Patent attributes
A pin assembly includes a spring held in compression inside a case by a thermal fuse located at the back end of the pin. The fuse is thermally activated to collapse, which allows the back end of the pin to move forward. The spring drives the front end of the pin out of the case into latching engagement between a first object, such as a fire door, and a second object, such as a floor or a doorframe. The fuse and spring are located on opposite sides of a restrictive opening at the back end of the case. The fuse is preferably cylindrical, surrounds the back end of the pin and is provided with holes oriented perpendicular to the cylindrical axis of the fuse forming a web. The holes weaken the fuse and cause it to collapse in a controlled manner at the desired activation temperature.
