Abstract: A blocking slab for a pulp grinder, which blocking slab comprises a striplike frame to be mounted between a wall of a grinding chamber in the grinder and a grindstone, said frame being parallel to the axle of the grindstone. In order to prevent splinters and chips from getting out of the grinding chamber, the frame is provided with a longitudinal retaining edge facing to the peripherical surface of the grindstone. The retaining edge has at least one longitudinal recess, which is limited by two longitudinal retaining ribs, to prevent splinters and chips from getting out of the gap between the grindstone and the blocking slab.

Abstract: A sealing arrangement for a shutter for a feeding chamber of a continuously operating pressure grinder. The feeding chamber is provided with an inlet opening for feeding wood batches at atmospheric pressure into said feeding chamber and with an outlet opening for feeding said wood batches into the grinding chamber at overpressure. Each opening of said feeding chamber is provided with a shutter movable between an opened position and a closed position for preventing of escape of said overpressure through said feeding chamber.The feeding chamber is provided with a fixed guide supporting the shutter during its movement between opened and closed positions. Said guide comprises two parallel support surfaces between which the shutter is slidably mounted. The distance between said support surfaces is greater than the thickness of the shutter adjacent said support surfaces so that the shutter is displaceable towards and away from said support surfaces in a direction perpendicular to said support surfaces.

Abstract: A classifying apparatus for a suspension, especially for a pulp suspension, having a screen drum, means for feeding the suspension to one side of the screen drum, for removing thickened suspension from the same side of the screen drum and liquid from the opposite side of the screen drum, blades inclined in relation to their direction of rotation so that any one of the ends of the inclined blades is substantially on the same screen drum line parallel to the screen drum axis as the opposite end of some other blade and fitted to sweep at least one surface of the screen drum, and driving means for moving the blades in relation to the screen drum.