Abstract: In a forage harvester, a plurality of spaced knife supports are angularly spaced apart around the periphery of a rotatable cutter drum. A straight beater bar is displaceably fixed to each knife support so that the beater bars have an impact edge which rotates past a counterknife at the inlet of the harvester. The side surfaces of the beater bars leading in the direction of rotation are disposed at a slight angle to the side surfaces of the counterknife. The beater bars are spaced apart at about 15 to 20 degrees relative to the axis of rotation of the cutter drum and the dimension of the overall arrangement is such that the spacing between impact edges of adjacent beater bars is about 60 to 100 mm.