How an elevator works:

An electric motor turns a pully and a flexible rope wind or unwinds along which the elevator car rises or lowers. Counterweight travels along vertical guide rails opposite to the direction of the elevator car causing the elevator to be stable.

A wheel is attached to the shaft of the motor with two brake arms on either side of the wheel. An electromagnetic system and a spring are used to disengage and engage the brakes. Next to the brake is a worm wheel mechanism, it has a very high gear reduction ratio. It can convert low torque high speed motor input to a very high torque low speed output.

Elevators have multiple steel cables to hold the carriage and counterweight even if one snaps it would still hold. If the counterweight falls off it would land on springs, but the car would stay in place because of back up breaks. The back up brakes are controlled by something called overspeed governor. It’s a combination of a sheave and a centrifugal braking system. A cable runs along the sheave which is connected to a lever.

If the main cable snaps and starts falling rapidly and causes the governor sheave to spin quickly, the arms fly out and lock with teeth in the stationary casing. This suddenly stops the sheave and cable and then the brake lever is pulled upwards. This pulls the two wedged brakes and clamps them along the guide rails to prevent it from falling.

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