How can a ski lift allow turns to the left and the right on its route? [video]
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They solve the problem by having the bar below the clamp be a flexible section, as the bar approaches the turn, a section a static rails forces the bar to rotate 30-40 deg around the cable, moving the protruding part of the clamp out of the horizontal plane. Then the cable passes around a large diameter wheel, also 30-40 from vertical, to create the turn.
Because both the bar and the wheel are both 30-40 degrees from vertical, the wheel meets the top of clamp, rather than the side, but cable can still make a turn in the horizontal plane. They're a little uncomfortable for the rider, because the bar you holding onto gets jerked left and right, but you make around the bend just fine, and without an elaborate 2 wire system.
I think the Chardonnet ski lift at Val d'Isère is an example of this type of lift, but I can't find any photos of the corner unfortunately.
For chair lifts, the lift at Ski Dubai has turn half way up, and their chairs are permanently clamped to the cable. For going up the chair just goes around the outside of normal wheel. For going down, to passes around an elaborate wheel with cutouts to make space for the chair clamp and bar. The running surface of this wheel is made up of smaller rollers, and there's a big friction break on hub. So a computer watches for incoming chairs, then slows the big wheel down as needed to align the chair with a cut out. You can catch a glimpse of this here (best video I could find)[2].
Video quality is bad, but this is what it looks like on a picture: https://blog.jacomet.ch/wp-content/20170120-schwanden-052.jp...
cf. http://cable.cocolog-nifty.com/sakudo/2006/02/post_d5e1.html
Compare that to most household products with a thousand warning labels for things that are common sense and/or completely harmless. Like do idiots not go skiing or something?
(I don’t know about the legalities of that as a contract, but it’s how it’s almost always done at ski resorts.)
Do you really expect a human to usefully monitor the whole thing continuously? If you look at a modern lift, there is quite an array of sensors on each tower.
> no way to stop in an emergency
There's an emergency stop button at both ends. They get used on a regular basis due to emergencies. By far the most common emergency is someone falling in the loading or unloading area. (I think a lot of high capacity lifts actually have multiple emergency stop buttons at each end so that any of several operators can stop the lifts.)
The way the San Francisco cable cars work is more brutal. You can look up the details. Some tough spots involve metal sliding on metal. There are soft metal grip guides and "chafe bars" at turns intended to wear out and be replaced frequently. The cable itself has to be replaced every 6 months or so. It's 1870s technology.
Anyone know how this was architected?
And how to architect it: you need steep rock walls not farther than about 300 meters (not sure here, just from what I've seen). Then «just» hang the mast from ropes attached to the rock walls.
I am sure that the word «just» is wrong here as this needs complicated engineering and as in the mountains the weather is harsh you'll need solid and antifragile solutions, as well.
the grip itself is spring loaded and the spring force is measured every time the grip passes through a terminal. if a grip is weak, the lift stops.
if you look closely at a detachable grip, you'll see two wheels. those go into a funnel that squeeze open the spring loaded grip to release the haul rope. the chair or gondola cabin then is guided with one of those wheels while powered by the 20 or so small rubber wheels mentioned above that move the chair through the terminal. reattachment works the same, the wheels progressively speed up to the haul rope speed (5-6 m/s) as the funnel opens releasing the grip to snap back onto the haul rope.
position sensors throughout the terminal and at the towers stop the lift if anything is out of position. (or a grip is weak, as mentioned above)
and like any safety critical reliable system, a lot of hardworking humans check the system regularly.
In the station it detaches from the cable and just rides on the flat track, and then motor-driven tires push on the gondola to propel it at a controlled speed through the station.
But for many European languages, the word "wind turbine" would be translated to "windmill", even going as far as labelling parts with the word. Never worked with wind turbines, but been curious about this for years since the language is so systematic. A documentary I recently watched had a Danish wind turbine marked as "Mølle 1" or something like that, translating to "Mill 1".
I'd be surprised if Norwegians didn't use the word "kabel" (cable) to refer to the thing that carries ski lifts.
The material that a rope is made out of, doesn't really matter. What matters is it being built up of smaller fibers.
I probably never would have even thought about it, if it wasn't for the name!
The truly amazing thing, though, is the safety record: they have a mechanism to switch from a fast rope to a separate, slow rope and back. This transition (and, indeed, the grip on the rope) manages to have an excellent safety record despite being relatively complicated and dealing with snow and ice.
Okay, so it was three rights to make a left, but same idea. I shall call this lift "Zoolander" in honor of [0].
Instead of making a thinner clamp that can go through the rollers as I would have expected, they used two ropes with a hinge from which the "seat" (t-bar) hangs. That way, they can put either the left or the right rope on top, causing the "clamp" part to be on the left/right accordingly, allowing turns in both directions.
Thanks for link to the amazing video, it's truly in the spirit of gratifying intellectual curiosity!
"Please use the original title, unless it is misleading or linkbait; don't editorialize."
https://news.ycombinator.com/newsguidelines.html
When rewriting a title for correct (by the guidelines) reasons, the main thing is to use representative language that accurately and neutrally says what the article is about. Preferably the language should come from the article itself, though that's harder to check with a video. In any case, the rewrite here wasn't editorialized.
But now you've got twice as much cable and twice as many rollers needed.
Not impressed. Do it without doubling all the equipment, that would impress me.
Ultimately the thing to achieve is an economical solution and this scheme (admittedly the last machine of its type) might be a lot cheaper than more earthworks or changing ski runs or building two lifts.
Everything in this is extremely simple and easy to maintain. You basically have 3 unique components:
* Dual left and right hangers for guides
* The mounting for the t-bar
* Dual line bullwheel
Of those, the t-bar grip is the only unique thing.