Abstract: A fire damper having a temperature-sensitive link assembly designed to permit ease of maintenance of the damper. In one embodiment, the link assembly includes a fusible link that extends across and holds the blades folded. At each end, the link is coupled to a bracket embracing the blades by a pivot pin and an associated latch that is manually releaseable. During maintenance of the damper, either latch can be released and the link will then swing down about the pivot pin at the opposite end of the link, permitting the damper blades to close. In normal use, the blades will also close in response to an over-temperature condition causing the fusible link to break. In an alternative embodiment, a plain non-fusible link is used and one of the latches is released by a temperature-sensitive actuator made of memory metal.

Abstract: An air control damper is provided with an actuator coupled to a shaft for operating the blades of the damper. The actuator includes an electric drive motor that turns the shaft by way of a lever that is coupled to the shaft. The lever has a pulley at an outer end and a cable extends from the drive motor around the pulley and back to a fixed point adjacent the motor. When the motor is operated, the cable is wound around the motor drive shaft, pulling the lever towards the motor and turning the shaft. The arrangement provides a mechanical advantage in transmitting the motor output force to the blade actuating shaft.

Abstract: Fire dampers are disclosed for use in air ducts to arrest the flow of gases and flame through the ducts in the event of a fire. The dampers each include a frame defining a generally rectangular central opening and a plurality of blades which are normally disposed in a folded position at one side of the frame but which can be moved by spring means to an unfolded position in which they extend across the opening of the frame in the event of a fire. A fusible link means normally retains the blades in their folded position. Locking members are provided for retaining the blades in their unfolded position after they have been released by the fusible link means. In one embodiment, the locking members engage integral tabs formed on the endmost blade. In another embodiment, the endmost blade has an end portion which is deflected at an acute angle with respect to the remainder of the blade and which engages over locking brackets secured to the frame.

Abstract: The disclosure relates to one piece frames for fire dampers and the like. The frames are formed from elongate sheet metal blanks each of which is folded into a centrally open, generally rectangular form. In one embodiment, ends of the blank are secured together by a central tab on one end which extends through a T-shaped slot formed at the opposite end of the blank. In another embodiment, the blank is secured in its folded form by an angle shaped end bracket and the frame is provided with at least one corner bracket forming a gusset. The blanks have inwardly directed flanges which are formed with V-shaped notches to permit folding of the blank. In one embodiment, the notches each define an angle of less than 90.degree. and portions of the flange on each side of the notch are overlapped when the blank is folded to provide for frictional engagement between the overlapped portions. In another embodiment, the notches each define an angle of 90.degree.