Jeff has it all correct, except for the ground brushes. Many streetcars had ground brushes, but for some reason most of our heavy interurban cars, including the ones in the video, do not. The current flows to ground through the main bearings. This seems to work OK as long as they are all properly lubricated.

But there's a hitch: since oil is an insulator, if one of the bearings runs dry, it is now the lowest resistance path to ground, and the motor current will tend to flow through that one dry bearing, thus making a bad situation worse. That's why we are careful to check the main bearings every morning before operating.

No apologies needed; as it is, you brought up some points I missed, such as the current return brushes street railway cars commonly had (didn't know about those), and that the trolley shoes included copper and bronze as materials, along with carbon.

Thanks for the replies. I thought I was in the ballpark, but never have been around anything like that.

I worked on the overhead crane in the MKT railroad shop here in town about 10 years ago. It ran 230vdc on two overhead wires- pos. and neg. They had two big selenium rectifiers that powered the DC stuff in that building, and all the machinery except the cranes and one big punch/shear machine was long gone.

It was solid, round copper clamped in some neat hard to describe clamps. Bronze looking wheels. All ancient original stuff. The bores in the trolley wheels were loose and wobbly, but it still worked. I was working on the trolley wire because it snapped in half one day and they were dead in the water. Had to stand on top of the big, wide crane beams on a step ladder to reach the wire, pull it back together with rope and pulleys and silver solder the splice!

On any "K control" streetcar, you have line voltage (600v) in the controller. Streetcars were built with K control into the 1930s.

Views of some of what we have been speaking of.

Trolley wire; clamps grip the upper section, the trolley wheel or shoe runs on the lower section.

http://www.alibaba.com/product-gs/62244 ... power.html

An insulated hanger:

http://reference.insulators.info/public ... w/?id=8803

Like the rails below them, trolley wire needs "switches," or "frogs" to allow the shoe or wheel to follow one route or another. Most are "passive," in that they rely on the sideways pressure or tension of the pole being pulled aside by the car below it to pull the trolley shoe or wheel to the correct route, but in some cases a miniature powered mechanical switch is in the "frog" as well. Such applications are rather rare; the example shown below is much more typical:

http://www.docstoc.com/docs/147827097/O ... ire-device

This is from a museum line in Australia, which gives you an idea of the size of one of these trolley frogs. It's not that large in full size; that in turn amazes me when the model railroad types build trolley lines with working overhead, including frogs, in HO scale!

http://www.sydneytramwaymuseum.com.au/i ... 296887.JPG

The site where the frog shot came from--some great photos of what it's like to build a full-scale trolley line. And although the equipment is from Australia, some of it, particularly the work motors, look awfully familiar:

http://www.sydneytramwaymuseum.com.au/t ... ints.shtml

Another view of a wire hanger, also from Australia:

http://www.sydneytramwaymuseum.com.au/i ... 125529.jpg

This would be right at home on any museum road here:

http://www.sydneytramwaymuseum.com.au/i ... 296888.JPG

Electric trolley coaches didn't have the track to use as a return circuit, and had to use a second wire for current return. As you can imagine, it made for some complicated work at junctions. This was very rarely also used on some rail systems, among then the street railway line in Cincinnati.

http://rememberwhen.gazettelive.co.uk/2 ... rolle.html

Pantograph collection, which is used in heavy mainline electrification, doesn't use frogs, but simply crosses the wires at intersections or junctions, relying on the wide shoe of the pantograph to just slide from one wire to another.

I was looking at a photo from 1958 at 5th ave. Maywood station, and the platform edges appear to be on hinges and folded back. Were these edges hinged to allow freight trains to pass? If so, did that mean that a freight crew had to stop at each platform and manually fold up the edges each trip?

They didn't have to stop, actually. I've seen this done on an old movie, and you have to see it to believe it. The hinged flaps are in sections about six feet long. The freights typically ran with two steeple cabs, and the locomotives were narrow enough to fit between the flaps. So there would be a crewman riding the front steps on each locomotive. They would slow to 5 MPH or so, and the first man would flip up each flap as he went by. If he missed any, the second man would get them. Then a man on the caboose would flip them all back down. I should think a gauntlet track would be a better way to go, but for some reason they had these goofy flaps.

And trolley bus plays well with streetcars. The trick is you put the hot wire directly center on the streetcar track, and the return in the usual position. If the streetcar man puts his pole on the return wire, he doesn't go anywhere . Also you put trolley bus frogs where streetcars do not diverge, and vice versa.

Trolley bus switches are actively thrown, actuated one of several ways. One is a "buzz box" actuated by the turn signal switch on the bus, this goes to an induction coil on the return trolley pole. This is half of a transformer, the other half is hung on the return wire. If the latter induction coil picks up current, it knows the bus's turn signal is on, and snaps the switch over. This allows switches a block or more ahead of the turn proper, which avoids clumping a bunch of special work in a busy intersection where it is hard to service.

For instance, if you are eastbound on Folsom and pass Fourth. There is a trolley switch mid block. It splits you into two tracks, both of which turn left on Third. The right track joins the Third St. wire. The left track stays separate to Howard and turns left there, merging with the Howard wire mid block. The result is no special work over intersections.

The other way only works on trolleybus frogs right at the intersection. It is two contact switches, which will detect the passing of the trolley shoe. If the bus is going straight, the shoes are directly across from each other. If the bus is swinging around a turn to the right, the left shoe leads significantly. There is a switch on each wire, placed slightly staggered, to exploit this.

One thing trolley buses do not play well with, however, is pantographs. I suppose you could push the return wire a couple more feet toward streetside, however you are sunk if a trolley bus route must diverge left. Its return wire would have to cross the pan-friendly hot wire, and that is hard enough at 90 degree angles.

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If you need to share wire with trolley pole equipment, you certainly can and should have frogs. Many light rail installations have them so they can run historic cars.

There are two ways to go. One is frogs designed with some extra ears along the edges to push the pan down and away from the frog proper, which could snag it. We have several at WRM and they work fine. Ohio Brass, nee ImPulse NC , sells them.

The other is, a short length of trolley wire parallel and several inches outside the main wire, which starts above the main wire, ramps below it through the frog, and ramps back up. The pantograph picks up this wire and is pushed below the frog. This is the "easy way" lol.

Of course, pan operation absolutely requires wire tension. I had to invent a barn hanger to allow tension to be drawn in a carbarn without pulling the building over.