Abstract: Release mechanism and method for fire doors and the like. The door is normally held in an open position by an electrically energized actuator and is released for closing upon deenergization of the actuator. An eneergizing current is supplied to the actuator from a source to energize the actuator, and a limited amount of energy from the source is stored in an element such as a capacitor. Upon interruption of the current from the source to the actuator, the actuator is energized with the stored energy to prevent the door from closing for a limited period of time after the current is interrupted. An alarm circuit is included in some embodiments to porivde a warning when the current has been interrupted and the door is about to close.

Abstract: Release mechanism and method for fire doors and the like. The door is normally held in an open position by an electrically energized actuator and is released for closing upon deenergization of the actuator. An energizing current is supplied to the actuator from a source to energize the actuator, and a limited amount of energy from the source is stored in an element such as a capacitor. Upon interruption of the current from the source to the actuator, the actuator is energized with the stored energy to prevent the door from closing for a limited period of time after the current is interrupted.

Abstract: A clutch or rolling door operating mechanism permits use of two sources of power for moving the door between open and closed positions. A drive gear rotates about an eccentrically mounted shaft which itself is turned through a clutch of the fixed drag type to swing the gear into engagement with the drive train for moving the door via manual power and to permit the gear to swing into disengagment with such drive train for moving the door by electric power operation. In one form a circuit interlock prevents motor operation during manual driving of the door; in a second form an audible "clacker" sounds to indicate manual operation of the operating mechanism.

Abstract: A time delayed releasing device serves to hold fire closures from being actuated during periodic testing and momentary power failure while still permitting the closure to respond to power outage of more than a momentary nature or to the presence of heat.