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Comment by jsiepkes | Hacker News Reader

There are indeed a whole bunch of security features which prevent a lift from free-falling.

However there is another risk of it flying up and slamming into the ceiling for most types of lifts. For that kind of malfunction there is often no safe guard. A lot of lifts are of the type where they use a large weight which is about half the weight of the maximum load capacity of the lift. This weight is used as a contra weight and hangs in the elevator shaft (so it goes down if the lift goes up). If the brakes in the engine on top of the lift shaft fail there is nothing stopping the contra weight and the lift will fly up.

This is a YouTube video of that happening: https://youtu.be/Ys0rDAxdd-g (warning its not graphic but obviously a disturbing thing to see)

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Back in university I had a side job as a security guard in an office building, when this happened. Someone took the cargo elevator, which was built to carry a higher load than the regular elevators, so it had a massive counter weight. The thing slammed into the ceiling with a bang that could be heard through the entire building, and the damage was quite extensive. Took a while for the guy to calm down as well.

Why wouldn't the counterweight also have its own emergency braking system? Seems like an obvious oversight.

A free fall safe guard is often mandated by law / regulation. A "shoot up slam into ceiling safe guard" is not.

That makes it simply a cost thing. Since most people don't know about this risk and there aren't many accidents there is simply too little incentive.

in the European Union, nowadays, it is required to have a safeguard for "shooting up" as well[0]. If I recall correctly for quite some time it wasn't though. My Father who works in the elevator industry told me that in the GDR (German Democratic Republic) it was already mandatory but after reunification for some years Germany had more lax regulations til catching up again.

[0] https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CEL... (See Annex I , 3.2)

Some horrible looking things here in Europe, like the Paternoster:

https://www.youtube.com/watch?v=YgJBD1wf-YQ

Or the elevators without an interior door: https://webshop.flinks.se/Img/105/96/1059669l.jpg

Most freight elevators are like that, though. So while that's a slightly horrifying diagram, a lot of people will have experiences what it's like being in on.

They generally have a light curtain to stop the lift if you go too near the door and such lifts usually move quite slowly.

Oh wow, that diagram...

I also like the word, "Klämrisk"...

(In German, there's the word "klemmen" = to tuck, get stuck, get trapped, get caught; presumably it's a cognate. So, the above presumably is a Swedish word for "the risk of getting stuck and squeezed".)

My uni had one of those (still does I think?). They're actually not that bad. Look far scarier than they are in reality.

Which weirdly, are illegal to build but can just happily stay in operation

Not weird at all, I'd wager close to every five year old or more car would be illegal so sell new...

I think the parent means why not have a safety mechanism stopping the counterweight from falling? That would stop the lift shooting up.

My answer also meant to address that :-). I meant: There are plenty of technical ways to implement it (and the parent proposes a good one) but its not mandatory to do so, it costs money, and therefore its simply not implemented most of the time.

Because it costs money and isn't mandated by pesky regulations.

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