A process for disintegrating elongated lignocellulosic material in an apparatus in the form of a drum chipper with connecting input means for the purpose of achieving a predetermined quality of the disintegrated lignocellulosic material, comprising - feeding the elongated lignocellulosic material to the drum chipper that consists of a stand carrying a horizontal and rotatable drum/rotor, the periphery of which has a plurality of knifes contained in knife holders as well as with every knife interacting radially adjustable wear plates positioned at a certain distance from the knife and its edge, and a space (37,38) for temporarily collecting the disintegrated lignocellulosic material, said space (37,38) being positioned between each knife and one or more anvil steels that interact(s) with each respective knife, said anvil steel(s) preferably being attached to the stand, and - intermittently or continuously analysing the outputted disintegrated lignocellulosic material primarily regarding its configuration in length, width and thickness, wherein - at least one process variable is changed during operation without stopping the drum chipper by - setting a certain chipping angle ( ε) by regulation of the input means' position vis-a-vis the rotor causing the fed elongated lignocellulosic material to approach and be brought towards the rotor at a certain angle and/or - setting a certain T dimension value corresponding to a distance between the knife's edge and the wear plate by changing the wear plate's radial distance from the rotor's centre, preferably after temporary lowering of the rotor's speed and/or - setting a certain cutting speed, i.e. knife speed through the lignocellulosic material, by changing the rotor's speed, characterized in that - the generated comminuted lignocellulosic material is collected in a duct with a first opening at the knife's edge and which extends towards the rotor's centre and which then deflects towards the periphery of the rotor with its second opening in the rotational direction after the knife, and - the breadth and T dimension of the first opening is set by means of an adjustment device, in the form of a rod with a concentric cross section or a cross section with stepwise increasing height, said rod being enclosed in a holder for the wear plate, which is spring-loaded connected (32, 33, 34 and 35) to the holder, and the rod's outwardly facing side rests against the wear plate's inner side, and - said setting is achieved by turning the rod so that the wear plate is forced outwards or inwards depending on the turning direction, which rotational motion is automatic. - feeding the elongated lignocellulosic material to the drum chipper that consists of a stand carrying a horizontal and rotatable drum/rotor, the periphery of which has a plurality of knifes contained in knife holders as well as with every knife interacting radially adjustable wear plates positioned at a certain distance from the knife and its edge, and a space (37,38) for temporarily collecting the disintegrated lignocellulosic material, said space (37,38) being positioned between each knife and one or more anvil steels that interact(s) with each respective knife, said anvil steel(s) preferably being attached to the stand, and - intermittently or continuously analysing the outputted disintegrated lignocellulosic material primarily regarding its configuration in length, width and thickness, wherein - at least one process variable is changed during operation without stopping the drum chipper by - setting a certain chipping angle ( ε) by regulation of the input means' position vis-a-vis the rotor causing the fed elongated lignocellulosic material to approach and be brought towards the rotor at a certain angle and/or - setting a certain T dimension value corresponding to a distance between the knife's edge and the wear plate by changing the wear plate's radial distance from the rotor's centre, preferably after temporary lowering of the rotor's speed and/or - setting a certain cutting speed, i.e. knife speed through the lignocellulosic material, by changing the rotor's speed, characterized in that - the generated comminuted lignocellulosic material is collected in a duct with a first opening at the knife's edge and which extends towards the rotor's centre and which then deflects towards the periphery of the rotor with its second opening in the rotational direction after the knife, and - the breadth and T dimension of the first opening is set by means of an adjustment device, in the form of a rod with a concentric cross section or a cross section with stepwise increasing height, said rod being enclosed in a holder for the wear plate, which is spring-loaded connected (32, 33, 34 and 35) to the holder, and the rod's outwardly facing side rests against the wear plate's inner side, and - said setting is achieved by turning the rod so that the wear plate is forced outwards or inwards depending on the turning direction, which rotational motion is automatic.