Earth working – Lawn edger – Rolling or driven cutter
Reexamination Certificate
2002-06-03
2004-02-10
Pezzuto, Robert E. (Department: 3671)
Earth working
Lawn edger
Rolling or driven cutter
C172S017000
Reexamination Certificate
active
06688404
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a portable handheld edge cutter especially for lawn cutting.
BACKGROUND OF THE INVENTION
In a work apparatus of this kind, a cutterhead is mounted at one end of a guide tube and an internal combustion engine is mounted at the other end of the guide tube. The engine is connected to a cutter blade via drive means in the guide tube and in the cutterhead. The cutter blade is mounted for rotation about an axis lying parallel to the ground during the cutting operation and is guided along the edge with the cutterhead. Such edge cutters with perpendicularly cutting blades are also known as edgers.
U.S. Pat. No. 4,364,435 discloses a lawn edger wherein a guide wheel is provided on the end of the cutterhead facing toward the internal combustion engine. The cutterhead is movable over the ground with the aid of the guide wheel. The guide wheel or roller is mounted at the rearward end of the cutterhead and aids the operator in maintaining a uniform cutting depth. On the one hand, the operator carries the edge cutter including the engine and, on the other hand, guides the cutterhead.
A light construction is desirable especially for edge cutters of the above kind which are carried by the operator.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an edge cutter of the kind described above which is improved so that the service life of the edge cutter is increased while at the same time providing lower manufacturing costs.
The portable handheld edge cutter for edging a lawn or cutting turf includes: a drive motor; a cutterhead; a guide tube having a first end connected to the drive motor and a second end connected to the cutterhead; the cutterhead including a gear case having a drive shaft disposed transversely to the guide tube and approximately parallel to the ground; drive means disposed in the guide tube for connecting the drive motor to the drive shaft in the gear case; the drive shaft protruding at one end thereof from the gear case; a cutter blade mounted on the drive shaft at the one end thereof so as to be driven by the drive shaft for lawn edging or turf cutting; a guide wheel mounted between the drive motor and the gear case to facilitate rolling the cutterhead over the ground; the guide wheel defining a first rotational axis lying approximately parallel to the drive shaft; spacer means mounted on the cutterhead so as to be in contact engagement with the ground; the gear case having a side facing away from the cutter blade; the gear case having a support lug on the side thereof lying approximately coaxially with the drive shaft; a spacer wheel rotatably mounted on the support lug so as to define a second rotational axis; and, the first and second rotational axes being spaced from each other at a distance (z) viewed in the work direction of the edge cutter.
According to a feature of the invention, the cutterhead is provided with spacer means approximately at the elevation of the drive axis of the cutter blade. The spacer means project forward from the cutterhead. During operation of the edge cutter, the spacer means is placed on the ground and the cutterhead itself has no contact with the ground. In this way, a reliable guidance of the cutterhead and cutter blade along the edge to be trimmed is ensured. At the same time, the housing of the cutterhead is protected against wear.
The spacer means is configured as a wheel whereby no greater force is needed when guiding the tool along the edge. The additional spacer wheel lies at a distance to the guide wheel and stabilizes guiding the cutterhead along the edge. The spacer wheel is mounted on the side of the cutterhead facing away from the cutter blade and therefore rolls outside of or away from the ground region to be cut.
An advantageous position for the spacer wheel is when the spacer wheel is mounted for rotation at the elevation of the drive shaft of the cutter blade. In this way, a compact configuration of the cutterhead is achieved. The diameter of the spacer wheel is greater than the radial spacing of the bottom region of the cutterhead from the drive shaft. The spacer wheel can be held advantageously on a support lug formed on the gear housing.
In an alternate embodiment, the spacer for the cutterhead is configured as a skid which is placed with its running surface on the ground during operation of the edge cutter. The skid then protects the housing of the cutterhead against contact with the ground and from deterioration caused by wear.
A gear unit is mounted between the blade shaft and the drive shaft of the engine in the region of the cutterhead, which is spaced from the ground, and is therefore protected. The cutterhead housing advantageously comprises several joinable housing parts. The housing part, which is the lower housing part during operation, is configured as one piece with the skid. The housing part, which is configured with the skid, can be advantageously attached to the housing as a separate component. The part of the skid element defining the interior of the housing is formed to accommodate bearings for the blade shaft or the parts of the gear assembly.
REFERENCES:
patent: 2708335 (1955-05-01), Newton
patent: 3946815 (1976-03-01), Ajdukovic
patent: 4364435 (1982-12-01), Tuggle et al.
patent: 5263303 (1993-11-01), Stroud
patent: 5325928 (1994-07-01), Wagster et al.
patent: 5383330 (1995-01-01), Yokocho et al.
patent: 5402627 (1995-04-01), Trompler et al.
patent: 5407012 (1995-04-01), Klopfer
patent: 5826667 (1998-10-01), Notaras et al.
patent: 6092608 (2000-07-01), Leger
patent: 6116350 (2000-09-01), Notaras et al.
Rosskamp Heiko
Strodthoff Claus
Uhl Klaus-Martin
Andreas Stihl AG & Co.
Florio Kristine
Ottesen Walter
Pezzuto Robert E.
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