Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DISC AND KNIFE CUTTER ASSEMBLY FOR MOWING
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to cutter members and
assemblies for cutting machines, particularly rotary
cutting machines, and more particularly to cutting as-
semblies having a plate or a disk and a plurality of
knife members mounted therewith, particularly for use
for lawn maintenance and more particularly for use in
operations to provide commercial lawn-care maintenance.
Description of the Art
Lawnmower assemblies long have been and most com-
monly are constructed with a elongated bar, or arm,
member Which extends substantially linearly and is
connected at an end-to-end and side-to-side mid-point to
a rotatable means, such as is known as a spindle, which
is integrated with means for providing motive driving
force. In these mowers, which are known as rotary
mowers, the bar member terminates at its opposing ends
with beveled longitudinally-extending portions which
provide cutting edges. In lawnmower models employed by
the home-owner, such, as. push-type and walk-behind mow-
ers, driving force is' applied to rotatable means, again
such as a spindle, directly by a motor. In larger-
capacity, so-called riding mowers, including those
employed by the home-owner and by those engaged in
supplying lawn-care services commercially, means for
rotating the cutting bar includes such as a spindle and
also pulley and belt means interconnected with motor
motive driving force.
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Although mowers having one or more cutting bar mem-
bers provide a generally reliable construction and gen-
erally satisfactory aesthetic results at acceptable
cost, the cutting capacity of these mowers is limited by
motor power which, for example, in cases wherein the
grass is particularly thick, or dense, and/or in excess
of about 3 inches, limits mower ground-speed. Thus, to
avoid what is known as over-driving, i.e., a ground-
speed at which the rotational speed of the cutter bar
member capacity is insufficient to cut the grass cleanly
and/or to avoid dragging down the motor, slower ground
speeds must be employed to avoid matting of at least
some grass, such as due to a lack of lift, and an uneven
cut. So, too, when such mowing devices turn a corner,
cutting effectiveness is substantially diminished and
grass is inevitably cut unevenly.
Additionally, a further distinctive result of using
such mowers is that the apparent color of the cut lawn,
when viewed particularly from a distance, differs. That
is, a cut made in one ground-travel direction presents a
perception of color different from the apparent color of
cuts made in different ground-travel directions, in that
the cuts present dark/light contrast.
In addition to concerns of cutting capacity and
aesthetics, of particular concern in the commercial
lawn-care business, wherein mowers are employed for a
plurality of hours each day, as opposed to only once
every 10 to 14 days by a home-owner, is wear and tear
and cost of maintenance. In general, it is not uncom
mon, even with lawns which are frequently maintained,
to have to sharpen even the highest quality blades
available, at least, on an average of after 20 to 30
hours of mowing time which, in a commercial operation,
as will be appreciated, can lead to down-time, and care
must be taken during sharpening to avoid the blades from
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becoming out of balance which can lead to other machine-
part wear and tear.
Furthermore, in general, even the best blades
available can be sharpened on the order of, at most,
only about 10 to 15 times before they must be replaced,
and although cutting bar member blades are available
Which have four cutting edges, i.e., opposing cutting
edges at each end, so that they may be reversed to ex-
tend their useful life, blade replacement is not an in-
expensive proposition. So, too, blade replacement may
be necessitated by striking an object such as a rock,
and much effort has been devoted in the art to minimize
this problem.
Efforts in the mowing~art to at least reduce, if
not avoid, the consequences of blade damage upon en-
countering an obstruction extend back at least 50 years.
Chadwick, U.S. Patent No. 2,916,867, for example, dis-
closes one such effort Wherein a cutting member blade is
mounted movably pivotally to each end of a bar member so
that in operation, the blades are thrust into and main-
tained in a cutting position by centrifugal force, and
if an obstruction is struck, the affected blades)
yields) to minimize damage.
Others have suggested construction of a cutting
assembly wherein a plurality of blades are mounted
pivotally to and extend from a disk member so that,
again, upon rotation of the disk, these blades aze
thrust and maintained in a cutting position by operation
of centrifugal force and so that if an obstruction is
encountered, the affected blades) yields) to minimize
damage, as illustratively shown by Cauble, U.S. Patent
No. 2,529,797.
As the art also shows, however, the lift and/or
throw provided by disk and cutting member designs was
less than satisfactory. Thus, to address the problem,
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Kirk, U.S. Patent No. 3,320,733, proposed a blade con-
struction which has a flat blade surface and an upturned
trailing edge "impeller" portion for driving cuttings
out a mower housing chute portion. So, too, seeking to
improve upon prior blade design such as Kirk discloses.
Lindblad, U.S. Patent No. 4,214,426, presents disclosure
of a blade structure which also has a concave and convex
shape to manipulate air flow further.
Another assembly along the lines of Kirk with a
trailing edge impeller/deflector member is that dis
closed in Goserud, U.S. Patent No. 3,715,874, which also
includes disclosure of a blade configuration wherein the
blade end is rounded and downwardly turned and angled,
Which is said to operate to protect the blade upon en
countering an obstruction.
In addition, Jacobsen, U.S. Patent No. 2,737,772,
discloses an assembly which includes a plate shaped so
that the plate has a centrally disposed concentric
frustoconical portion, which is said to improve air
flow, and has an essentially undulated periphery which
provides portions to which blades having a fiat surface
are affixed so that in operation, the flat surface of
the blades is inclined, or pitched, relative to the
horizontal, which is said to effect suction within the
mower housing and improve mulching capability. Addi
tionally, it is known that wing-like members were ap
plied to the upper surface of the Jacobsen disk at a
position adjacent cutting blades for, it is believed,
further complementing/improving the air flow and/or lift
or throw characteristics.
Further, in the context of the Jacobsen mulching
capability, as also will be appreciated by one skilled
in the art, there are a plurality of specialized blade
designs which are said to improve mulching capability,
and some of the designs are analogous to the deflector/
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impeller configurations noted above. However, even the
best designed mulchers leave noticeable residue, and a
significant problem which remains with mulching mowers,
as well as with conventional cutting bar mowers, is that
mowing under wet conditions yields clumping of the cut
material and build-up on the interior of the mower cut-
ter housing, if not machine clogging, which limits pro-
ductivity, particularly in commercial lawn-care opera-
tions.
In the art area of harvesting crops such as alfal-
fa, clover and tall grasses, for example, assemblies
including plate-like and knife-blade members also have
been employed, and auxiliary devices to provide lift arid
propel the cut material also are employed, such as dis-
closed in Erhart, et al., U.S. Patent No. 4,531,349,
wherein a ramp portion is positioned adjacent the cut-
ting knives, the ramp being inclined upwardly from a
position of the knives towards the plate-like member
central axis. So, too, in a commonly-assigned predeces-
sor patent, Meek, et al., U.S. Patent No. 3,656,284,
which discloses a machine to which the improvement of
Erhart is directed, it is disclosed that, analogous to
the concept of Jacobsen noted above, the plate-like
member is arranged so that the plane of the cutting
blade knives is inclined slightly downward toward the
leading edge, such as at an angle of about 5.
As will be appreciated, solving the lift and/or
throw problem with auxiliary parts adds cost to manu-
facture and further parts which require maintenance.
Furthermore, trailing edge deflectors/impellers such as
noted above, preclude providing the blade portion of the
cutting knife with two opposing cutting edges so that it
may be reversed when one cutting edge is too worn to use
further, thus resulting in only one-half the life of a
double-edge blade. Moreover, in the competitive area of
a
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commercial lawn-care maintenance, improvement in aesthe-
tic results coupled with efficiency/productivity of cut-
ting time is constantly sought. Hence, notwithstanding
the developments in the art, further need for improve-
s ment remains.
SUMMARY OF THE INVENTION
The present invention provides a cutting assembly
which is characterized by a disk and knife member as-
sembly wherein the disk has at least a peripheral sur-
face portion which is planar, wherein at least three
knife members having a cutting edge are mounted to the
disk at positions so that the knife members are dis-
placed substantially equidistantly one from an other and
so that upon rotation of the disk in a plane about a
disk central axis, the cutting edge of the knife members
extends away from the disk, i.e., beyond the peripheral
edge of the disk, and wherein the knife members have a
body surface which extends from a beveled surface por-
tion, which extends from the cutting edge, and are
mounted so that the body surface is, with respect to the
disk planar surface, inclined at an angle for propelling
cut material in a direction away from the assembly. In
the context of the present invention, the inclination is
such that the thrust provided to propel cut material in
a direction away from the assembly is greater than that
compared with an assembly wherein a blade surface is not
inclined.
More particularly, the assembly of the present in-
vention is characterized by disk member which defines a
planar surface which extends from the peripheral edge of
the disk towards a center of the disk and by an inclined
surface of the knives wherein the apex of the angle of
inclination is defined at a position of the juncture of
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the beveled surface and inclined surface. Furthermore
particularly, the disk comprises a planar surface which
extends from a centrally disposed disk portion to the
peripheral, or circumferential, edge of the disk, and
the planar surface preferably comprises the entirety of
the disk surface and extends from a centrally disposed
disk aperture, and preferably, the entirety of each
_ opposing surface of the disk is planar.
The present invention includes means for mounting
the knife members to the disk so that the knife members
are rigidly or pivotally mounted.
To realize further benefit of the present inven-
tion, at least four knives, as defined herein, are re-
quired.
Additionally, to achieve even further benefit. the
disk of the assembly of the present invention should
have a mass so that, when the assembly is rotationally
accelerated, the disk operates as a fly-wheel. That is,
for rotational driving force which provides for disk
rotation on the order of from about 2,000 RPM to about
5,000 RPM, and particularly on the order of from about
2,500 RPM to about 4,000 RPM, the mass of the disk
should be such that kinetic energy applied to the as-
sembly is stored by the disk so that upon encountering
variation of load, the assembly rotation at least tends
to remain constant and upon encountering a load in ex-
cess of driving force, the assembly at least tends to
minimize motor power reduction, or drag.
The present invention also provides a method/pro
cess for restructuring a mowing machine which comprises
a bar cutter member and means to which the bar cutter
member is affixed for rotating the bar in a plane, the
means including but not limited to a spindle, comprising
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replacing the bar cutter member of the mowing machine
with a disk and knife member assembly as defined herein.
The present invention further provides a method/
process for restructuring a mowing machine which com
prises a plate and knife member assembly and means to
which the plate is affixed for rotating the plate in a
plane, the means including but not limited to a spindle,
comprising replacing the plate and knife member assembly
with a disk and knife member assembly as defined herein.
The present invention additionally provides a
method/process for restructuring a mowing machine which
comprises a disk member having a planar surface as de-
fined herein and which comprises knife members affixed
to the disk comprising replacing the knife members with
knife members as defined herein to construct an assembly
as defined herein.
DETAILED DESCRIPTION OF THE INVENTION
Although the term "disk" is intended to be inter-
preted herein in its normal sense of having the nature
of a flat circular plate, the term is not intended to
exclude the presence of additional appendages or inden-
tations which do not detract from a disk member of an
assembly in accordance with the present invention re-
sembling a disk, and the disk member need not be cir-
cular but also may .have other rounded shape, including
but not limited to having or approaching an oval-shaped
circumference.
In the present invention, the knife members em-
ployed comprise a blade portion and a "handle" portion.
As in conventional usage of the term "knife", the handle
portion is integral with and extends from the blade por-
tion, and the handle portion is configured, by means
r__. __.__.. __-_
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such as an aperture therethrough, for mounting to the
disk. The blade portion comprises two edge portions
which extend in a direction,~generally linearly, from
the handle portion to one knife end which extends be-
tween and transversely with respect to the Two edge
portions, these boundaries thereby defining a blade
body. The blade portion further comprises a beveled
surface portion which extends from one edge portion to
a body surface portion which, in turn, extends from the
beveled portion. The beveled surface portion is beveled
with respect to the knife edge so that the blade edge is
suitable for cutting (a "cutting edge" as above), and
the blade portion may comprise a second beveled surface
portion which extends from the second edge to provide a
second cutting edge and thereby, a two-edge blade.
Essential to achieving improved results and ef-
fects, as compared with known mowing assemblies, is a
disk which comprises a planar surface which extends from
the peripheral circumferential edge of the disk towards
the center of the disk, and as indicated above, more
preferably, the planar surface extends from the peri-
pheral circumferential edge of the disk to a centrally
disposed portion, which may inciude, for example. a
portion out of the plane about an area for affixation to
a mowing machine rotational drive means, such as a spin-
dle. However, most preferably, the entirety of at least
one of the opposing disk surfaces is planar. In all
cases, however, it is necessary that the disk planar
surface extends from the disk peripheral edge for a dis-
tance at least sufficient for accommodating positioning
of the knife handle portion, and such should be deemed
as a definition of what is meant by "at least a planar
peripheral portion".
Critical to achieving improved results and effects,
as compared with known mowing assemblies, is a disk and
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knife configuration wherein the knife is mounted to the
disk so that the blade body surface portion, as defined
above, is inclined with respect to the planar disk sur-
face, the apex of the inclination being determined at
the juncture of the beveled surface portion and body
surface portion and with respect to the disk planar
surf ace .
Notwithstanding the foregoing, should the disk em
ployed have sufficient thickness relative to blade
thickness, the disk may be constructed and configured so
that it provides indentations to accommodate fitting of
the knife handle portions therein so that the area about
the indentations and at least a peripheral portion of
the disk is planar and so that blade body surface is
inclined with respect to a plane of the planar disk
surface. Hence, as will be appreciated, at least a
peripheral planar portion which accommodates the handles
and preferably, the entire surface of the disk, exclu-
sive of the indentations for accommodating the knife
handles, is planar and should not otherwise contain
other irregularities, including but not limited to an
undulated form, which preclude surfaces adjacent or in
proximity to the knife members from being defined as
forming a planar surface. Preferably, in such embodi-
ments, at least a portion of a surface of the knife
handle portions are flush with the disk planar surface.
In the most practical embodiment envisioned, how-
ever, the knife handle portion is mounted against the
disk planar surface. Thus, the handle portion of the
knife is configured to have a planar surface for being
positioned adjacent the disk planar surface, and the
blade portion is configured so that the blade body
surface portion is inclined with respect to the handle
planar surface and thereby, when the knife is affixed to
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the disk, the blade body surface portion is inclined
with respect to the disk planar surface.
In general, when the assembly of the invention is
affixed with a mowing machine for operation, the blades
will be affixed to the disk surface which faces the
ground over which the mower travels. However, the knife
members may be affixed to the disk surface which faces
the mowing machine, i.e., the disk surface which opposes
the disk ground-facing surface, and in this case, it may
be desired that only a peripheral portion of the disk
sufficient to accommodate the blades be planar, but in
this case also, it is preferred that the ground-facing
surface be substantially entirely planar, but for pos-
sibly a central portion as noted above.
The knife members preferably are made of and com-
prise a rigid metallic composition including but not
limited to iron and alloys thereof and steel, including
but not limited to solingen steel.
The angle of inclination may be on the order of
from about 3 to 20, and preferably from about 4 to
15, and more preferably from about 5 to 10, and most
preferably from about 6 to 9.
Although the knife members employed may have only
one blade portion cutting edge, a double-edge blade is
preferred. As will be appreciated, knife members may be
forged and/or tooled in a variety of configurations for
mounting to achieve, an assembly in accordance with the
present invention wherein a blade surface portion, as
defined, extends out of the plane of the planar disk
surface, and the body surface portion need not be pla-
nar. The body surface portion may have a curvature
which need not be uniform along a longitudinal extent of
the blade portion from the handle portion to the knife
member end between the blade portion edges. It may have
a slight convex-to-concave shape as it extends from the
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handle portion to the knife end between the edges, the
essential feature being, again, that the blade body
surface portion extends from one point to another point
displaced one-from-the-other to define a plane inclined
with respect to the glane of the disk planar Surface.
In the interest of construction material economy
and particularly in the context of providing a double-
cutting edge blade portion configured so that the cen-
tral surface is inclined with respect to the handle, it
is believed that the knife portion is formed best with a
curvature at an area of transition between the handle
and blade portions so that two opposing central body
portions are formed which provide the requisite inclin-
ation. Although not required, each of two beveled por-
tions, which provide the two cutting edges, may depend
in their inclination from a common central body surface
portion. Such a blade, one having some curvature and
two cutting edges as described, is known and may be ob-
tained from New Holland North America, Inc. equipment
dealers, these blades having found use in a machine
known as a New Holland DISC BINE mower conditioner ma-
chine.
For mounting, knife members of the assembly of the
present invention are configured with such as an aper
ture through a portion,of the handle to accommodate a
mounting means, and mounting means may include any
number of manners known in the art and to those skilled
in the art. Means for mounting the knives may provide
for rigid affixation, and thus, such may include bolting
and other equivalent means which enable removal of the
blades for blade replacement. Preferably, however,
means for mounting the knives provide for pivoting so
that upon being subjected to disk rotation, the knives
are movable and are positioned for cutting by centri-
fugal force and so that upon a knife, or knives, strik-
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ing a rigin object, a knife, or knives, at least tends)
to yield to the object to minimize damage. Of course,
as will be appreciated, should the embodiment be selec-
ted wherein a disk is supplied with indentations to
S accommodate the knife member handles, if it is desired
that the knives be pivotable, the indentations should be
of a size and configuration which allows the knives to
yield at least somewhat.
Means for pivotable knife member assembly mounting
may be as simple as affixing the knife member to the
disk with a bolt and nut with a bushing therebetween via
an aperture in the disk and in a corresponding knife
handle portion aperture, so that the knife member is
movable freely, as shown further below. So, too, mount
ing means configurations as indicated in art identified
above are acceptable, and the disclosures thereof are
incorporated herein by reference as if fully set forth
herein.
In all embodiments, the knife members should be
mounted at positions so that the at least three and pre
ferably four knives are spaced apart so that the assem
bly is balanced about a disk central axis, and thus, the
blades are substantially, if not exactly, spaced equi
distantly apart.
The disk further i.s constructed for ready instal-
lation in any mowing machine for replacing cutter bar
members and other plate and disk cutting assemblies, in
that the disk is provided most conveniently with a cen-
trally disposed aperture to enable affixation to means
for effecting rotary drive, such as, but not limited to,
a driving spindle, be it a means which is directly motor
driven or which is belt and pulley or otherwise equiva-
lently driven, including gear driven. Accordingly, the
circumference of the aasembly of the invention is selec-
ted to provide a cutting swath substantially equivalent
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with that intended by the cutting device of any parti-
cular machine. Thus, the assembly may be sized to be
installed in and to meet the needs of the cutting dimen-
sions of any particular mowing machine.
As indicated above, it is preferable that the cut-
ting assembly of the invention have a mass which pro-
vides fly-wheel characteristics, and in this regard, the
assembly has a mass in excess of that had by bar blades
which it replaces. In general, the weight of the assem-
bly preferably is on the order of at least about 1.5
times the weight of bar blades conventionally employed
and preferably at least about 2 times and preferably at
least about 2.5 times greater. Thus, while commercial
lawn-care-type mowing machine bar blades have, for ex-
ample, a weight of about 4 pounds (-3.6 kg), the weight
of the assembly of the present invention is on the order
of from about 6 pounds (--2.7 kg) to about 12 pounds
(-5.5 kg) and more preferably about 9 pounds (-4.1 kg)
to about 10 pounds (-4.5 kg).
In general, knife member dimensions may be on the
order of about 3 inches to about 6 inches (76.2 mm to
152.4 mm) in length and about 1.5 inches to about 3
inches (38.1 mm to 76.2 mm) in width to provide for a
blade portion cutting edge on the order of about 1.5
inches to about 2.5 inches (38.1 mm to 63.5 mm). Knife
thickness may range from about 0.06 inches to about
0.375 inches (-1.5 mm to ~9.5 mm). Weight of the knife
membe r may range from about 2 oz . to about 6 oz . ( 57 g
to 170 g ) and preferably from about 3 . 5 oz . to about 5
oz. (99 g to 142 g).
Although disk construction with rigid plastic ma-
terial such as KEVLAR and the like and rigid plastic
loaded with metal to increase mass, are not intended to
be excluded from the scope and embrace of the present
invention, the disk is constructed preferably of metal
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so that sufficient weight and mass is provided, the
metal preferably being a steel. Illustrative is use of
steel having a thickness on the order of from about
0.080 inches to about 0.500 inches (~2.0 mm to 12.7 mm)
in general, although larger thicknesses are not intended
to be precluded, and it is preferred that the disk have
a thickness on the order of about 0.090 inches to about
0.300 inches (~2.3 mm to ~7.6 mm).
As should be appreciated, disk strength and/or
yield stress is affected by the size of the circumfer
ence of the disk as is the ability to impart a fly-wheel
characteristic of significance. Hence, in general, for
any particular component material, as disk circumference
is increased, the thickness should be increased. Addi
tionally, the weight of the disk must be heavier than
the combined weight of the blades so that the disk re-
mains rigid and/or thereby substantially avoids being
subjected to a bending moment, and it has been found
that a feature of disk mass greater than knife member
mass enables the assembly to remain in balance even if,
for example, the knife members are not spaced apart
equidistantly with perfect precision. Hence, the mass
of the disk enables effects due to knife member spacing
imprecision to be damped, and thus, the fly-wheel
characteristic also damps possible weight differences
between knife members Idue to wear and/or differences
caused by sharpening.
Operation of a mower with an assembly of the pre
sent invention yields a plurality of results and effects
different from other mowing assemblies. For example, in
testing under cutting conditions and ground-speed at
which the motor power of a cutter bar mower utilized for
commercial lawn care operations is subjected to drag, it
surprisingly has been discovered that replacement of the
cutter bar with an assembly in accordance with the pre-
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sent invention enables attaining ground-speeds which are
up to about 2%~ times in excess of those which may be
employed with the conventional bar blade mower without
noticeable motor drag, and in addition, cutting quality
is improved. Hence, improved productivity is provided.
So, too, it has been found that the assembly of the
invention cuts cleanly and evenly when turning corners
and further, differences between the color of swaths cut
in opposing directions is not noticeably apparent to the
naked eye.
Additionally, it surprisingly has been found that
utilization of an assembly in accordance with the
present invention in place of a conventional cutter bar
on a mowing machine results in less stress, and hence
less wear, on the rotational drive means, e.g., a spin-
dle, and hence on the bearings for such as a spindle, as
compared with that imparted by the bar cutter.
Moreover, it has been found that, in operation, the
assembly of the present invention operates to re-cut
already cut material and thereby provides a mulching
feature without auxiliary equipment, without other spe-
cialized blade configuration, and without closing off
the cut material outlet chute of conventional mowing
machines. However, also, when the assembly of the
present invention is employed, the mulching capability
is improved and enhanced further by closing the outlet
chute, and this enhanced capability is achieved without
noticeable loss of motor power efficiency.
Further, tests carried out with a closed outlet
chute show that the present invention provides further
improved mulching efficiency. In this regard, a mower
equipped with LESCO GATOR blades manufactured by Lesco,
Inc., which are believed to be the state of the art, is
first used to cut a swath and then, the GATOR blades are
replaced with an assembly of the present invention, and
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d swath is cut. Substantially less noticeable
a secon
ground residue is present after cutting with the assem-
bly of the present invention than ~~ith the LESCO GATOR
blades.
Furthermore, it also surprisingly has been found
that the assembly of the present invention enables
mowing wet grass without clumping of the cut grass and
without machine clogging, which is a principal hindrance
to commercial lawn care productivity and operation under
wet lawn conditions, and it has been found that the
housing also stays remarkably clean in that the amount
of cuttings adhering to the housing interior are sub-
stantially less than is the case with conventional cut-
ting assemblies.
The invention is further described with reference
to the accompanying drawing Figures, and the description
below is presented to show, illustratively, a configura-
tion which operates to achieve the results, effects and
advantages described above and should not in any sense
be deemed as limiting the scope of the present inven-
tion.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
Figure 1 illustrates an exploded perspective view
of an assembly according to the present invention.
Figure 2 illustrates a perspective view of a knife
member configuration of an assembly according to the
present invention.
Figure 3 illustrates an end view of a knife for use
in an assembly according to the present invention.
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DETAILED DESCRIPTION OF THE INVENTION
An assembly according to the present invention is
illustrated in an exploded perspective in Figure 1 and
is designated generally and collectively by reference
numeral 10.
Although the illustration of Figure 1 only shows
disk 12 as having planar surface 14 which extends from
peripheral disk edge 16, as is preferred in accordance
with the present invention, the opposing surface of disk
12 also may be understood to be entirely planar. As
indicated by the exploded view, knife members 18 are to
be mounted adjacent lower planar surface 14. Mounting
means include bolt 20 and nut 22 and bushing 24 which
are sized and configured, together with disk apertures
26 (4 in number) and knife aperture 28, so that knife 18
is pivotally movable so that upon rotation of the disk,
the knife is thrust and maintained in a cutting position
by centrifugal force.
As will be noted, disk apertures 26 are spaced at
distances so that adjacent knife members are positioned
substantially equidistantly apart one from the other.
Disk 12 is provided further with centrally disposed
aperture 36 which is sized to accommodate bolt 38 which,
in turn, is sized to engage fixedly threads of spindle
40 which is integral with a mowing machine and its drive
means, indicated and represented by a labeled box, for
driving disk 12. A washer 41 may be employed between
the head of bolt 38 and disk surface 14. As will be
appreciated, the spindle and bolt 38 should be threaded,
as should bolts 20, relative to direction of rotation so
that the bolts remain tight during rotation.
Knife member(s) 18 is illustrated in each of Fig
ures 1 and 2 as comprising handle portion 42 which has
a planar surface portion in the area surrounding aper
CA 02271966 1999-OS-14
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ture 28. Knife member handle po~tion.42 extends from
aperture 28 to a somewhat curved ;portion 44, which de-
fines an area of transition (dashed line) between handle
portion 42 and blade portion 46, ~:.rie distinction between
blade portion 46 and handle portion 42 being seen more
readily at the juncture (44) of handle portion 42 and
blade portion beveled surface 48, which trails from
cutting edge 50. As will be noted, a second blade edge
52 opposes cutting edge 50, and knife end 54 extends
transversely between the opposing edges.
The blade body surface which is inclined is desig-
nated in Figure 2 by reference numeral 60, and the in-
clination may be seen by the view of knife end 54 in
drawing Figure 3, that Figure, in sum thereby also
presenting a cross-sectional view of blade portion 46 of
Figure 1. As is preferred, and as illustrated in Figure
3, the blade is provided with two beveled surfaces 48,
as in Figure 1( and 62 and two cutting edges 50, as in
Figure 2, and 64, and the blade portion also is con-
figured so that upon wearing down cutting edge 50 upon
its use as a leading edge for cutting and turning the
knife over for use as a leading cutting edge, surface 66
is likewise inclined in accordance with the present
invention. Thus, additionally, both opposing surfaces
of knife handle 42 which surround aperture 28 (Fig. 2)
should, in this embodiment, be planar for surface-to-
surface-contact with a planar disk surface in an in-
timate manner.
As may be gathered from the foregoing drawing de
scription and in view of the present conventional con
struction of mowing machines, particularly those em
ployed for home-owner use and for commercial lawn-care
maintenance, replacement of cutter means heretofore em
ployed with an assembly according to the present inven
tion and/or reconfiguring a prior cutter means to be in
a i ii
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accord with the present invention, so that a mower
drives an assembly as defined herein, is a relatively
simple matter.
As also is clear from the foregoing, various modi
fications of the present invention may be made without
departure from the spirit and scope of the disclosure,
and the invention may be embodied suitably in the ab
sence of elements or members not specifically disclosed
herein.
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