, on the Queensland coal networks there are places where there is a level crossing for large mining equipment that is too high to fit under the wires, so there is a gap that the trains have to coast across. The pantographs on the locos stay up, they obviously use a special design with a mechanical stop that prevents them raising too high where there are no wires. With appropriately sized traction capacitors you could potentially do this in G scale too. I did consider it, but I use trolley poles as well as pantographs and it would be tricky to design a system for reliably putting the pole back on the wire! Also my current traction capacitors probably aren't quite big enough to reliably cross a half meter gap without power.

The LGB system is definitely a high budget option. To avoid cost I used copper wire salvaged from old mains wiring, and moderately straight sticks or tomato stakes for overhead wire poles. This fits in well with my light tramway prototype, but if you're going for a more heavy rail system a bit more involved modelling would be needed.

Here's some close up pictures of the type of fittings I use to suspend the contact wire. There are probably many ways to do this and this is by no means the best, but I found it meets my requirements of being cheap, quick to assemble, robust and reliable.

132787_fecb4d84c0032a6e301a4a5df616a5a3.jpg


Here's a broken overhead fitting we're going to repair. The brass wire hanger has come off the copper contact wire. This one is pretty typical, a short bit of brass or copper wire has about 5-10mm bent 90 degrees at the end, which is soldered directly to the top of the contact wire.


132788_2181c1d254ede15fbdee15a936469a0f.jpg


First we clip it back in place with a broken crocodile clip.


132791_35b63b47ed157b94035b14db44f6ab65.jpg


Then solder with a small butane torch. Very convenient for working outside, you don't need to wait for it to warm up like a soldering iron, and less risk of burning yourself or setting something on fire!


132792_83831a095b137314bbe55deaac4bf301.jpg


All fixed. This one is nice and clean, but if the solder drips a bit you need to file the bottom of the contact wire smooth. This type of fitting works for trolley poles and pantographs. Despite how it looks the solder join is plenty strong enough for this purpose.

Here are some other types of fittings used in different places:

132794_9b87567375e876324f6c616268dc7ea0.jpg


This one attaches the contact wire to a span wire, made from a little bit of code 100 rail with a hole drilled in it. It resembles a prototype tramway fitting a bit more closely.


132797_fd4cd0c92b0d338364d1356320fa7fca.jpg


Another one made from code 100 rail for attaching to a span wire. Here the span wire is fed directly through a hole drilled in the rail.

132798_0a6dc3f5e77a5cd1acdd593c05518a20.jpg


Random typical overhead wire pole on straight track. This type is the simplest and quickest to make.

132800_eac89b0bba905a76dc6382b40e6d47ad.jpg


Join between the copper contact wire, and code 100 nickel silver rail used as contact wire in tunnels. Where the contact wire is looped through the hole in the joiner it isn't soldered, it will come apart here if something pulls on it.

132802_3cd1f52bda7000cc3caa4d35fbb1cfca.jpg


Another join, using a washer. Clearly I should have used a brass washer so it doesn't go rusty!

132804_b69d1183f5cd568911f64b7469661826.jpg


Even this works, crude though it looks.

Anyway hopefully this is helpful, it's always interesting to see the different ways people tackle these problems.
 
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Ralphmp

Ralphmp

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Herts
Wow. Thanks v much for the info and the pictures - really appreciate you taking the time to do this. Has given me the confidence to have a crack at making my own.

I have a friend who has access to 3 different 3D printers so we're hoping to create some masts using one/all of them, and armed with the info and pics above hopefully we can create a workable system quite swiftly.

Cheers!
 
PhilP

PhilP

G Scale, 7/8th's, Electronics
5 Jun 2013
23,864
612
Tamworth, Staffs.
I have a friend who has access to 3 different 3D printers so we're hoping to create some masts using one/all of them, and armed with the info and pics above hopefully we can create a workable system quite swiftly.
It will be interesting to see how you get on..

I would be concerned the horizontal components of the supports, may not be strong enough? - ?If 3D printed..

Good luck!
PhilP.