Cutlery – Blades – Rotary
Patent
1985-12-05
1987-05-26
Peters, Jimmy C.
Cutlery
Blades
Rotary
56 127, 56295, A01D 5000
Patent
active
046674101
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a cutting head of the type set forth in the preamble of claim 1.
In cord or filament-type cutters there is the problem of adjustment of the filament length because in particular on striking stones, edges and the like the rotating filament is cut or worn. Hitherto it was necessary to adjust the filament length in that a coupling between the filament spool and housing of the cutting head was released by pressing a button, whereafter the filament could be pulled out radially.
It is also already known to carry out an adjustment without switching off the motor. According to Gardena this is solved by stepping on a foot button disposed on the upper side of the housing and effecting an unlocking. This greatly reduces the cutting height of the filament, which continues to operate, and brown cut areas in the lawn result.
It is further known (Toro) to strike the filament box against the ground, a button facing the ground thereby effecting unlocking. In this case as well difficulties similar to those in the aforementioned construction are encountered because the cut height is reduced.
However, in all known arrangements the unlocking must be actuated by hand or foot. The invention is therefore based on the problem of providing a filament-type cutter in which the adjustment of the filament takes place automatically without additional manipulation.
The problem set is solved by the features set forth in the characterizing clause of claim 1. According to the latter, on each switching on and off of the motor a short filament length is advanced, the dimensioning being such that account is taken of natural wear. If under particular conditions the filament should be greatly shortened by striking a sharp object, by repeated switching on and off of the motor the filament can be successively advanced and this represents a substantial simplification because it is not necessary to actuate additional controls. With some experience the necessity of adjustment can be detected by ear because the speed increases greatly when the filament length is reduced.
It has been found that this automatic adjustment should for each switching on and off lie in a range of about 5 mm in each case and that in this manner normal wear can be compensated. However, it is also to be possible with the invention to make the arrangement such that the speed of rotation depending on the filament length still available provides a measure for the advance of the filament and thus the advance takes place only when the filament length must indeed be adjusted.
An example of embodiment of the invention will be explained hereinafter with the aid of the drawings, wherein:
FIG. 1 is an axial section through a cutting head constructed according to the invention;
FIG. 2 is an axial section turned through 90.degree. with respect to FIG. 1, the axis of rotation of the cutting head being shown on the left in the rest position and on the right in the rotating position;
FIG. 3 is a schematic view of the cutting head constructed according to the invention of a filament-type cutter in the rest position;
FIG. 4 is a sectional view of the cutting head corresponding to FIG. 3 in the rotating position;
FIG. 5 is a schematic horizontal section of the cutting head according to FIGS. 3 and 4;
FIG. 6 is a development of the locking cam arrangement.
The cutting head 10 comprises according to FIGS. 1 and 2 a pot-shaped housing 14 which is integrally formed with a hollow hub 12 and which is closable by a cover 16 with a bayonet fastener 18. Said cover 16 faces the ground during cutting and comprises a central circular hole 20 through which the end face 22 of a sleeve 24 axially displaceable on the hub 12 is accessible. On the inside a pressure helical spring 26 bears axially on the end face 22 and the other end of said spring bears on a pin 28 which is inserted radially into the hub 12. The spring 26 lies in the cavity 30 of said hub 12. The sleeve 24 is provided on the outside with radially projecting locking teeth 32 which cooperate with inner locking teeth 34 (FIG
REFERENCES:
patent: 4104796 (1978-08-01), Sheldon
patent: 4138810 (1979-02-01), Pittinger
patent: 4183138 (1980-01-01), Mitchell et al.
patent: 4254550 (1981-03-01), Satoh
patent: 4285127 (1981-08-01), Zerrer
patent: 4347666 (1982-09-01), Moore
patent: 4352243 (1982-10-01), Lombard
patent: 4426780 (1984-01-01), Foster
patent: 4493151 (1985-01-01), Mitchell
patent: 4566189 (1986-01-01), Muto
Orthey Gebhard
Weid Helmut
Peters Jimmy C.
Wolf-Gerate GmbH
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