CA1093845A - Safety cutter blade assembly for a rotary trimmer - Google Patents
Safety cutter blade assembly for a rotary trimmerInfo
- Publication number
- CA1093845A CA1093845A CA320,197A CA320197A CA1093845A CA 1093845 A CA1093845 A CA 1093845A CA 320197 A CA320197 A CA 320197A CA 1093845 A CA1093845 A CA 1093845A
- Authority
- CA
- Canada
- Prior art keywords
- hub
- blade assembly
- drive shaft
- blade
- blades
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01D—HARVESTING; MOWING
- A01D34/00—Mowers; Mowing apparatus of harvesters
- A01D34/01—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus
- A01D34/412—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters
- A01D34/63—Mowers; Mowing apparatus of harvesters characterised by features relating to the type of cutting apparatus having rotating cutters having cutters rotating about a vertical axis
- A01D34/73—Cutting apparatus
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Environmental Sciences (AREA)
- Harvester Elements (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A safety cutter blade assembly for a rotary trimmer is provided herein. It includes a circular hub formed with a central opening for mounting it on the drive shaft of a rotary trimmer and three blades intergal therewith, and extending outwardly from the hub in equiangularly spaced relation. Each blade is formed with convex cutting edges, the inner end portion of which is tangential to the hub and a comparatively short straight cutting edge on the side of the blase opposite to that having the curved cutting edge. Either of these cutting edges is adapted to be effective when it is the leading edge as determined by the direction of rotation of the trimmer drive shaft and the position of the blade assembly relative thereto. The blade assembly is of rub-ber which may be reinforced by plastic fibers or layers of fabric. The blade thus has cutting edges in its opposite sides, with one cutting edge being particularly designed to cut long grass or weeds with a negative cutting action which throws the cut foliage outwardly away from the hub and trimmer drive shaft, while the cutter edge on the opposite side of the blade is designed to cut short grass with a positive cutting action.
A safety cutter blade assembly for a rotary trimmer is provided herein. It includes a circular hub formed with a central opening for mounting it on the drive shaft of a rotary trimmer and three blades intergal therewith, and extending outwardly from the hub in equiangularly spaced relation. Each blade is formed with convex cutting edges, the inner end portion of which is tangential to the hub and a comparatively short straight cutting edge on the side of the blase opposite to that having the curved cutting edge. Either of these cutting edges is adapted to be effective when it is the leading edge as determined by the direction of rotation of the trimmer drive shaft and the position of the blade assembly relative thereto. The blade assembly is of rub-ber which may be reinforced by plastic fibers or layers of fabric. The blade thus has cutting edges in its opposite sides, with one cutting edge being particularly designed to cut long grass or weeds with a negative cutting action which throws the cut foliage outwardly away from the hub and trimmer drive shaft, while the cutter edge on the opposite side of the blade is designed to cut short grass with a positive cutting action.
Description
313'~S
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This invention relates to a safety blade assembly for trimmers.
Rotary trimmers of the type with which ~he in~tant in~ention is concerned may be classified in three categories. One of Lhese classes is for brush cutters, a second ls for long grass or weeds and the ~hird is for short grass Drdinarily encountered by a lawn mower. The prior art references of which the present applicant is aware and which he believes comes closest to the subject invention are as follows: U.S. Patent Number 3,781,991 issued January 19 1974 to Stretton, et al is directed to a brush cutter, Brush is heavy material as compared to weeds or grass and because of this, the blade comprises a flat plate of steel. While other suitable materials are suggested a flexible materlal, e.g. rubDer or reinforced rub-ber would not be suitable for this purpose since it simply would not cut throu~h the heavy brush. Thus, tha safety factor inherent in a flexible blade is lost and this is of the utmost importance when it ls considered that`these trimmer blades rotate at high speed which, in present day times reach 6400 r.p.m.
While this patent discloses a blade assemhly comprising a central portion and hub from which three equiangularly spaced blades extend with each blade having oppositely disposed cutting edgesA The edges on each blade are allke in contour and dimension. There is no hint or suggestion that the cutting edge on one side is particularly adapted for cutting foliage of a certain type and the edge on the opposite side for cutting foliage of a different character. U.S. Patent Number 3,343,350 issued September 26, 1967 to Friedlander, et al is directed to a lawn mower blade.
It is of an elastomeric material, e.g. rubber or reinforced rubber and thus, provides the safety factor which,so important in a high speed rotary mower. Mowover, this patent depicts a blade assembly comprising a central portion or hub from which extend three equiangularly spaced blades~ Each of these blades has a leading edge that
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This invention relates to a safety blade assembly for trimmers.
Rotary trimmers of the type with which ~he in~tant in~ention is concerned may be classified in three categories. One of Lhese classes is for brush cutters, a second ls for long grass or weeds and the ~hird is for short grass Drdinarily encountered by a lawn mower. The prior art references of which the present applicant is aware and which he believes comes closest to the subject invention are as follows: U.S. Patent Number 3,781,991 issued January 19 1974 to Stretton, et al is directed to a brush cutter, Brush is heavy material as compared to weeds or grass and because of this, the blade comprises a flat plate of steel. While other suitable materials are suggested a flexible materlal, e.g. rubDer or reinforced rub-ber would not be suitable for this purpose since it simply would not cut throu~h the heavy brush. Thus, tha safety factor inherent in a flexible blade is lost and this is of the utmost importance when it ls considered that`these trimmer blades rotate at high speed which, in present day times reach 6400 r.p.m.
While this patent discloses a blade assemhly comprising a central portion and hub from which three equiangularly spaced blades extend with each blade having oppositely disposed cutting edgesA The edges on each blade are allke in contour and dimension. There is no hint or suggestion that the cutting edge on one side is particularly adapted for cutting foliage of a certain type and the edge on the opposite side for cutting foliage of a different character. U.S. Patent Number 3,343,350 issued September 26, 1967 to Friedlander, et al is directed to a lawn mower blade.
It is of an elastomeric material, e.g. rubber or reinforced rubber and thus, provides the safety factor which,so important in a high speed rotary mower. Mowover, this patent depicts a blade assembly comprising a central portion or hub from which extend three equiangularly spaced blades~ Each of these blades has a leading edge that
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is bevelled, whereby it i6 constituted a cutting edge. Both the leading and trailing edges may be bevelled to permit the blade to be turned upside down and used in the opposite d-lrection.
This patent is lacking in the blade having a long convex cutting -dge and any concept that a cutting edge on one side of the blade is adapted to perform a particular cut~ing operation and that on the opposite side, a diEferent cutting function.
U.S. Pa`rtent NulDber 3,343,355 issued September 26, 1967 to Friedlander~ et al is another example of lawn blade of a flexible elastomer-lc material and thus, provides the safety factor discussed. The blade assembly comprises a central portion or hub from which extend two arms or blades. Each arm has a leading edge. The leading edges being curved in the plane of cutting and being bevelled whereby they are constituted cut-ting edges. The trailing edges, that is the edges opposite to the bevelled edges are no~ bevelled or otherwise Eormed to impart to them the ability to functlon as cutting edges.
Other prior patents disclose mower blades made of an elastomeric material e.g. rubber or rubber reinforced by plas~ic fibers or fabric layers.
The known art of safety cutter blades for rotary trimmers is singularly lacking in a blade assembly comprising a hub from which a plurality of equiangularly blades extend and which are integral with the hub, with each blade having cutting edges on its opposite sides with one cutting edge being particularly designed to cut long grass or weeds with a negative cutting action which throws the cut foliage outwardly away from the hub and trimmer drive shaft, while the cutter edge on the opposite ~ide of the blade is designed to cut short grass with a positive cutting action.
, , With the foregoing conditions in mind, the present invention has in vièw the Eollowing ob~ectives of various aspects thereof:
1. To provide a safety blade assembly for a rotary trimmer com-prising a circular hub~ from which outstand a plurality of blades which are integral with the hub, with each blade having opposite sid~ edges, either of which may be the leading edge when the assembly is mounted on the drive shaft of a rotary trimmer and in which one side edge is designed to perform one c~t~ing function and the opposite side edge is designed to carry out a different cutting action.
2. To provide, in a safety blade assembly of the type noted, a plurality of blades each of which has a comparatively long cutting edge curved in the cutting plane and a relatlvely short straight cutting edge opposite to the curved edge;
3. To provide, in a safety blade assembly of the character aforesaid, three blades, equiangularly spaced apart and each blade of which has bevelled edges on opposite sides, constituting cutting edges;
is bevelled, whereby it i6 constituted a cutting edge. Both the leading and trailing edges may be bevelled to permit the blade to be turned upside down and used in the opposite d-lrection.
This patent is lacking in the blade having a long convex cutting -dge and any concept that a cutting edge on one side of the blade is adapted to perform a particular cut~ing operation and that on the opposite side, a diEferent cutting function.
U.S. Pa`rtent NulDber 3,343,355 issued September 26, 1967 to Friedlander~ et al is another example of lawn blade of a flexible elastomer-lc material and thus, provides the safety factor discussed. The blade assembly comprises a central portion or hub from which extend two arms or blades. Each arm has a leading edge. The leading edges being curved in the plane of cutting and being bevelled whereby they are constituted cut-ting edges. The trailing edges, that is the edges opposite to the bevelled edges are no~ bevelled or otherwise Eormed to impart to them the ability to functlon as cutting edges.
Other prior patents disclose mower blades made of an elastomeric material e.g. rubber or rubber reinforced by plas~ic fibers or fabric layers.
The known art of safety cutter blades for rotary trimmers is singularly lacking in a blade assembly comprising a hub from which a plurality of equiangularly blades extend and which are integral with the hub, with each blade having cutting edges on its opposite sides with one cutting edge being particularly designed to cut long grass or weeds with a negative cutting action which throws the cut foliage outwardly away from the hub and trimmer drive shaft, while the cutter edge on the opposite ~ide of the blade is designed to cut short grass with a positive cutting action.
, , With the foregoing conditions in mind, the present invention has in vièw the Eollowing ob~ectives of various aspects thereof:
1. To provide a safety blade assembly for a rotary trimmer com-prising a circular hub~ from which outstand a plurality of blades which are integral with the hub, with each blade having opposite sid~ edges, either of which may be the leading edge when the assembly is mounted on the drive shaft of a rotary trimmer and in which one side edge is designed to perform one c~t~ing function and the opposite side edge is designed to carry out a different cutting action.
2. To provide, in a safety blade assembly of the type noted, a plurality of blades each of which has a comparatively long cutting edge curved in the cutting plane and a relatlvely short straight cutting edge opposite to the curved edge;
3. To provide, in a safety blade assembly of the character aforesaid, three blades, equiangularly spaced apart and each blade of which has bevelled edges on opposite sides, constituting cutting edges;
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4. To provide, in a safety blade assembly of the kind described, blades having convex cutting edges, the inner ends of which are tangential to the circular hub;
4. To provide, in a safety blade assembly of the kind described, blades having convex cutting edges, the inner ends of which are tangential to the circular hub;
5. To provide, in a safety blade assembly of the type noted, a hub having a central aperture and a bushing positioned in said aperture whereby the hub is adapted to be mounted on the drive shafts of rotary trim-mers of different diameters;
6. To p~ovide, ln a safety blade assembly of the character aforesaid, a hub and a plurality of blades, outstanding therefrom9 ~hich are of a flexible elastomeric material; and
7. To provide, in a safety blade assembly of the kind described, a plurality of blades, each of which has scored lines in parallel spaced relation on its outer end portion, which facilitate breaking off a portion of the blade to achieve a required length thereof.
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By one broad aspect of this invention, aD improvemellt is provided in a safety blade assembly for trimmers, includlng a drive shaft that ro-tates in one direction, (a) a hub in the Eorm of a disc and of a flexible material; ~b) a plurality of blades integral and coplanar with the hub and extending outwardly therefrom in equiangularly spaced relation, (c) means on the hub for mounting it on the drive shaft; (d) a convex cutting edge on one side of each of the blades that is comparatively long; and (e) a cvm-paratively short s~tralght cutting edge on the side of each blade opposite to the side having the convex edge; whereby the hub may be mounted on the drive shaft in one position to render it with the convex cutting edge effec-tive to cut long grass and weeds with a negative action, and in a reversed position to bring the short straight edge into effective position to cut short grass with a positive action.
By one variant thereof, there are three such blades.
By another variant, the hub has a periphery and the convex cut-ting edge of each blade an inner end portion tangential to the periphery of the hub.
By still another variant, the means on the hub for mounting it in a drive shaft takes the form of an aperture at the center oE the hub By a variation thereof, the safety blade includes a bushing re movably positioned in the aperture, whereby one hub is adapted to be moun-ted on drive shafts of different diameters.
By yet another variant, the cutting edges are defined by bevelled surface.
By variations thereof, the bevelled surfaces are parallel to each other; or converge to provide a frustroconical structure.
By yet another variant, each of the blades has-a plurality of parallel scored lines in the region adjacent to its outer end with the scored lines identifying sections which may be removed by breaking off at a scored line.
.... . . ~ . ,: ~ .
Accordingly by an exemplary aspect of this invention safety blade assembly is provided of a flexible elastomeric material, e.g~ rub-ber, which may be reinforced by plastic fibers or fabric fibers, and which comprises a hub in the form of a circular disc having a central aperture for mounting the hub on the drive shaft of a rotary trimmer. A bushing may be detachably positioned in this aperture to adapt the hub to flt on drive shafts of different dimensions.
Integral with and extending outward:Ly from the hub and coplanar therewith, are three blades egulangularly spaced apart. Each of these blades has a comparatively long convex cutting edge on one side, the inner end portion of which is tangential to the hub~ This cutting edge is in-tended to operate on long grass or weeds with a negative cutting action, which throws foliage outwardly and away from the drive shaft of the trimmer. ~ relatively short straight cutting edge is formed on the opposite side of ~he blades. This cutting edge functions with a positive cutting action on shor~ grass such as is ordinarily found on lawns.
Both of the cutting edges take the form of bevelled surfaces on the respective side edges. In one embodiment, these bevelled surfaces are parallel to each other while in another species they converge to de-fine a frusto-conical blade structure. Each blade is scored along spaced parallel lines in the region ad~acent to its outer end to define sections which may be easily broken off to achieve a required length of the blades.
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~3~5 In the accompanying drawings, Figure 1 is a perspective of a safety blade assem~ly for a rotary tri~mer embodying the precepts of an aspect of the present invention, Figure 2 is a plan view taken on a large scale of the blade assembly;
Figure 3 is a section taken about Oll the plane of the lines 3-3 of Figure 2, Figure 4~is a transverse section through the end of a blade~
being taken about on the plane of l~ne 4-4 of Figure 2;
Figure 5 is a sectional view similar to Figure 4 of a modified blade structure of another aspect of this invention; and Figure 6 is a perspective depicting a portion of the hub and the bushing which is removably positioned relative thereto in exploded rela-tion.
Referring now to the drawings, wherein like reference characters represent corresponding parts and first, more particularly to Figures 1 and ~, a safety blade assembly made on principles of an aspect of this in-vention is identified ill its entirety by the reference character 10.
Blade assembly 10 includes a hub 11 in the form of a disc having a circu-lar periphery 12, and a central aperture 13. The latter constitutes ameans for mounting the hub 11 on the drive shaft of a rotary trimmer. In-asmuch as rotary trimmers of the type with which aspects of this invention is concerned are well known and include drive shafts, it is deemed un-necessary to encumber the drawing and specification with an illustration and description of the trimmer and its rotary shaft.
Drive shafts for trimmers ordinarily come in two diametric sizes.
To adapt the hub 11 for mounting on drlve shafts of two different diame-ters a bushing 14, is removably positioned in aperture 13.
'' , ' 1,, ~ , . ',; .. , '~ ~ ,' , ~D3~5 Three blades, 15, 16 and 17 are for~ed integrally with hub ll and are coplanar therewith. They are equiangularly spaced about hub ll from which they outstand. Moreover, hub 11 and blades 15~ 16 and 17 are of a flexible elastomeric material e.g., rubber which may be reinEorced by plastic fibers and fabric layers. As these blades 15, 16 and 17, are all al-lke, only one of them is herein described in detail. Thus, blade 16 has a comparatively long convex cutting edge 18, the inner portion of which is tangential to the periphery 12 of hub 11, as shown at 19. The opposite side of blade 16 is formed wi th a relatively short straight cut-ting edge 20.
In one embodiment, cutting edges 18 and 20 are defined by be-velled surfaces 21 and 22, whlch are substantially parallel to one another as illustrated in Figure ~. In the modified embodiment oE Figure 5, ~hey are defined by bevelled surfaces 23 and ~, which converge and as illus-trated in Figure 5, cooperate with the body of blade 16 to define a frustro-conical blade struc~ure.
Trimmers of different sizes require blades of various lengths.
As produced by the manufacturers, they will all be of the same standard length as shown in Figure 2. However, each blade 15, 16 and 17, is scored along lines 25 in the region ad~acent to its outer end to define sections 2~, any of wh:Lch may be removed by breaking off along a weakened score line 23.
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, . .
38~;
While the manner in which the sub~ect safety blade assembly of aspects of thls invention operates i5 believed to be obvious from the illustration of the drawing and description of parts set forth above, it is briefly outlined as follows:
The drive shaft in which blade assembly 10 is mounted will always rota~e in the same direction. Assuming ~his direction is counter-clockwise, speaking with reference to Figure 2 and with the assembly 10 mounted on the drive shaft as illustrated, cutting edge 18 is the leading edge. It is designed to cut long grass and weeds with a negative action.
This means that not only is the edge 18 engaged with the foliage with a wiping or slicing action which not only facilitates cutting but the cut ; foliage is thrown outwardly and away from hub 11 and the drive shaft on which it is mounted. Thus, wrapping or winding of the cut foliage about the drive shaft or any part of the trimmer is obviated.
When short grass e.g., as is usually present on lawns is to be cut, the assembly 10 is removed from the drive shaft, its position there-on reversed whereupon it is again mounted on the drive shaft in a position in which cutting edge 20 becomes the leading edge and cuts the grass with a positive action; as the cut foliage in this case is short, there is no danger of it becoming entangled in the trimmer.
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. ., "
;, . . ~ .
, , ", ~ ' ~ , ' ' ' . .
3~
By one broad aspect of this invention, aD improvemellt is provided in a safety blade assembly for trimmers, includlng a drive shaft that ro-tates in one direction, (a) a hub in the Eorm of a disc and of a flexible material; ~b) a plurality of blades integral and coplanar with the hub and extending outwardly therefrom in equiangularly spaced relation, (c) means on the hub for mounting it on the drive shaft; (d) a convex cutting edge on one side of each of the blades that is comparatively long; and (e) a cvm-paratively short s~tralght cutting edge on the side of each blade opposite to the side having the convex edge; whereby the hub may be mounted on the drive shaft in one position to render it with the convex cutting edge effec-tive to cut long grass and weeds with a negative action, and in a reversed position to bring the short straight edge into effective position to cut short grass with a positive action.
By one variant thereof, there are three such blades.
By another variant, the hub has a periphery and the convex cut-ting edge of each blade an inner end portion tangential to the periphery of the hub.
By still another variant, the means on the hub for mounting it in a drive shaft takes the form of an aperture at the center oE the hub By a variation thereof, the safety blade includes a bushing re movably positioned in the aperture, whereby one hub is adapted to be moun-ted on drive shafts of different diameters.
By yet another variant, the cutting edges are defined by bevelled surface.
By variations thereof, the bevelled surfaces are parallel to each other; or converge to provide a frustroconical structure.
By yet another variant, each of the blades has-a plurality of parallel scored lines in the region adjacent to its outer end with the scored lines identifying sections which may be removed by breaking off at a scored line.
.... . . ~ . ,: ~ .
Accordingly by an exemplary aspect of this invention safety blade assembly is provided of a flexible elastomeric material, e.g~ rub-ber, which may be reinforced by plastic fibers or fabric fibers, and which comprises a hub in the form of a circular disc having a central aperture for mounting the hub on the drive shaft of a rotary trimmer. A bushing may be detachably positioned in this aperture to adapt the hub to flt on drive shafts of different dimensions.
Integral with and extending outward:Ly from the hub and coplanar therewith, are three blades egulangularly spaced apart. Each of these blades has a comparatively long convex cutting edge on one side, the inner end portion of which is tangential to the hub~ This cutting edge is in-tended to operate on long grass or weeds with a negative cutting action, which throws foliage outwardly and away from the drive shaft of the trimmer. ~ relatively short straight cutting edge is formed on the opposite side of ~he blades. This cutting edge functions with a positive cutting action on shor~ grass such as is ordinarily found on lawns.
Both of the cutting edges take the form of bevelled surfaces on the respective side edges. In one embodiment, these bevelled surfaces are parallel to each other while in another species they converge to de-fine a frusto-conical blade structure. Each blade is scored along spaced parallel lines in the region ad~acent to its outer end to define sections which may be easily broken off to achieve a required length of the blades.
" . . , . ~ . .
~3~5 In the accompanying drawings, Figure 1 is a perspective of a safety blade assem~ly for a rotary tri~mer embodying the precepts of an aspect of the present invention, Figure 2 is a plan view taken on a large scale of the blade assembly;
Figure 3 is a section taken about Oll the plane of the lines 3-3 of Figure 2, Figure 4~is a transverse section through the end of a blade~
being taken about on the plane of l~ne 4-4 of Figure 2;
Figure 5 is a sectional view similar to Figure 4 of a modified blade structure of another aspect of this invention; and Figure 6 is a perspective depicting a portion of the hub and the bushing which is removably positioned relative thereto in exploded rela-tion.
Referring now to the drawings, wherein like reference characters represent corresponding parts and first, more particularly to Figures 1 and ~, a safety blade assembly made on principles of an aspect of this in-vention is identified ill its entirety by the reference character 10.
Blade assembly 10 includes a hub 11 in the form of a disc having a circu-lar periphery 12, and a central aperture 13. The latter constitutes ameans for mounting the hub 11 on the drive shaft of a rotary trimmer. In-asmuch as rotary trimmers of the type with which aspects of this invention is concerned are well known and include drive shafts, it is deemed un-necessary to encumber the drawing and specification with an illustration and description of the trimmer and its rotary shaft.
Drive shafts for trimmers ordinarily come in two diametric sizes.
To adapt the hub 11 for mounting on drlve shafts of two different diame-ters a bushing 14, is removably positioned in aperture 13.
'' , ' 1,, ~ , . ',; .. , '~ ~ ,' , ~D3~5 Three blades, 15, 16 and 17 are for~ed integrally with hub ll and are coplanar therewith. They are equiangularly spaced about hub ll from which they outstand. Moreover, hub 11 and blades 15~ 16 and 17 are of a flexible elastomeric material e.g., rubber which may be reinEorced by plastic fibers and fabric layers. As these blades 15, 16 and 17, are all al-lke, only one of them is herein described in detail. Thus, blade 16 has a comparatively long convex cutting edge 18, the inner portion of which is tangential to the periphery 12 of hub 11, as shown at 19. The opposite side of blade 16 is formed wi th a relatively short straight cut-ting edge 20.
In one embodiment, cutting edges 18 and 20 are defined by be-velled surfaces 21 and 22, whlch are substantially parallel to one another as illustrated in Figure ~. In the modified embodiment oE Figure 5, ~hey are defined by bevelled surfaces 23 and ~, which converge and as illus-trated in Figure 5, cooperate with the body of blade 16 to define a frustro-conical blade struc~ure.
Trimmers of different sizes require blades of various lengths.
As produced by the manufacturers, they will all be of the same standard length as shown in Figure 2. However, each blade 15, 16 and 17, is scored along lines 25 in the region ad~acent to its outer end to define sections 2~, any of wh:Lch may be removed by breaking off along a weakened score line 23.
: :
,, :: . . . .
, . .
38~;
While the manner in which the sub~ect safety blade assembly of aspects of thls invention operates i5 believed to be obvious from the illustration of the drawing and description of parts set forth above, it is briefly outlined as follows:
The drive shaft in which blade assembly 10 is mounted will always rota~e in the same direction. Assuming ~his direction is counter-clockwise, speaking with reference to Figure 2 and with the assembly 10 mounted on the drive shaft as illustrated, cutting edge 18 is the leading edge. It is designed to cut long grass and weeds with a negative action.
This means that not only is the edge 18 engaged with the foliage with a wiping or slicing action which not only facilitates cutting but the cut ; foliage is thrown outwardly and away from hub 11 and the drive shaft on which it is mounted. Thus, wrapping or winding of the cut foliage about the drive shaft or any part of the trimmer is obviated.
When short grass e.g., as is usually present on lawns is to be cut, the assembly 10 is removed from the drive shaft, its position there-on reversed whereupon it is again mounted on the drive shaft in a position in which cutting edge 20 becomes the leading edge and cuts the grass with a positive action; as the cut foliage in this case is short, there is no danger of it becoming entangled in the trimmer.
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Claims (9)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a safety blade assembly for trimmers, including a drive shaft that rotates in one direction, (a) a hub in the form of a disc and of a flexible material;
(b) a plurality of blades integral and coplanar with said hub and extending outwardly therefrom in equiangularly spaced relation;
(c) means on said hub for mounting it on said drive shaft;
(d) a convex cutting edge on one side of each of said blades that is comparatively long, and (e) a comparatively short straight cutting edge on the side of each blade opposite to the side having the convex edge;
whereby the hub may be mounted on the drive shaft on one position to render it with the convex cutting edge effective to cut long grass and weeds with a negative action, and in a reversed position to bring said short straight edge into effective position to cut short grass with a positive action.
(b) a plurality of blades integral and coplanar with said hub and extending outwardly therefrom in equiangularly spaced relation;
(c) means on said hub for mounting it on said drive shaft;
(d) a convex cutting edge on one side of each of said blades that is comparatively long, and (e) a comparatively short straight cutting edge on the side of each blade opposite to the side having the convex edge;
whereby the hub may be mounted on the drive shaft on one position to render it with the convex cutting edge effective to cut long grass and weeds with a negative action, and in a reversed position to bring said short straight edge into effective position to cut short grass with a positive action.
2. The safety blade assembly of Claim 1 in which there are three of said blades.
3. The safety blade assembly of Claim 1, in which the hub has a periphery and the convex cutting edge of each blade an inner end portion tangentlal to the periphery of said hub.
4. The safety blade assembly of Claim 1, in which the means on the hub for mounting it in a drive shaft takes the form of an aperture at the center of said hub.
5. The safety blade assembly of Claim 4, together with a bushing removably positioned in said aperture, whereby one hub is adapted to be mounted on drive shafts of different diameters.
6. The safety blade assembly of Claim 1 in which said cutting edges are defined by bevelled surface.
7. The safety blade assembly of Claim 6, in which said bevelled surfaces are parallel to each other.
8. The safety blade assembly of Claim 6, in which the bevelled surfaces converge to provide a frustro-conical structure.
9. The safety blade assembly of Claim 1, in which each of said blades has a plurality of parallel scored lines in the region adjacent to its outer end with the scored lines identifying sections which may be removed by breaking off at a scored line.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US91916478A | 1978-06-26 | 1978-06-26 | |
| US919,164 | 1978-06-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1093845A true CA1093845A (en) | 1981-01-20 |
Family
ID=25441621
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA320,197A Expired CA1093845A (en) | 1978-06-26 | 1979-01-24 | Safety cutter blade assembly for a rotary trimmer |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JPS553790A (en) |
| CA (1) | CA1093845A (en) |
| DE (1) | DE2922013A1 (en) |
| FR (1) | FR2429551A1 (en) |
| GB (1) | GB2023390B (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55151129U (en) * | 1979-04-19 | 1980-10-31 | ||
| JPS55152937U (en) * | 1979-04-19 | 1980-11-04 | ||
| FR2498884A1 (en) * | 1981-01-30 | 1982-08-06 | Courtois Michel | Cutter for tree pruner - comprises rigid planar radial arms with two blades along each leading edge and cutting teeth on tips |
| DE8513596U1 (en) * | 1985-05-08 | 1985-06-27 | Bayerische und Tiroler Sensen-Union GmbH, 8203 Oberaudorf | Cutting device for lawn trimmers |
| AU1183988A (en) * | 1987-01-23 | 1988-08-10 | Paul Richard Adcock | Blade for rotary lawnmowers and the like |
| US5620055A (en) * | 1989-05-02 | 1997-04-15 | Javerlhac Jean C | Plow disk of the type intended to be mounted free in rotation on a shaft integral with the frame of a plow |
| US5495897A (en) * | 1989-05-02 | 1996-03-05 | Javerlhac Jean C | Plow disk of the type intended to be mounted free in rotation on a shaft integral with the frame of a plow |
| US5287686A (en) * | 1992-08-14 | 1994-02-22 | Lindsay David P | Anti-scalping blade for rotary lawn mower |
| US6467246B1 (en) * | 1999-03-24 | 2002-10-22 | Deere & Company | Knife section having breakage holes |
| US6470662B1 (en) | 2000-10-31 | 2002-10-29 | Terry A. Burke | Multiple blade cutting apparatus for rotary lawn mower |
| US6938402B2 (en) | 2002-11-01 | 2005-09-06 | Deere & Company | Mowing blades having an impact energy absorbing structure |
| CN104472239B (en) * | 2014-11-26 | 2016-05-11 | 济南大学 | A kind of clipping device |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1115677A (en) * | 1954-12-02 | 1956-04-27 | Lawn mower | |
| GB977308A (en) * | 1959-12-31 | 1964-12-09 | Bisset & Sons Ltd J | Cutter for a digger for root crops |
| US3087298A (en) * | 1960-08-19 | 1963-04-30 | Sr Walter J Phillips | Rotary mower blade |
| FR92900E (en) * | 1966-09-14 | 1969-01-10 | Dayco Corp | Mower blade, especially for lawns. |
| US3563015A (en) * | 1968-05-21 | 1971-02-16 | Charlie C Renfroe | Rotary lawnmower cutter bar |
| US3781991A (en) * | 1971-09-17 | 1974-01-01 | Textron Inc | Brush cutter |
| US3911652A (en) * | 1974-01-11 | 1975-10-14 | Houle Elmer Richard | Safety blade for rotary lawn mowers |
-
1978
- 1978-12-05 GB GB7847203A patent/GB2023390B/en not_active Expired
- 1978-12-26 JP JP16445678A patent/JPS553790A/en active Pending
-
1979
- 1979-01-24 CA CA320,197A patent/CA1093845A/en not_active Expired
- 1979-01-30 FR FR7902325A patent/FR2429551A1/en active Granted
- 1979-05-30 DE DE19792922013 patent/DE2922013A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| JPS553790A (en) | 1980-01-11 |
| FR2429551A1 (en) | 1980-01-25 |
| FR2429551B1 (en) | 1984-01-06 |
| GB2023390A (en) | 1980-01-03 |
| DE2922013A1 (en) | 1980-01-10 |
| GB2023390B (en) | 1982-08-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |