A brush cutter in more powerful version usually brush cutters , in the weaker as grass trimmers or lawn trimmers called (in Switzerland also dish Sense ) is a motor-driven device for mowing of grass , herbaceous plants or woody undergrowth . If equipped with a circular saw blade, more powerful devices can also be used to cut smaller trees up to about seven centimeters in diameter, for example when thinning . Due to the comparatively low area coverage, it is used for mowing in commercial applications where larger devices such as bar mowers or mulchers cannot be used due to a slope, poor accessibility, confinement or obstacles or insufficient soil load- bearing capacity . As drive serve at less powerful brushcutter partially electric motors , but weight-saving constructed, moreover, two or four-stroke - Gasoline Engines kW to about 4 performance.
Function and structure
The principle of operation is the same for the brushcutter and the brushcutter: A shaft is driven by the motor, partly via a gearbox, a rapidly rotating cutting tool, which cuts the material to be mowed using the so-called free-cut process without a counter blade. Various systems are used as cutting tools, either one or more robust nylon threads mounted on a thread head , discs with plastic blades as knives or knife discs (steel or aluminum) or circular saw blades. On less powerful brushcutters there is usually only one line head as a cutting tool.
In the case of small, less powerful machines, the motor is located directly above the mower head, but in the case of more powerful machines it is usually as a counterweight at the upper end of the scythe handle. Smaller devices are held by a handle construction, larger devices also have a shoulder strap or a harness that can be worn around the neck. There are also devices available in which the motor on a guide on the device to be worn Kraxe is mounted and the cutting head about a partially flexible shaft is driven.
The knife disc of a brushcutter can have different shapes depending on the area of application: double-edged double knife ("grass cutting blade") for light use when mowing grass, star-shaped knives ("thicket knife") for mowing matted grass or undergrowth or circular saw blades for removing wood towards thin trees.
The pieces of thread fastened in a thread head or rolled up on a spool are tensioned by centrifugal force during operation and knock off the blades of grass. They have the advantage of adapting to obstacles (stones, walls, trees); Tree bark or walls are less damaged if they are accidentally touched, and you can mow right up to the object. However, sensitive or thin bark is destroyed, which can lead to the death of the trees.
In contrast to the knife disks, the threads are very easy to replace: if the end of the thread is worn out, either a new piece is inserted or the thread is simply pulled further out of the bobbin in the thread head. With many brushcutters, pulling the line is made easier by a semi-automatic mechanism. You knock the mower head on the ground and gently accelerate. By knocking on the floor, a large button is pressed in, which releases the thread so that another piece of the wound thread is pulled out of the head by centrifugal force.
The devices should only be operated with the appropriate safety equipment:
- For grass trimmers: sturdy shoes
- For brushcutters: thread cover, protective goggles , sturdy shoes
- For brushcutters: knife cover, safety glasses, hearing protection , cut protection suit , gloves , safety shoes .
Because of the stones thrown around or the like. In accordance with the regulations of the German trade associations, no one except the machine operator is allowed to stay in the vicinity (15 m) of the working machine.
The mowing lines wear out with use and remain in the meadow. Conventional mowing lines consist mainly of nylon, which hardly decomposes and thus contributes to the problem of microplastics . At least one manufacturer offers an oxo- (biodegradable) plastic mowing line, which should decompose (completely) in the wild within 5 to 10 years.
- Horst Eichhorn (Ed.): Landtechnik . 7th edition, Ulmer, Stuttgart 1952/1999, ISBN 3-8001-1086-5 , p. 427.
- Ulrich Sachweh (ed.): The gardener, Volume 3, tree nursery, fruit growing, seed growing, vegetable growing . 2nd edition, Ulmer, Stuttgart 1986/1989, ISBN 3-8001-1148-9 , p. 20 f.
- Information brochure "Forest work" of the Arge der Landwirtschaftlichen Berufsgenossenschaften, Kassel 1999, p. 16.
- http://www.oregonproducts.de/de/biotrimtm/back-to-nature.html .