Sealing device for shafts

Claim 1

In a sealing device for shafts passing through a wall separating media of different pressures, said sealing device including a packing box adapted to be mounted around a shaft, said packing box being mounted on a wall element, said packing box including a ring shaped chamber in which is disposed at least one layer of sealing material, the inner surface of said layer of sealing material being adjacent to the outer surface of said shaft, the improvement comprising a cuff or sleeve mounted around the outer surface of said layer of sealing material, said cuff or sleeve being radially flexible and being formed from an elastic material, and first means for applying a pressurized medium to the outer surface of said cuff or sleeve so that the pressure exerted thereon is transmitted radially inwardly through said cuff or sleeve to said layer of sealing material, said transmitted pressure causing said layer of sealing material to be pressed in its entire axial extension against said shaft; the entire inner surface of said layer of packing material being shaped to conform to the outer surface of said shaft so that said layer of sealing material is maintained in a flush, contiguously abutting relationship with the outer surface of said shaft; and second means for applying a pressurized medium to the interface between the outer surface of said shaft and the inner surface of said layer of sealing material, said pressure applied by said second means being less than said pressure applied to the outer surface of said cuff or sleeve by said first means.