Can Elevators crash?
The probability of falling in an elevator is so low that elevators are among the safest means of transportation in the world. This is due to the fact that an elevator is not only suspended from ropes, but that other safety mechanisms ensure that a free fall is impossible. Thus, the safety system of an elevator is made up of several components:
- Ropes: These can hold 12 to 16 times the maximum permissible weight. An elevator has firstly traction ropes and secondly safety ropes, the latter taking over the work of the traction ropes in an emergency. This second safety device is backed up by another set of safety ropes, which can also take over the complete traction force.
- Safety gear: this is a device which, in the event of overspeed or breakage of the suspension means, holds the car in the guide rails by means of wedges or eccentrics. After the safety gear has been released, the elevator can initially only be moved upwards. This invention can be traced back to the US American Elisha Graves Otis, who demonstrated it as early as 1853.
- Overspeed governor: This safety component prevents the car from traveling too fast. If a limit value is exceeded, the drive is switched off electronically and the car is braked to a standstill mechanically. This safety device is independent of other operating parts of the elevator and functions even in the event of a power failure.
In the case of skyscrapers over 600 meters in height, it should be noted that the ropes or cables become so heavy that they would eventually give way under their own weight. Skyscrapers with such heights therefore work with other transport systems, for example hydraulic drives.
Elevator ropes with carbon fiber core
Example of a safety gear
However, elevator safety goes beyond preventing a fall. Safety features also include door safety devices, buffer devices in shaft pits or emergency alarm switches. Furthermore, emergency lighting is also included. Optional features include emergency power systems, emergency call and evacuation systems as well as fire protection systems.
In principle, elevator safety is framed by directives issued by the EU, which are implemented by law at the state level. The Elevator Directive regulates the requirements for placing elevators on the market and the condition of elevators in Europe and includes, among other things, the requirements for the emergency call system of elevators. In addition, elevator manufacturers such as Schindler or Thyssenkrupp are required to carry out a safety hazard assessment including risk evaluation for all installations. The current safety level is assessed by TÜV, for example.
Overspeed governors prevent the car from going too fast
Elevators must be subjected to a main inspection at least every two years