When an elevator fails, several things can happen, but complete freefall is unlikely thanks to safety mechanisms.
Let's break down what "elevator failure" can mean and what the consequences might be:
Types of Elevator Failure
- Power Failure: The elevator stops. Safety brakes are designed to engage if power is lost.
- Cable Breakage: Modern elevators use multiple cables. If all cables were to break, safety brakes would engage.
- Safety Brake Malfunction: This is the most dangerous scenario.
- Door Malfunction: The doors may not open or close properly.
What actually happens?
While the movies often depict elevators plummeting uncontrollably, this is a rare outcome in reality due to multiple built-in safety systems.
- Safety Brakes: Elevators have braking systems designed to automatically engage if the elevator exceeds a certain speed or experiences a cable failure. These brakes grip the rails in the elevator shaft to bring the car to a stop.
- Speed Governors: These devices monitor the elevator's speed. If it exceeds a set limit, the governor activates the safety brakes.
- Buffers: At the bottom of the elevator shaft are buffers (often hydraulic) to cushion the impact if the safety brakes fail entirely.
Plunging but not Freefalling
According to reference material, even if the safeties failed:
If the safeties failed, you would be plummeting rapidly, but you wouldn't quite be in a free fall. Friction from the rails along the shaft and pressure from the air underneath the car would slow the car down considerably (you would feel lighter than normal though).
This means you would accelerate downwards quickly, but air resistance and friction with the elevator shaft walls would reduce the acceleration, making it feel like you're falling, but not at the rate of gravity alone.
Key Takeaways
- Elevator failures are rare due to redundant safety systems.
- Complete freefall is highly unlikely.
- Even in a worst-case scenario, air resistance and friction will slow the descent.
