How do you hang trolley wire in wooden carbarns? If you bolt the wire hangers to the building, and you later try to tension the wire, you pull the building over :( What's more you get building stresses all the time as the wire changes length/tension with temperature.

Is there some kind of floating hanger that is commonly used?

I recall the trolley wire in barns being enclosed in an inverted wooden trough made of 2x12's with sides of 2x8's. The trolley ears were fastened to this trough, which was in turn fastened to the roof beams. I would assume any tensioning stress would be absorbed by the trough, but admit I never thought about that...

Not a problem unless you have a very weak building. The wire clamps are not designed to hold much tension and will slip as the wire moves. Most of the tension is taken at the wire deadend at the back of the building. In some cases, such as WRM barn #1, the wire is tensioned to poles behind the building to avoid stresses on the building. Also, if you use wire boards and H-3 barn hangers, you can get by without a tension deadend as each clamp will carry very little tension, as they are spaced closely enough. In our original building, there are around 15 clamps over a 150' length and no deadend is used.

It is also feasible to use a tension reducer at the front of the building to releive the load. Wire in the building is generally supported at much closer intervals than the 100' spans used on running tracks, so the tension can be lower.

If you are oging to use wire, the ears in a trough can be as close as every 10 feet and they will serve to support even two ought wire.

But why use wire? Many barns used a type of contact bar that fit into the regular ear clamps and was quite rigid, needing no tension. Of course where do you find that now? I cannot even give you a spec or name, but know we have some in the air at IRM.

Bob Kutella

Bob,

As I recall, the material was called "spacer bar" and was used in trackless trolley overhead in the curve segments, etc. It had kind of a figure eight cross section.

Bob:

In both tracks in the George Isaacs carbarn on our Museum's Como-Harriet line we simply screwed steel 1 1/2 inch angle iron (steel) onto the wooden trough mentioned by someone else in this thread. The steel angles have to be bonded to each other of course. But for such a short distance and low speed use this works just fine for us.

Out at our Excelsior line we have the copper bars for the overhead inside the barn. The bars are about an inch-and-a half high and look like a stretched figure eight. This stuff is probably overkill but the bars are rigid and also work fine. The contractor who built our Excelsior line used commercially available stock, probably from Phoenix Mining.

Thanks!

The issue in the original post is larger than supporting wire in the barn (Car House 1 at WRM). The urgent problem is the wire in the yard in front of the barn, which is extremely slack. That wire runs through the barn and is terminated on poles at the far end of the barn. It is also anchored to every roof truss in the barn.

Car House 1 is well beyond its useful lifespan, and we are afraid that pulling on the wires in the yard in order to tension them will damage the building.

Our problem is to design a "floating" hanger which will support the wire in the barn but not put any stress on the roof trusses when we tension the wire in the yard, and will also prevent stress when the wire changes length due to temperature changes.

The description given of the bar that was used sounds very much like Buss (sp?) bar that we used inside high voltage electrical panels. I remember seeing it on many job sites in three and four foot lengths and it may be available in longer lengths. Check with your local electrical supply house for availability.

Later!
Mr. Ed

Al:
Do you have enough vertical clearance in the barn to drop the wire six inches or so? If so, you could hang the wire from the trusses using regular ears and hangers, but suspend the hangers from the trusses using a woven wire bridle. That way the trolley wire , and the hangers, can move longitunally an inch or so without putting any significant forces into the trusses. You could get even fancier and run a bridle parallel to the wire through pulleys suspended from the trusses.

There were many drawbridges in Chicago on streets served by trolley, as I am sure there were in Milwaukee, and other cities. The tension in the wire over the streets approaching was maintained and the wire had a sort of stress relief 'bridge' or anchor poles at the start of the DRAW. As well there was a flip up (or down) device that allowed continuity of mechanical path for the passeage of trolley poles, and yet the raising of the bridge. As I recall its appearance was not that different from a section insulator, but of course that is rigid. If the situation is as tenuous as you suspect, certainly additional poles and stress relief hardware is in order as described by Jeff D.

Bob Kutella

That is what I was going to say. It is best to take the tension outside and before the building. That way the building is only supporting the wire and not providing a "back guy" for the tension.

Hi Bob -

Your statement about Chicago drawbridges and streetcar routes reminded me of an old story. When I was a kid, my folks had recently purchased a home out in suburban Dolton, Illinois (140th Place) and my grandmother decided to pay us a visit. In those days, that meant riding the CTA (or was it still CSL; I don't remember for sure). Anyway, getting to our house meant taking the Riverdale/Leyden line out to 138th Street and Indiana Avenue. Well, when the streetcar got to the Calumet River crossing on Indiana Avenue, the bridge gates came down. My grandmother was terrified! The streetcar was ON THE BRIDGE!! Well, you probably figured it out; this was one of those swing center span bridges and my grandmother, and the other passengers and crew, got a free spin, while a barge passed between the bridge and the shore. By the time my grandmother made the two block walk down Indiana Avenue to our place, she was laughing at herself and at her fear!

Of course, there must have been some kind of a device on this type bridge too so that the trolley wheel or shoe, could make the transition onto, and off of, the bridge.

Les

AND must be pantograph friendly. For instance upward pressure on the wire must not bend the hanger sideways, nor allow the wire to be pressed above any dangling hardware.

Egads, has this never been done?

Oh, and what's worse -- there are 72 hangers in barn 1, so it would help a lot if whatever we build was easy to make.

Bob M: yes, it can be done, but it is not simple or cheap. If the building is so weak that it can not take the minor stress of trolley wire tension which should be mostly carried by the poles behind the building, what will happen in the next earthquake? I really think the answer is to strengthen the building.

Another possibility might be the contact strips used by overhead cranes. Not sure how well they would accommodate trolley poles or pantographs, but if there were an abandoned factory in the area, this could be worth investigating. Since many of these installations are 3-phase rather than DC, there might be three strips instead of one or two. Odds of finding something like this aren't that great, but worth considering.
Bob Davis
former member of Vulture Iron and Metal crew