|View single post by Herb Kephart|
|Posted: Wed Nov 17th, 2010 10:09 pm||
|POLES- (the non-European ones)
The poles that were used to support the overhead ("line" poles) were usually metal in cities, wood in towns and rural areas. The metal poles were often stepped diameters, approximately 10" diameter at the base and 6" at the top, with usually three different diameters. These can be modeled with telescoping brass tube. The top of a metal pole had a cast iron plug, or finial, which could be very plain, serving to only keep the rain out of the hollow pole, or could be ornamental, with several diameters and perhaps a pointed top. In O scale I would make these poles from 3/16" and 5/32" tube slid (and soldered) over a 1/8" brass rod. Look in Gardenvilles links for Arendt's scrapbook 54A-" Tramspotting in Dusseldorf" for this type of pole-although the ones shown have far too pronounced steps for American practice.
Wooden line poles, by rights, should be slightly tapered- starting at about 12" diameter at the ground, and about 8" at the top. Often the real poles were also called on to support cross arms holding feeder or signal wires. In this case the poles would be significantly higher, with a corresponding increase in diameter at the ground end. The top end of a wood pole should be "roofed" to shed water- either cut on a 45* angle, or cut on two 45* angles, like the roof of a house. Even in O scale model poles made of wood usually aren't satisfactory, because they lack enough rigidity. I have used metal (usually steel, because of cost) but have never found a way of replicating the very slight taper with out spending far too much time on one pole. One variety of pole (see later) requires drilling cross holes and the taper significantly interferes with this, so my "wooden" poles are straight 7/32" diameter, a compromise between top and bottom diameters.
The poles should be "planted" back from the track a sufficient distance to give about 30" clearance with the widest car- to prevent someone becoming trapped between the car and the pole. Poles placed on a curve should be checked with the longest, widest car, remembering that the ones on the outside of the curve will come closest to the front and rear overhanging portion of the car, and those on the inside should have the clearance checked at the middle of the car, which will overhang the inside of the curve. Since poles are put up after the track is laid, this checking is not a problem. When drilling holes for the poles, they should be canted away from the track a degree or two, to counteract the pull and weight of the wire.
There are "bracket poles" and "span poles". The later are just two plain poles with a cross, or span, wire between them
I use the same .020” PB wire for spans, pull offs, and backbone -we'll get to the second and third later. To attach the span wire to a pole, make two complete wraps around the pole, and then 4-6 wraps around the span and cut off excess.
Here is a good place to mention the “warts” on the span wire. They represent insulators, used on the prototype. I use small glass beads that are available in craft stores (Michaels, in the US) I use brown, because the real insulators that we used at the museum were that color- although they were/are available in green and black, I'm told. Get the smallest beads that you can still get the wire through, and even then they will be oversize. My opinion is that oversize looks better than none at all.
The other type of poles-bracket- are next.
As previously mentioned the pole is 7/32” diameter, the heavy horizontal bar is 1/16” diameter, and the light horizontal and angular is one piece of .030” wire. There is a small wrap of shim stock, about 1/16” wide between the two horizontal pieces between where the ear is fastened and the pole, but closer to the ear. A long time ago I made a hardened drill jig to drill the 3 holes crosswise through the pole. All the pole pieces are soldered together. Bracket poles are nearly always planted on the outside of a curved track, for reasons that will be shown later. Bracket poles were not all that common in US cities, with the exception of when two parallel tracks were going down a "median" (usually grass covered) between the opposing lanes of a major street-boulevard-avenue. In this case, the pole was located centered between the two tracks, with one bracket arm mounted opposite another. Since the locations where this was called for were in somewhat higher class neighborhoods, frequently the poles and/or arms were decorated with fancy cast iron scroll work, etc.
Next fascinating (?) installment will cover ears---
Fix it again, Mr Gates--it still works!"