|View single post by Herb Kephart|
|Posted: Mon Nov 15th, 2010 11:47 pm||
|This will be presented in a series of short snippets. It certainly isn't the only way, and may not be the best way for some- but it is the way that I have refined with ideas of my own, and stolen from others (for which I will gladly take credit).
There is something that I should make clear, before starting. Many years ago, I did some trolley modeling in HO scale, but since then all my experience with trolleys has been 1/48 (US O scale) and full size- with too many years at a trolley museum. I have a very limited knowledge of systems in GB, and Europe, and I'm only slightly more familiar with modeling in those places. Also because I have been in the hobby for so long, I have not kept up with what is offered commercially. I have so much stuff squirreled away I don't remember half what I have. Being a scratch builder doesn't help either- because what little I buy is in the nature of materials.
So -- if that hasn't convinced you that I have no idea what I'm writing about---read on.
First, you should decide on the height your wire will be above the rail. Prototype practice was 14 to 22 foot- with city cars using the lower height, and the larger interurbans the higher. In cases (mainly in the Midwestern states) where interurbans came into town under the same wire used by the city cars, the wire was high to suit the larger cars, and in some instances the city cars, if they had low roofs, would have their poles mounted on 12"-18" high lattice work towers to get the angle of the pole where it intersects the wire the same for both cars. This angle can also be adjusted, to a limited extent by varying the length of the pole also. I have always gone with the lowest wire height consistent with being reasonable with the largest cars. If nothing else, the lower the wire- or rather the pole/wire angle, the easier it will be to back up with a pole, if the situation requires. There are two types of wire systems. Direct suspension is what nearly all trolley and interurban lines used-this is where a single copper conductor-between 3/8" and 7/16" in diameter (00 to 0000 Huw) was supported, and sagged to some extent, by poles beside the track approximately 100' apart. Another type called catenary was used, mostly by electrified railroads. In this system there is a suspension wire, which has a definite sag between supports, which are usually spaced farther apart. The contact wire is suspended from this by vertical wires of varing lengths (spaced abt. 10' apart) so that the contact wire is a constant height. This is much more involved to model, and since it is not typical trolley, will not be covered here.
The wire that I (and most other modelers) use is phosphor-bronze, .020" diameter.
It comes in coils, and is springy and resists efforts to straighten. Also, it will break if bent too severely (or bent and re-straightened) neither of which makes hanging the wire any easier. Here is what I have done for years. Although others continue to fight with the wire, (and lose) I remove some of the hardness, and end up with dead straight pieces to work with- so here is one of the secrets of my method. You need a source of low voltage with at least 10 amps. A large Lionel transformer will work (just), a big battery charger, or even a half dead car battery. Fasten one end of a piece of the wire to something solid- I have used a vise, and also a screw in the benchwork of the layout. Measure off and cut a length of wire- the length will depend on how big a power source you have, and experimentation will have to be done. Grab the free end with pliers. Now, with one wire from the power source connected to the fastened end, and a wire from the other terminal of the source in your free hand, pull 1-2 pounds force on the wire, and touch the second wire to the pliers. The wire should start to heat, possibly smoke a little from residual oil. Keep tension on the wire with the pliers. When the wire gets hot enough, you will feel the pliers start to move as the wire stretches. As soon as this happens, remove the electric connection from the pliers, but maintain the pulling force. The pliers will move a total of 4"-6" before the wire cools. When cool, the wire will be dead straight. and while not soft, will not be as hard and springy as it was when you started. If, with your power source you can't get the wire hot enough to lengthen, either shorten the length of wire that you are starting with, or get another larger supply of amps.
On the other hand, if everything happens too quickly -including the wire turning red and melting- go with longer wire, or less 'lectric. I use a 250 watt transformer, about 18 volts, and work with pieces 5-6 foot long wire.
Fix it again, Mr Gates--it still works!"