Abstract: A revolving door assembly in which the individual door wings are releasably secured to a central support member, such that the door wings are retained in respective operative positions in which the wings extend substantially radially from the central hub in diametrically opposed pairs. The door wings are releasable from their operative positions in response to the exertion of a predetermined force thereon to allow one or more of the door wings to be rotated about their respective pivot axes to a folded position. The support member has a plurality of arm members projecting substantially radially therefrom. Each door wing is attached to a corresponding arm member by means of a ball and catch mechanism at a distal position relative to the support member. The ball is disengaged from the catch to allow the door wing to swing free of the arm member when a predetermined force is exerted thereon.

Abstract: Obstruction detector apparatus operatively coupled to an automatic electric door operator compares the time span of transmission and receipt of reflected echoes of ultrasonic energy within a door passageway obstruction zone with predetermined time spans in order to prevent door closure under conditions indicating passageway obstruction or system malfunction. Signal generators provide timing signals respectively representative of the anticipated time span of reflected echoes from locations in front of, and beyond, the door jamb opposite the ultrasonic transmitter and receiver transducers for comparison by a relay controller with the time of generation of a signal representing a reflected echo at the transducer receiver, the relay controller appropriately actuating a door operator relay in response to such comparison.