Importance

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Abstract

A delayed closing mechanism for a rolling fire door is provided wherein an AC solenoid having its sliding rod pivoted to one end of a connecting rod which is also pivoted at a central portion while the other end of the connecting rod is pivoted to the lower end of a spring biased actuation rod, a recess is provided on a side of the actuation rod to form a shoulder, the upper end of a latch rod pivoted at its central portion swings into the recess of the actuation rod and its lower end is acted on through a DC solenoid which can be controlled by an operator or activated through the discharge from a capacitor in the event power is cut off, the DC solenoid sliding rod is activated to swing the latch rod to move away from its position blocking the actuation rod, and cutting off power to the AC solenoid. The spring biased actuation rod pushes the braking rod in the braking device to pivot and thereby release the brake so as to permit the door to open or close. In the event of fire and the door is open where power is not yet cut off, the control system excites the DC solenoid in the circuit to extend the sliding rod and pivot the latch rod to move away from the position blocking the actuation rod which is pushed out to release rotor braking, and the door is closed by its own weight.

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First Claim