Sealing device for an offset printing machine

In combination with a dampening unit of an offset printing machine having a dampening-medium applicator roller and a metering roller in rolling engagement with one another, the rollers defining an upper wedge forming a duct for receiving a supply of dampening medium therein, each of the rollers having an axis and having an end face, and at least one lateral part adjacent said rollers, and a pin fixed on said lateral part of the dampening unit and extending parallel to the axes of the metering and application rollers and defining a swivel axis parallel to said rollers;

• a sealing device comprising a sealing support bracket swivellably mounted on said swivel axis and means for pre-stressing said sealing support bracket in a direction towards the end faces of the rollers, and a sealing element held by said sealing support bracket, said sealing element being in frictional engagement with the rollers and being sealingly supported radially on the metering roller and being in sealing engagement with the end face of the dampening-medium applicator roller, a sealing element exchange device including means defining a path wherein the sealing element is swivellable a given distance about the metering roller in a direction opposite a rotational direction of the metering roller and from a sealing position thereof into a make-ready position wherein said sealing element is removable from the sealing device, and means for selectively allowing said sealing element to be freely turned about the metering roller, in said path, said sealing support bracket being formed with a support projection located outside an area brushed by said sealing element on said swivelling path thereof, said swivel axis and said support projection, in said sealing position of said sealing element, being disposed with respect to said sealing element so as to define means actuated primarily by prevailing friction forces and by rotation of the dampening medium applicator roller and said metering roller for holding said sealing support bracket in said sealing position of said sealing element with a holding force transmitted by said sealing element onto said support projection so as to maintain said sealing element in said sealing position thereof.