BrainStuff Classics: What Happens When Elevator Cables Break?

you may have heard about it in the news. In November of twenty 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 cables 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 is 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 a villain cuts a single cable and disaster ensues usually never happens. Here's the breakdown.

and the counterweight both ride 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 at 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's 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 elevator's safeties would kick in. Safeties are braking systems on the elevator car that grab onto the rails running up and down the elevator shaft. Some safeties clamp the rails, while others drive a wedge into notches in the rails. Typically, safeties are activated by a mechanical speed governor. The governor is a pulley that rotates when the elevator moves. When the governor spins too fast,

the centervigal force activates the braking system. Even if the cables and the safeties all failed, sure, you would be plummeting rapidly, but you wouldn't quite be in freefall. A 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. On impact, the car would stop and you would keep going, slamming

you into the floor. But two things would cushion that blow. First, the elevator car would compress air at the bottom of the shaft as it 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 oil filled cylinder that would push

in the impact too. 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's spooksman 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 be toly 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 is based on the article what if you are on an elevator and the cable broke on HowStuffWorks dot com, written by Catherine Whitbourne. A brain Stuff is production by Heart Radio in.