Patent ID: 7543387

Claim:
A cutting unit for a plant cutting device such as an edge trimmer or a brush cutter, comprising: a plurality of cutting filaments, with each filament having a cross section defined by four flat intersecting faces, with at least two of the faces intersecting to define a toothed cutting edge and with at least two edges devoid of teeth, and a rotary cutting head comprising: (a) a generally cylindrical tubular drum which defines a central axis and includes a peripheral wall, said wall being provided with a plurality of axially extending slots, wherein said slots each comprise at least one side inclined at an angle between approximately 35° and approximately 55° relative to the horizontal and to the vertical, with each filament positioned to extend through at least one of the slots in an orientation wherein the toothed cutting edge faces circumferentially forward with respect to the central axis, and (b) a retaining member adapted to press the filament against said inclined side of the slot in such a manner that the filament is maintained in a position such that the toothed cutting edge of the filament constitutes the leading edge that engages the plants, and such that the two faces defining the toothed cutting edge slope back respectively upwards and downwards relative to the cutting edge.