What Happens When Elevator Cables Break?



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Hey, Brian stuff on more invoke bomb, and you may have heard about it in the news in November of two thousand eighteen six people boarded an elevator at the former John Hancock center in Chicago for the ride down from the signature room bar on the ninety fifth floor to the lobby but one of the cable snapped and the elevator plunged eighty four floors to the eleventh floor amazingly, none of the passengers had to be hospitalized. And there were no serious injuries. The passengers thought they had only fallen a few floors. However, they did have to wait three hours to be rescued by firefighters because there were no openings between the floors. So how was it possible? That one of the worst things that can happen to people in an elevator occurred and everyone survived elevators in the real world. Have so many safety features that the kind of thing you see in movies where villain cuts a single cable disaster. Ensues usually never happens. Here's the breakdown. First. Let's look at those cables and a cable elevator system. Steel cables bolted to the car loop over a sheaves achieve is a pulley with a grooved rim surf. Office at the top of the elevator. Shaft the sheaves grooves grip the steel cables. So when an electric motor rotates, the shave the cables, moved to the cables that lift the car are also connected to a counterweight which hangs down on the other side of the sheaf the car and the counterweight both right along on steel rails. Each elevator cable is made from several lengths of steel material wound around one another these cables, very rarely snap. And inspectors look them for wear and tear. But even a steel cable can break. So what happens then almost all pulley? Elevators have multiple cables between four and eight in total. Even if one cable snapped the remaining cables would hold the elevator car up. In fact, just one cable is usually enough. But let's say all the cables did snap. Then. The elevators safeties would kick in safeties are breaking systems on the elevator car that grab onto the rails. Running up and down the elevator. Shaft some safeties clamped the rails. While others drive a wedge into notches in the rails. Typically, safeties are active. Aided by a mechanical speed governor. The governor is poli that rotates when the elevator moves when the governor's spins too fast. The internal force activates the braking system, even if the cables and the safeties all failed. Sure, you would be plummeted rapidly. But you wouldn't quite be in freefall friction from the rails along the shaft and pressure from air underneath the car would slow the car down considerably though, you would feel a bit lighter than normal. Unim- packed the car would stop, and you would keep going slamming you into the floor, but two things would cushion that blow. I the elevator car would compress air at the bottom of the shaft as it fell just as a piston compresses air in a bicycle pump. The air pressure would slow the elevator car down second most cable. Elevators have a built in shock absorber at the bottom of the shaft typically a piston in an oilfield cylinder that would cushion the impact to with all of these features in place. You would have an excellent chance of surviving. Any elevator mishap in the case of the Chicago. Elevator incident. Once the firefighters figured out where the passengers were the crew put up struts to make sure the elevator did not drop any further, then they broke through a wall. Forced to the elevator door open and put a ladder into the elevator to help people up and out. Chicago fire department spokesman Larry Langford told the Chicago Tribune, we don't like to have to go through walls, unless it's absolutely necessary. The only other way to get to the elevator would have been ropes from the ninety seventh floor and that would not be safe. We don't come down like Batman. So we must go through the wall. You sometimes hear that you should jump immediately before an elevator crashes. So that you would be floating at the second of impact would that work? Now, even if you could perfectly time such a leap it wouldn't help. Let's say you and the elevator are falling at a hundred miles per hour. That's around one hundred sixty one kilometers per hour. Unless you have some superhero powered legs when you jump up in the elevator. You'd still be going about one hundred miles per hour. And then you would hit the ground at one hundred miles per hour. Just like the elevator. Your best bet would be to live flat on the floor. This would stabilize you and spread out the force of the impact. So that no single part of your body would take the brunt of the blow. Today's episode was written by Kathryn Witt, born and produced by Tyler for more on this. Lots of other well backed up topics visit our home planet. Testif- works dot com. Hey listeners in lieu of an ad today. 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