Abstract: The present invention relates to a door operating system for controlling the movement of a door, the system having a motor with a motor shaft for providing rotational energy to the system and a gear chain assembly for receiving the rotational energy from the motor shaft and applying the received rotational energy to the door to move the door, comprising a sprocket rotatably mounted on the gear chain assembly for rotation around an axis of the gear chain assembly and fixedly coupled to the motor shaft for receiving and transmitting the rotational energy from the motor shaft; a drive pin fixedly disposed on the sprocket for rotational movement around the axis of the gear chain assembly as the sprocket rotates around the axis; a rotational energy receiving extension rotatably mounted on the gear chain assembly and drivingly coupled to the door for moving the door; a drive dog fixedly disposed on the energy receiving extension for rotational movement around the axis of the gear chain assembly as the energy receiv

Abstract: An air lock has a chamber and a pair of doors in respective walls of the chamber. Operators associated with the doors include closers normally biasing the doors to closed positions and fluid powered openers associated with the closers capable of overriding the bias of the closers. A control system, operation of which may be initiated by initial opening displacement of one of the doors or (in one embodiment of the invention) by manually operable remote switch means, provides for opening of one of the doors and latching of the other to prevent simultaneous opening of both doors. The latch means for the doors may be overriden by direct displacement of the doors for safety purposes. The control system also triggers air handling apparatus associated with the chamber.