Catenary/pantograph question

[BR60103]

I heard that the idea of using the rear pantograph was that if it snagged and tore loose, it would not carry off the other pan. Makes less sense when there are 7 (or 14) other pans behind it.
The pantographs usually have carbon shoes on the main contact section. Streetcars (lately, anyway) have a cabon insert in the trolley shoe. This was intended to wear more quickly than the contact wire.

[MichaelSol]

QUOTE: Originally posted by erikthered

All the information here is great- thanks everyone! Electric locomotives seem to have "shoes" (for lack of a better word) on top of their pantographs while trolley cars have, well, trolleys- flanged wheels at the top of the pole.

A couple of questions- First, would not the pantograph "shoes" cause some kind of wear on overhead wiring, particularly with a train at high speed? I know that some interurbans were capable of fairly high speed, and they seemed to have poles with trolleys. Did the railroads experiment with a roller type arrangement on the pantograph? Wouldn't that reduce wear on the wiring? Seems to me that a shoe in contact with wire moving at 80 plus MPH would cause a lot of friction and heat....

The Butte, Anaconda & Pacific first tried rollers on the pantographs. By the time the Milwaukee Road's higher voltage operation was finished, GE had changed the pantograph design to copper shoes mounted on the pantograph bar. The copper shoes were replaced periodically. There was some contact wire wear. A graphite grease was soon added to the copper shoes, and this ultimately was worked into the contact wire surface, created a mirror smooth finish. The overall wear after that point was neglible. When the wires came down in 1974 on the RM, they were the same wires that had been installed in 1915. Their estimated life span at that point was judged to be indeterminate because of the lack of wear since the introduction of the graphite grease.

The overall catenary/pantorgraph design was estimated to handle maximum speeds of 150 mph without overheating or adverse effects from harmonic resonance.

Best regards, Michael Sol

[Anonymous]

In the very early days there was some experiments using roller contacts on top of pantographs. It was fairly quickly found that there was less wear on the steel wire when copper and later carbon wear pads were used instead. Not even considering what would happen to the wire structure when one of the bearings on the roller would eventually fail.

[CSSHEGEWISCH]

The bearings on roller contacts also had the bad habit of throwing out their lubricant all over the place, leading to the problem mentioned above.

One further word on South Shore, while the MU cars raised the rear pantograph, freight motors (R2's and Joes) raised the front pantograph, the reason for the difference in operation is unknown.

[Anonymous]

Thank you all for your information!

Erik

[daveklepper]

Note that for many years streetcars did use trolley wheels, but around WWII, when hard graphit became available, shoes started replacing wheels, and even some of the heritage operations that try to be authentic uses shoes, including most trolley museums,

[CSX FAN]

Would any of you know where I could find blueprints of the PRR catenary system? I'm modeling the PRR cat and was having problems in my Yards and with cross over air gaps. I think I resolved the cross over issues out on the line yesterday, but haven't addressed the yards yet.

Thanks

Jamie

[daveklepper]

Yes. Call up the website for the Light Railway Transit Association (actually headquarted in London, England): www.lrta.org

Then go to links, then to clubs and historical groups

Then find the website of the Electric Railroaders Association

They should be able to help you. Or you can search with Google

One of the historical societies for the Pennsylvania Railroad would have the details on the catenary. also, I would think.

The book "Route of the Electroliners" of the Central Electric Railfans Association, also with a website, and accessable through the LRTA's, does have a scale drawing of the cantenary towers of the Skokie Valley line of the CNS&M (North Shore).

One of the ERA railfans should have access to the material you want.

Gibbs and Hill were the engineers. Their offices were in one of the two World Trade Center Towers. They are not currently in business, even via a successor firm. So I doubt we can put our hands on the original drawings. There should be plenty of copies though.

Another source might be Amtrak's Northeast Corridor operation, and their offices are at the 30th Street Station in Philadelphia, but you might have to go through the the Washington DC offices at Union Station first. They definitely have copies of the drawings.

[CSX FAN]

Dave

THanks for the tip. I found one old artical that detailed the cross over pieces an extention of New Haven. It was written in 1912 Sorry I forgot the railroad. It detailed how a deverging line would be OK for the pantogragh but the second line would tend to droop and then would fall under the pan and snag it. Causing great damage to the pan and the Catenary. By building the box both pieces of cat are raised as the pan goes by keeping them even, thus the pan would not get snagged. The distance is from 5' to 2' in the artical. the area below 2' would automaticaly raise it self. The converging direction doesn't mater.

Jamie

[daveklepper]

You are on the ball. The New Haven electrication preceded the PRR's AC electrification and set the standards for it, the Reading's suburban electrication, and the second GN electrification -and Hoosack Tunnel on the B&M.

[tormadel]

My comment is just that Electrafied routes always seemed to me like a good idea. Disels are more exciting [8D] but electric units do have good points. I know one of the big arguements against it is that it's very expensive to install. But, there are some parts of the country that used to have them and don't anymore. I know is some cases disels overcame the tunnel issues but it still seems like keeping the electrics would have been a good idea. Why was this not so?

[Kevin C. Smith]

Part of it was that the electric (tunnel/mountain) divisions weren't always very long (MR being the BIG exception). When most steam runs would be about 150 miles between engine changes, a 50 or 75 mile electric division (just using hypothetical numbers here) wasn't that different. Once diesels came in and could handle a run for 500-600 miles, it wouldn't make sense to trade power for a relatively small part of that run. It would just add one or two locomotive changes (with attendant terminals, yards & shops, possibly).

[tormadel]

Ah ok, so the operations just were not extensive enough to make them worth while. The exceptions being the PRR northeast corridor and the Milw pacific operation. Milw would have been even better had the plan to connect the 2 parts of the electric operation would have come about. As I read the Milw went bankrupt in 1925 and that pretty much ended that.

[MichaelSol]

QUOTE: Originally posted by tormadel
Milw would have been even better had the plan to connect the 2 parts of the electric operation would have come about. As I read the Milw went bankrupt in 1925 and that pretty much ended that.

The consulting engineers working for the Trustees, Coverdale & Colpitts, gave the electrification of the "gap" the highest priority, and it was in fact included in the capital improvement budgets for 1926 and 1927.

In September, 1971, Washington Water Power, Puget Power & Light and Montana Power Company proposed a plan whereby they would have, in effect, paid for electrifying the gap and provided new motive power.

In 1972 General Electric proposed electrifying the gap, and showed that doing so, with augmented power supplies and new motive power, provided an instant cash flow advantage over dieselization with SD-40-2s, an advantage that increased with the passage of time. GE did a cash flow analysis out to 2003, showing an accumulated net benefit to the Milwaukee of $402.7 million over the time period, assuming diesel costs increased at a 5% annual rate. That was before the explosion in diesel fuel costs that began in March, 1973. The study was prepared by the Locomotive Products Department, Transportation Systems Business Division, General Electric Co., dated March 20, 1972.

There had been comments on an earlier thread about costs of catenary. My recollection on DC catenary of the Milwaukee type was considerably different than some other opinions which went as high as $1 million per mile. I note that the GE study shows an estimate of $36,021 per mile for stringing catenary across the "gap" which was just about exactly my recollection based on our independent cost estimates. Another $2.9 million would have provided fully automated silicon rectifier substations across the "gap."

Although GE had its own locomotive --oops, "motor" -- proposal, EMD proposed to support the project with a modified SD-40-2 locomotive. Recognizing that the diesel version SD-40-2 was underpowered for its traction motor configuration, EMD offered a heavyweight, dual-use DC electric version of the SD-40-2 to the Milwaukee Road, rated at something like 6000 hp under the wire, continuous, with 25% adhesion. I suppose that would have been a real sight for railfans, #261 with Milwaukee pantographs on four SD-40-2s.

EMD also pitched a design based on ASEA proposals for Milwaukee, and ASEA discussed it independently with Milwaukee, for a 3,000 vDC "locomotive that would be very similar to modern Thyristor units in that each traction motor would be individually controlled and thus provide the advantages of the so-called modern AC "Chopper" locomotives" at 6,000 hp, 25% adhesion. [Letter, Upton to Kellow, 10/6/72].

It was a close call. The Electrification almost made it ....

[tormadel]

Yeah I'm with you Micheal. It just seems that in the 1970's Milwaukee management was just hell bent on giving up. I've read a few different articles over the years saying the pacific extension (after the BN trackage rights) was the best hope for Milw.

It seems almost like someone with lung cancer decides to amputate a leg as a cure, just didn't make any sense.

That the PCE is gone yet the rinky dinky backassward line to Louisville survives (at least last I heard) just astounds me.