How Lift/elevator works?

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.

Inside a lift

Electric motor

This drives the ropes that are looped around the sheave, which is a grooved pulley system.

Counterweight

A collection of metal weights that help conserve energy by adding accelerating power when the lift is ascending but have a braking effect when the lift is descending.

Shock absorber

If the brakes fail and the car falls, a piston mounted in an oil-ﬁ lled cylinder can save lives as a last resort.

Guide rails

These run the length of the shaft to keep the car and counterweight from swaying when in motion. Rollers attached to the car also keep transit smooth.

Braking system

Some lifts have electromagnetic brakes that are activated automatically if the lift loses power.

Cables

In cable-based lifts, the car is raised and lowered by traction steel ropes. Most lifts have between four and eight cables.

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