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Treatise on overhead construction
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 Posted: Tue Nov 23rd, 2010 08:42 pm
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Herb Kephart
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Huw-

The nice thing about the little brass tubes was that they were so cheap, and convenient. It wouldn't be impossible to cut tubing into short lengths, as you mentioned in your first post, just fiddly.

Two or three turns of wire would also serve the purpose just fine, although I think that I would go with bare copper wire- easier to wrap tight, and no need for the insulation , so a little larger gauge wire could be used.

Good thinking!

Herb  :old dude:
 



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 Posted: Thu Nov 25th, 2010 02:24 am
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johnnie58
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If any of you fella's out there are at all interested in doing street tram things,check out the  Melbourne Victoria tramway system:it's the largest in the world.They might have some idea of what you're after.

Check out some pics of Aussie trams in Photovault or many others as well.

             John the Aussie bloke:old dude:.

 



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 Posted: Thu Nov 25th, 2010 10:18 am
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W C Greene
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All I have to do to see real trolleys is ride the Dallas Area Rapid Transit (an overhead operation) down to town and catch the McKinney Avenue trolley. It's free and a nice 1 hour ride. Soon, the line will be extended quite a bit which will be close to what Dallas used to have before the advent of nasty busses.

                               Woodie

Last edited on Sun Nov 28th, 2010 01:11 pm by W C Greene



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 Posted: Wed Dec 1st, 2010 10:29 pm
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Herb Kephart
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First, a pix of the two aids that I mentioned last time-



The upright mounted on the truck has a line scribed on the top denoting the center of the track. Normally on straight track, the wire is hung over the center. The way that I do this is to temporally fasten the wire to something near the center of the track, and then grab the wire in the paper clip that is on the top of the steel block. Next, I tack solder the ear to the cross span or lower bracket arm wire, visually lining it up so that it is over the track center, using the upright on the truck. then, moving the truck out of the way, I lift the first end of the wire up, align it with ear, and solder both sides. If the initial tack doesn't come undone, go over it anyway to add more solder, maintaining the center of the track alignment.Clip off the extended "handle" on the ear as close to the running wire as closely as possible Proceed to next pole(s), moving the steel block as necessary. The second ear will be a little easier, because you have the wire correctly located.

A word about soldering. Just because you are soldering tiny wires, DO NOT try to use the smallest iron that you can find. Rather, use the largest iron that isn't clumsy. The reason is that the larger iron will transfer heat quicker, allowing you to solder the joint that you are working on, without unsoldering the other leg of the ear. If the solder does not flow instantly, something is wrong--probably the wire needs cleaning, or the iron isn't up to temperature. Cleanliness is vital! That includes the iron. Periodically, wipe the iron on something like a heavy rag, quickly. I use my finger, but I've had a little practice at soldering- my father showed me how about 68 years ago, it was part of his trade. As to materials, I use rosin dissolved in alcohol for flux, but since this is somewhat of a specialty item, a second choice would be rosin core solder, although with that it is sometimes hard to get enough flux on the part, without getting excess solder too.

On curves, the wire is hung closer to the inside rail of the track- notice how the shoe lines up with the wire in the pix below.



Obviously, since the wire, when hung, isn't a smooth curve--rather it is a series of short straight segments, perfection in this regard can't be obtained--just try to even the pole misalignment out. Between the supports, pulloffs to the backbone are used--see fig 7 in the previously posted drawing for how they differ. solder the ear to the running wire, then pull the wire that is right angles to the track in the direction of the backbone, and when it looks right bend it over the backbone just enough to hold it in place (don't solder yet). After some wire is hung past that point, go back and see how all the pulloffs look in regard to having the running wire in line with the pole shoe- some adjustment will probably be needed.

 


Crossings can be accomplished with a #2 brass washer- just be sure to locate it where the pole is perfectly in line with the car body, for each wire



Switches need wire frogs, which are best purchased, although in the bad old days, I made my own from .010" brass shim. I have seen all kind of methods for locating a frog relative to the track. I have tried nearly all of them. Don't waste your time. Here is a foolproof (well as foolproof as frog location can be) method.
Start by hanging the wire over the straight (or straighter) track. Off set the wire off center so that the car pole is about 10 degrees relative to the car body over the switch.



Now, push the car around the curve with the pole on the wire, until the car pole is offset by about the same angle



This pix is taken with the car a little past the point in the wire where the frog is, but the angle is what i was trying to show. Right at that spot on the straight wire is the spot where the frog wants to be. Easy, and it works. If it can be arranged, fastening the frog to a cross span helps to keep it in the right location, with changes in wire tension.

One thing that I see that I missed, is that I use #0 brass washers to connect pieces of overhead running wire. If you have a section that gives you trouble with the pole dewireing, annalise what is wrong, but don't spend trying to fix what is there. Most times it will be better to cut out the old and splice in a new piece

That's about it. I know that there must be questions, and things that I forgot. If you need further help--post!

Herb  :old dude:


Last edited on Thu Dec 2nd, 2010 07:37 pm by Herb Kephart



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 Posted: Thu Dec 2nd, 2010 11:49 am
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Huw Griffiths
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ebtm3 wrote: A word about soldering. Just because you are soldering tiny wires, DO NOT try to use the smallest iron that you can find. Rather, use the largest iron that isn't clumsy. The reason is that the larger iron will transfer heat quicker, allowing you to solder the joint that you are working on, without unsoldering the other leg of the ear. If the solder does not flow instantly, something is wrong--probably the wire needs cleaning, or the iron isn't up to temperature. Cleanliness is vital! That includes the iron. Periodically, wipe the iron on something like a heavy rag, quickly.As to materials, I use rosin dissolved in alcohol for flux, but since this is somewhat of a specialty item, a second choice would be rosin core solder, although with that it is sometimes hard to get enough flux on the part, without getting excess solder too.
If you have a section that gives you trouble with the pole dewireing, annalise what is wrong, but don't spend trying to fix what is there. Most times it will be better to cut out the old and splice in a new piece


Excellent points - actually, the whole series of articles have been great, but I think these points warrant particular attention - and not just for traction modellers.

In my last job, I installed and wired thousands of resistance strain gauges. (Anyone who actually wants to know what these things are like will find plenty of info on transducer suppliers' sites.) What matters here is that I needed to solder wires to tiny pads, which wanted to detach themselves from their backing.

This meant I needed to use a powerful iron (so I could melt the solder and make the joint, fast enough not to damage the gauge), with a bit large enough to transfer heat instantly (but small enough to get in). I often needed to temporarily hold the wire in place with masking tape, to stop the wire jumping out as I applied the iron - and this was very much a case of "in - out" and no hanging about.
 

Turning to the flux, some firms sell a lot of soldering related stuff - but most of them are mainly trade. I know some people use plumbing solders and fluxes (surprisingly enough, from plumbers' merchants) for assembling metal bodyshell kits. These are not what's needed here.

Overhead wiring has more in common with electronics soldering - albeit soldering up a large network of wires, which wants to draw heat away from the joints. This is why rosin based fluxes are appropriate here. You could use Carr's Orange Label Flux (sold in some UK model shops - excellent stuff, but not cheap). Another option would be rosin gel flux - I don't know about the USA but, in the UK, this stuff is sold by some of the electronic components suppliers that also supply trade, colleges and places like that. It might be worth checking out firms like RS / Electrocomponents, Farnell / CPC, or Rapid.
 

If I need to undo any electronic solder joints, I often use a short length of braid from coaxial wire (with the braid flattened and dipped in Orange Label, or a rosin gel flux) - with a hot soldering iron on it, this stuff quickly wicks away excess solder - it also wicks away heat, if you're not careful, so I remove the braid before I even think of removing the iron.
 

I'd also agree with the comments about trying to fix dodgy sections of overhead. OK, initial fiddling is sometimes needed to get things to work - but more than that would be bad news, as any "adjustments" carry with them the risk of pulling everything else out of alignment. There's also the risk of melting loads of other joints, every time you try to "re-work" any particularly troublesome one - partly because of the heat transfer - partly because the iron would probably be spending rather a long time on this one spot.

This heat transfer business is a good reason why clamping sections of wire in place can be a good idea - the clamps act as heatsinks and prevent damage to other joints. This also reinforces the need for a powerful iron - exactly how powerful I don't know (but I certainly wouldn't mess around with the tiny 12W one I use for soldering integrated circuits).
 

In short, this has been an excellent series of articles - full of excellent advice.
 

Many thanks,

Huw.

Last edited on Thu Dec 2nd, 2010 12:11 pm by Huw Griffiths

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 Posted: Thu Dec 2nd, 2010 02:14 pm
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Herb Kephart
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Huw- Thanks for the comments. I'm glad that you found the series interesting.

While on the subject of solder- two things that I, and possibly you, have noticed-

A soldered assembly will move, and it's parts will get out of line right after it is soldered if subjected to transmitted heat, but a few days later (provided there are no outside forces involved) it will retain its position, even if the solder melts.
Not sure why this happens, but have an idea that has something to do with the lead-tin (hereafter l-t) molecules "settling down". I know that large thin l-t castings left over from my days of kit production develop a sag over a period of 5 or so years, if not stored on edge, or flat, with continuous support. They say that the molecules in glass slowly move over time also.

It takes more heat to unsolder a joint than to solder it. Kestler, a solder manufacture, says that the l-t, when hot forms an alloy on the molecular level with the base metal, and this alloy has a higher melting point. This is especially evident when silver soldering, since higher temperatures are involved.

One of the things that I forgot to mention is the pole placement on the car body.
On a double truck car, the best position is about 3 scale feet towards the center of the car from the truck kingpin. This seems to give the best tracking, both prototype and model. Single truck cars require a compromise. Some prototype cars had a single pole mounted in the center of the car which was swung around when the car changed direction. Others had two poles, mounted as far apart as possible. Mixing the types is possible, wire wise, but will require some fiddling with the wire position. If all your cars are the same pole placement, it is much easier. Even the real cars have this problem. Having a "standard" pole length, is a big help also.

Herb  :old dude:



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 Posted: Thu Dec 2nd, 2010 07:39 pm
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Huw Griffiths
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ebtm3 wrote: If all your cars are the same pole placement, it is much easier. Even the real cars have this problem. Having a "standard" pole length, is a big help also.

From what I've read in various places, it seems that height also affects things (not surprising really - as it alters the angles and clearances).

This isn't so much of an issue in countries where all cars are single deck and around the same height as each other (often the case on the European mainland).

However, in the UK, the same city's system might include a wide range of tramcars - some single deck - others open top "Preston" style double deck - others full height double deck with full roofs - yet others "reduced height" double deck (designed to go under low railway bridges). As built, all of these would have had different roof heights, with the poles or (in a few cases) bow collectors or pantographs often being fitted in different ways - and describing different arcs.

All of this forced loads of compromises in the design of overhead - and tramcars (with trolley pole, or pantograph, towers sometimes needing to be fitted to single deck cars). The existence of low railway bridges wouldn't have helped matters - it sometimes led to some designs of tramcars being banned from some routes (either because of reduced clearances - or because wires might have been skewed under certain bridges to allow some pole equipped double deck cars to pass, whilst stopping pantograph or bow collector equipped single deck cars).


Anyway, I think that's enough from me for now.

Regards,

Huw.

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 Posted: Thu Dec 2nd, 2010 10:41 pm
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Herb Kephart
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Huw-
I understand that some of the UK systems had a swiveling shoe atop the pole. I also wondered in the past how they accommodated the various car heights Tonight, you turned the light bulb on. :!:

That's probably why the swiveling shoes!

Herb:old dude:



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 Posted: Wed Jan 25th, 2012 08:41 pm
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ebtnut
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Looking forward to your treatise on poles.  I've been drafted to help my club put in a city trolley line with working overhead.  I did some of this in the distant past using the Suydam brass pole and arm units, but I'm not sure whether any of that is still available.  I'm not sure I'm tough enough any more to use the old Dick Orr stuff, so may be content with the bigger hardware.  But keep it coming. 

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 Posted: Wed Jan 25th, 2012 10:38 pm
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Bill Fornshell
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Hi,

I have bought some of my poles and other traction things from this ebay seller:

http://www.ebay.com/sch/brianweisman/m.html?_nkw=&_armrs=1&_from=&_ipg=&_trksid=p3686

He also sells direct so if you are looking for something not listed, you can email him direct. If you want to do this send me a PM for his email address.

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