Abstract: A sealing apparatus for use with a door which swings over a threshold between an open position and a closed position and has a door lower end spaced above said threshold and defining a gap between the door lower end and the threshold when the door is in the closed position, and has a door face and a door frame includes a mechanism mounting member; a gate member for closing the gap; a leaf spring having a leaf spring first end and a leaf spring second end, the leaf spring first end being secured to the gate member with a securing structure, and the leaf spring second end being secured to the mounting member with an anchoring structure, where a segment of the leaf spring angles upwardly and laterally to form a spring cam surface; a structure for guiding the gate member to move up and down relative to the door; a cam engaging member positioned above and substantially parallel with the gate member, the cam engaging member having a protruding end extending laterally from the door toward the door frame to abut the