safety-hatch

from The Century Dictionary.

• noun A hatch for closing an elevator-shaft when the cage is not passing, or a hatchway when not in use.
• noun A hatchway or elevator-shaft arranged with doors or traps at each floor, which are opened and closed automatically by the elevator-car in passing; or a series of traps in a shaft arranged to close in case of fire by the burning of a cord or by the release of a rope, which permits all the traps to close together.