Abstract: This invention relates to a quarter point return mechanism for a manually driven revolving door. Revolving door leaves extending outwardly from a shaft are partially enclosed between opposed curved sidewalls. The return mechanism has a number of elements including an actuator, a rack arranged to be linearedly displaced by the actuator, and a pinion engaging the rack and being rotatable in opposite directions. The pinion is rotatably connected to the central shaft of the door. When the pinion is rotated in one direction, rotation is transmitted to the shaft. When the pinion is rotated in the opposite direction, the rotation is not transmitted to the shaft. Also included is a circumferential displacement sensor which operates the actuator when the outer ends of the door leaves are in a position circumferentially displaced from the sidewalls. The return mechanism returns the door leaves to a rest position in which the door leaves are in contact with the curved sidewalls.

Abstract: This invention relates to a quarter point return mechanism for a manually driven revolving door. Revolving door leaves extending outwardly from a shaft are partially enclosed between opposed curved sidewalls. The return mechanism has a number of elements including an actuator, a rack arranged to be linearedly displaced by the actuator, and a pinion engaging the rack and being rotatable in opposite directions. The pinion is rotatably connected to the central shaft of the door. When the pinion is rotated in one direction, rotation is transmitted to the shaft. When the pinion is rotated in the opposite direction, the rotation is not transmitted to the shaft. Also included is a circumferential displacement sensor which operates the actuator when the outer ends of the door leaves are in a position circumferentially displaced from the sidewalls. The return mechanism returns the door leaves to a rest position in which the door leaves are in contact with the curved sidewalls.

Abstract: A collapsible revolving door is described and includes upper and lower latching mechanisms which normally retain leaves of the door in radially disposed, angularly spaced positions but which allow the leaves to collapse flat against one another in the event that abnormal forces are applied thereto. Each latching mechanism includes one latch member for each leaf. The latch member is mounted on a pivot pin for the leaf so that the latch member will turn with the leaf from a normal radial position to a collapsed position. The latch member is retained in its normal position by spring biassed detents which will release when abnormal forces are applied to the associated leaf.