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| (486490) | |
Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by RonInBayside on Thu Sep 6 09:18:17 2007 Is there a significant difference in the pantograph pickup arrangement between the Trackless Trolley (electric bus) and streetcar or light rail?Obviously, you have two poles instead of one to create a full circuit, since the bus' rubber tires do not create a ground leg for the electricity. But I am asking specifically about the physical arrangement of the pickup mechanism. If you created a ROW for electric buses served by catenary, and wanted to add tracks later on to use light rail instead, would you have to completely restring the catenary and change the type of catenary used? |
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| (486493) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Fytton on Thu Sep 6 09:25:55 2007, in response to Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 09:18:17 2007. Not sure about the US, but trolley buses in the UK always had trolley poles, not pantographs. It's difficult to see how you could have two contacts with two overhead wires, insulated from each other, with a pantograph.i think there were places in the UK and in Europe where trams and trolley buses ran on the same streets, but I can't remember how the overhead wires were arranged. I think the trams had trolley poles too, and contacted only the live wire, leaving the neutral one for the trolley buses alone to use. |
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| (486494) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by RonInBayside on Thu Sep 6 09:31:42 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Fytton on Thu Sep 6 09:25:55 2007. Meaning that you could have a duel arrangement with basically the same voltage supplied. |
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| (486511) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by UWS Greg on Thu Sep 6 10:02:02 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Fytton on Thu Sep 6 09:25:55 2007. Philly had stretches of street shared by both trolleys and trackless trolleys. The 2 types of vehicles shared a common overhead wire with a 2nd wire for the trackless. |
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| (486522) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Orange Blossom Special on Thu Sep 6 10:16:30 2007, in response to Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 09:18:17 2007. I recall someone posting a photo, possibly from Ohio, of a streetcar with two poles.with a pantograph i had thought of just putting the streetcar wire lower probably. But then I just realized, it would have to be the exact same route, even depot. and no turn-off's. So I wonder if your tram can have a trolley pole and panto, and switch off possibly. |
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| (486533) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by WillD on Thu Sep 6 10:35:25 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Orange Blossom Special on Thu Sep 6 10:16:30 2007. Cinncinatti Street Railway used two poles rather than the wheel and track for power return. I believe the wire was much closer than is commonly done on trolleybus systems, but that the Cinncinatti trolleybuses used the same wire spacing as the trolleys.http://davesrailpix.com/csr/csr.htm with a pantograph i had thought of just putting the streetcar wire lower probably. But then I just realized, it would have to be the exact same route, even depot. and no turn-off's. So I wonder if your tram can have a trolley pole and panto, and switch off possibly. You probably could have a switch off, you'd just have to bring the trolleybus wires down to the same height as the streetcar wire. In order to keep the pantograph from shorting across the trolleybus wires they'd have to be isolated from the ground for a few feet on either side of the junction. This would mean the trolleybuses would be without power for a few dozen seconds, but with current trends toward batteries, diesel generators, supercapacitors or some other mode of energy storage or generation that wouldn't be a significant problem. Of course once you get the trolleybus wire down to the same level as the streetcar wire then you can do whatever you want with some form of a switch, frog, and skate combination, diverge the trolleybus, diverge the streetcar, or whatever. |
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| (486547) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by WillD on Thu Sep 6 11:08:10 2007, in response to Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 09:18:17 2007. There are non-rail vehicles which use pantographs for electric power collection, but the only one I can think of off the top of my head are trolley-assisted off road mining dump trucks.http://hutnyak.com/Trolley/trolleyphotos.html San Fran manages to run trolleybuses and pantograph-equipped LRVs side by side without too much incident. Because the pickup shoes on a trolleybus swivel the wire can be offset from the lane of travel by a considerable distance. Thus you could in theory have trolleybuses and pantograph-equipped LRVs operating on the same transit lane for example, but you'd need three wires for power distribution. I don't see why restringing the wire would be a big deal if you're installing LRV tracks. The street is already going to be ripped up for the installation, so you don't have to maintain trolleybus service on that particular segment and can work on the wire while it's grounded. Also the trolley wire support poles and such are already there, so that's not a big deal. All you'd end up paying for would be the new streetcar wire and the labor to install that and the relocate the trolleybus wire. It's likely impractical for a regular trolleybus to use a pantograph for pickup. The vehicle itself is perfectly able to maneuver out from under the wire, and a fixed LRV-like pantograph would rob it of that ability. Mounting the pan atop the pole as seen in ISR's concept here are also likely a poor idea for the near future as that'd require some sort of logic and control system to recognize the wire, recognize the pole position, and control the pole accordingly. Such a system would likely be fairly prone to failure. That being said I've always wished Seattle would have ordered their DE60LFs with provisions for dual mode operation using 750-1500vdc power picked up from the LRV wire in the downtown tunnel. The DE60LFs, diesel electric parallel hybrids, have permiated the once clean tunnel with the stench of diesel exhaust. By fitting a large pantograph as wide as the body just ahead of the battery enclosure, placing two small, retractable electric return wheels on independent traversers ahead of the center wheel, then modifying the hybrid electric transmission to deal with the higher voltage they could get a fairly simple, lightweight dual mode hybrid bus. Outside the tunnel it'd operate just like any other DE60LF, with the battery, diesel engine, and electric motor working in concert. Once in the tunnel the pantograph would go up, the return wheels would drop down and contact each running rail, and the battery and motor would take their power from the 1500vdc overhead power. In the event they need to pass a broken down vehicle or some other obstruction, the battery could provide some power, and the diesel would be there if absolutely neccesary. |
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| (486556) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Wado MP73 on Thu Sep 6 11:35:51 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Fytton on Thu Sep 6 09:25:55 2007. The same arrangement can be seen on Market St. in SF, where the F line PCCs share the positive wire with the buses. |
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| (486559) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Jackson Park B Train on Thu Sep 6 11:39:36 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 09:31:42 2007. current example Market St SF between Castro and Steuart i e all of the F Market streetcar line. makes for interesting wire patterns at intersecvtion with turnouts. |
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| (486571) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Red Line to Glenmont on Thu Sep 6 11:55:11 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Jackson Park B Train on Thu Sep 6 11:39:36 2007. San Francisco is like a surrealistic painting. where you see streetcar single wires, trolley-coach double wires, with switches for one line to pass another, then for left and right turns. It's a wonder that the thing works so well, which it does. |
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| (486589) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Jackson Park B Train on Thu Sep 6 12:08:59 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by WillD on Thu Sep 6 11:08:10 2007. San Fran manages to run trolleybuses and pantograph-equipped LRVs side by side without too much incident. NOT SO! The pan equipped LRV's are NOT run on the track segments with dual wire for TC's. Streetcars w/ poles are operated there |
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| (486591) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Jackson Park B Train on Thu Sep 6 12:11:59 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Red Line to Glenmont on Thu Sep 6 11:55:11 2007. yeah, a mayor now Senator was whining about the wire 'pollution' until a railfan and transit advocate pointed out that the electricity came from a city owned hydro plant and was thus way cheaper than buying fuel for the diesel buses. |
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| (486608) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by TransitChuckG on Thu Sep 6 12:30:12 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Wado MP73 on Thu Sep 6 11:35:51 2007. It's wild to stand om Market Street in S.F. on a trolley platform and a trackless comes by and switches to the curb lane from the trolley lane.The twin poles of the trackless go right over your head as they angle by. |
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| (486652) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Olog-hai on Thu Sep 6 13:23:36 2007, in response to Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 09:18:17 2007. Wrong forum. |
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| (486654) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Olog-hai on Thu Sep 6 13:24:57 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Jackson Park B Train on Thu Sep 6 12:08:59 2007. Correct.If we all beat the smugness out of him, then perhaps he'll learn humility at last. |
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| (486659) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Olog-hai on Thu Sep 6 13:27:17 2007, in response to Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 09:18:17 2007. Is there a significant difference in the pantograph pickup arrangement between the Trackless Trolley (electric bus) and streetcar or light rail?Yes. Trolleybuses don't use pantographs. |
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| (486660) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Robert King on Thu Sep 6 13:28:01 2007, in response to Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 09:18:17 2007. I grew up with both streetcars and trolley coaches, and used the latter every day as the system was abandoned so I can shed some light on why pantographs aren't used on trolley buses:A pantographs on trolley buses wouldn't work because as soon as the bus steered a bit off dead centre, the pantograph would short out both wires! Also bear in mind that a trolley coach would need two pantographs, one for each wire. I think the best place to see why pantographs wouldn't work with trolley coaches would be San Francisco because they have both, and the LRVs have pantoraphs. If you find a picture of a streetcar crossing a trolley coach line, you can see how a pantograph would short out the two trolley coach wires if placed on the bus. The reason why poles are used is because they're narrow - they won't slide around and short out both wires - and because they swing to follow the wire's position relative to wherever the driver steers the bus. Pantographs would just slide out from underneath the wires at best, or one would slide beneath both and short circuit the whole thing in the worst case. -Robert King |
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| (486697) | |
Addenda - Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Robert King on Thu Sep 6 14:10:06 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Robert King on Thu Sep 6 13:28:01 2007. I forgot to mention one important thing:Wire junctions where streetcars cross a trolley coach line have to be at a sharp angle so that the pantograph slides under one trolley coach wire and then the other, so that the pan doesn't short out the two trolley coach wires. This problem can also be avoided by putting section insulators on the positive trolley coach wire and the streetcar wire so the whole area where the pantograph meets all the other wires is just dead, at ground. That still requires a fairly sharp angle in the intersection to keep the dead section short, to reduce occurences of slow moving vehicles coasting through from stopping under the dead section and getting stranded. There are some other, minor things about streetcar and trolley coach junctions when the streetcars are using poles instead of pantographs: In areas where both are being used in parallel, the trolley coach's positive wire can be shared between the streetcars and the trolley coaches; the streetcars just use the tracks as usual for their ground and the tracks and trolley coach ground wire are connected together. However, this means that even though trolley coaches can be steered around, they still can't pass streetcars without knocking poles off the positive wire. This is why the TTC usually - with only one exception that I know of - kept the trolley coach overhead entirely separate from the streetcar wire. The pair of trolley coach wires would be located at the outside of the road, between the curb and the streetcar wire with the streetcar wires in the centre of the street above the tracks as usual. Section insulators were also used extensively where trolley coach lines met streetcar lines to prevent the ground wire from shorting out the positive trolley coach wire or the positive streetcar wires. The positive wires could be made common without section insulators since they were both 600 volts, but the insulators were usually there anyways to rationalize the flow of the 600 volt direct current around the streetcar and trolley bus systems. Technically, that kind of isolation isn't needed to prevent shorts but it does prevent strange current flows resulting from slight differences in the 600 volt potential in both systems and it allows for greater flexibility in controlling exactly what sections of wire are energized and where. All of this became a non issue in Toronto in 1993 when the TTC abandoned the trolley coaches and the wires came down. They replaced them with the 'environmentally responsible' natural gas buses that turned out to be a noisy, hugely expensive, low reliability, low performance replacement that lasted until sometime early last year. They kept buying natural gas buses well into the late 90s so the new ones didn't last long at all. The only CNG buses left are the ones that got diesel engines from retired diesel buses. Not exactly a ringing endoresement of the trolley coach replacements... -Robert King |
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| (486698) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by WillD on Thu Sep 6 14:12:28 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Jackson Park B Train on Thu Sep 6 12:08:59 2007. NOT SO! The pan equipped LRV's are NOT run on the track segments with dual wire for TC's. Streetcars w/ poles are operated thereThat's not what I said, or at least not what I meant. I believe I made it overwhelmingly clear that what I meant was that the pantograph equipped LRV would use one wire directly over the lane it is travelling in, while the trolleybus uses two wires offset to one side, perhaps as much as one lane. And yes, San Fransisco does do this where the J and 22 share Church St:  Note that there's nothing to keep a trolleybus from operating over the LRV's tracks other than reach of the poles, which should be more than sufficient. Thus a trolleybus could follow right behind a LRV using wires offset from the center of the lane of travel without incident. Perhaps a better illustration is below, where the trolleybus has no choice but to operate under the LRV wire with the trolleybus's two wires offset from the vehicle centerline. 
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| (486700) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by R42 4787 on Thu Sep 6 14:14:13 2007, in response to Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 09:18:17 2007. NJT modified the Newark City Subway from a trolley wire type to a standard pantograph. |
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| (486704) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Robert King on Thu Sep 6 14:25:22 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by WillD on Thu Sep 6 14:12:28 2007. Both pictures show what I was getting at in my two posts. In the top one, you can see how the width of the Breda car's pantograph would short out the two trolley coach wires to the left of it, if placed directly underneath.The bottom picture shows how the trolley coach wires were strung on the outside of the streetcar wires. In Toronto, this was done so the trolley coaches could drive by streetcars without knocking poles off the positive wire but here it has to be done because the streetcars have pantographs wich would short out the trolley coach wire, meaning there's no choice about whether to use a common positive wire or not. And you can clearly see how putting two pantographs on top of the trolley coach would cause them to slide out from underneath the wires as soon as it's steered to the left or right of the wires. One would pop up outside the pair of wires and the other would short the two wires out. That's why trolley coaches always, without exception, have poles. -Robert King |
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| (486713) | |
Re: Addenda - Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by WillD on Thu Sep 6 14:40:51 2007, in response to Addenda - Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Robert King on Thu Sep 6 14:10:06 2007. This is why the TTC usually - with only one exception that I know of - kept the trolley coach overhead entirely separate from the streetcar wire. The pair of trolley coach wires would be located at the outside of the road, between the curb and the streetcar wire with the streetcar wires in the centre of the street above the tracks as usual.Thank you, that's exactly what I was getting at in another post here. I suppose with the cost of copper these days that'd be slightly more expensive than just two. Just out of curiousity would it be possible to change the wire spacing to accomodate a pantograph? Since the trolleybus's poles can presumably move independently you probably could go to a 6 to 10 foot wire spacing between the positive wire over the tracks and the ground wire. That way the pantograph could contact the positive wire without shorting to the ground wire. The big problem I see with this arrangement is that it'd severely limit the bus's maneuverability. If the bus is normally able to go 12 feet on either side of the centerline of the wire run then if the wires are 8 feet apart there'd only be 4 feet on either side before it'd likely dewire. Are trolleybus operators averse to operating their buses with the poles askew? |
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| (486746) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by RonInBayside on Thu Sep 6 15:24:43 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Robert King on Thu Sep 6 14:25:22 2007. Before Iforget, I want to thank everyone who contributed to this thread. I appreciate it very much. |
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| (486760) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Olog-hai on Thu Sep 6 15:54:43 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by RonInBayside on Thu Sep 6 15:24:43 2007. 73h 6u77k155 15 1n 3ff3c7 |
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| (486800) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Rail Blue on Thu Sep 6 17:23:53 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Fytton on Thu Sep 6 09:25:55 2007. i think there were places in the UK and in Europe where trams and trolley buses ran on the same streets, but I can't remember how the overhead wires were arranged. I think the trams had trolley poles too, and contacted only the live wire, leaving the neutral one for the trolley buses alone to use.Yes. Loads of them. There were exceptions though -- for instance, after Birmingham's line 7 (Nechells) was trolleybustituted in 1922, the wires were doubled on the actual route, but to get to or from any depot required fitting a plough to the rear of the trolleybus to make a return contact with the tramway running rails. |
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| (486803) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by FYBklyn1959 on Thu Sep 6 17:32:06 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Red Line to Glenmont on Thu Sep 6 11:55:11 2007. Only problem with Market is that LRVs with pantographs can't use the overhead (I forget the technical reason why). Way back before the F-Market (and wharves), Muni had a summertime trolley festival on the Market St tracks (it started when the cable cars were down for 2 years for refurbishment, but it proved so popular, they kept it every summer). They had to use 2 Boeings (1220 and 1221, or was it 1221 and 1222?) to help out, but since the pantographs wouldn't work, they had to fit them with trolley poles. |
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| (486821) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Wado MP73 on Thu Sep 6 18:22:42 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by FYBklyn1959 on Thu Sep 6 17:32:06 2007. Only problem with Market is that LRVs with pantographs can't use the overhead (I forget the technical reason why).The pantos will touch the negative wire too, creating a nice short circuit. They had to use 2 Boeings (1220 and 1221, or was it 1221 and 1222?) to help out, but since the pantographs wouldn't work, they had to fit them with trolley poles. 1220-1221(now 1212-1213) originally had poles so they could run during testing on surface tracks. They put them back on for the festival. |
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| (486852) | |
Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Dan Lawrence on Thu Sep 6 19:42:33 2007, in response to Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by R42 4787 on Thu Sep 6 14:14:13 2007. Actually, NJT replaced all the overhead structure. The PCC cars got a pantograph mounted over the front roof and the trolley pole was hooked down and tied so it could not be used. |
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| (486940) | |
Re: Addenda - Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by Robert King on Thu Sep 6 22:43:29 2007, in response to Re: Addenda - Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by WillD on Thu Sep 6 14:40:51 2007. The poles on a trolley bus are different than the ones used on streetcars in several ways.Trolley bus poles are insulated, and have a thick copper wire inside each pole instead of the pole itself forming the conductor the way streetcar poles do. If you look closely, you can see wire pop out from the bottom part of the trolley coach pole and make a little arc up to the brass shoe that holds the carbon insert. Also, the shoes on trolley coach poles swivel in two planes so that it'll follow the wire straight, regardless of the angle of the pole with respect to the wire. This lets the bus steer around without twisting the shoe against the wire, causing it to pop off. Streetcar shoes don't swivel around. The twisting against the wire's actually used to an advantage on streetcars. At turnouts, the frogs are positioned in the wire after the streetcar's started to turn away from the straight through direction. That causes the shoe to twist agains the wire, and when the twisting shoe passes through the frog, it pushes the pole through the frog in the correct direction so that it followes the right wire - the one above the track the streetcar's just turned on to - if everything works right. Since trolley coach poles don't work that way, passive streetcar style frogs can't be used, and the trolley coach overhead has to have powered switches that actually throw to the selected direction at trolley coach turnouts, to guide the poles through the turnout to the correct pair of wires. Trolley coach poles are also much longer than streetcar poles, to provide enough reach so that they'll be able to get up high enough to make contact with the wires even when the bus is steered a good distance away from the wires. Streetcar poles aren't long enough to reach the wire all the way across from the next lane over while making a turn at the same time. What all this means is that you could spread the wires out to eight feet apart, four times normal. In fact, I've seen video of this happening in Hamilton by accident at a large bus station with two parallel sets of wires for adjacent lanes. The positive pole followed one lane's positive wire and the ground pole followed the other lane's ground wire so the bus kept running fine even though the poles were bent out wildly. It only came apart when the two lanes merged back into one at the end of the bus station, and the poles got knocked off the wires when one got knocked off by the overhead switch, which was going to be mis-set for one of the poles no matter what since it could only be set for one lane at a time - not both. The one free pole started swinging and knocked the other one off it's wire. However, from the video, it severely impacted the manoeverability of the trolley coach to the point where it had to be driven very slowly, the poles were near the limits of their movability and the ability of the springs to pull them up against the wires with enough tension to stay on. There's also the issue of having clearance up in the air to string two pairs of wire with eight feet of space between each pair when you take into account other utility wiring up there, tree branches etc. etc.. When you get into tradeoffs like this, with the operating difficulty and reduced flexibility, you're better off stringing a separate set of trolley coach wires beside the streetcar wire, far enough away so that the streetcar pantographs won't be able to reach over and contact the trolley coach wires. -Robert King |
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| (486958) | |
Re: Addenda - Re: Pantograph for Trackless Trolley vs. Light Rail or MU |
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Posted by RonInBayside on Thu Sep 6 23:17:02 2007, in response to Addenda - Re: Pantograph for Trackless Trolley vs. Light Rail or MU, posted by Robert King on Thu Sep 6 14:10:06 2007. Thank you! |
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