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sorry if stupid question, but how do the trolley cars get enough traction to travel up/down steep hills ? is there a rubber wheelset ? I can't imagine metal whe

sorry if stupid question, but how do the trolley cars get enough traction to travel up/down steep hills ? is there a rubber wheelset ? I can't imagine metal wheels on rails would have enough friction to climb up or descend safely. edit: I see below that someone says there's an underground cable. Is there an emergency backup (like a rubber foot or something) in case of cable snap?

seany 10y ago
The ones that go up and down hills are "cable cars". There is literally a moving cable under the street that they grab onto. So the traction issue is only there when you've released the cable grip, and are breaking.
cr0sh 10y ago
> I see below that someone says there's an underground cable. Is there an emergency backup (like a rubber foot or something) in case of cable snap? There is a brake system on the cars, that basically presses down on the rail - they're made of wood, like they've always been: http://www.cablecarmuseum.org/the-brakes.html http://www.cablecarmuseum.org/the-brakes.html That museum is at the "head" of the lines - it has the motors which drive the cables, and so in the museum you can learn about how it all works, see the cables running, all the sheaves and such, and down below the machine room where they do maintenance. That said - cable-snaps are probably the rarest of rare things to occur. What happens first, as the cable runs (and it is always running), it frays (steel cable - and you don't want one of the "threads" to pierce ya!). As the cable runs, there is a "switch" sensor mechanism that can tell when the fray passes. When that happens, they know then they have to change the cable. At night, then (when no cars are running) they run the cable at a slow speed (I think it is to keep it lubed and not rust or something), and wait for it to trigger again, then they slowly run it to find the fray. At that point, they stop the line (all lines, actually), and splice in a new cable (they have many reels in the work area), put tension on it, then turn the motor back on and let it winch the new cable thru (and take in the old cable), until the splice come back 'round, then they cut out the splice, and splice the ends of the new cable together. I can't recall how often this happens, but IIRC, one line or another would need replacing on a monthly basis (?) - I might be completely wrong.
- digler999 10y ago
  thanks for the info. I wonder if they "braid" the cables? Like I've heard they do for ski lifts. Supposedly they dont weld/solder them in, they just braid them very carefully and friction is enough to hold it together!
  - cr0sh 10y ago
    > I wonder if they "braid" the cables? I don't know - maybe I'll look it up when I get home (I purchased this huge and expensive history book on cable cars from the museum when I last went - it probably has info in it about that aspect). My best guess would be that they do; I can't imagine another way (like welding or soldering) wouldn't cause issues going over the sheaves, possible causing the cable to jump the pulleys. Plus there'd be potential issues with the cable pinch system on the car itself should such an area be "hooked" so to speak...

seany 10y ago

The ones that go up and down hills are "cable cars". There is literally a moving cable under the street that they grab onto. So the traction issue is only there when you've released the cable grip, and are breaking.

cr0sh 10y ago

> I see below that someone says there's an underground cable. Is there an emergency backup (like a rubber foot or something) in case of cable snap? There is a brake system on the cars, that basically presses down on the rail - they're made of wood, like they've always been: http://www.cablecarmuseum.org/the-brakes.html http://www.cablecarmuseum.org/the-brakes.html That museum is at the "head" of the lines - it has the motors which drive the cables, and so in the museum you can learn about how it all works, see the cables running, all the sheaves and such, and down below the machine room where they do maintenance. That said - cable-snaps are probably the rarest of rare things to occur. What happens first, as the cable runs (and it is always running), it frays (steel cable - and you don't want one of the "threads" to pierce ya!). As the cable runs, there is a "switch" sensor mechanism that can tell when the fray passes. When that happens, they know then they have to change the cable. At night, then (when no cars are running) they run the cable at a slow speed (I think it is to keep it lubed and not rust or something), and wait for it to trigger again, then they slowly run it to find the fray. At that point, they stop the line (all lines, actually), and splice in a new cable (they have many reels in the work area), put tension on it, then turn the motor back on and let it winch the new cable thru (and take in the old cable), until the splice come back 'round, then they cut out the splice, and splice the ends of the new cable together. I can't recall how often this happens, but IIRC, one line or another would need replacing on a monthly basis (?) - I might be completely wrong.

digler999 10y ago
thanks for the info. I wonder if they "braid" the cables? Like I've heard they do for ski lifts. Supposedly they dont weld/solder them in, they just braid them very carefully and friction is enough to hold it together!
- cr0sh 10y ago
  > I wonder if they "braid" the cables? I don't know - maybe I'll look it up when I get home (I purchased this huge and expensive history book on cable cars from the museum when I last went - it probably has info in it about that aspect). My best guess would be that they do; I can't imagine another way (like welding or soldering) wouldn't cause issues going over the sheaves, possible causing the cable to jump the pulleys. Plus there'd be potential issues with the cable pinch system on the car itself should such an area be "hooked" so to speak...