Patent ID: 6955594

Claim:
A mine door for installation in a passageway of a mine comprising: a leaf adapted to be mounted in the passageway for swinging between a closed position and an open position, the leaf having a first face facing in a direction in which it swings open and a second face facing an opposite direction in which it swings closed, said leaf being adapted for installation in the passageway where the leaf when closed is subject to a differential in air pressure involving higher pressure on one of said faces of the leaf than on the other of said faces of the leaf, said leaf having an opening therein for passage of air therethrough from adjacent said one of said faces of the leaf to adjacent the other of said faces to more nearly equalize the pressure on said faces and thereby reduce the force required to open or close the leaf, a closure mounted adjacent said opening and movable between a closed position blocking passage of air through said opening and an open position allowing passage of air, and a first actuator mounted adjacent said closure for moving said closure between the open position and the closed position.