WizlishI am frankly amazed that this thread has gotten to 67 posts and there is still contention about what kinds of cable system are being discussed.
“Never wrestle with pigs. You both get dirty and the pig likes it.” ― George Bernard Shaw
I don't think I'm the pig, but don't know for sure. Maybe I'm biased
Seriously a lot of good information about cable propulsion has been presented in this thread
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.
CSSHEGEWISCHA cable railway sounds similar to the system in place on Brazil's Sao Paulo-Santos line before it was converted to a cog-and-rack system.
Which one? There were two very different systems, one dating from the opening of the line in the 1860s, and another on the new line built around the turn of the century.
The newer system is probably the one of interest. Although it worked like a funicular ('up' trains balancing 'down' trains, and I believe gantleted track above and below a passing siding halfway down each plane), the 'locobreque' system clearly involved a grip, which was released so a train could proceed under its own power across each bankhead to the next 'endless-cable' run.
The principal difference, I think, between this and a traditional cable system is that the Brazilian system stopped and started its cable for each pair of trains, and did not keep it running continuously as the transit systems we were discussing did. So the presence or absence of a discrete grip is not exactly the discriminating factor -- the way the cable is used for traction is.
It is difficult to imagine where a modern system would go to the trouble of providing a loop of engine-driven cable and also an arrangement of mechanical grips (presumably automatic) that would engage and release from that cable. The same could be said for a system that would work like PRT, with individual motors in each car, for those areas of a system where individually-routed or -scheduled cars were wanted, but either assembling these cars into trains that grip a moving cable, or 'automatically' attach to a cable at inherently fixed short headway for longer stretches.
Automotive engineers would love the latter system, but it would work only as long as all the grips were kept perfectly maintained. Let one fail, either in engagement or in release... and the results will be interesting. (There are other problems behind that one, too... but you'd have to be awfully wedded to the overall cockamamie concept to stick with it long enough to start addressing those...)
I am frankly amazed that this thread has gotten to 67 posts and there is still contention about what kinds of cable system are being discussed.
No matter how complicated the system is, unless the cars can be operated independently by operators on the cars, who can attach and detach the car from the cable and operate the brakes as needed, they are not cable cars. They are a different cable powered technology.
Cable powered people mover systems are viable in controlled situations, but the traditional cable car whether run in the street or on controlled access R/W is not. The cable car was developed to replace the horse car on street railways and for use on very steep hills (there were already cable assists for horse cars on some steep hills). There appeared to be nothing better at the time. Both motor and engine powerered vehicles were in very early stages of developement, not as well known as cable power. Some street railways used small steam locomotives but they were noisy, dirty, often accused of scaring the horses and not popular with the public. The cable car was an advancement on existing mature technolody increasing its flexability and allowing it to be used mixed with other traffic on the streets. If they did not already exist today, cable cars systems (as opposed to cable powered people movers, which as stated before are not the same thing) would not be built because they are not economical and also because they would probably be banned in the USA due to the hazards. They only suvive in San Francisco as a historic artifact and tourist attraction.
DSchmitt gardendance Please give examples to back up your statement. Where is cable powered "transit" in airports that is not limited to their own track, have switches to meet other cable cars, or have multiple cars running on the same track and multiple cables? I doubt he can. ...
gardendance Please give examples to back up your statement. Where is cable powered "transit" in airports that is not limited to their own track, have switches to meet other cable cars, or have multiple cars running on the same track and multiple cables?
Please give examples to back up your statement. Where is cable powered "transit" in airports that is not limited to their own track, have switches to meet other cable cars, or have multiple cars running on the same track and multiple cables?
I doubt he can. ...
See my previous post.
The 2 examples that come to mind are Detroit Metro Airport (which has been cited earlier in this thread by someone else) and Minneapolis-St. Paul Airport. Luckily the MSP cable car is outside, so you can see it clearly on Google Earth at:
44°52'56.84"N 93°12'19.81"W
A clearer and more illustrative view is shown in historical image dated 9/15/2013. The reference point is at the switch between the 2 intermediate station platforms. The passing siding and platform for inbound cars is to the upper left (NW), and the platform for the outbound cars is to the lower right. In the 9/2013 image there is a 2 car train almost totally within the patform/canopy area. While the inbound train platform stop is in the passing siding, the outbound train must go thru the siding, before getting to its platform to access the airport concourse. It's more complicated than the Detroit example, where both cars stop at the same time in the intermediate station at the passing siding. That the MSP situation is more complicated is borne out by the fact that they had a collision between cars when they were testing the system.
NorthWestMy understanding is that those wooden blocks are replaced quite often, too.
About every three days per the Museum website.
The steel plate emergency brake is a last resort. If used a torch may be needed to cut it out of the slot.
My understanding is that those wooden blocks are replaced quite often, too.
An additional safety issue with cable cars is the great amount of inertia present in the cable. If the car is stuck on the cable in an accident, it will continue to drag whatever it hit until the cable is stopped or the car disengaged.
Paul of Covington Just curious: How do the brakes on San Francisco cable cars work? Do they grip a stationary cable or rail? I can't imagine conventional brake shoes on the wheels being effective on those steep hills.
Just curious: How do the brakes on San Francisco cable cars work? Do they grip a stationary cable or rail? I can't imagine conventional brake shoes on the wheels being effective on those steep hills.
The San Francisco Cable Cars have three types of brakes.
1 Brake shoes that press on the wheel.s
2 Wooden blocks that press on the rails.
3 Emergency Brake - A steel plate that wedges into the slot.
http://www.cablecarmuseum.org/the-brakes.html
With Cable cars, cables wear is faster and more severe do to the gripping and ungripping of the cable.
One hazzard of the cable car, not present in other cable technologies, is that because of a malfunction the grip does not release the cable. This could be because the cable is frayed, or because the cable has stretched and somehow gotten wrapped around the grip. When this happens the only practicle way to stop the car is to use the emerengcy brake.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
A cable railway sounds similar to the system in place on Brazil's Sao Paulo-Santos line before it was converted to a cog-and-rack system.
I doubt he can. From earlier posts by me with edits for emphasis:
"While the the "people movers" may superficially resemble traditional cable cars, they do not release the cable to stop. The cars are "permanately" attached to the cable. The cable stops moving to stop the cars. The movement of the cable (and thus the cars) is controlled automatically by a program to stop the cars at pre-set locations. They also operate on controlled access right of way so there is no conflict with other traffic.
--This type system has can have multiple cars but the all operate on one cable in lockstep. Station spacing and car spacing is such that they all stop at a station at the same time--
This type system goes back to the earliest days of cable car operations, where the cable movement was manually controlled by an engine operator. --on the ground at the location of the engine--
The Detroit Airport system is a little different and more advanced than most other systems. It consists of two separate cars each on its own cable. Each car operates like an elevator (a horizontal elevator) It is actually a little more complicated because both cars use the same guideway (track) and must pass in opposite directions at a central location where there is a passing section. --so there are switches on the track-- The system is programed to override (delay the execuation) of passenger calls as necessary to prevent a conflicts."
--Neither system can operate like the traditional cable car. The ability of an operator on the car to attach/detach from the cable and control speed by partial release (allowing the cable to slip through the grip) and brakes on the car is the essence of a cable car system.--
"Cable cars are distinct from funiculars, where the cars are permanently attached to the cable, and cable railways, which are similar to funiculars, but where the rail vehicles are attached and detached manually --not by an operator on the car, click links for more detail on each type--."
Patrick Boylan
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Buslist As has been pointed out earlier the new generation of cable powered "transit" in airports are really horizontal elevators. They are limited to their own track, no switching they have the advantage of having a centrally located driving motor and no need to have propulsion power distribution. That is a very limited application environment.
As has been pointed out earlier the new generation of cable powered "transit" in airports are really horizontal elevators. They are limited to their own track, no switching they have the advantage of having a centrally located driving motor and no need to have propulsion power distribution. That is a very limited application environment.
They are not limited to their own track, they have switches to meet other cable cars, and they have multiple cars running on the same track and multiple cables. They are only limited by how complicatd you want to build the system.
In reply to usmc1401: There is no need to spend the required new money on extending the California Street line since that street west of Van Ness has trackless trolleys to serve the travel needs of residents. Tourists, the real market for cable cars these days, are perfectly happy to go out to Van Ness and back to Market Street.
In reply to the larger question of cable cars having a renaissance in other cities: This will happen when transit authorities in Cleveland, Pittsburgh, Chicago, etc. can figure out a way to have people pay $6 a ride as they do on the Barbary Coast. But I don't think any city in the USA can match San Francisco in its tourist appeal, do you?
By the way, in 1971 I paid 25 cents per ride for cable cars, streetcars, buses, etc. But I unhesitatingly shell out $6 to ride the cable cars because, really, where else can one do that?
Cable railways of the Funicular type will continiue to be built because they are an economical solution to specific transportation situations. Except for the possible historic revival in Dundee, New Zealand, I doubt very much if any new grip-type cable. The Glascow and Haifa subway lines are really Funiculars. But Glascow's is a circular line, not a hill-climber.
Longer cable not a problem. It is replaced at regular intervals by a very neat cable splicing method.
I seriously doubt it. The expense of extending a cable car route, even a mile, would be astronomical. Consider that you would need to extend the rails and cable slot, install new cable machinery under the slot, install a longer cable, etc.
Has San Francisco Muni ever proposed putting back any cablecar routes that were abandoned in the early 1950's. Such as the California Street line going west of Van Ness for a mile or so.
Falcon48, I don't argue with what was happening with technology 80 years ago. Nevertheless, in modern times, after a number of electric tram systems were built at airports, I noticed new cable systems starting to be built there. Technology evolves, and some airports saw advantages to cable. I don't expect to see something like a San Fran. central hoist cable system to be built, however, I would not rule out some more modern concept of a cable street system to be developed.
MidlandMike CSSHEGEWISCH All of this begs the question, why would any agency use obsolete cable car technology when electrically-powered cars powered by overhead wire are much more practical? The fact that they are still building cable cars at airports (where they could and do use electric) indicates it is still a viable technology, that could possibly be modified for street use.
CSSHEGEWISCH All of this begs the question, why would any agency use obsolete cable car technology when electrically-powered cars powered by overhead wire are much more practical?
All of this begs the question, why would any agency use obsolete cable car technology when electrically-powered cars powered by overhead wire are much more practical?
The fact that they are still building cable cars at airports (where they could and do use electric) indicates it is still a viable technology, that could possibly be modified for street use.
DragomanOn the very steepest hills, they do continue to have a function -- it's called a funicular.
Buslist MidlandMike CSSHEGEWISCH All of this begs the question, why would any agency use obsolete cable car technology when electrically-powered cars powered by overhead wire are much more practical? The fact that they are still building cable cars at airports (where they could and do use electric) indicates it is still a viable technology, that could possibly be modified for street use. Because they are not it the street railway sense of cable cars but horizontal elevators. Please read earlier comments.
Because they are not it the street railway sense of cable cars but horizontal elevators. Please read earlier comments.
And I have explained how they may be applicable to street railways. Please read earlier comments that may be contrary to your line of thought.
Other solutions include rack-pinon-operation for the steep grade only, typical in Switzerland, or use of funicular assist, either the Cincinnati Mt. Adams variety (train rides a flat-car funicular) or the Triest Optotrain variety (train is pushed up and braked down by funicular dummies on the down end of the train)
YOu can ride and photograph the Optotrain in Triest. I think the Mt.Adams incline still works-for buses. Several routes in Switzerland for the rack examples, including Diessentis - Andat, Interlaken - Lucern, Interlaken - Klein Sheidigg (spelling on all?).
The original question was "would cable propulsion work if grades were too steep for conventional traction". My answer "select a different route"
DSchmitt MidlandMike The same companies that make people movers also make aerial trams with multiple cars that detatch from the cable to load/unload. I would not count out the application of the automatic detactchable grip technology to rail cable cars. Would be very dangerous on a street railway.
MidlandMike The same companies that make people movers also make aerial trams with multiple cars that detatch from the cable to load/unload. I would not count out the application of the automatic detactchable grip technology to rail cable cars.
Would be very dangerous on a street railway.
I would envision that a modern cable car would run on traffic lanes that exclude cars, and traffic lights would be controlled for transit preference. Still an operator would be needed to stop for errant cars and emergency vehicles.
MidlandMikeThe same companies that make people movers also make aerial trams with multiple cars that detatch from the cable to load/unload. I would not count out the application of the automatic detactchable grip technology to rail cable cars.
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