Modern elevators involve an ingenious and complex system of supposedly fail-safe systems. These devices, including brakes, cables, and counterweights, are designed to be so redundant that the failure of several would still not jeopardize passenger safety.
Nevertheless, these systems do fail on a regular basis-indicating that the problem is almost always the result of mechanical errors or negligent disrepair.
This is the first of a two-part series that will look at each of the systems that plays a safety role in the elevators we ride every day without a second thought.
The first safety measure intended to prevent elevator accidents is the system of cables or “ropes” that keeps each car hanging in the shaft. Building codes usually require the combined cables to be strong enough to hold up to 12 times the rated weight limits of a fully loaded car. This means that each individual cable is theoretically capable of holding the car up-even if all of the others fail or are cut.
Check back later this week for more on elevator safety.
Source: Washington Post, “Elevator plunges are rare because brakes and cables provide fail-safe protections,” Brian Palmer, June 10, 2013