Elevators include many features to ensure that passengers remain safe. One of the most important safety features is the doors.
An elevator uses two sets of doors – one set on the cab and another set that opens into the elevator shaft. Most elevators have two door panels that meet in the middle and slide open to the sides. A cascading telescopic configuration has doors that run on independent tracks. When they are open, the doors are tucked behind each other. When they are closed, they form cascading layers on one of the sides. This configuration allows for two sets of cascading doors that operate in the same way as doors that open in the center, which allows for a wider elevator cab. The elevator can also use a single door that opens to one side. Some buildings have a single door on the side near the shaft and double cascading doors on the side near the cab.
The doors on the elevator cab are operated by an electric motor that works in conjunction with the elevator’s computer system. The electric motor turns a wheel that is attached to a long metal arm, which in turn is linked to another arm. The second arm is attached to the door. The door slides along a metal rail.
The elevator’s computer system turns the motor to open the doors when the elevator arrives at its destination and closes them before it starts moving. The motor turns the wheel, which causes the first metal arm to rotate. That arm pulls the second arm and the door to the left and causes it to open. The two door panels close in on each other when the door is opened and extend outward when the door is closed. Many elevators feature a motion detector that can tell when a person is between the doors to prevent them from closing.
A clutch mechanism unlocks the outer doors and opens them when the elevator reaches the desired floor. This causes the doors to open only when the elevator is stopped at a floor and prevents them from opening into an empty elevator shaft.