To the best of my knowledge, the North Shore line of Chicago was the highest speed traction line to use trolley poles. What are the challenges of using poles at high speed, and how reliable are they? The modern equivalent would be trolley buses, but I am not aware of any that operate at higher than 40 mph.

The Skokie Valley route was catenary, this kept the wire smooth. The freight service wire was always set next to the main at turnouts, this kept overhead frogs off the wire. Cincinnati and Lake Erie was high speed as well and well as the indiana Railroad but not always catenary, normal strung wire. All the traction lines were in a speed competition and there was a trophy given to the fastest one. Its all about how well you hang your wire it won't be a problem.

Trolleybusses use a swiveled shoe so it can swing out and the bus can steer far over to the curb. How high rated for speed may be the open question but the question is still the same, its how well you hang your wire you could go any speed.

The rumor on the North Shore catenary is that it might convert to pantagraph in the future especially since it and the South Shore were owned by Insull the concept would not be impossible and we've theorized if it was running today it would be pantagraph and new cars obviously but that did not happen.

In the US we have some museum operations that have a lot of electrified track maintained to a high standard. I've been at both WRM and IRM at the right time to ride 'test runs' in interurban cars run at full parallel. Impressive. Maybe one of these groups can chime in on the challenge of keeping the trolley poles on the wire.

One key element would be a very dependable and powerful retriever, to jerk that pole down instantly should it de-wire. Otherwise you'll be re-installing a lot of overhead.

The thought that trolley poles were not suitable for high speed operation dates back to the early days of the industry, when streetcars typically used wheels on the poles. Wheels running at high speed can cause considerable arcing, which is bad for wire life. Interurbans built in the first five years of the twentieth century tended to be built as third rail lines because of this.

But somewhere along the line it was realized that steel slider shoes, running on lubricated wire, were up to the service conditions, and were less hassle than third rail, so later most lines built, extended, or modified were built with wire.

Meanwhile, city lines migrated from wheels to carbon insert slider shoes to increase wire life. Wheels were relegated to switching service, some lines putting dual poles on locomotives; a wheel for switching, and steel sliders for use on the road.

Perhaps as a more direct answer to what I think the original question was asking:

The use of a long trolley pole with self-guiding pulley wheel at the end was a relatively cheap and simple answer to low-speed contact, tracking, and absolute minimization of mechanical wire wear. I don't think it was readily understood that arcing damage to the pulley and rotating bearing on the pole would be severe, or uncompensated/unrepaired over time, or that arc damage to the wire might become a cumulative problem of some magnitude. Of course there is the fundamental problem that a wheel almost approximates a point or short lateral-wire-circumference line contact, whereas a pan shoe can have longer contact (and the wire shifted relative to it to spread wear) and a good slider has area contact.

There are problems at high speed with a pole in a number of respects, the first being that anything that causes the tracking contact to cease will not be self-correcting (as is the case inherently with pantograph contact except for wild fouling problems). When this is combined with the need for prompt and strong pulldown (as noted in a previous post) it is difficult to combine the flexibility needed for good tracking and wheel contact with the relatively continuous firm contact needed for decent high current transfer.

Most wire systems usable for 'pole contact' are likewise not easily stabilized or lined and surfaced for high speed. It is theoretically possible to build a single-trolley-wire system with its pulloffs, hangers, etc. at high enough level to permit wheel contact on the trolley; it may even be possible to work a constant-tension catenary design that way. Normal single-conductor trolley wire arrangements are NOT particularly good for high-speed following without arcing induction.

Airflow around and trailing the pole structure, both from the car and from the pole itself, may couple with the pole's modes of oscillation or harmonics and in a variety of ways facilitate either 'bounce' or lateral dewiring. I have seen discussions of airfoil elements to stabilize pole pickups under these conditions; how successful they might have been, especially in the absence of active servo methods, I don't know.

There is also the referred carbody motion from suspension and aerodynamics acting on the pole base, then amplified through the pole structure and characteristics. From most of what I have seen of interurban-car motion, it would almost be necessary to develop a Steadicam-like stabilized platform for a pole base to eliminate this as a critical source of dewiring at high speed.

It may be useful to look up and study some of the 'modern' overhead-wire schemes that preserve the fundamental simplicity of the 'pole' approach, some of which extend the number of tracked wires to 3 in the absence of running return and where there is need for full and effective grounding.

This is going back a ways, because I've not been active at IRM for a long time, but in the ten years I was active, I don't recall ever seeing a de-wirement at speed. It just doesn't happen that much.

I think the North Shore found likewise, as I recall few wire stories from Howard and the other old heads.

The worst wire damage I recall seeing at IRM was when someone making the "long run-around" on the mainline past the depot forgot to change ends and got up to a good 30 or 35 MPH when the front pole, backpoling, snagged. That one put a kink in the wire that needed to be cut out, but did no other damage other than the pole.

Seeing the name of this thread, and the references in various replies about the Chicago, North Shore & Milwaukee got me to thinking about an old North Shore operation. That of course was the raising of trolley poles on to the overhead wire AT SPEED! There was a section of the railroad north of Howard Street, where the third rail and overhead wire sections overlapped. Heading northbound, the conductor and trainmen would raise the poles onto the overhead while the cars were in motion. This included not only the standard cars but also the Electroliners. I'm not sure if there was a specific speed limit for this operation. I don't know if anyone ever got any film or video of this operation from trackside. Wonder if IRM ever considered replicating this during one of their North Shore observances.

Les

Really interesting replies. Thank you!

Ditto what Dennis said. We've had some dewirements at speed (30-40mph) at IRM due to kinks in the wire but the poles tend to dewire at 20mph too. And the North Shore ran pretty fast without any real issues. That said, as a CA&E fan, I'd like to point out that obviously third rail is better.

Not to my knowledge. Lacking third rail as IRM does, being at speed and having your trolley poles lowered are not typically concurrent situations.

The Pacific Electric experienced problems with the air flow on the pole that would pull it down from the wire. This lead to the development of the pneumatic trolley base that held the pole to the wire with air presssure until there was a quick upward movement. When that occurred a valve was tripped that directed compressed air onto the other side of the piston to pull the pole down. Without this design it would have converted to pantograph or 3rd-rail.

The PE 1200-21 class cars built for service between LA and San Bernardino were motored and geared for 60mph operation. And could probably reach a higher speed in multiple motor-car trains. Other 1200 series cars were geared for a lower top-end speed. All of these cars were equipped with the pneumatic trolley bases.

There is the story that the officials, the engineers and mechanical department in 1904 or 05 wanted to see what Henry Huntington's private car "Alabama" would do wide open. It had motors totaling 800 hp, 36" wheels and a gear ration of 40:42. So late one night the line to Long Beach was cleared and the car was taken to the end of street running in Los Angeles and opened up. The alignment had but four broad curves on the way to Long Beach. It is said that the car got up to 90mph on the tangents and slowed to 45 for the curves. It made the 20 miles trip in 15 minutes.

Frank -

I wasn't advocating IRM install an electrified 3rd rail! What I was saying was that, since photos, videos or films of the North Shore raising trolley poles at speed may well not exist, a replication of the operation might be something that IRM could do during one of the special North Shore observances that occur at Union on occasion. Not a high speed replication of course but at a safe 10-15 m.p.h. with say a 3 car train with the pole on one car raised for recordings of the event. I think that the IRM overhead is pretty good and a careful Trainman could conceivably do it, I would think. Yeah I know....I'm just dreaming!

Les

Speaking of the North Shore, someone correct me if I'm wrong, but I seem to recall that was a 79 MPH railroad... and I remember Howard crabbing that the much vaunted Electroliners were not the fastest cars on the property. But that was because they had had their field shunts disabled, later removed.

More than a few years ago John D. Harachek (sp?) had an article in Trains about the origin and history of the 'Liners, including a report of the test run made when the trains were first delivered, and the field shunts operative. I don't recall the reported speed, but the trains ran so fast that they were overrunning the crossing protection... that is, the crossing flashers would come on when the train entered the circuit, and the train would be on the street crossing before the gates had come down. Since there was no money for the work it would take to lengthen the signal circuits, Cordell ordered the field shunts disabled after the tests. What I don't recall is any mention of tracking problems with the poles, even at speeds well in excess of 80 MPH.

I rode the electroliners as a kid, I swear they hit 90.

I have film here of an IRM dewirement ZAP FLASH.. slow speed backup woops hitting a frog.

What IRM could do as demonstration could be one of skill for the conductors, as they pass the station before they arrive they could take the poles down at speed coasting (throttle off coasting) , then as watchers watch at the station the train passes on the main as the conductors attempt putting the poles on. This was everyday on the North Shore on every train in/out of chicago, so its a great test/demo of skill, IRM should do it. Probably slow speed.

The Sacramento Northern (Oakland Antioch and Eastern) passenger cars were designed to run at 62 MPH at 1200 volts. They would run somewhat faster when the voltage was raised to 1500 volts, but voltage drop was always a problem and the cars rarely got the rated voltage. They started service with 6" wheels but had problems with the bearings. To correct this the OA&E changed to 12" wheels. This slowed the wheel down and corrected the bearing problem, but now the wheel was so heavy it would not track the wire at higher speeds. They then went to a TS and W iron shoe, same as North Shore I believe, and their problems went away. Since the freight locos used pantographs, there were no trolley frogs on the mainline. If a passenger train had to take a siding the pole was changed on the fly. The passenger cars did have pantographs but they were only used on the Key System between 40th and Shafter in Oakland to the Key Pier. This was mostly street running and should have been run at half speed or less.

The Western Railway Museum runs on about five miles of the former Sacramento Northern railroad in Solano County. Both the track and overhead are in good condition and higher speeds are possible. But the overhead is energized at 600 volts, not the original 1500 volts, so if the voltage change over switch is set in the 600 volt position to allow full speed operation, the current draw is too high for the iron shoes and they have to be changed frequently. As for the poles coming off the trolley wire, there are really only two causes, and they are both operator error. The trolley rope has to be free to move up and down or the shoe will not go up when the wire does. When the wire comes back down, most likely the shoe does not end up back on the wire. The operator has to be sure the rope is not wrapped around the retriever housing, which is a operating practice at WRM for the front pole that is not in use. The other problem is when the front pole does not get pulled down. A car will run the entire five miles with the front pole up, but when the car gets to the first trolley frog near the Museum it is all over. This problem has been mostly eliminated by allowing only the motorman to handle the pole. No other crew members are to touch it. This way there is no confusion as who was to pull the front pole down.

WRM runs trolley wheels, trolley shoes, and pantographs on the same overhead contact wire system. The pantograph shoes are kept well lubricated with graphite. This graphite transfers to the trolley wire. The wire is so slick due to the graphite that sometimes there is not enough friction to cause the trolley wheels to turn. This arrangement makes the iron shoes operate well.

As for putting the pole on the wire at speed, not an easy task. The wire appears to be constantly moving back and forth, the car is rocking, and the rocking of the car is causing the trolley pole to be swinging back and forth. You hold the pole as still as you can just below the wire and the the wire passes above the shoe, let the shoe up quickly, but is still kept under control in case it is a miss. You do all this while trying not to get a face full of hot debris.