Note: Descriptions are shown in the official language in which they were submitted.
; _ .
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PROTECTIVE GUARD MEMBERS FOR CUTTING TOOTH ASSEMBLIES
MOUNTED ON A BRUSH CUTTING HEAD
FIELD OF THE INVENTION
100011 The present invention relates generally to brush cutting heads, and
more
specifically, to protective guard members for cutting tooth assemblies mounted
on brush
cutting heads.
BACKGROUND OF THE INVENTION
100021 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] To protect the cutting tooth and its associated mounting assembly,
certain brush
cutting heads have been provided with protective collars. One such brush
cutting head is
described in United States Patent No. 6,764,035. This patent discloses a brush
cutting head
that has a cylindrical support base and a plurality of cutting tooth 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 carries a cutting tooth on its front face. To protect the
mounting blocks
from rocks, 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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[00041 While the protective collars described in United States Patent No.
6,764,035
afford the cutting tooth assemblies some protection, the cutting teeth remain
nonetheless
exposed to violent impact with hard objects, like stones, and thus are still
vulnerable to
damage during brush cutting operations.
[0005] United States Patent Application Publication No. 2007/0261763 describes
a brush
cutting head provided with differently configured collars and cutting tooth
assemblies. This
brush cutting head has a cylindrical support body with a curved outer surface
and a
plurality of penannular collars. The collars are mounted to the support body
at spaced apart
locations and extend radially from its curved outer surface. Each collar
cooperates with an
adjacent collar to define a mounting station between adjacent collars. A
plurality of cutting
tooth assemblies are carried on the outer surface of the support body. Each
cutting tooth
assembly has a cutting tooth for placement within a mounting station, and a
mounting
assembly engageable with the adjacent collars to secure the cutting tooth in
the mounting
station.
[0006] By having the cutting tooth and its associated mounting assembly
disposed
between adjacent collars, two-fold protection is afforded to the cutting
teeth. The collars
shield the cutting teeth from rocks and other hard objects and reduce the
stresses to which
the cutting teeth are subjected during operations by improving the
distribution of forces
through the mounting assembly.
[0007] While the brush cutting head described in United States Patent
Application
Publication No. 2007/0261763 has proven itself successful on the field and
constitutes an
improvement over what was previously available on the market, efforts continue
to be
made to lengthen the service life of the cutting teeth and their mounting
assemblies by
reducing the incidence of destructive impact with rocks. In light of the
foregoing, it would
be advantageous to have a brush cutting head with improved means for
protecting cutting
teeth and their mounting assemblies from violent impact with hard objects.
Preferably,
such protection means would be relatively easy to fabricate and install and
would not add
significant weight to the brush cutting head so as to minimize power
consumption.
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SUMMARY OF THE INVENTION
[0008] In accordance with one embodiment of the present invention, there is
provided a
brush cutting head. The brush cutting head has a support body with a first
end, an opposed
second end and an intermediate portion extending therebetween. The
intermediate portion
has an outer surface. A plurality of collars is mounted to the support body at
spaced
intervals along the intermediate portion. Each collar extends outwardly from
the outer
surface. The brush cutting head also includes a plurality of cutting teeth
carried on the outer
surface of the support body. Each cutting tooth is associated with at least
one collar. Also
provided is at least one guard member for protecting at least one cutting
tooth of the
plurality from impacts with hard objects. The at least one guard member is
carried on one
of the collars with at least a portion thereof projecting beyond the outermost
edge of the one
collar.
[0009] In an additional feature, the at least one guard member has an
outermost margin.
The outermost margin defines a protective envelope that at least partially
encompasses the
at least one cutting tooth.
[0010] In a further feature, the plurality of collars includes first, second,
third and fourth
collars; the second collar is disposed between the first and third collars and
the third collar
is disposed between the second and fourth collars. The at least one guard
member includes
first, second, third and fourth guard members. The first guard member is
carried on the first
collar; the second guard member is carried on the second collar; the third
guard member is
carried on the third collar and the fourth guard member is carried on the
fourth collar.
[0011] Additionally, the support body is a cylindrical support body. The outer
surface of
the support body is a curved surface defining the circumference of the support
body. The
first guard member is circumferentially spaced from the second guard member;
the second
guard member is circumferentially spaced from the third guard member; and the
third guard
member is circumferentially spaced from the fourth guard member. In an
additional feature,
the first guard member is circumferentially spaced from the third guard member
by a first
acute angle and the second guard member is circumferentially spaced from the
fourth guard
member by a second acute angle. The first acute angle equals the second acute
angle. In
. .. . . , . . , .
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yet another additional feature, the first guard member is circumferentially
spaced from the
second guard member by a first obtuse angle and the third guard member is
circumferentially spaced from the fourth guard member by a second obtuse
angle. The first
obtuse angle equals the second obtuse angle. The second guard member is
positioned so as
to be substantially opposed to the third guard member.
[0012] In still another feature, the plurality of cutting teeth includes
first, second and third
cutting teeth. The first cutting tooth is mounted between the first and second
collars; the
second cutting tooth is mounted between the second and third collars; and the
third cutting
tooth is mounted between the third and fourth collars. The second guard member
is
disposed forwardly of the first cutting tooth. The third guard member is
disposed forwardly
of the second cutting tooth. The fourth guard member is disposed forwardly of
the third
cutting tooth. Further still, the outermost edge of each of the first and
second guard
members defines a protective envelope. The protective envelope defined by the
first guard
member at least partially encompasses the second cutting tooth; and the
protective envelope
defined by the second guard member at least partially encompasses the third
cutting tooth.
Additionally, each cutting tooth has a cutting portion terminating with a
leading cutting
edge. The protective envelope defined by the first guard member substantially
encompasses the cutting portion of the second cutting tooth. Optionally, the
protective
envelope defined by the first guard member entirely encompasses the cutting
edge of the
second cutting tooth.
[0013] In yet another feature, the plurality of cutting tooth includes first,
second, third
and fourth cutting tooth. The first cutting tooth is associated with the first
collar; the second
cutting tooth is associated with the second collar; the third cutting tooth is
associated with
the third collar; and the fourth cutting tooth is associated with the fourth
collar. The
outermost edge of each of the first, second, third and fourth guard members
defines a
protective envelope. The protective envelope defined by the first guard member
at least
partially encompasses the second cutting tooth; the protective envelope
defined by the
second guard member at least partially encompasses the first cutting tooth;
the protective
envelope defined by the third guard member at least partially encompasses the
fourth
cutting tooth; and the protective envelope defined by the fourth guard member
at least
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partially encompasses the third cutting tooth. Additionally, each cutting
tooth has a cutting
portion terminating with a leading cutting edge. The protective envelope
defined by the first
guard member substantially encompasses the cutting portion of the second
cutting tooth.
Optionally, the protective envelope defined by the first guard member entirely
encompasses
the cutting edge of the second cutting tooth. As a further option, the
protective envelope
defined by the first guard member entirely encompasses the second cutting
tooth.
100141 In a further feature, each cutting tooth has a cutting portion
terminating with a
leading cutting edge. The plurality of cutting tooth includes first, second,
third and fourth
cutting tooth. The first cutting tooth is associated with the first collar;
the second cutting
tooth is associated with the second collar; the third cutting tooth is
associated with the third
collar; and the fourth cutting tooth is associated with the fourth collar.
Each of the first,
second, third and fourth guard members has a leading end and a trailing end.
The leading
end of the second guard member is disposed forwardly of the leading cutting
edge of the
first cutting tooth.
[00151 In still another feature, the at least one guard member has a first
portion mounted
to the one collar and a second portion joined to the first portion. The
portion of the at least
one guard member projecting beyond the outermost edge of the one collar
corresponds
substantially to the second guard member portion. The first portion is welded
to the second
portion. In a first alternative feature, the first portion is integrally
formed with the second
portion. In a second alternative feature, the first portion is releasably
attached to the second
portion.
[00161 In yet another feature, the one collar has a substantially penannular
structure
defined by a circumferentially extending sidewall. The sidewall has an inner
edge fixed to
the outer edge of the support body and an outer edge. The outer edge of the
sidewall
corresponds to the outermost edge of the one collar. The first guard member
portion is
releasably attached to the sidewall of the one collar. The sidewall of the one
collar has a
pair of apertures defined therein and the first guard member portion has a
pair of apertures
defined therein. The pair of apertures defined in the first guard member
portion is aligned
,
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with the pair of apertures defined in the second guard member portion so as to
permit
fasteners to be received therethrough.
[0017] In a further feature, the second guard member portion is at least
partially
supported on the outer edge of the sidewall.
[0018] In another feature, the second portion includes a crescent-shaped body
defined
substantially by a convex edge and an opposed concave edge. The convex edge
defines the
outermost margin of the at least one guard member. The concave edge conforms
substantially
to the curvature of the outer edge of the sidewall. Each of the first and
second guard
member portions has an abutment face and an opposite face. At the juncture
between the first
and second guard member portions, the abutment face of the first guard member
portion bears
against the abutment face of the second guard member portion along a margin. A
portion of the
abutment face of the first guard member portion cooperates with the concave
edge of the
second guard member portion to define a shoulder. The shoulder abuts a portion
of the
sidewall and outer edge of the one collar. In the vicinity of the convex edge,
the second
guard member portion has a thickness measured between the abutment face and
opposite
face thereof. The thickness of the second guard member portion in the vicinity
of the
convex edge corresponds substantially to the thickness of the collar as
measured between
the opposed faces thereof.
[0019] In still another feature, the crescent-shaped body has a leading end
and a trailing
end. The leading end is a mirror image of the trailing end. In alternate
feature, the trailing
end terminates with a bull-nose tip to provide increased protective coverage
for the at least
one cutting tooth.
[0020] In yet another feature, the second guard member portion has a curved
edge
constituting the outermost margin of the at least one guard member. The curved
edge defines a
protective envelope that at least partially encompasses the at least one
cutting tooth. The
curved edge is a convex edge.
[00211 In a further feature, the at least one guard member is releasably
attached to the one
collar. In a first alternative feature, the at least one guard member is
fixedly mounted to the
,
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one collar. In a second alternative feature, the at least one guard member is
integrally
formed with the one collar.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] 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:
[0023] FIG. 1 is a front right perspective view of a brush cutter according to
a first
embodiment of the present invention;
[0024] FIG. 2a is a front left perspective view of the brush cutting head
shown in FIG. 1;
[0025] FIG. 2b is another perspective view similar to that shown in FIG. 2a
showing the
brush cutting head rotated 180 degrees;
[0026] FIG. 3 is an end view of the brush cutting head shown in FIG. 2a taken
from the
opposite end, rotated 90 degrees and with a collar removed therefrom for the
sake of
clarity;
[0027] FIG. 4 is an enlarged view similar to that illustrated in FIG. 3
showing the
encircled portion `4';
[0028] FIG. 5 is an end view of the brush cutting head shown in FIG. 2b with a
section thereof cut along the line `5-5';
[0029] FIG. 6 is an enlarged perspective view of the brush cutting head of
FIG. 2a
taken from the opposite end and rotated 270 degrees, showing a representative
cutting
tooth and a portion of its corresponding mounting assembly exploded, and the
protective cutting tooth guard members removed;
[0030] FIG. 7 is an enlarged perspective view similar to that illustrated in
FIG. 6
showing the cutting teeth mounted on the brush cutting head, and a
representative
cutting tooth guard member and its fasteners exploded;
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[0031] FIG. 8 is a side elevation view of one of the collars shown in FIG. 6;
[0032] FIG. 9 is a perspective view of one of the cutting teeth shown in FIG.
6;
[0033] FIG. 10 is a side elevation view of the cutting tooth shown in FIG. 9;
[0034] FIG. 11 is a perspective view of the mounting block shown in FIG. 6;
[0035] FIG. 12 is a perspective view of the mounting plate shown in FIG. 6;
[0036] FIG. 13 is a perspective view of the abutment plate shown in FIG. 6;
100371 FIG. 14 is an end elevation view of the retaining member shown in FIG.
6;
[0038] FIG. 15 is a top left perspective view of one of the guard members
shown in FIG. 5;
[0039] FIG. 16 is a side elevation view of the guard member shown in FIG. 15;
[0040] FIG. 17 is a bottom right perspective view of the guard member shown in
FIG. 15;
[0041] FIG. 18 is a front left perspective view of an alternative brush
cutting head to that
shown in FIG. 2a;
100421 FIG. 19 is an end view of the brush cutting head shown in FIG. 18; and
[0043] FIG. 20 is an end view of the brush cutting head shown in FIG. 18 with
a
section thereof cut along the line `20-20';
[0044] FIG. 21 is a top left perspective view of one of the guard members
shown in FIG. 18;
[0045] FIG. 22 is a side elevation view of the guard member shown in FIG. 21;
and
[0046] FIG. 23 is a bottom right perspective view of the guard member shown in
FIG. 21.
DETAILED DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
[0047] The description which follows, and the embodiments described therein
are
provided by way of illustration of an example, or examples of particular
embodiments of
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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.
[0048] 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
FIGS. 2a and 2b). A drive assembly (not shown) is operatively connected to the
brush
cutting head 24 to drive rotation thereof.
100491 Referring now to FIG. 2a, 2b and 3, 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. This.
however, need not
be the case in every application. In alternative embodiments, the support body
may be
shaped differently.
[0050] The intermediate portion 46 has a curved outer surface 48 (shown in
FIG. 4) 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 50u
(collectively,
"collars 50"). As will be explained in greater detail below, pairs of adjacent
collars 50
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cooperate with each other to define mounting sites or stations 52 for each
receiving a
cutting tooth assembly 54 therein.
[0051] Referring to FIG. 8, 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
cutout 70
formed in the collar 50. The cutout 70 is disposed slightly off centre of the
centreline CL of
the collar 50.
[0052] At second sidewall end 68, the outer edge 62 has been trimmed back (by
laser
cutting) at a first location 72 to define a first substantially planar edge
74. A short distance
away from the second sidewall end 68, the edge 74 terminates at a relatively
small shoulder
78 defined in the outer edge 62. Inwardly of the first end 66 (i.e. moving
counterclockwise), there is a rebate 80 that has been formed by a cut away in
the outer edge
62. The outer edge 62 has also been trimmed at a second location 82
circumferentially
spaced from the first location 72, to define a second substantially planar
edge 84 and rebate
86. The edge 84 also terminates at a shoulder 88 of a size similar to that of
shoulder 78. The
rebates 80 and 86 are provided to facilitate the removal of bits of wood or
debris that may
be lodged within the cutting assembly 54.
[0053] Adjacent each of the first and second locations 72 and 82, the inner
edge 64 of the
sidewall 60 has a generally channel-shaped rebate 90, 92 (as the case may be)
defined
therein. The first rebate 90 is circumferentially spaced from the second
rebate 92. The
rebates 90 and 92 provide access to the space between adjacent collars 54
thereby
facilitating the welding of a portion of the cutting tooth assembly 54 to the
collar sidewalls
60. Proximate the second rebate 92, the collar 50 has defined therethrough a
pair of bores
282 and 284 to permit fixation of a protective guard member 94 for the cutting
tooth
assembly 54.
100541 The collars 50 are radially mounted to the support body 40 with their
inner
sidewall edges 64 welded to the curved surface 48. The spacing between
adjacent collars
50 is sized to correspond generally to the width of the cutting tooth assembly
54 and tends
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to minimize the risk that the cutting tooth assembly 54 will be damaged by a
rock. As
explained in greater detail below, to further protect or shield the cutting
tooth assemblies
from violent impact with large rocks or the like, the collars 50 each carry
thereon the
protective guard member 94.
[0055] Each collar 50 is radially offset from its adjacent collar 50 such that
the cutouts 70
of adjacent collars are staggered relative to each other. In this embodiment,
each station 52
is defined between the cutout 70 formed in a given collar 50 and that portion
of the sidewall
60 of the adjacent collar 50 that is disposed opposite the cutout 70.
Referring to FIG. 6, the
station 52tu (previously identified generically as "station 52") can be seen
to be defined
between the cutout 70 in collar 50tu and the portion of sidewall 60 of collar
50t located
opposite the first cutout 70. Each of the other stations 50, identified in
FIG. 2a is similarly
defined between the cutout 70 of one collar 50 and a portion of sidewall 60 of
an adjacent
collar 50. As best shown in FIGS. 3, the station 52tu is circumferentially
staggered from the
station 52st by an angle wl. In this embodiment, the angle w, measures
approximately 180
degrees.
[0056] 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 wz.
Taking as an
example stations 52tu and 52rs, it can be seen in FIG. 4 that station 52rs is
circumferentially staggered relative to station 52tu by an angle w2.
Preferably, the angle wz
is an acute angle. In this embodiment, the angle 0)2 measures approximately 20
degrees.
[0057] 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'.
As shown in FIGS. 2a and 2b, the cutting tooth assemblies 54 mounted in
alternate stations
52ab, 52cd, 52ef, 52gh, 52ij, 52k1, 52mn, 52op, 52qr, and 52st define a first
helical layout,
whereas the cutting tooth assemblies 54 mounted in the remaining alternate
stations 52bc,
52de, 52fg, 52hi, 52jk, 521m, 52no, 52pq, 52rs and 52tu define a second
helical layout.
While this double helix pattern is generally preferred, it will be appreciated
that the cutting
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tooth assemblies 54 could be laid out differently along the support body 40.
More
specifically, the angles wl and 0)2 could be varied 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.
[0058] The cutting tooth assembly 54 is now described in greater detail with
reference to
FIGS. 2a, 3 and 9 to 14. The cutting tooth assembly 54 includes a cutting
tooth 100 and a
mounting assembly 102 for securely fixing the cutting tooth 100 within a
respective station
50. The cutting tooth 100 has a base portion 104 having a first end 106 and a
second end
108, and a cutting portion 110 mounted to the second end 108 of the base
portion 104.
[0059] The base portion 104 has a generally planar, leading face 112, an
opposing trailing
face 114 and two, spaced apart, lateral faces 116 and 118. Defined in the base
portion 104
is a bore 120 that extends between the leading face 112 and the trailing face
114. The bore
120 is adapted to receive a fastener therethrough to permit fastening of the
cutting tooth
100 to the mounting assembly 102. Adjacent the second end 108, the trailing
face 114 of
the base portion 104 flares outwardly to partially define a wedge-shaped
abutment shoulder
128. The abutment shoulder 128 serves to reinforce the cutting tooth 100 and
enables it to
better resist the high impact forces to which it may be subjected during
operation of the
brush cutting head 24. As a result, the cutting tooth 100 tends to be less
vulnerable to
cracking failures along the area where the cutting portion 110 meets the base
portion 104.
As will be explained in greater detail below, when the cutting tooth 100 is
mounted within
its respective station 52, the abutment shoulder 128 will rest on a portion of
the mounting
assembly 102.
[0060] The cutting portion 110 is carried on the second end 108 of the base
portion 104
in a generally, forwardly leaning or canted fashion, and is integrally formed
with the base
portion 104. The cutting portion 110 has a leading face 130, an opposed
trailing face 132
and two spaced-apart lateral faces 134 and 136. The leading face 130 of the
cutting portion
110 joins the leading face 112 of the base portion 104 while the trailing face
132 joins the
trailing face 114. Adjacent the juncture of the leading face 130 and the
leading face 112, a
spur 134 projects from the leading face 130. The spur 134 is provided for
further chipping
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cutting debris. As best shown in FIG. 10, an external obtuse angle 01 is
formed between the
leading face 130 and the leading face 112. In this embodiment, the angle 01
measures
approximately 116 degrees.
[0061] The leading and trailing faces 130 and 132 cooperate with each other to
define a
tapering, wedge-like, profile 140 that terminates in a cutting edge 142. The
cutting edge
142 is carried forwardly of the leading face 112 of the base portion 104 such
that it tends to
be the first element of cutting tooth 100 to make contact with the brush. The
cutting edge
142 extends generally linearly between the lateral faces 134 and 136 and
substantially
parallel to the rotational axis R-R of the brush cutting head 24. However, in
alternative
embodiments, the cutting edge could be configured differently. For instance,
the cutting
edge could be configured to extend generally diagonally between the lateral
faces 134 and
136, 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 cutting
edge could be scalloped or formed to extend in a generally, zigzagging
fashion.
[0062] When the cutting tooth 100 is mounted within the station 52, the
cutting edge 142
extends beyond the first and second edges 74 and 84 of the sidewall 60 (of
adjacent collars
50) to facilitate the cutting action of the tooth. The reduced profile of the
sidewall 60 at the
edges 74 and 84 tends to facilitate evacuation of the cutting debris away from
the station 52
and the cutting tooth 100. In operation, the cutting edge 142 of each cutting
tooth 100
comes into contact with the brush thereby creating debris as a result of the
cutting action of
the cutting tooth 100. As the debris passes over the cutting edge 142, it
abrades the surface
of the cutting edge 142 thereby sharpening the cutting tooth 100. 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 travels along the
channels 144 to
be carried away from cutting edge 142.
[0063] Returning to FIG. 10, the trailing face 132 of the cutting portion 110
has an upper
portion 150, a lower portion 152 and an intermediate portion 154 disposed
between the
upper portion 150 and lower portion 152. The upper portion 150 extends between
the
cutting edge 142 and the intermediate portion 154. The upper portion 150 is
bent relative to
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the intermediate portion 154 such that an internal obtuse angle 02 is defined
therebetween.
In the present embodiment, the angle 02 measures approximately 158.5 degrees.
Similarly,
the lower portion 152, which partially defines the abutment shoulder 128, is
also canted
relative to the intermediate portion 154.
[0064] The cutting portion trailing face 132 has a plurality of knuckle-like
protuberances
in the nature of ridges 156 formed thereon. The ridges 156 are generally
evenly spaced and
extend generally transverse of the cutting edge 142 between the upper and
intermediate
portions 150 and 154 of the trailing face 132. Defined between each pair of
adjacent ridges
156 is a channel or groove 144 which when viewed from the side (as shown in
FIG. 10) is
generally curved. The alternate arrangement of ridges 156 and channels 144
define
corrugations 158 on the trailing face 132. These corrugations serve to direct
rocks, wood
chips and other debris away from the cutting edge 142 thereby minimizing
dispersion of the
debris over the cutting area. In addition, the ridges 156 can themselves
define additional
cutting edges for improved cutting performance.
[0065] In this embodiment, the grooves 144 are machine ground into the
trailing face 132
during fabrication. However, it should be appreciated that in alternative
embodiments, the
cutting portion 110 could be cast or forged in such a way that grooves and
ridges are
formed.
[0066] While in this embodiment, the corrugations 158 have a generally
crenellated
profile when view in cross-section, it will be appreciated that this need not
be the case in all
applications. In alternative 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.
[0067] While it is preferred that the brush cutting head 24 be used with
cutting teeth 100,
it will be appreciated that other types of teeth could also be used to similar
advantage. More
specifically, it may be advantageous to change the cutting tooth to adapt to
the nature of the
materials likely to be encountered during cutting operations. For instance,
where the terrain
to be cleared is rocky, the cutting tooth 100 described above could be
replaced with a
CA 02638898 2008-08-19
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hammer-type tooth which tends to be better suited to resisting frequent
impacts with rocks
and the like.
[0068] Referring to FIGS. 6 and 11 to 14, the mounting assembly 102 includes a
mounting block 170 disposed forwardly of the cutting tooth 100, a mounting
plate 172
disposed rearwardly of the cutting tooth 100, a fastener in the nature of a
nut 174 and bolt
176, an abutment plate 178 for placement on the substantially planar edges 74
and 84, and a
C-shaped retaining member 180.
[0069] Referring to FIG. 11, the mounting block 170 is defined by a top face
182, a
bottom face 184 disposed opposite the top face 182, leading and trailing faces
186 and 188
which extend between the top and bottom faces 182 and 184 and a pair of spaced
apart
lateral faces 190, 192. The bottom face 184 is generally arcuate - its radius
of curvature
matching that of the curved surface to thereby facilitate welding of the
mounting block 170
to the support body 48. The trailing face 188 extends generally upwardly from
the bottom
face 184 to join the top face 182. As compared to the bottom face 184, the top
face 182 is
relatively short. The leading face 186 extends away from the top face 182 at a
downward
angle toward the bottom face 184. A narrow band 194 joins the leading face 186
to the
bottom face 184. The leading face 186, the narrow band 194 and the bottom face
184
cooperate with each other to impart to the mounting block 170 a generally
tapering (wedge-
like) profile. It will be appreciated that the configuration of the mounting
block 170 with
its sloped leading face 186 tends to encourage the deflection of debris away
from the
cutting tooth 100.
[0070] Formed centrally in the leading face 186 and extending partially into
the top face
182, is a relatively large rebate 196. The rebate 196 defines a generally
curved bottom wall
198 and a leading wall 200 that is generally parallel to and spaced apart from
the trailing
face 188. The rebate 196 communicates with a bore 200 that extends between the
trailing
face 188 and the leading face 186. The rebate 196 and the bore 200 are sized
to
accommodate the bolt 176 extending therethrough.
[0071] With reference to FIG. 12, the mounting plate 172 is now described in
greater
detail. The mounting plate 172 is a generally rectangular plate with truncated
corners, its
,
CA 02638898 2008-08-19
-16-
shape defined primarily by a pair of opposed, relatively short, sides 202 and
204 and a pair
of opposed, relatively long sides 206 and 208 that extend between the short
sides 202 and
204. Moreover, the mounting plate 172 has a leading face 210, an opposed
trailing face
212 and an aperture 214 defined therein between the leading and trailing faces
210 and 212.
The aperture 214 is adapted to receive the bolt 176 therethrough.
[0072] Referring now to FIG. 13, there is shown the abutment plate 178.
Abutment plate
178 is generally C-shaped when viewed in top plan. It has a back portion 220
and a pair of
spaced apart arm portions 222 and 224 joined to the back portion 220 and
extending away
therefrom. The abutment plate 178 further includes a top face 226, an opposed
bottom face
228 and a leading face 230 spanning the back portion 220. The leading face 230
extends
downwardly from the top face 226 toward the bottom face 228. A narrow band 232
joins
the leading face 230 to the bottom face 228. The leading face 230, the narrow
band 232 and
the bottom face 228 cooperate with each other to impart to the abutment plate
178 a
generally tapering (wedge-like) profile. A portion of the outer-facing side
234 of each arm
portions 222, 224 is also trimmed inwardly starting at a point roughly one
third of the way
from the top face 226 and terminating at the bottom face 228.
[0073] With reference to FIG. 14, the retaining member 180 has a back portion
240 and a
pair of spaced apart arm portions 242 and 244, each depending from one end of
the back
portion 240. To facilitate welding of the arm portions 242 and 244 to the
collars 50, the
terminal end 246 of each arm portion 242, 244 is trimmed on an angle. The
spacing
between the arm portions 242 and 244 is sized so that the retaining member 180
can span
the distance between two adjacent collars 50, with one arm portion 242
abutting the first
face 248 of one collar 50 and the other arm portion 244 abutting the second
face 250 of
another adjacent collar 50.
[0074] As best shown in FIG. 6, during fabrication of the brush cutting head
24, the
mounting block 170 and the abutment plate 178 are fixed to adjacent collars
50u and 50t (as
the case may be). More specifically, the mounting block 170 is positioned
between adjacent
collars 50u and 50t with its bottom face 184 abutting the curved surface of
the support body
40 and its trailing face 188 disposed flush with the sidewall end of collar
50u so as to allow
CA 02638898 2008-08-19
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unobstructed access to the cutout during re-tooling. The mounting block 170 is
then welded
to the adjacent collars 50 about the first and second rebates 90 and 92. The
abutment plate
178 is mounted to span the space between adjacent collars 50u and 50t. The
first arm
portion 222 of the abutment plate 178 is supported on the first substantially
planar edge 74,
while the second arm portion 224 rests on the second substantially planar edge
84. At their
terminal extremities the arm portions 222 and 224 abut the shoulders 78 and 88
defined on
the outer edges of the collars 50u and 50t. Thus disposed, the abutment plate
178 is welded
in place.
[0075] Referring now to FIGS. 4 and 6, the attachment of the cutting tooth 100
to the
brush cutting head 24 is now described in greater detail in the context of
station 52tu. The
cutting tooth base portion 104 is placed between the mounting block 170 and
the abutment
plate 178 with its leading face 186 abutting the trailing face 188 of the
mounting block 170
and its abutment shoulder 128 bearing on the leading face 130 of the abutment
plate 178.
The mounting plate 172 is then placed between the collars 50u and 50t with its
long side
206 abutting the curved surface 48 and its opposed long side 206 abutting the
bottom of the
abutment plate 178. Thereafter, the bolt 176 is inserted into the aligned
apertures of the
mounting block 170, the cutting tooth 100 and the mounting plate 172 and
securely
fastened with the nut 174. The space between the arm portions 222 and 224
facilitates the
use of a tool to tighten or loosen (as the case may be) the nut 174.
[0076] As best shown in FIGS. 2a and 2b, the brush cutting head 24 is provided
with a
plurality of protective guard members 94 designated with reference numerals
94a through
to 94u (collectively, "guard members 94"). In preferred embodiment, the guard
member
94 is fabricated from two steel plates that are welded to each other - a first
plate 260
attachable to a collar 50 and a second plate 262. In other embodiments, the
guard member
may be cast or machined from a single piece of hardened steel. In further
alternative
embodiments, the first and second plates may designed so as to be releasably
attachable to
each other using fasteners or the like.
[0077] The margins of the first plate 260 are defined by a first arcuate edge
264, an
opposed second arcuate edge 266 and two lateral edges 268 and 270 that extend
between
CA 02638898 2008-08-19
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the first and second edges 264 and 266. As best shown in FIG. 16, the lateral
edge 268
forms substantially a right angle with both the first and second arcuate edges
264 and 266.
At the juncture of the second arcuate edge 266 and the lateral edge 270, the
first plate 260
has been trimmed back such that the lateral edge 270 forms an acute angle with
the first
arcuate edge 264 and correspondingly, an obtuse angle with the second arcuate
edge 266.
100781 The first plate 260 also has an outer face 272 and an opposed inner
face 274. The
inner face abuts the face 276 of collar 50 when the guard member 94 is mounted
to the
collar 50. Adjacent the second arcuate edge 266 is a pair of spaced apart
bores 278 and 280
that are machined to extend through the outer and inner faces 272 and 274 of
the first plate
260. The bores 278 and 280 are alignable with corresponding bores 282 and 284
formed in
the collar 50, thus permitting fasteners in the nature of bolts 286 and 288 to
be received
therethrough in order to fix the guard member 94 to the collar 50.
[00791 The second plate 262 includes a first leading end 290 and a second
trailing end
292. The midpoint between the first leading end 290 and the second trailing
end 292
defines the midpoint M of the protective guard member 94. The second plate 262
has a
relatively crescent-shaped profile P, (shown in dashed lines in FIG. 4 on a
representative
guard member - guard member 94t). The crescent-shaped profile P1 is defined by
a first
convex edge 294 and an opposed second concave edge 296 extending between the
leading
and trailing ends 290 and 292. The crescent-shaped profile P1 and in
particular, the curve
of the first convex edge 294, tend to reduce friction between the guard member
94 and
material encountered during the brush cutting operation. Additionally, as
explained in
greater detail below, the profile P1 defines a protective envelope at least
partially
encompassing the cutting tooth 100.
[0080] It should also be recognized that the profile of the second plate 262
need not be
crescent-shaped in every embodiment. Other profiles could also be successfully
employed.
[00811 The second concave edge 296 is shaped to conform substantially to the
curved
profile of the outer edge 62 of the collar 50. At the first leading end 290,
the second plate
262 tapers where the first convex edge 294 meets the second concave edge 296.
As will be
appreciated, the taper serves a friction/resistance reducing function. There
is no such taper
,
CA 02638898 2008-08-19
-19-
at the second trailing end 292. The second plate 262 being fuller at this
extremity, it
terminates with a relatively large, bull-nose tip 298 to provide increased
protective
coverage for the cutting tooth 100.
[0082] To increase the guard member's wear, abrasion and impact resistance and
service
life, the surface of the second portion along the first convex edge 294 has
been subjected or
exposed to a hardfacing treatment of the type generally known in the art.
[0083] In like fashion to the first plate 260, the second plate 262 also has
two opposed
faces 300 and 302. The inner face 274 of the first plate 260 is welded to the
face 300 of the
second plate 262 along a portion that is located closer to the second concave
edge 296 than
to the first convex edge 294. The thickness of the second plate 262 as
measured between
the faces 300 and 302 matches or at least corresponds substantially to, the
thickness of the
collar 50 as measured between its opposite faces.
[0084] As best shown in FIG. 17, the second concave edge 296 of the second
plate 262
and the inner face 274 of the first plate 260 define a shoulder 304 that is
adapted to abut the
outer edge 62 and the face 276 of the collar 50 when the guard member 94 is
mounted to
the collar 50. The shoulder 304 tends to facilitate placement of the
protective guard
member 94 on the collar 50 prior to fastening. Additionally, the provision of
the shoulder
304 tends to allow the forces acting on the guard member 94 to be better
distributed within
the guard member and transferred to the collar 50. In this way, a reduction in
the shearing
forces acting through the bolts 286 and 288 may be achieved thereby mitigating
the risk
that the guard member may become detached from the collar as a result of the
fasteners
having failed in shear.
[0085] Referring now to FIG. 7, the attachment of a representative guard
member 94t to
its associated collar 50t is now described. The guard member 94s is placed
onto the collar
50s such that the shoulder 304 abuts the outer edge 62 and the face 276 of the
collar 50t.
The bores 278 and 280 in the first plate 260 are aligned with the bores 282
and 284 defined
in the collar 50t. Thereafter, the bolts 286 and 288 are introduced through
the aligned bores
278, 282 and 280, 284, respectively, and securely fastened with nuts 306, 308.
It will thus
be appreciated that attachment of the guard members 94 to the collars 50 tends
to be a
CA 02638898 2008-08-19
-20-
simple task that may be performed relatively, quickly and easily, thereby
minimizing the
down time required for tooling/servicing of the brush cutting head 24 and
enhancing
productivity.
[0086] In this exemplary embodiment, the cutting tooth assemblies 54 are
mounted onto
the brush cutting head 24 prior to the attachment of the guard members 94 onto
the collars
50. This need not be the case in every application. In other embodiments, the
sequence of
assembly may be performed in reverse order with the guard members 94 being
installed
first followed by the mounting of the cutting tooth assemblies 54.
[0087] It will be apparent to one skilled in the art that, in this embodiment,
the first plate
260 serves two functions. Its primary purpose is to attach the second plate
262 to the collar
50. But to a certain extent, it also functions as a reinforcement member for
the second plate
262, and the protective guard 94 as a whole allowing them to better withstand
repeated
impacts with rocks and other hard objects. While this arrangement is generally
preferred, it
should be noted that in alternative embodiments, the protective guard member
could be
designed without a first plate portion. In one such an embodiment, the first
plate could, in
effect, be incorporated into a larger, generally planar, second plate. This
modified second
plate could be affixed directly to the collar.
[0088] It can be seen in FIGS. 2a, 3 and 5 that the protective guard members
94 are
disposed along the support body 40 according to the first and second helical
layouts defined
by the mounting stations 52 and cutting teeth assemblies 54. Accordingly, each
protective
guard member 94 within a respective helical layout is circumferentially
staggered from the
next adjacent protective guard member 94 in the sequence by an angle w3
(measured from
the midpoint M of one protective guard member 94 to the midpoint M of the next
adjacent
protective guard in the sequence) in much the same way as each mounting
station 52 is
staggered from the next adjacent mounting station 52 in that helical layout.
Preferably, the
angle (03 is an acute angle. In this embodiment, the angle w3 shown in FIG. 3
defined
between the midpoints M of protective guard members 94r and 94t, is 20
degrees.
[0089] Each protective guard member 94 is circumferentially staggered from the
guard
member adjacent thereto by an angle c04 or an angle w5. As shown in FIG. 3,
the guard
CA 02638898 2008-08-19
-21-
member 94t is radially offset from the guard member 94s by an angle co4, which
in this
embodiment is approximately 180 degrees. In contrast, the guard members 94r
and 94s are
circumferentially staggered from each other by the angle w5. In this
embodiment, the angle
(05 is an obtuse angle measuring approximately 160 degrees.
[0090] Furthermore, as shown in FIG. 4 the guard member 94t is mounted to
collar 50t at
a location forwardly of, and radially offset from, the mounting station 52rs
by an angle w6
as measured from the midpoint M of the protective guard member 94t to the
centerline of
the cutout 70 defined in the collar 50s. Preferably, the angle (o6 is an acute
angle. In this
embodiment, the angle 0)6 measures 28.5 degrees. Preferably, the angle w6lies
between 20
and 35 degrees. But it should be appreciated that in alternative embodiments,
the angle w6
(and correspondingly the position of the guard member 94t relative to the
mounting station
52rs) and the angles (04 and w5 could be varied to suit the particular
application.
[0091] A clearance C is provided between the trailing extremity of the guard
member 94
(i.e. the trailing end 292 of the second plate 262) and the leading extremity
of the cutting
tooth 100 (i.e. the cutting edge 142). The clearance C facilitates the
evacuation of debris
away from the cutting tooth 100.
[0092] Within a respective helical layout, each cutting tooth assembly 54
tends to be
protected by a pair of adjacent guard members 94 in the sequence. For
instance, as shown
in FIG. 5, guard members 94a and 94c tend to protect the cutting tooth 100
held in
mounting station 52ab, while the guard members 94c and 94e tend to shield from
damage
the cutting tooth 100 in mounting station 52cd. The same applies to the other
guard
members 94 and their associated cutting tooth assemblies.
[0093] In the context of cutting tooth 100 held within the mounting station
52ab, two-
fold protection is afforded by guard member 94a and 94c. First, being disposed
forwardly
(or ahead) of the cutting tooth 100, the guard members 94a and 94c tend to be
the first
components to make contact with a rock or other hard object as the brush
cutting head 24
rotates. Depending on the size of the rock, the convex edges 294 or the
leading ends 290 of
either guard members 94a and 94c, or both (if the rock is sufficiently large)
tend to be the
site of first impact for a rock striking the brush cutting head 24.
Accordingly, the guard
CA 02638898 2008-08-19
-22-
members 94a and 94c may absorb the brunt of the impact and cause the rock to
be deflected
away from the cutting tooth 100.
[0094] Second, the guard member 94c serves to protect the cutting tooth 100 in
another
way. As best shown in FIGS. 4 and 5, the profile P, of the second plate 262
encompasses a
substantial portion of the cutting portion 110, thereby creating a protective
envelope that
safeguards the cutting portion 110 from violent impact with hard objects. In
this way,
should the brush cutting head 24 encounter a large rock during brush cutting
operations,
there is a greater likelihood that the rock will strike the guard member 94c
and be deflected
away from the cutting tooth 100 rather than directly impact the cutting
portion 110. As a
result, the service life of the cutting tooth 100 may be extended and its
cutting edge 142
may remain sharp for a longer period of time.
[0095] The size of the protective envelope can be varied to suit the
particular application.
That protective envelope can be made smaller or it can be enlarged to cover
the entire
cutting portion 110. While it is generally preferred that the cutting edge 142
of the cutting
tooth 100 be contained within the protective envelope defined by the profile
PI, in some
embodiments it may be desirable to configure the profile of the second plate
262 to allow
the cutting edge 142 to project beyond (or lie just outside) this protective
envelope to allow
for more aggressive cutting action by the cutting edge 142.
[0096] It will be appreciated that with appropriate modifications the
protective guard
members described above could be used to protect different cutting tooth
assemblies, for
instance, those described and shown in United States Patent Application
Publication No.
2007/0261763; the contents of which are hereby incorporated by reference.
[0097] In further alternative embodiments, the protective guard members could
used with
a differently configured brush cutting head, one with different collars and
different cutting
tooth assemblies than the ones shown in FIGS. 2a and 2b. For instance, it may
be possible
to employ protective guard members in accordance with the principles of the
invention on
the brush cutting head described in United States Patent No. 6,764,035; the
contents of
which are hereby incorporated by reference. As the general structure of this
brush cutting
CA 02638898 2008-08-19
- 23 -
head (i.e. the collars and the cutting tooth assemblies) is already well known
in art, only a
very brief description of the structure is provided.
[0098] Referring now to FIGS. 18 and 19, there is shown an alternate brush
cutting head
designated generally with reference numeral 320. The brush cutting head 320
has a
cylindrical support base or body 322 with an outer surface 326 and a plurality
of cutting
tooth mounting blocks 324a to 324w (collectively, "mounting blocks 324")
fastened to the
outer surface and disposed in a generally double helix pattern along the
support body 322.
Each mounting block 324 is circumferentially staggered from the mounting block
adjacent
thereto. As a result of this staggered arrangement, every alternate mounting
block 324 is
also radially offset from its respective reference mounting block by an angle
(31. Taking as
an example mounting blocks 324a and 324c, it can be seen in FIG. 18 that
mounting block
324a is circumferentially staggered relative to station 324c by an angle (31.
While in this
embodiment, the angle (31 measures approximately 30 degrees, it may be varied
in other
embodiments.
[00991 Each mounting block 324 carries on its leading face 328 a cutting tooth
330. In
this embodiment, each mounting block 324 and cutting tooth 330 combination
defines a
cutting tooth assembly. The cutting tooth 330 has a base portion 332
fastenable to the
mounting block 322 and a cutting portion 334. The cutting portion 334 is
carried on the
base portion 332 in a generally, forwardly leaning or canted fashion, and is
integrally
formed with the base portion 332. The cutting portion 334 has a leading face
336 and an
opposed trailing face 338 which cooperate with each other to define a
tapering, wedge-like,
profile that terminates in a cutting edge 342. The cutting edge 342 is carried
forwardly of
the base portion 332 such that it tends to be the first element of cutting
tooth 330 to make
contact with the brush.
[00100] The brush cutting head 320 is further provided with a plurality of
collars 344a to
344w (collectively, "collars 344") - one for each mounting block 324. Each
collar 344 is
radially offset from its adjacent collar 344 by an angle corresponding to
angle (31. Each
collar 344 has a generally penannular structure with a first end 346, a second
end 348 and a
relatively large space S disposed between the first and second ends 346 and
348. Each
,
CA 02638898 2008-08-19
-24-
protective collar 344 is welded to the outer surface 326 of the support body
322 and extends
radially therefrom, transverse to the longitudinal axis of the support body
322. Each collar
344 terminates with its respective first end 346 circumferentially spaced from
the leading
face 328 of the mounting block 324. At its respective second end 348, each
collar 344 is
welded to the trailing face 350 of the mounting block 324 to which it is
associated.
[00101] To further protect or shield the mounting blocks 324 and the cutting
teeth 330
mounted within them from violent impact with large rocks or the like, each of
the collars
344 has attached thereto a protective guard member 360. While in the
embodiment shown
in FIG. 2a and 2b, there is only one protective guard member provided for each
collar, it
will be appreciated that this need not be the case in every application. In a
modified brush
cutting head, each collar could carry two or more protective guard members
circumferentially staggered from each other.
1001021 With reference to FIGS. 21 to 23, it will be seen that the guard
member 360 is
generally similar to the guard member 94 earlier described in that it is also
fabricated from
two steel plates that are welded to each other - a first plate 362 attachable
to a collar 344
and a second plate 364.
[00103] The first plate 362 however differs from its counterpart (first plate
260) in guide
member 94. It has a generally arcuate body 366 provided with a first end 368
and a second
end 370. At a location intermediate the first and second ends 368 and 370, a
concavity 372
has been machined out of the body 366 thereby defining a first lobe 374 and a
second lobe
376. Defined in each lobe 374 and 376 is a bore 378, 380 for receiving
therethrough a
fastener in the nature of a bolt 382, 384 to fix the guard member 360 to the
collar 344. The
first plate 362 also has an outer face 386 and an opposed inner face 388. The
inner face 388
abuts the face 390 of collar 344 when the guard member 360 is mounted to the
collar 344.
[00104] The second plate 364 in this embodiment has a crescent shaped body
392, but its
profile P2 differs from that of the second plate 262 shown in FIGS. 15 to 17.
The crescent
shape of the body 392 has a first leading end 394 and a second trailing end
396. The
midpoint between the first leading end 394 and the second trailing end 396
defines the
midpoint M of the protective guard member 360. The profile P2 is defined by a
first convex
I
. .. .. . . . . .. ~ . . . . .. . .. .. . .. . . . . .... ... . . . . . . . .
.
CA 02638898 2008-08-19
- 25 -
edge 398 and an opposed second concave edge 400 extending between the leading
and
trailing ends 394 and 396. Similar to the surface along first convex edge 294,
the surface
along the first convex edge 398 may be subjected to a hard-facing treatment to
enhance
wear, impact and abrasion resistance. The second concave edge 400 is shaped to
conform
substantially to the curved profile of the outer edge 402 of the collar 344.
Unlike ends 290
and 292 of the second plate 262, in this embodiment, the leading end 392 is a
mirror image
of the trailing end 394.
[00105] In like fashion to the first plate 362, the second plate 364 also has
two opposed
faces 404 and 406. The inner face 388 of the first plate 362 is welded to the
face 404 of the
second plate 364. The thickness of the second plate 364 as measured between
the faces 404
and 406 matches or at least corresponds substantially to, the thickness of the
collar 344 as
measured between its opposite faces.
[00106] As best shown in FIG. 23, the guard member 360 has a shoulder 408
which is
generally similar in shape and function to the shoulder 304 of guard member
94. In this
embodiment, the shoulder 408 is defined by the second concave edge 400 of the
second
plate 364 and the inner face 388 of the first plate 362 and is adapted to abut
the outer edge
402 and the face 410 of the collar 344 when the guard member 360 is mounted to
the collar
344.
[00107] The installation of guard members 360 is accomplished in like fashion
to that of
guard members 94. A respective guard member 360 is placed onto its associated
collar 344
such that the shoulder 406 abuts the outer edge 402 and face 410 of the collar
344. The
bores 378 and 380 in the first plate 362 are aligned with corresponding bores
(not shown)
defined in the collar 344. Thereafter, the bolts 382 and 384 are introduced
through the
aligned bores and securely fastened with nuts 412, 414.
[00108] The protective guard members 360 are disposed along the support body
322
according to the first and second helical layouts defined by the mounting
blocks 324 and
the cutting teeth 330. Accordingly, each protective guard member 360 within a
respective
helical layout is circumferentially staggered from the next adjacent
protective guard
member 360 in the sequence by an angle [i2 corresponding to angle (31 in much
the same
CA 02638898 2008-08-19
-26-
way as each mounting block 324 is staggered from the next adjacent mounting
block 324 in
that helical layout. Preferably, the angle [32 (like angle [31) is an acute
angle. In this
embodiment the angle P2 measures 30 degrees.
[00109] Each protective guard member 360 is circumferentially staggered from
the guard
member adjacent thereto by an angle (33 or an angle (34. As shown in FIG. 20,
the guard
member 360a is radially offset from the guard member 360b by an angle [i3. In
this
embodiment, the angle (33 measures approximately 180 degrees. In contrast, the
guard
members 360b and 360c are circumferentially staggered from each other by the
angle (3a,
which in this embodiment is approximately 150 degrees.
[00110] In contrast to the guard member 94t shown in FIG. 2a which is mounted
to the
collar 50t adjacent the mounting station 52tu, each guard member 360 is
mounted to a
collar 344 at a location almost directly opposite or at least substantially
opposed to the
space S defined between the first and second ends 346 and 348 within which the
mounting
block 324 lies. It will be appreciated that in other embodiments, the guard
members 360
could be positioned differently relative to the space S.
[00111] Within a respective helical layout, each mounting block 324 and
cutting tooth 330
combination is protected by the pair of guard members 360 in the sequence that
are
mounted to collars disposed on either side of the mounting block and cutting
tooth
combination. For instance, as shown in FIG. 20, guard members 360b and 360d
tend to
protect the cutting tooth 330 held in mounting block 324c, while the guard
members 360d
and 360f tend to shield from damage the cutting tooth 330 in mounting block
324e. The
same applies to the other guard members 360 and their associated mounting
block and
cutting teeth combinations.
[00112] Generally speaking, the pair guard members 360a and 360c protects the
cutting
tooth 330 held within the mounting block 324a, in much the same way as the
guide
members 94a and 94c described earlier. Being disposed forwardly (or ahead) of
the cutting
tooth 330, the guard members 360a and 360c tend to be the first components to
make
contact with a rock or other hard object as the brush cutting head 320
rotates. Depending
on the size of the rock, the convex edges 398 or the leading ends 370 of
either guard
CA 02638898 2008-08-19
-27-
members 360a and 360c, or both (if the rock is sufficiently large) tend to be
the site of first
impact for a rock striking the brush cutting head 320. Additionally, by having
the profile P2
of the second plate 362 encompass a substantial portion of the cutting portion
334, the
guard member 360c creates a protective envelope that safeguards the cutting
portion 334
from violent impact with hard objects.
[00113J In this embodiment, the entire cutting portion 334 (not just the
cutting edge 342)
is contained within the protective envelope defined by the profile P2 of the
second plate
362. However, in alternative embodiments, the size of the protective envelope
may be
reduced or enlarged as required.
[00114] For reasons of versatility, it is generally preferred that the
protective guard
members be releasably mounted or attached to the collars (as is the case in
the
embodiments shown in FIGS. 2a and 18) since this allows the brush cutting head
to be
flexibly tooled to adapt to field conditions. For example, the operator of a
brush cutter may
not want to have the protective guard members installed when clearing brush
from sandy
terrain that does not have many large rocks. In such cases, the operator may
choose to
remove the protective guards to lighten the brush cutting head and reduce the
energy
consumption and power draw on the motor. Additionally, should a protective
guard
member be damaged or require servicing, it can easily be removed and replaced
with
another. Along the same vein, in certain applications, an operator may elect
to have only
selected collars outfitted with protective guard members, while the remaining
collars are
not provided with any guard members.
[00115] On the other hand, if a particular brush cutting head is intended to
be employed on
very rocky terrain, it may be practical to have the protective guard members
mounted on
the collars at all times. In such instances, it is contemplated that the
protective guard
members could be permanently fixed to the collars. In one such embodiment, a
crescent-
shaped plate similar to the second plate 262 (see FIG. 15) or the second plate
364 (see FIG.
21) could have its concave edge welded to the outer edge of the collar. In
another
embodiment, a collar could be fabricated with a protective guard member
integrally formed
,
CA 02638898 2008-08-19
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therein, that is, the protective guard could be incorporated into the design
and structure of
the collar itself.
1001161 In other embodiments, an alternate brush cutting head could be
outfitted with a
combination of protective guard members in accordance with the principles of
the
invention. That is, such a brush cutting head could have some protective guard
members
that are fixedly mounted to, and/or integrally formed with, their respective
collars and
others that are releasably attached to their respective collars.
[00117] 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.
,
