Lift/elevator mechanics

 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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