Abstract: An apparatus is disclosed for releasably locking a fireproof door in an open position. A latch mechanism includes a hook connected to the door. The hook is releasably engaged with an actuator plate swingable between a latching position and a release position. Its motion is restricted by resilient means having bias adjustment means. A toggle mechanism keeps the actuator plate in its latching position until the toggle mechanism is struck by a remote-controlled solenoid plunger to release the door and let it close. If the solenoid malfunctions, the door can be closed manually with a force dependent on the setting of the bias adjustment means.

Abstract: In an apparatus for closing a fireproof door, a holding device comprises a latch mechanism and a slider. The latch mechanism comprises an actuator member swingably supported in a housing which is provided with a tubular portion wherein a stopper is inserted and downwardly biased by a spring, the biasing force of the spring being adjustable by a screw which is threaded into the tubular portion. The slider is provided with an inclined surface at the front end thereof and a through-hole to receive the stopper therein. The slider is slid into the spacing formed between the actuator member and the housing with upwardly guiding the stopper by the inclined surface of the slider and the slider is locked by the stopper when it falls into the through-hole of the slider. The slider is released from the latch mechanism by swinging the actuator member or upwardly pushing the stopper against the biasing force of the spring.

Abstract: In an apparatus for closing a fireproof door in case of emergency, the fireproof door and a release, which is secured to a door frame, are interconnected by a link mechanism comprising first, second and supplemental link arms. One end of the first link arms is pivoted to a driving shaft of a door closer secured to the fireproof door. The other end of the first link arm is pivoted to one end of the second link arm, the other end of which is pivoted to the release. The supplemental link arm is connected between the central point of the second link arm and a slider which is slidably mounted inside the release and latched by a latch mechanism when the fireproof door is open.When the slider is released from the latch mechanism by electrizing a solenoid which operates the latch mechanism, the slider is slid inside the release by the closing force of the door closer transmitted via the link mechanism, thereby closing the fireproof door.