A sealed pick-up head for a mobile sweeper, said sealed pick-head comprising: a housing defining a substantially hollow interior and having a front, a back, a left end and a right end, a top and a bottom, and a suctioning bottom opening for suctioning dust and small debris into said substantially hollow interior of said housing; a suctioning front opening disposed in the front of said housing for receiving debris into said substantially hollow interior of said housing, in debris receiving relation with respect to a surface being cleaned; a door frame surrounding said suctioning front opening; a rotatable door means having at least a first door portion and a second door portion (51, 52, 53, 54) joined together at a central pivot axis, and operatively mounted at said central pivot axis in rotatable relation on said pick-up head at said suctioning front opening; a dust and debris outlet in said housing for permitting dust and debris to be suctioned from said substantially hollow interior of said housing into a hopper of the mobile sweeper characterised in that it further comprises a selectively operable actuation means for causing said rotatable door means to rotate in a single direction ("A") to thereby admit debris into the substantially hollow interior of the housing in the same direction as the relative travel of debris with respect to the pick-up head as the pick-up head travels forwardly; sealing means operatively disposed between said rotatable door means and said door frame for sealing said rotatable door means with respect to said door frame, to thereby substantially preclude air from ingressing into said substantially hollow interior of said housing by being suctioned through said suctioning front opening, as said rotatable door means rotates to permit debris to enter the substantially hollow interior of said housing. a housing defining a substantially hollow interior and having a front, a back, a left end and a right end, a top and a bottom, and a suctioning bottom opening for suctioning dust and small debris into said substantially hollow interior of said housing; a suctioning front opening disposed in the front of said housing for receiving debris into said substantially hollow interior of said housing, in debris receiving relation with respect to a surface being cleaned; a door frame surrounding said suctioning front opening; a rotatable door means having at least a first door portion and a second door portion (51, 52, 53, 54) joined together at a central pivot axis, and operatively mounted at said central pivot axis in rotatable relation on said pick-up head at said suctioning front opening; a dust and debris outlet in said housing for permitting dust and debris to be suctioned from said substantially hollow interior of said housing into a hopper of the mobile sweeper characterised in that it further comprises a selectively operable actuation means for causing said rotatable door means to rotate in a single direction ("A") to thereby admit debris into the substantially hollow interior of the housing in the same direction as the relative travel of debris with respect to the pick-up head as the pick-up head travels forwardly; sealing means operatively disposed between said rotatable door means and said door frame for sealing said rotatable door means with respect to said door frame, to thereby substantially preclude air from ingressing into said substantially hollow interior of said housing by being suctioned through said suctioning front opening, as said rotatable door means rotates to permit debris to enter the substantially hollow interior of said housing.