Motor Unit (Powerhead): The central drive unit containing the motor and logic board, typically mounted to the ceiling using perforated angle iron and lag screws. Rail and Drive System: A steel rail (belt, chain, or screw drive) that houses the traveling mechanism (trolley) to move the door. Safety Infrastructure: Infrared safety sensors (photo eyes) installed 6 inches above the floor to detect obstructions and trigger an auto-reverse. Control Interface: Hardwired wall-mounted stations and programmed wireless remotes or keypads.