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Did you know that cable cars poop sand? [Tue, 15-Jul-2008 11:48 AM]
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[music |Big Black -- Cables]

There's something you don't see every day:

A Powell-Mason cable car jumped the tracks while turning onto Powell Street just before midnight Sunday night, July 13, 2008, leaving at least four people injured.

I assumed they were, you know, attached.

Which led to me learning about that sand thing:

The track brake does the lion's share of the work. The friction between wood and steel is what primarily stops the car. Make that dry wood and dry steel. Wet equals slick... this is not good.

This is where sand comes to the rescue. A small pedal on the floor is pressed to drop sand on the rails. The wheels crush the sand into powder, the powder soaks up the moisture and provides -- the magic word -- friction!


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Comments:
[User Picture]From: [info]tjcrowley
Tue, 15-Jul-2008 6:59 PM (UTC)

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The grip goes down into the cable slot to grab the cable, that's the only attachment. From the way it is sitting it looks like the grip is still in the slot of the eastbound track and the rear end came off the tracks. That grip is probably twisted all to hell now, I wonder how they got it out of the slot?

I have spent a long time studying the mechanisms of the cable cars because cable car is the is easiest way to get to my apartment. What really impresses me is the actual cable-grabbing mechanism, it's something you can't see from the car because its under the street -- they have a lot of examples at the cable car museum. I highly recommend going to the cable car museum to see the cable vaults too. It's free and full of massive wheels, gears and turn of the century mechanisms. They build all those cable cars by hand.
[User Picture]From: [info]205guy
Wed, 16-Jul-2008 11:42 AM (UTC)

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The grip twisted unless it just tore off of whatever holds it to the car, but I also wonder if there is enough play in the slot to put a kink in the cable--that would be bad. Seems like the cable slot could be damaged too.
[User Picture]From: [info]mc_kingfish
Tue, 15-Jul-2008 7:05 PM (UTC)

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The streetcars poop sand, too... At least the old Boeing ones did (I'm pretty sure the Breda one do, too.) That's a pretty typical and ancient railroad-tech.

Many's the time I've seen the slick, slippery tracks out here in the fog belt covered in sand trails.
[User Picture]From: [info]zonereyrie
Wed, 16-Jul-2008 4:01 AM (UTC)

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Yeah, most rail-based transport uses sand for traction. Even today modern railroads use it. Just like putting sand on ice in the winter.
[User Picture]From: [info]lohphat
Wed, 16-Jul-2008 3:49 PM (UTC)

You can see the sand hopper from inside the Breda cars

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It's under the fold-up seniors/wheelchair seats. It has a transparent window to show the sand level.

/Sand? In my hopper?
[User Picture]From: [info]latemodel
Tue, 15-Jul-2008 7:14 PM (UTC)

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From the jaunty attitude of the car in the photo, and the circular skid marks, it is clear that the operator was actually doing donuts. Bravo to him/her.

And [info]tjcrowley is right about the cable grips, and the fact that you should go to the cable car museum. I went the first time I ever came to SF, and ever since I've had it in my head that skateboarders need their own cable grips so they can hitch a ride up the hills.
[User Picture]From: [info]tjcrowley
Tue, 15-Jul-2008 7:26 PM (UTC)

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Now I'm trying to figure out how to make a skateboard grip, thanks a lot.

I want to figure out how to get into the cable vaults, actually. From what you can see in the museum, there's got to be miles of urban spelunking to be done under the streets just from those alone.
[User Picture]From: [info]enf
Tue, 15-Jul-2008 7:45 PM (UTC)

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The vaults are not large, though. You would have to be the diameter of a cable to be able to explore effectively through them.
[User Picture]From: [info]erg
Tue, 15-Jul-2008 7:51 PM (UTC)

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China Town used to have, may still, a lot of tunnels too.Many have been walled up. I know nothing of how to do such things safely,(map the tunnels, hell, just see them) but I'd love to do it.
[User Picture]From: [info]kingfox
Tue, 15-Jul-2008 8:13 PM (UTC)

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Egg Shen, who runs "Egg Foo Young Tours", would be a valuable resource for such an endeavor.
[User Picture]From: [info]jsbowden
Wed, 16-Jul-2008 12:25 AM (UTC)

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Just be careful not to get any black blood of the earth on you, and watch out for the giant fish head monster things.
[User Picture]From: [info]skywaterblue
Tue, 15-Jul-2008 7:41 PM (UTC)

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I'm stunned it hasn't happened yet. Skateboarders skimming off the cable car lines seems such like such a San Francisco line of thought.
[User Picture]From: [info]jayrtfm
Wed, 16-Jul-2008 7:49 PM (UTC)

or a Norwegian thought

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http://www.trondheim.com/content.ap?thisId=1117614134

The bicycle lift helps cyclists up the steep Brubakken hill near Gamle Bybro, almost all the way up to Kristiansten Fort.

To use the lift you insert your key card, put your right foot on the foot rest and sit back on your bicycle seat while you glide up the 130 metre hill at a comfortable speed of 2 metres a second.
[User Picture]From: [info]fgmr
Tue, 15-Jul-2008 10:55 PM (UTC)

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My great-uncle once told me about a prank the kids in Chicago would play with the cables. Take a sheet or two of newspaper, and roll it up on the diagonal so it makes a long, flimsy tube. Hold one end, and flick the rest down into the cable slot. If you did it right, the bottom of the tube would wrap around and grab the cable, jerking the paper out of your hand. The part sticking out of the ground would partly unroll, and go rattling down the street, scaring the hell out of all the horses and making them panic.
[User Picture]From: [info]lohphat
Wed, 16-Jul-2008 3:53 PM (UTC)

Try rotten mangoes

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My grandparent's generation would rub old mangoes on the tracks of the old Honolulu electric streetcars at the bottom of a hill -- they could not continue as they did not have sand hoppers.

In Hawaii.

Wouldn't it be cool if they only had a convenient supply of sand...
From: [info]hattifattener
Wed, 16-Jul-2008 3:32 AM (UTC)

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I had a similar notion after reading about the trampe in Trondheim.
[User Picture]From: [info]detritus
Wed, 16-Jul-2008 3:35 AM (UTC)

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The slow and the stately: san francisco drift!
[User Picture]From: [info]a_0001
Tue, 15-Jul-2008 7:19 PM (UTC)

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Almost all rail vehicles--locomotives, light rail vehicles, and multiple unit trains--dispense sand to improve traction for starting and braking; it's no surprise that cable cars have a similar arrangement.

On the light-rail trains here in Los Angeles, the sandboxes are mounted underneath passenger seats at the ends of the cars and have windows to see the sand itself.

[User Picture]From: [info]pikuorguk
Tue, 15-Jul-2008 7:24 PM (UTC)

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Yes, from some highly interesting work I did for a major UK train company (who are also a record label, TV channel and Broadband provider) I know possibly too much about trains and their inner workings.

I can make train spotters wet themselves with glee by describing the logic that prevents the train from moving if its doors are open.

Oh, and these high speed trains also shit sand (and the contents of their holding tanks when they fill up) onto the track.
[User Picture]From: [info]stilettowhore
Tue, 15-Jul-2008 9:54 PM (UTC)

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So they shit shit then ? :)
[User Picture]From: [info]pikuorguk
Tue, 15-Jul-2008 10:06 PM (UTC)

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They do actually :)

Trains have holding tanks that the toilets empty into. These get emptied when the train goes to the depot, or at a station.

However if it fills up mid journey they just dump it onto the tracks. There must be a few old trains around that empty onto the tracks anyway as my local station's tracks are covered in bits of toilet roll.

Yet another reason why playing on the railway is bad, kids.
[User Picture]From: [info]zonereyrie
Wed, 16-Jul-2008 4:05 AM (UTC)

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Yeah, for a long, long time railway toilets just opened right onto the tracks. You could look down and see the roadbed going by under the toilet. Modern regulations tend to restrict such things, hence the holding tanks.
[User Picture]From: [info]macguyver
Wed, 16-Jul-2008 4:33 AM (UTC)

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Many international railroads still open right to the tracks. The first time I saw it, it was freaky.
[User Picture]From: [info]jace
Wed, 16-Jul-2008 11:03 AM (UTC)

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The toilets in all the trains around here are just holes in the floor. You should see how the railway stations stink.
[User Picture]From: [info]editer
Wed, 16-Jul-2008 6:47 PM (UTC)

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Hence the old bit of verse made out of what was probably a real-life train announcement: "Passengers will please refrain from flushing toilets while the train is stopping in the station."
[User Picture]From: [info]karlshea
Thu, 17-Jul-2008 6:37 AM (UTC)

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I can make train spotters wet themselves with glee by describing the logic that prevents the train from moving if its doors are open.
So what logic does prevent a train from moving when the doors are open?
[User Picture]From: [info]pikuorguk
Thu, 17-Jul-2008 10:01 AM (UTC)

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Right...

The doors have switches in them that open when the doors are open. All the doors are linked together into a safety circuit. If the continuity of this circuit is broken, the train's motor controller is instructed to put the brakes on and turn off the engine (if it's moving) or to keep the brakes on and attempt to close any open doors (if at a station). I think the emergency stop was connected to this as well.

Next time you get in a train, sit near the carriage with the generator and pantograph in it (aptly for this thread it is probably the carriage with the toilet in) and listen. You'll hear half a dozen relays opening and closing as everything is checked, re-checked and locked.

The engines are clever too. When the train is doing anything but accelerating they turn off and turn into dynamos instead, converting the train's motion back into AC current which is fed back into the power grid.
[User Picture]From: [info]karlshea
Thu, 17-Jul-2008 2:45 PM (UTC)

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That's pretty slick
[User Picture]From: [info]pikuorguk
Thu, 17-Jul-2008 2:47 PM (UTC)

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Yeah. Now we just need to make them run on time and all will be well ;)
[User Picture]From: [info]lifelike001
Tue, 15-Jul-2008 7:39 PM (UTC)

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yes... but then i live in melbourne, where any endeavor not restricted to one's own abode involves a load of that sand in your eyes from the wind.


weather wind, not tramwind whipping up the sandy trampoop.
[User Picture]From: [info]mutiny
Tue, 15-Jul-2008 7:59 PM (UTC)

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[User Picture]From: [info]kineticfactory
Tue, 15-Jul-2008 9:44 PM (UTC)

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The trams in Melbourne (the new, European ones, not the vintage wooden ones) have transparent windows in the wall panels/under the seats, which show the level of sand in the reservoir. From time to time, the passenger witnesses a sandquake as the bottom of the reservoir falls out.
[User Picture]From: [info]kowh
Tue, 15-Jul-2008 10:29 PM (UTC)

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You can catch a brief video segment on the sand system (for Toronto streetcars) from around 0:40 to 0:50 (a whole 10 seconds!) in this video.

That clip is actually part 3/3 (Part 1 and Part 2) of an episode on Toronto streetcars, from some tv show called Things That Move that apparently airs on the Canadian History Channel. I've never seen the show outside of those clips, but apart from the annoying host the episode itself is mildly interesting.
[User Picture]From: [info]mysterc
Wed, 16-Jul-2008 2:14 AM (UTC)

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Something you may or may not want to know about the brakes on the cable cars, they (at least when I was in middle school) are made by middle school students at Marina Middle School. The kids would shape and cut them and burn their names and class into the the block and after it was used MUNI would return the used brake to the school and/or student. I stopped riding them when my friends at Marina showed me the returned, used scorched wood block.
[User Picture]From: [info]lafinjack
Wed, 16-Jul-2008 4:05 AM (UTC)

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