Abstract: This invention relates to a method and an apparatus for controlling the speed and/or direction of movement (A, B) of a screw discharger (1, 11, 101, 201). According to the invention, the bending load on the screw (2, 12, 102, 202) of the screw discharger is measured by means of one or more transducers (112, 212) which generate a loading signal on the basis of which the drive system (110, 210) controlling the speed and/or direction of movement (A, B) of the screw discharger (1, 11, 101, 201) is controlled.

Abstract: The invention relates to a method and an arrangement for cleaning the screening device (2) of a screen (1). The screen (1) comprises at least said screening device (2) which has openings for the separation of particles of different sizes into fine material and coarse material, an actuator means for moving the screening device, a first conveying means (4) for guiding the material to be screened to the screening device (2) of the screen and a second conveying (8) means for moving the fine material that has passed through the screening device (2) and means (9) for guiding the separated coarse material away from the screen (1). For cleaning the screening device (2) a material is blown with the pressure medium at least at intervals through the screening device (2) in the opposite direction regarding fine material passing through, the particle size of which material being at least mainly smaller than the size of the openings of the screening device (2).