In small elevators, where the payload of the car is about 300 kg, doors are often retrofitted or modernized by folding doors. This design is often used, when spaces for sliding doors are too limited.
Folding doors have the advantage that they can be installed in the cabin. Conditioned by design, folding doors are only used for passage widths up to 800 mm. For example, in passenger lifts, which are additionally integrated in stairwells, telescopic sliding doors cannot be used often due to its low shaft width.
The folding doors of elevators consist of several thin door panels that fold up zigzag-shaped as bus doors do. A mechanical interlock of the car door has to be installed in accordance to EN 81, if the distance between car and shaft wall cannot be adhered to.
Once the landing door is closed and issued the command for the desired floor, the folding door closes automatically. The elevator moves to the requested floor without the user having press and hold teh Button in the cabin. When the elevator arrives at the desired floor, the folding door opens automatically and the user can exit the elevator/lift through the revolving door.
Due to the complicated mechanism, the maintenance costs are quite high. Therefore, folding doors are rarely used as shaft doors.