Abstract: A rotor for use in a disintegrating machine comprises a rotor body adapted to be rotated about its axis and provided at its periphery with a plurality of receptacles extending parallel to the axis, each receptacle having on one side an opening facing in the direction of rotation. The rotor further comprises a plurality of beater bars, each of which has a bar body extending in a direction which is parallel to the axis and has a symmetrical cross-section. Each bar body has at least one retaining extension supported in a respective receptacle, has a longitudinal plane of symmetry extending in a direction which is substantially parallel to a tangent to a flight circle defined by an outer periphery of the bar bodies of the beater bars upon rotation of the rotor body, and is provided with axially spaced apart knife edges which protrude at the periphery to be contiguous to the flight circle, are symmetrical to the plane of symmetry and extend in planes which are normal to the axis.