Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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CUTTING TOOTH WITH DUAL CUTTING EDGES
FOR A BRUSH CUTTING HEAD
FIELD OF THE INVENTION
[0001] The present invention relates generally to brush cutting heads, and
more
specifically, to a cutting tooth with dual cutting edges for a brush cutting
head.
BACKGROUND OF THE INVENTION
[0002] Extensive felling and mulching operations are often performed with a
heavy-duty
brush cutter mounted to the front of a work vehicle. A typical brush cutter
includes a brush
cutting head provided with an elongate support body that carries about its
outer surface a
plurality of teeth adapted to cut trees, brush or the like. The cutting teeth
are typically fixed
to the outer surface of the drum via mounting blocks.
[0003] An example of one such brush cutting head is described in United States
Patent
Publication No. 2010/0044487. This published patent application discloses a
brush cutter
that has a cylindrical support base and a plurality of mounting blocks
fastened to the outer
surface of the base. The bottom surface of each mounting block is concavely
curved to
match the radius of the base thereby allowing each mounting block to be welded
onto the
base with its bottom surface flush with the outer surface of the base. Each
mounting block
has a front face which is recessed from the front end of the mounting block so
as to define a
horizontal shelf near the bottom surface of the mounting block. Each mounting
block
carries a cutting tooth on its front or leading face. The cutting tooth is
fastened to the
mounting block by a nut and bolt combination, the bolt being inserted through
a smooth
bore defined in the mounting block.
[0004] To protect the mounting blocks from rocks and large trees, each
mounting block is
provided with a protective collar. Each protective collar is welded to the
outer surface of
the base and extends radially therefrom, transverse to the longitudinal axis
of the base. Each
collar terminates circumferentially a short distance from the front face of
the mounting
block with which it is associated to provide a front clearance space. The
opposed end of the
collar is welded to the back face of the associated mounting block to
strengthen it.
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[0005] The cutting tooth shown in this published patent application is formed
with a
relatively long, base portion at one end of which is carried a relatively
short cutting portion.
The cutting portion is angled forwardly and its front and rear (or leading and
trailing) faces
taper terminating in a cutting edge. A smooth-walled bore extending through
the base
portion is sized to accommodate therethrough a bolt which is inserted through
the aligned
bores in the cutting tooth base portion and the mounting block. The bolt
secures the cutting
tooth to the mounting block with a nut. At the end opposite the cutting
portion, the base
portion is provided with a projecting guide member sized to fit within fitting
welded on the
horizontal shelf of the mounting block. The guide member and fitting cooperate
with each
other to ensure that the cutting tooth maintains its proper orientation
relative to the cutting
block during operation of the brush cutting head. Additionally, the
combination of guide
member and fitting assists in distributing the impact forces applied to the
cutting tooth
through to the mounting block, thereby reducing the shear stress on the bolt.
[0006] In the field, the brush cutting head shown in United States Patent
Publication No.
2010/0044487 has proven itself to be effective and well-suited to the task of
brush cutting
and land clearing. However, the design of the cutting tooth for this brush
cutting head
tends to suffer from certain disadvantages. Manufacture of the guide members
projeeting
from the base portions of the cutting tooth must be precise and can be time
consuming.
Moreover, certain problems have been encountered when replacing old, broken or
worn
cutting teeth on the brush cutting head. In some cases, it has been found that
the guide
members projecting from the base portions of replacement cutting teeth do not
always line
up with the fittings on the mounting block into which they are to be received.
As a result of
this misalignment, some cutting teeth could not be properly secured to the
mounting blocks,
thereby causing delay, excessive warranty claims and requiring operators to
carry on hand a
greater number of replacement cutting teeth than would ordinarily be required.
[0007] Based on the foregoing, it would be desirable to have a cutting tooth
which does
not require a guide member to maintain its proper orientation on the mounting
block,
thereby obviating the drawbacks associated with the cutting tooth shown in
United States
Patent Publication No. 2010/0044487. Such a cutting tooth would be robust and
capable of
being securely fastened to the mounting block. It would be of further benefit
if such a
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cutting tooth could possess an extended service life as compared to existing
cutting teeth,
so as to reduce the maintenance, repair and replacement of cutting teeth on a
brush cutting
head.
SUMMARY OF THE INVENTION
100081 In accordance with one broad aspect of the present invention, there is
provided a
cutting tooth for attachment to a mounting block carried on a brush cutting
head. The
cutting tooth includes a longitudinal body provided with a leading face; a
trailing face; and
a pair of opposed, first and second cutting portions carried at either end of
the longitudinal
body. The leading face has a projection disposed thereon to reinforce the
longitudinal body.
The projection has a leading projection face. The trailing face has defined
therein at a
location intermediate the ends of the longitudinal body at least one threaded,
blind bore.
The at least one blind bore extending substantially into the projection but
stopping short of
the leading projection face. The at least one blind bore is configured to
receive therein a
threaded bolt for securing the cutting tooth to the mounting block. The first
cutting portion
has a tapering profile that terminates in a first cutting edge. The first
cutting edge has a first
angle of attack relative to a first plane parallel to the midplane M. The
first angle of attack
lies between 20 degrees and 75 degrees. The second cutting portion has a
tapering profile
that terminates in a second cutting edge. The second cutting edge has a second
angle of
attack relative to a second plane parallel to the midplane M. The second angle
of attack lies
between 20 degrees and 75 degrees. When the cutting tooth is secured to the
mounting
block one of the first and second cutting portions is in an operative position
and the other of
the first and second cutting portions is in an inoperative position.
100091 In one feature, the longitudinal body further includes a midplane M
oriented
transverse of the longitudinal body. The longitudinal body is symmetrical
about the
midplane M such that the first cutting portion is a mirror image of the second
cutting
portion. In another feature, the longitudinal body further includes a plane P
perpendicular
to the midplane M. The longitudinal body is symmetrical about the plane P. In
a further
feature, the longitudinal body has an hourglass shape.
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[0010] In an additional feature, the longitudinal body further includes a base
portion
having a leading face and an opposed trailing face. The base portion is
disposed between
the first and second cutting portions. In one feature, the base portion is
sized longer than at
least one of the cutting portions. In another feature, the base portion is
sized longer than
both the cutting portions. The base portion has a length L1 and the first
cutting portion has a
length L2. The ratio L2:Li lies between approximately 0.17 and approximately
0.44. The
second cutting portion has a length L3. The ratio L3:L1 lies between
approximately 0.17 and
approximately 0.44.
[0011] In yet another feature, the base portion has a pair of opposed lateral
faces. The
width of the base portion as measured between the lateral faces tapers toward
the midplane.
[0012] In still another feature, the projection occupies a substantial portion
of the base
portion leading face. Moreover, the projection has a substantially rectangular
shape defined
by smoothly-radiused sides. In one feature, the leading projection face is
planar and is
generally parallel to the base portion trailing face.
[0013] In a further feature, the at least one blind bore includes a first
blind bore located
adjacent the juncture of the base portion and the first cutting portion, and a
second blind
bore located adjacent the juncture of the base portion and the second cutting
portion.
[0014] In an additional feature, the cutting tooth further includes means for
preventing
rotation of the cutting tooth relative to the mounting block. The rotation
preventing means
includes a pair of spaced apart, raised abutment members projecting from the
trailing face
of the base portion and extending longitudinally therealong. The spacing
between the
abutment members being sized large enough to accommodate a portion of the
mounting
block therein.
[0015] In a different feature, the first angle of attack is equal to the
second angle of attack
and measures 49 degrees. In an alternative feature, the first angle of attack
is greater than
the second angle of attack.
[0016] In yet another feature, the first and second cutting edges define a
cutting tooth
envelope capable of accommodating a circle having a diameter ranging between
3.5 and 4.9
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in. When the first and second angles of attack measure 20 degrees, the cutting
tooth
envelope is capable of accommodating a circle having a diameter measuring 3.5
in. When
the first and second angles of attack measure 49 degrees, the cutting tooth
envelope is
capable of accommodating a circle having a diameter measuring 4.4 in. When the
first and
second angles of attack measure 75 degrees, the cutting tooth envelope is
capable of
accommodating a circle having a diameter measuring 4.9 in.
100171 In accordance with another broad aspect of the present invention, there
is provided
a cutting tooth assembly for a brush cutting head. The cutting tooth assembly
includes a
mounting block carried on the brush cutting head. The mounting block has a
leading face, a
trailing face and a bore extending between the leading and trailing faces of
the mounting
block. Also provided is a cutting tooth releasably attachable to the mounting
block. The
cutting tooth having a longitudinal body provided with a leading face; a
trailing face; and a
pair of opposed, first and second cutting portions carried at either end of
the longitudinal
body. The leading face has a projection disposed thereon to reinforce the
longitudinal body.
The projection has a leading projection face. The trailing face has defined
therein at a
location intermediate the ends of the longitudinal body at least one threaded,
blind bore.
The at least one blind bore extending substantially into the projection but
stopping short of
the leading projection face. The at least one blind bore is configured to
receive therein a
threaded bolt for securing the cutting tooth to the mounting block. The first
cutting portion
has a tapering profile that terminates in a first cutting edge. The first
cutting edge has a first
angle of attack relative to a first plane parallel to the midplane M. The
first angle of attack
lies between 20 degrees and 75 degrees. The second cutting portion has a
tapering profile
that terminates in a second cutting edge. The second cutting edge has a second
angle of
attack relative to a second plane parallel to the midplane M. The second angle
of attack lies
between 20 degrees and 75 degrees. The cutting tooth assembly further includes
a bolt for
fastening the cutting tooth to the mounting block. The bolt is insertable into
the at least one
blind bore of the longitudinal body and the bore defined in the mounting
block. When the
cutting tooth is secured to the mounting block one of the first and second
cutting portions is
in an operative position and the other of the first and second cutting
portions is in an
inoperative position.
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100181 In another feature, the at least one blind bore includes a first blind
bore located
nearer to the first cutting portion than to the second cutting portion, and a
second blind bore
located nearer to the second cutting portion than to the first cutting
portion. When the
cutting tooth is secured to the mounting block with the first cutting portion
in the operative
position, the bolt extends through the second blind bore. When the cutting
tooth is secured
to the mounting block with the second cutting portion in the operative
position, the bolt
extends through the first blind bore.
[0019] In accordance with yet another broad aspect of the present invention,
there is
provided a brush cutting head. The brush cutting head includes a plurality of
mounting
blocks carried on the brush cutting head. Each mounting block of the plurality
has a leading
face, a trailing face and a bore extending between the leading and trailing
faces of the
mounting block. Also provided is a plurality of cutting teeth releasably
attachable to the
plurality of mounting blocks. Each cutting tooth has a longitudinal body
provided with a
leading face; a trailing face; and a pair of opposed, first and second cutting
portions carried
at either end of the longitudinal body. The leading face has a projection
disposed thereon to
reinforce the longitudinal body. The projection has a leading projection face.
The trailing
face has defined therein at a location intermediate the ends of the
longitudinal body at least
one threaded, blind bore. The at least one blind bore extending substantially
into the
projection but stopping short of the leading projection face. The at least one
blind bore is
configured to receive therein a threaded bolt for securing the cutting tooth
to the mounting
block. The first cutting portion has a tapering profile that terminates in a
first cutting edge.
The first cutting edge has a first angle of attack relative to a first plane
parallel to the
midplane M. The first angle of attack lies between 20 degrees and 75 degrees.
The second
cutting portion has a tapering profile that terminates in a second cutting
edge. The second
cutting edge has a second angle of attack relative to a second plane parallel
to the midplane
M. The second angle of attack lies between 20 degrees and 75 degrees. The
brush cutting
head further includes a plurality of bolts for fastening the plurality of
cutting teeth to the
plurality of mounting blocks. Each bolt of the plurality is insertable into
the at least one
blind bore of one of the cutting teeth of the plurality and the bore defined
in the
corresponding one of the mounting blocks of the plurality.
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100201 In accordance with still another broad aspect of the present invention,
there is
provided a cutting tooth for attachment to a mounting block carried on a brush
cutting head.
The cutting tooth includes a longitudinal body provided with a leading face; a
trailing face;
a midplane M oriented transverse of the longitudinal body; a pair of opposed,
first and
second cutting portions carried at either end of the longitudinal body and
extending away
from each other and away from the leading face in a forwardly leaning fashion;
and at least
one threaded blind bore defined in the trailing face at a location
intermediate the first and
second cutting portions. The at least one threaded blind bore is configured to
receive
therein a threaded bolt for securing the cutting tooth to the mounting block.
The first cutting
portion has a tapering profile that terminates in a first cutting edge. The
first cutting edge
has a first angle of attack relative to a first plane parallel to the midplane
M. The first angle
of attack lies between 20 degrees and 75 degrees. The second cutting portion
has a tapering
profile that terminates in a second cutting edge. The second cutting edge has
a second angle
of attack relative to a second plane parallel to the midplane M. The second
angle of attack
lies between 20 degrees and 75 degrees. The first and second cutting edges
define a cutting
tooth envelope capable of accommodating a circle having a diameter ranging
between 3.5
and 4.9 in. When the cutting tooth is secured to the mounting block one of the
first and
second cutting portions is in an operative position and the other of the first
and second
cutting portions is in an inoperative position. When the first and second
angles of attack
measure 20 degrees, the cutting tooth envelope is capable of accommodating a
circle
having a diameter measuring 3.5 in. When the first and second angles of attack
measure 49
degrees, the cutting tooth envelope is capable of accommodating a circle
having a diameter
measuring 4.4 in. When the first and second angles of attack measure 75
degrees, the
cutting tooth envelope is capable of accommodating a circle having a diameter
measuring
4.9 in.
BRIEF DESCRIPTION OF THE DRAWINGS
100211 The embodiments of the present invention shall be more clearly
understood with
reference to the following detailed description of the embodiments of the
invention taken in
conjunction with the accompanying drawings, in which:
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[0022] FIG. 1 is a front perspective view of a brush cutter provided with a
housing and a
brush cutting head, all according to an embodiment of the present invention;
[0023] FIG. 2 is a front perspective view of the brush cutting head of FIG. 1
shown in
isolation;
[0024] FIG. 3 is an end view of the brush cutting head shown in FIG. 2;
[0025] FIG. 4A is an enlarged view similar to that illustrated in FIG. 3
depicting the
encircled portion '4A' except that it is taken in cross-section, the first
cutting edge being
shown occupying its operative position and the second cutting edge being shown
occupying
its non-operative position;
[0026] FIG. 4B is a view similar to that shown in FIG. 4A, except that the
first cutting
edge is shown occupying its non-operative position and the second cutting edge
is shown
occupying its operative position;
[0027] FIG. 5 is a front, partial perspective view of the brush cutting head
of FIG. 2
showing a representative cutting tooth and its corresponding mounting assembly
fixed
to the tubular support body of the brush cutting head;
[0028] FIG. 6 is a rear, partial perspective view of the brush cutting head of
FIG. 2
showing a representative cutting tooth and its corresponding mounting assembly
fixed
to the tubular support body of the brush cutting head;
[0029] FIG. 7 is a side elevation view of one of the collars shown in FIG. 2;
[0030] FIG. 8 is a front perspective view of the mounting block shown in FIG.
5;
[0031] FIG. 9 is a rear perspective view of the mounting block shown in FIG.
5;
[0032] FIG. 10 is a side elevation view of the mounting block shown in FIG. 5;
[0033] FIG. 11 is a front perspective view of the cutting tooth shown in FIG.
5;
[0034] FIG. 12 is a rear perspective view of the cutting tooth shown in FIG.
5;
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[0035] FIG. 13 is a front end view of the cutting tooth shown in FIG. 5;
[0036] FIG. 14 is a rear end view of the cutting tooth shown in FIG. 5;
[0037] FIG. 15A is a side elevation view of the cutting tooth shown in FIG. 5;
[0038] FIG. 15B is another side elevation view of the cutting tooth similar to
that shown
in FIG. 15A; and
[0039] FIG. 16 is an end view of the brush cutting head similar to that
illustrated in
FIG. 3 except that the plurality of collars and mounting blocks are made
transparent to
better reveal different possible orientations of the cutting edges of the
plurality of the
cutting teeth.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
[0040] The description which follows, and the embodiments described therein
are
provided by way of illustration of an example, or examples of particular
embodiments of
principles and aspects of the present invention. These examples are provided
for the
purposes of explanation and not of limitation, of those principles of the
invention. In the
description that follows, like parts are marked throughout the specification
and the
drawings with the same respective reference numerals.
[0041] Referring to FIG. 1, there is shown a brush cutter generally designated
with
reference numeral 20. Brush cutter 20 may be of the type attached to the front
of a vehicle,
such as a loader, skid steer, or the like. Brush cutter 20 includes an open-
bottom housing
22 and a brush cutting head 24 rotatably mounted within the housing 22. The
housing 22 is
defined generally by a front cover panel 26, a rear cover panel 28 and a pair
of side panels
32 and 34. The cover panels 26 and 28 extend longitudinally between, and are
joined to,
the side panels 32 and 34. A curved wall (not shown) disposed within the
interior of the
housing 22 spans the space between the side panels 32 and 34, its curved
profile partially
defining a well 36 sized to accommodate the brush cutting head 24. The brush
cutting head
24 is mounted longitudinally between the side panels 32 and 34 and supported
on bearing
assemblies (not shown) for rotational motion about an axis of rotation R ¨ R
(shown in
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FIG. 2). A drive assembly (not shown) is operatively connected to the brush
cutting head
24 to drive rotation thereof.
[0042] Referring now to FIG. 2, there is shown the brush cutting head 24. The
brush
cutting head 24 includes a tubular support body 40 that has a first end 42, an
opposed
second end 44 and an intermediate portion 46 extending between the first and
second ends
42 and 44. In this embodiment, the support body 40 is cylindrical and has an
outer
diameter of 9.94 in. This, however, need not be the case in every application.
In alternative
embodiments, the support body may be sized or shaped differently.
[0043] The intermediate portion 46 has a curved outer surface 48 that defines
the circular
cross-section of the support body 40. Concentrically mounted to the support
body 40 at
spaced intervals along the intermediate portion 46, is a plurality of
protective collars
designated with reference numerals 50a through to 50gg (collectively, "collars
50"). As will
be explained in greater detail below, each collar 50 has associated therewith
a mounting site
or station 52 for receiving a cutting tooth assembly 54 therein.
[0044] Referring to FIG. 7, each collar 50 is has a substantially penannular
structure
defined by a relatively flat, circumferentially extending, sidewall 60. The
sidewall 60 is
bounded circumferentially by an outer edge 62 and inner edge 64, and has first
and second
spaced apart ends 66 and 68. The space between the ends 66 and 68 defines a
relatively
large cutout 70 formed in the collar 50. In this embodiment, each station 52
is defined at
least partially within the cutout 70 formed in a given collar 50.
[0045] The first end 66 of the sidewall 60 has a relatively straight edge 72
that spans
between the outer and inner edges 62 and 64. Jutting out from the edge 72
adjacent the
outer edge 62 is a relatively short, finger-like projection 74 which extends
toward the
second end 68. During operation of the brush cutting head 24, the projection
74 serves to
block or prevent large pieces of wood from getting wedged or stuck in the
space defined
between the collar 50 and the cutting tooth assembly 54. The second end 68 of
the sidewall
60 is also formed with a relatively straight edge 76 disposed opposite the
edge 72 of the
first end 66 in a substantially parallel arrangement. The orientation of the
edges 72 and 74
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is skewed relative to a notional radial line RL of the collar 50. Adjacent the
inner edge 64,
the edge 76 has defined therein a relatively small shoulder 78.
[0046] The collars 50 are radially mounted to the support body 40 with their
inner
sidewall edges 64 welded to the curved surface 48. Each collar 50 is
longitudinally spaced
and radially offset from its adjacent collar 50 such that the cutouts 70 of
adjacent collars
(and their associated stations) are staggered relative to each other.
Preferably, adjacent
stations 50 are staggered relative to each other by an angle of approximately
160 degrees.
However, in alternative embodiments, adjacent stations could be staggered by a
greater or
lesser angle.
[0047] Due to this stagger and the geometry of the collars 50, every alternate
station 52 is
also radially offset from its respective reference station by an angle col.
Preferably, the
angle col is an acute angle. In this embodiment, the angle CO1 measures
approximately 20
degrees.
[0048] In this embodiment, the staggered arrangement of the collars 50 allows
the
plurality of cutting tooth assemblies 54 to be disposed along the support body
40 in a
generally double helix pattern thereby permitting cutting across the entire
length of the
support body 40 when the brush cutting head 24 is rotated about its
longitudinal axis 'R-R'.
While a double helix pattern is generally preferred, it will be appreciated
that the cutting
tooth assemblies 54 could be laid out differently along the support body 40 to
achieve a
particular distribution or arrangement of cutting tooth assemblies 54 on the
support body
40. For instance, the cutting tooth assemblies could be disposed in a triple
or quadruple
helix arrangement.
[0049] In this embodiment, the diameter of the support body 40 with collars 50
mounted
thereto (as measured to the outer edge 62 of the collars 50) is 17.75 in. In
other
embodiments, this diameter may be different.
[0050] The cutting tooth assembly 54 is now described in greater detail with
reference to
FIGS. 8 to 15B. The cutting tooth assembly 54 includes a cutting tooth 90 and
a mounting
assembly 92 for securely fixing the cutting tooth 90 within a respective
station 52. The
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cutting tooth 90 has a body provided with a first cutting portion 94, a second
cutting portion
96 disposed opposite the first cutting portion 94 and a base portion 98
integrally formed
with, and extending between, the first and second cutting portions 94 and 96.
As best
shown in FIGS. 14 and 15A, in this preferred embodiment, the cutting tooth 90
can be seen
to be symmetrical about the midplane M of the base portion 98, such the first
cutting
portion 94 is a mirror image of the second cutting portion 96. Preferably, the
cutting tooth
90 is also symmetrical about a plane P perpendicular to the midplane M.
[0051] The base portion 98 has a first end 100, an opposed second end 102, a
leading
face 104, a trailing face 106 and two, spaced apart, lateral faces 108 and 110
which extend
between the leading and trailing faces 104 and 106. A generally rectangular
projection 112
is centrally disposed on the leading face 104. The projection 112 can be seen
to be defined
by a generally planar face 114 projecting further in the leading direction
than the leading
face 104, two opposed short sides 116 and 118, and two opposed long sides 120
and 122.
As best shown in FIG. 13 and 15A and 15B, the sides 116, 118, 120 and 122 are
all
smoothly radiused to enhance clearance of the cutting debris away from the
cutting tooth
90, and more specifically, from the first and second cutting portions 94 and
96. Moreover,
by having sides 116, 118, 120 and 122 smoothly radiused improved stress
distribution may
be achieved.
[0052] The projection 112 thickens the base portion 98 thereby permitting for
the
provision of sufficient threading 123 in blind bores 130 and 132 formed in the
trailing face
106 of the base portion 98 so as to accommodate a longer bolt for fastening
the cutting
tooth 90 to mounting block 200 which forms part of the mounting assembly 92.
As visible
in FIGS. 4A and 4B, such threading 123 extends substantially into the base
portion 98 just
short of face 114 of the projection 112. Additionally, the projection 112
reinforces the base
portion 98 and serves as an impact-absorbing function.
[0053] In this embodiment, the thickness T of the base portion 98 (as measured
between
the trailing face 106 and the planar face 114 of the projection 112) is 1.19
in. In other
embodiments, the thickness T could be made larger.
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[0054] Moreover, in this embodiment, the face 114 of the projection 112 is
planar and is
generally parallel with the trailing face 106 of the base portion 98. In other
embodiments,
the face 114 could have a different orientation and be skewed relative to the
trailing face of
the base portion.
In FIGS. 12 and 14, there is shown a pair of spaced apart, raised abutment or
shoulder
members 124 and 126 projecting from the trailing face 106 of the base portion
98. More
specifically, the abutment members 124 and 126 extend longitudinally along the
outer
margins of the trailing face 106 and are positioned centrally between, but at
a short distance
away from, the first and second ends 100 and 102 of the base portion 98. The
outer edges of
the abutment members 124 and 126 are disposed flush with the lateral faces 108
and 110 of
the base portion 98. The spacing between the abutment members 124 and 126 is
sized large
enough to accommodate a portion of the mounting block therein. The abutment
members
124 and 126 cooperate with each other to hold the cutting tooth 90 in place
and discourage
rotation of the cutting tooth 90 relative to the mounting assembly 92 thereby
ensuring that
the cutting tooth 90 maintains the proper orientation for optimal cutting
effectiveness
during operation of the brush cutting head 24.
100551 The trailing face 106 of the base portion 98 is formed with a first
threaded blind
bore 130 proximate the first cutting portion 94 and a second threaded blind
bore 132
proximate the second cutting portion 96. Each blind bore 130, 132 is formed
with threading
123 which extends deeply into the base portion 98 stopping just shy of the
plane defining
the leading face 104. Beyond the threading 123, each blind bore 130, 132
tapers to a
conical end 133. Each end 133 extends beyond the leading face 104 and into the
projection
112, stopping only a short distance from the planar face 114 of the projection
112.
[0056] The first and second blind bores 130 and 132 are aligned with each
other along a
plane disposed perpendicular to the midplane M and are located roughly midway
between
the abutment members 124 and 126. Each blind bore 130, 132 is adapted to
receive a
fastener therethrough to permit the cutting tooth 90 to be fastened to a
portion of the
mounting assembly 92 in one of two orientations. As explained in greater
detail below,
when it is intended that the first cutting portion 94 engage or act upon brush
material to be
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cut, the fastener (or bolt) will be inserted through the second blind bore 132
(see FIG. 4A).
On the other hand, where the second cutting portion 96 is to engage or act
upon brush
material to be cut, then the fastener (or bolt) will be made to extend into
the first blind bore
130 (see FIG. 4B).
[0057] In alternative embodiments, the base portion 98 can be configured to
have a single
blind bore which would serve to locate a bolt for attachment of the cutting
tooth to a
portion of the mounting assembly. In such an embodiment, the blind bore would
be used
regardless of whether it was the first or second cutting edge that was
required to be put in
its respective operative position. The length of the base portion would likely
need to be
reduced in order to put into effect this change of configuration.
[0058] As best shown in FIGS. 13 and 14, the base portion 98 is tapered at the
midplane
M thereby imparting an hourglass-like shape to the base portion 98 (and the
cutting tooth
90). More specifically, starting from the juncture of the first cutting
portion 94 and the base
portion 98, the lateral faces 108 and 110 extend toward the midplane M in a
converging
fashion. Starting from the midplane M and moving toward the second cutting
portion 96,
the lateral faces 108 and 110 diverge. In this embodiment, the angle 13 formed
between
each of the lateral faces 108 and 110 and the midplane M is 85 degrees. Stated
another
way, there is 5 degree taper moving from the first end 100 or second end 102
of the base
portion 98 to the midplane M. In other embodiments, the angle 13 may be
modified (i.e.
increased or decreased) to suit a particular design. In still other
embodiments, the base
portion could be configured so that its lateral faces are disposed parallel to
each other.
[0059] In this embodiment, the narrowest width W1 of the base portion 98
occurs at the
midplane with the width W1 measuring 2.62 in. The length L1 of the base
portion 98 as
measured from the first end 100 to the second end 102 is 2.62 in. In other
embodiments, the
base portion could be proportioned differently (i.e. with a smaller or larger
width and/or
length).
[0060] At the midplane M, a groove 134 is defined in each lateral face 108,
110. In each
case, the groove 134 extends from the leading face 104 beyond the trailing
face 106 to
ultimately terminate at the trailing edge of the abutment shoulder member 124,
126 (as the
CA 02756326 2011-10-21
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case may be). The purpose of the grooves 134 is to prevent the concentration
of stresses
along the midplane M.
[0061] While it is generally preferred that the cutting tooth be provided with
a base
portion, it will be appreciated that this need not be the case in every
application. In
alternative embodiments, the cutting tooth could be made without a discernible
base
portion, as a result of the cutting portions having been reconfigured (and
resized) to
subsume the base portion.
[0062] A description of the first and second cutting portions 94 and 96 now
follows. The
first cutting portion 94 is carried on the first end 100 of the base portion
98 in a generally,
forwardly leaning or canted fashion. The first cutting portion 94 has a
leading face 140, an
opposed trailing face 142 and two spaced-apart lateral faces 144 and 146. The
leading face
140 of the first cutting portion 94 joins the leading face 104 of the base
portion 98 while the
trailing face 142 joins the trailing face 106. As best shown in FIG. 15B, an
external obtuse
angle 01 is formed between the leading face 140 and the leading face 104. In
this
embodiment, the angle 01 measures approximately 139 degrees. In other
embodiments, a
different angle may be employed.
[0063] Each lateral face 144, 146 is coplanar with the corresponding lateral
face 108, 110
of the base portion 98 such that the one merges smoothly with the other; the
orientation of
the lateral faces 144 and 146 contributing to the overall hourglass shape of
the cutting tooth
90.
[0064] The leading and trailing faces 140 and 142 cooperate with each other to
define a
tapering, wedge-like, profile 150 that terminates in a first cutting edge 152.
The first cutting
edge 152 is carried forwardly of the leading face 104 of the base portion 98
such that when
the first cutting portion 94 is in its operative orientation it tends to be
the first element of
the cutting tooth 90 to make contact with the brush to be cut. The first
cutting edge 152 is
carried at an angle al (as measured between the leading face 140 and a
notional plane
extending parallel to the midplane M). The angle al corresponds to the "angle
of attack" of
the first cutting portion 94, that is, the angle at which the first cutting
edge 152 approaches
the material to be cut. Preferably, this angle al measures between about 20
degrees and
CA 02756326 2011-10-21
16 -
about 75 degrees. In the embodiment shown in FIG. 15B, the angle al measures
49
degrees. It will be appreciated that a smaller angle of attack may be
desirable in instances
where the brush to be cut includes harder woods. Conversely, a larger angle of
attack may
be used where the first cutting edge 152 is intended to act on softer woods.
100651 The first cutting edge 152 extends generally linearly between the
lateral faces 144
and 146 and substantially parallel to the rotational axis R-R of the brush
cutting head 24.
However, in alternative embodiments, the first cutting edge could be
configured differently.
For instance, the first cutting edge could be configured to extend generally
diagonally
between the lateral faces 144 and 146, askew of the rotational axis R-R. This
configuration
would tend to favor one end of the cutting edge over the other contacting the
brush. In a
further alternative, the first cutting edge could be scalloped or formed to
extend in a
generally, zigzagging fashion.
[0066] In this embodiment, the width W2 of the first cutting edge 152 measures
3.0 in. In
other embodiments, the width of the first cutting edge could be greater or
lesser.
[0067] When the cutting tooth 90 is mounted within the station 52 and the
first cutting
portion 94 is in its operative orientation, the first cutting edge 152 extends
beyond the outer
sidewall edges 62 of adjacent collars 50 to facilitate the cutting action of
the tooth. In
operation, the first cutting edge 152 of each cutting tooth 90 comes into
contact with the
brush thereby creating debris as a result of the cutting action of the cutting
tooth 90. As the
debris passes over the first cutting edge 152, it abrades the surface of the
first cutting edge
152 thereby sharpening the cutting tooth 90. This sharpening action tends to
maintain or
enhance the cutting efficiency of the cutting tooth and tends to reduce the
need for
mechanical sharpening. Thereafter the debris may travel along the leading
and/or trailing
face 140 and 142 to be carried away from first cutting edge 152. As shown in
FIG. 4A, the
first cutting portion 94 is spaced away from the finger-like projection 74 of
the collar 50 so
as to provide a clearance for the passage of debris. Beyond the finger-like
projection 74, a
larger clearance for evacuating debris exists between the edge 72 of the
collar 50, and the
base portion 98 and the second cutting portion 96.
CA 02756326 2011-10-21
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[0068] Returning to FIGS. 12 and 15A and 15B, the trailing face 142 of the
first cutting
portion 94 has an upper portion 160 and a lower portion 162. The upper portion
160
extends between the first cutting edge 152 and the lower portion 162. The
upper portion
160 is bent relative to the lower portion 162 such that an internal obtuse
angle (pi is defined
therebetween. In the present embodiment, the angle (pi measures approximately
161
degrees. In other embodiments, a different angle may be employed.
[0069] In the embodiment shown in FIG. 12, the upper and lower portions 160
and 162 of
the trailing face 142 are shown to be planar. This need not be the case in
every application.
In other embodiments, it may be possible to define within these portions an
arrangement of
alternating grooves and ridges extending generally transverse of the first
cutting edge. This
arrangement of grooves and ridges would define corrugations on the trailing
face which can
serve to direct rocks, wood chips and other debris away from the first cutting
edge thereby
minimizing dispersion of the debris over the cutting area. In addition, the
ridges can
themselves define additional cutting edges for improved cutting performance.
In such other
embodiments, the grooves could be machine ground into the trailing face during
fabrication. Alternatively, the first cutting portion could be cast or forged
so as to form the
arrangement of alternating grooves and ridges.
[0070] In still other embodiments, the corrugations could be configured
differently. For
instance, the corrugations could have a generally arcuate or zigzag profile
when viewed in
cross-section. Other profiles may also be employed to similar advantage.
[0071] In this embodiment, the length L2 of the first cutting portion 94 (as
measured from
the first cutting edge 152 to the juncture where the lower portion 162 of the
trailing face
142 meets the first end 100 of the base portion 98) is 0.89 in. The ratio
L2:Li (i.e. the ratio
between the length L2 of the first cutting portion 94 and the length L1 of the
base portion
98) is approximately 0.34. In other embodiments, the first cutting portion may
be
configured to be shorter or longer to suit a particular application or to
achieve a particular
angle of attack. In such embodiments, preferably, the ratio L2:L 1 lies
between
approximately 0.17 and approximately 0.44.
CA 02756326 2011-10-21
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[0072] The second cutting portion 96 is carried on the second end 102 of the
base portion
98 in a generally, forwardly leaning or canted fashion. As mentioned earlier,
in this
preferred embodiment the second cutting portion 96 is configured to be the
mirror image of
the first cutting portion 94. In like fashion to the first cutting portion 94,
the second cutting
portion 96 includes a leading face 170, an opposed trailing face 172 and two
spaced-apart
lateral faces 174 and 176. The leading face 170 of the second cutting portion
96 joins the
leading face 104 of the base portion 98 while the trailing face 172 joins the
trailing face
106. As best shown in FIG. 15, an external obtuse angle 02 is formed between
the leading
face 170 and the leading face 104. In this embodiment, the angle 02 measures
approximately
139 degrees. In other embodiments, a different angle may be employed.
[0073] Each lateral face 174, 176 is coplanar with the corresponding lateral
face 108, 110
of the base portion 98 such that the one merges smoothly with the other; the
orientation of
the lateral faces 174 and 176 contributing to the overall hourglass shape of
the cutting tooth
90.
[0074] The leading and trailing faces 170 and 172 cooperate with each other to
define a
tapering, wedge-like, profile 180 that terminates in a second cutting edge
182. The second
cutting edge 182 is carried forwardly of the leading face 104 of the base
portion 98 such
that when the second cutting portion 96 is in its operative orientation it
tends to be the first
element of the cutting tooth 90 to make contact with the brush to be cut. The
second cutting
edge 182 is carried at an angle a2 (as measured between the leading face 170
and a notional
plane extending parallel to the midplane M). The angle ct2 corresponds to the
"angle of
attack" of the second cutting portion 96, that is, the angle at which the
first cutting edge 182
approaches the material to be cut. Preferably, this angle a2 measures between
about 20
degrees and about 75 degrees. In the embodiment shown in FIG. 15A, the angle
az
measures 49 degrees. It will be appreciated that a smaller angle of attack may
be desirable
in instances where the brush to be cut includes harder woods. Conversely, a
larger angle of
attack may be used where the second cutting edge 182 is intended to act on
softer woods.
[0075] The second cutting edge 182 extends generally linearly between the
lateral faces
174 and 176 and substantially parallel to the rotational axis R-R of the brush
cutting head
CA 02756326 2011-10-21
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24. However, in alternative embodiments, the second cutting edge could be
configured
differently. For instance, the second cutting edge could be configured to
extend generally
diagonally between the lateral faces 174 and 176, askew of the rotational axis
R-R. This
configuration would tend to favor one end of the cutting edge over the other
contacting the
brush. In a further alternative, the second cutting edge could be scalloped or
formed to
extend in a generally, zigzagging fashion.
[0076] In this embodiment, the width W3 of the second cutting edge 182
measures 3.0 in.
In other embodiments, the width of the second cutting edge could be greater or
lesser.
[0077] When the cutting tooth 90 is mounted within the station 52 and the
second cutting
portion 96 is in its operative orientation, the second cutting edge 182
extends beyond the
outer sidewall edges 62 of adjacent collars 50 to facilitate the cutting
action of the tooth. In
operation, the second cutting edge 182 of each cutting tooth 90 comes into
contact with the
brush thereby creating debris as a result of the cutting action of the cutting
tooth 90. As
was the case with the first cutting edge 152, as the debris passes over the
second cutting
edge 182, it abrades the surface of the second cutting edge 182 thereby
sharpening the
cutting tooth 90. This sharpening action tends to maintain or enhance the
cutting efficiency
of the cutting tooth and tends to reduce the need for mechanical sharpening.
Thereafter the
debris may travel along the leading and/or trailing face 170 and 172 to be
carried away
from second cutting edge 182. As shown in FIG. 4B, the second cutting portion
96 is
spaced away from the finger-like projection 74 of the collar 50 so as to
provide a clearance
for the passage of debris. Beyond the finger-like projection 74, a larger
clearance for
evacuating debris exists between the edge 72 of the collar 50 on the one side,
and the base
portion 98 and second cutting portion 96 on the other.
[00781 Returning to FIG. 15A, the trailing face 172 of the second cutting
portion 96 has
an upper portion 190 and a lower portion 192. The upper portion 190 extends
between the
second cutting edge 182 and the lower portion 192. The upper portion 190 is
bent relative
to the lower portion 192 such that an internal obtuse angle (p2 is defined
therebetween. In
the present embodiment, the angle cp2 measures approximately 161 degrees. In
other
embodiments, a different angle may be employed.
CA 02756326 2011-10-21
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100791 In the embodiment shown in FIG. 12, the upper and lower portions 190
and 192 of
the trailing face 172 are shown to be planar. This need not be the case in
every application.
As explained above in the context of upper and lower portions 160 and 162, the
former
portions can be formed with an arrangement of alternating grooves and ridges
extending
generally transverse of the second cutting edge. This arrangement of grooves
and ridges
would define corrugations on the trailing face which can serve to direct
rocks, wood chips
and other debris away from the first cutting edge thereby minimizing
dispersion of the
debris over the cutting area. In addition, the ridges can themselves define
additional cutting
edges for improved cutting performance. In such other embodiments, the grooves
could be
machine ground into the trailing face during fabrication. Alternatively, the
second cutting
portion could be cast or forged so as to form the arrangement of alternating
grooves and
ridges.
[0080] In still other embodiments, the corrugations could be configured
differently. For
instance, the corrugations could have a generally arcuate or zigzag profile
when viewed in
cross-section. Other profiles may also be employed to similar advantage.
[0081] In this embodiment, the length L3 of the second cutting portion 96 (as
measured
from the second cutting edge 182 to the juncture where the lower portion 192
of the trailing
face 172 meets the second end 102 of the base portion 98) is 0.89 in. The
ratio L3:1, i (i.e.
the ratio between the length L3 of the second cutting portion 96 and the
length L1 of the
base portion 98) is approximately 0.34. In other embodiments, the second
cutting portion
may be configured to be shorter or longer to suit a particular application or
to achieve a
particular angle of attack. In such embodiments, preferably, the ratio L3:L1
lies between
approximately 0.17 and approximately 0.44.
[0082] Preferably, the cutting tooth 90 is fabricated from hardened steel
selected for its
strength and improved resistance to wear and impact. However, in other
embodiments, the
cutting tooth could be fabricated from other suitable materials exhibiting
similar material
characteristics.
[0083] Advantageously, the provision of two (or dual) cutting edges 152 and
182 on the
cutting tooth 90 tends to lengthen the service life of the cutting tooth 90
and minimize
CA 02756326 2011-10-21
21 - =
maintenance and/or repair. When the first cutting edge 152 wears down, is
rendered
inoperative, or its cutting efficiency is otherwise impaired, the orientation
of the cutting
tooth 90 may be inverted so as to position the second cutting edge 182 in its
operative
orientation and have the first cutting edge in its inoperative orientation.
Brush cutting
activities can resume with the second cutting edge 182 of the cutting tooth 90
acting on the
brush to be cut.
[0084] In this embodiment, with both first and second cutting edges 152 and
182 oriented
at an angle of attack of 49 degrees, the notional diameter DI of a circle C1
drawn within the
envelope of the cutting tooth 90 (as shown in FIG. 1 5B) measures 4.4 in. In
other
embodiments, the diameter D may be different to suit a particular application.
However, in
order to ensure optimal cutting effectiveness of the cutting tooth 90 it has
been found that
preferably, the diameter D measures between 3.5 in. and 4.9 in., with the low
end of the
range for diameter D corresponding to an angle of attack for both first and
second cutting
edges of 20 degrees and the high end of the range for diameter D corresponding
to an angle
of attack for both first and second cutting edges of 75 degrees. In FIG. 15B,
the cutting
edges arranged at angles of attack of 20 degrees and 75 degrees are shown in
dashed lines.
The lower limit of the diameter D is identified in FIG. 15B with reference
symbol Dmin and
the corresponding notional circle with reference symbol Cmin. Along the same
lines, the
higher limit of the diameter D is identified in FIG. 15B with reference symbol
Drna, and the
corresponding notional circle with reference symbol Cmax=
[0085] In the embodiment shown in FIGS. 11 to 15A and 15B, the first cutting
portion 94
is a mirror image of the second cutting portion 96 such that it is identically
sized and the
first cutting edge 152 has the same angle of attack as the second cutting edge
182. This
need not be the case in every application. In certain embodiments, it may be
desirable to
have one cutting portion sized differently than the other, or to have one
cutting edge with a
different angle of attack than the other cutting edge. The orientation of the
cutting edges of
each cutting tooth on the brush cutter head could be modified to suit
particular field
conditions. For example, where soft woods are to be cut, the cutting edge with
the larger
angle of attack may be used. Conversely, where hard woods are to be cut, the
cutting edge
with the smaller angle of attack will be used. Because each cutting tooth
carries two
CA 02756326 2011-10-21
- = 22 -
=
opposed cutting edges, there is no need to have two sets of cutting teeth with
differently
angled cutting edges, thereby enhancing the versatility of the brush cutting
head. Moreover,
changing the orientation of the cutting tooth so that one cutting edge becomes
operative can
be accomplished quickly and efficiently resulting in less downtime during
maintenance and
enhanced convenience.
[0086] Referring to FIGS. 4A, 4B, 8 to 10, the mounting assembly 92 includes a
mounting block 200 which is configured for securely holding the cutting tooth
90, a
threaded fastener in the nature of a bolt 202 and a washer 203. The mounting
block 200 has
a body 204 that is formed with a sloping upper face 206, a curved lower face
208, a leading
face 210, a trailing face 212, and a pair of opposed lateral faces 214 and
216. The lower
face 208 has a leading end 218, a trailing end 220 and outer lateral margins
222 and 224
extending between the leading and trailing ends 218 and 220. The curvature of
the lower
face 208 corresponds substantially to the curvature of the curved outer
surface 48 of the
support body 40. In the regions where the lower face 208 meets the lateral
faces 214 and
216, the outer lateral margins 222 and 224 are trimmed back at an angle (or
truncated) to
facilitate welding of the mounting block 200 to the support body 40.
[0087] Referring specifically to FIG. 10, the trailing face 212 extends
straight from the
trailing end 220 of the lower face 208 to the upper face 206. At the juncture
of the trailing
face 212 and the upper face 206, the body 204 is formed with a cutout 228
shaped like an
inverted thumbprint. Defined in the end face 230 of the cutout 228 and
extending through
the body 204 to open onto the leading face 210 is a smooth bore 232. The bore
232 is
configured to receive the bolt 202.
[0088] The upper face 206 runs at incline towards the leading face 210. The
leading face
210 is recessed from the leading end 218 of the lower face 208 thereby
defining a
horizontal shelf 238 proximate the lower face 208. The leading face 210
extends upwardly
from the horizontal shelf 238 to meet the upper face 206. In the regions where
the leading
face 210 meets the lateral faces 214 and 216, narrow longitudinal rebates 240
and 242 are
formed which extend from the upper face 206 about two-thirds of the way toward
the
horizontal shelf 238. The provision of rebates 240 and 242 facilitates the
proper positioning
CA 02756326 2011-10-21
23 - '
of the cutting tooth 90 on the mounting block 200 by serving as guide means
for the
location of the abutment shoulders 124 and 126. During assembly of the cutting
tooth 90
with the mounting block 200, the abutment shoulders 124 and 126 are seated
within the
rebates 240 and 242.
100891 The width of the mounting block body 204 as measured between the
lateral faces
214 and 216 is slightly less than the narrowest width of the cutting tooth 90
taken at the
midplane M such that the lateral extremities of the cutting tooth 90 can be
seen to extend
beyond the lateral extremities of the mounting block body 204.
100901 Referring to FIGS. 5 and 6, during fabrication of the brush cutting
head 24, the
lower face 208 of the mounting block 200 is positioned onto the curved outer
surface 48 of
the support body 40 with the trailing face 210 of the mounting block 200
abutting and
welded to the straight edge 76 of the collar sidewall 60. The trailing end 220
of the
mounting block lower face 208 sits on the relatively small shoulder 78 defined
on the collar
50. The collar 50 is disposed centrally relative to the trailing face 210 and
serves the
function of a reinforcing spine for the cutting tooth assembly 54. When the
cutting tooth 90
strikes a hard object, the force of impact is distributed through the cutting
tooth 90, the
mounting assembly 92, the reinforcing collar 50 and the support body 40.
100911 In this embodiment, the mounting block 200 is fabricated from hardened
steel
selected for its strength and improved resistance to wear and impact. In other
embodiments,
the mounting block could be fabricated from other suitable materials
exhibiting similar
material characteristics.
[00921 Referring now to FIGS. 4A, 4B and 6, the attachment of the cutting
tooth 90 to the
brush cutting head 24 is now described in greater detail. The trailing face
106 of the base
portion 98 is brought to bear against the leading face 210 of the mounting
block body 204
with care being taken to ensure that each abutment shoulder 124, 126 of the
base portion 98
aligns with its corresponding rebate 240, 242 formed in the mounting block
body 204 and
that the blind bore 130 or 132 (as the case may be) defined in the trailing
face 106 of the
base portion 98 is aligned with the bore 232 formed through the mounting block
body 204.
Where the first cutting portion 94 is to be put into its operative position,
the blind bore 132
CA 02756326 2011-10-21
- 24 - =
will be aligned with the bore 232 and the first cutting edge 152 will be
located furthest from
the outer curved surface 48 of the support body. In contrast, the second
cutting edge 182
will be arranged closest to the outer curved surface 48 and where it will
occupy its non-
operative position (see FIG. 4A).
[0093] Alternatively, where the second cutting portion 96 is to be put into
its operative
position, the blind bore 130 will be aligned with the bore 232 and the second
cutting edge
182 will be located furthest from the outer curved surface 48. The first
cutting edge 152
will be arranged closest to the outer curved surface 48 where it will occupy
its non-
operative position (see FIG. 4B). Once the bore 130 or 132 is aligned with
bore 232, the
bolt 202 with washer 203 may be inserted therethrough and tightened until the
cutting tooth
90 is firmly secured onto the mounting block 200.
[0094] In either case where the first cutting edge 152 or the second cutting
edge 182 is its
non-operative position, it can be seen that there is sufficient clearance
between that cutting
edge and the horizontal shelf 238 of the mounting block 200 to avoid any
physical contact
or interference between them.
[0095] Because the end of the bolt 202 remains captive within the mounting
block body
and does not extend beyond the leading face, the risk that the bolt will
experience a sheer
failure as a result of a hard piece of wood or rock violently striking the
bolt is mitigated.
This is an improvement over the prior art cutting tooth and mounting block
combination
described in United States Patent Publication No. 2010/0044487, in which a
portion of the
bolt and the nut fastened thereon projected from the leading face of the
cutting tooth and
were thus exposed to such violent impacts.
[0096] As best shown in FIG. 6, when the cutting tooth 90 is fastened to the
mounting
block 200 the abutment shoulder 124 and 126 can be seen to wrap around the
leading face
210 of the mounting block body 204 and will tend to prevent the cutting tooth
90 from
rotating relative to the mounting block 200 and from bringing the cutting edge
152 or 182
(as the case may be) out of its proper orientation. In this way, the need to
provide locating
means (in the nature of a projecting guide member) on the bottom of the
cutting tooth and
CA 02756326 2011-10-21
25 -
on the horizontal shelf of the mounting block to ensure the proper orientation
of the cutting
tooth, may be obviated along with the problems associated therewith.
[0097] It will thus be appreciated that the cutting tooth fabricated in
accordance with the
principles of the present invention is optimally configured and sized for
attachment to the
mounting blocks of known brush cutting heads without physical interference
with same,
and for enhanced cutting efficiency and extended service life of the cutting
tooth.
[0098] FIG. 16 shows an end view of the brush cutting head 24 with all the
cutting teeth
90 visible with their first cutting edges 152 in their respective operative
positions. In this
figure, the first cutting edges 152 of the cutting teeth 90 can be seen to
have an angle of
attack al of 49 degrees shown in solid lines and minimum and maximum angles of
attack
20 and 75 degrees, respectively, shown in dashed lines. In this embodiment,
the diameter
DT of the brush cutting head 24 (as measured between the first cutting edges
152 of
opposed cutting teeth 90 at an angle of attack of 49 degrees) measures 19.82
in. In this
embodiment, the ratio of the diameter DI (i.e. the diameter of a circle CI
drawn within the
envelope of the cutting tooth 90) to the diameter DT.49 is 0.22.
[0099] Where the first cutting edges 152 are oriented at an angle of attack of
20 degrees,
the diameter DT20 measures 18.94 in. and the ratio of the diameter Dinh, to
DT20 is 0.18.
Where the first cutting edges 152 are oriented at an angle of attack of 75
degrees, the
diameter DT75 measures 20.44 in. and the ratio of the diameter Dm, to DT75 is
0.24. It has
been found that for optimal sizing and cutting efficiency the ratio of D to DT
should lie
between approximately 0.18 and 0.24.
[00100] Although the foregoing description and accompanying drawings relate to
specific
preferred embodiments of the present invention as presently contemplated by
the inventor,
it will be understood that various changes, modifications and adaptations, may
be made
without departing from the spirit of the invention.
