The lift was a world-changing invention because it enabled the creation of today’s stunning skyscrapers, not to mention saving an incredible amount of time and effort! Imagine a world with just stairs…
Most modern lifts use a cable system. The lift car runs up and down rails within a shaft, and at the top of the shaft is an electric motor that turns a large wheel, or sheave. Cables run over this, one end of which is attached to the car, the other end to a counterweight.
The counterweight weighs the same as the car plus a typical half load, which means that the two structures balance each other out, so the motor doesn’t need to work very hard to move the lift; it just needs to overcome the friction within the system. Of course, the motor must be strong enough to cope with the lift being fully loaded, but this only happens occasionally.
A number of cables are used as back-up in the rare event of one failing. In addition, an automatic brake activates if the lift falls too fast. So those horror-movie scenes of plummeting lifts and fl ailing cables can never become reality.
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