These devices work very similar to freight elevators, only they are used in show business. The mechanisms are really smart and work much quieter than loading platforms. Orchestra pit’s size and shape sometimes diverge from the traditional rectangular and adapt to the curve of the stage. They are available in various lifting speed and comply with security standards.
Similar technology can be used to automate not only the pit, but also the whole stage or parts of it, so that decorations could be lifted or moved horizontally.