The thought of being trapped in a plunging elevator frightens many city dwellers. Elevator accidents seldom happen, but when they do, the results are catastrophic. One important reason that elevator accidents are so rare is the safety features that are part of every elevator. An interesting article in the Washington Post recently summarized the history of elevator safety.
The biggest breakthrough in elevator safety was the safety brake, invented by Elijah Otis. This was a game-changer. Before this invention, elevators were only used for freight because cables and ropes sometimes broke. The brake stopped a falling elevator car by jamming a metal rod into the track on which the car rode, slowing it gradually.
Counterweights are another safety feature that will stop a failed elevator. The counterweights slow the ascent or descent of the elevator. Unlike the gradual stop provided by the safety brake, counterweights wills stop a car abruptly when the car reaches to top or bottom of the shaft. However, it will stop and passengers will almost certainly survive.
Although the technology and materials used are different, the basic safety systems on elevators are the same as they were 100 years ago. The refinements generally have to do with the increased speed and weight of current elevator cars.
Many of the updates have to do with materials. For example, steel would buckle under the higher temperatures produced by an elevator falling down a skyscraper shaft. Otis Elevator won’t reveal precisely what it uses instead of steel – it’s a trade secret – but a spokesman did say that it is the same material used in jet engines.
Most New Yorkers use elevators many times each day. They can take comfort in the fact that elevator accidents seldom occur and tat most of the elevators are inherently safe. Most accidents are the result of poor maintenance or incorrect installation and occur very rarely.
Source: Washington Post, “Elevator plunges are rare because brakes and cables provide fail-safe protections,” Jun. 10, 2013.