Door frame and door assembly for a mine stopping

A door frame and door assembly for installation in a man-door opening in a mine stopping, said assembly comprising a rectangular frame having a top, bottom and sides and a door hinged to the top of the frame and adapted to swing down for closing and to swing up for opening, the frame being adapted to be mounted in a man-door opening in a mine stopping with the bottom of the frame bearing on the stopping at the bottom of the man-door opening, the sides of the frame extending up at opposite sides of the man-door opening and the top of the frame forming a lintel at the top of the man-door opening, the top, bottom and sides of the frame each having a face engageable by the door when the door swings down, each said face constituting a forward face, the bottom of the frame extending forward beyond the vertical plane of the forward face of the top of the frame so that the forward face of the bottom is forward of the forward face of the top, the sides also extending forward beyond the vertical plane of the forward face of the top of the frame and the forward faces of the sides being inclined outwardly in downward direction from the ends of the forward face of the top of the frame to the ends of the forward face of the bottom of the frame, the door having sealing surfaces at the top, bottom and sides thereof engageable in face-to-face relation with the said forward faces of the top, bottom and sides of the frame when the door swings down to seal the opening in the frame, gravity and air pressure on the forward face of the door being adapted to hold the door closed with its said sealing surfaces in face-to-face engagement with said forward faces of the frame, the top of the frame having an upwardly extending forward flange, the bottom having a downwardly extending forward flange, and the sides having laterally outwardly extending forward flanges which are inclined forward in downward direction from the ends of the forward flange of the top to the ends of the forward flange of the bottom, the forward faces of said top, bottom and sides being constituted by the forward faces of the said forward flanges of said top, bottom and sides, the said sealing surfaces of the door being engageable generally flatwise in face-to-face engagement with the forward faces of said forward flanges so that the sealing surfaces may slide relative to said forward faces on distortion of the frame out of rectangular shape, e.g., to distort to a non-rectangular parallelogrammatic shape, to avoid jamming of the door, the door being free of any engagement around the outer edges of the said forward flanges so that the sealing surfaces may slide relative to the said forward faces.