What Prevents an Elevator from Falling?
The principle preventing uncontrolled descent relies on a mechanical anti-fall system.
Multiple Steel Ropes: This feature guards against descent caused by the failure of a single rope. Even if one rope is damaged, the remaining ropes can still safely support the elevator car, helping prevent free fall.
Brakes (Holding Brakes): When the elevator comes to a stop, the braking mechanism automatically locks down the traction machine.
Counterweight Design: The counterweight is designed to balance the elevator car and part of the rated load. If the system were to fail, the descent of the counterweight would actually pull the elevator car upward rather than allowing it to fall.
Speed Governor + Safety Gear: If the elevator’s speed exceeds a predetermined limit, the safety clamps automatically engage to grip the guide rails, bringing the car to a halt.
Pit Buffers: Even in the unlikely event that all other safety devices fail, the buffers located at the bottom of the elevator shaft will significantly absorb the impact, ensuring safety.
What Prevents an Elevator from Overshooting the Top?
Forced Deceleration Switches: A set of position switches is installed at the top of the elevator shaft. If the elevator car ascends past its normal deceleration point, these switches forcibly cut off the upward running command and apply electrical braking.
Limit Switches: Should the forced deceleration switches fail, a secondary set of limit switches—located even closer to the top of the shaft—will directly cut off the safety circuit, bringing the motor to an immediate stop.