Revolves, or rotating turntables, are a standard in stage play productions. Generally part of the permanent machinery in a theater, a rotating turntable is usually located at or near the center of the stage. It can be used for a variety of illusions in a play, including changing the scene quickly or changing the time. It can also show a transformation of a character, or move from an exterior shot of a building to the interior of the building. Rotating turntables also allow 360 degree views of a central set piece. Turntables also allow a kind of treadmill effect, where an actor gives the illusion of walking, while remaining at the same point on the stage.
Another common type of machinery in a play production is a pulley or lift system that allows vertical movement of actors or set pieces. The scenery that is lifted up is said to be "flown" into the "fly tower" -- the space above the stage where platforms and connecting walkways allow tech crew access to pulleys, winches and counterweights. In modern theater, pneumatic or hydraulic systems assist in the raising and lowering of equipment and sets. Those who operate these systems are called "flymen."
Like rotating turntables, elevators and lifts are located in the stage floor. A particular theater may have a number of stage floors, depending on the production. Elevators and lifts are used to raise and lower both scenery and set pieces as well as actors and actresses. In conjunction with trapdoors, a lift can produce a sudden, grand entrance such as a fairy or genie would make. Revolves can also be fitted with elevators for more versatility. Elevators may be operated with counterweights, but in modern theater, they often use hydraulics and computer programs to lift an actor or a set piece on cue.