Note: Descriptions are shown in the official language in which they were submitted.
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TREE STUMP GRINDING TEETH
BACKGROUND OF INVENTION
[Para 1 ] Field of Invention
[Para 2] The present invention relates to tree stump grinding teeth
and to tree stump grinding wheel assemblies that include the same.
[Para 3] Description of Related Art
[Para 4] Conventional tree stump grinding machines include a tree
stump grinding wheel assembly that comprises a vertically oriented
wheel having a plurality of grinding teeth (which are sometimes also
referred to in the art as "cutting teeth") mounted on both side
surfaces thereof. The wheel is typically mounted on an extension
arm or boom of a grinding machine, which rotates the wheel at
relatively high speed in a forward direction relative to the grinding
machine. An operator of the grinding machine moves the rotating
wheel in plunging and sweeping motions relative to a tree stump to
be removed, which causes the grinding teeth mounted thereon to
make contact with the tree stump. The grinding teeth grind
mounted to the rotating wheel impact against the tree stump and
thereby cut or otherwise pummel the tree stump into chips, chunks
or pieces until it is removed, typically below the grade of the
surrounding soil.
[Para 5] During tree stump removal operations, the grinding teeth
are subjected to very large impact and abrading forces. Over time,
these forces can cause one or more of the grinding teeth to break
off and/or to wear out. When this occurs, one or more of the
grinding must be replaced. Replacement of grinding teeth is often a
time consuming process because the radial projection of each
grinding tooth must be positioned in a predetermined optimal
orientation before it is fastened to the wheel.
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[Para 6] In some prior art tree stump grinding wheel assemblies, the
grinding teeth are positioned directly into contact with a side
surface of the wheel and are fastened directly thereto using
fasteners such as bolts. An example of such a prior art assembly is
shown in Bowling, U.S. Pat. No. 5,497,815. This patent discloses a
one-piece grinding tooth that includes a mounting base having at
least one substantially flat surface that directly contacts the wheel.
The grinding tooth is fastened to the wheel using at least one bolt,
which passes through a bore in the mounting base. In the
embodiments illustrated in the figures, two bolts are used to fasten
each grinding tooth to the wheel. In this arrangement, the bolts are
solely responsible for holding the grinding tooth to the wheel.
Thus, if the impact force applied to the grinding tooth were greater
than the shear strength of the bolts, the bolts would fail and the
grinding tooth would shear away from the wheel. The loss of mass
caused by the shearing away of one or more grinding teeth from the
wheel could cause the wheel to become unbalanced, which could
create potentially damaging vibration in the grinding machine.
[Para 7] Another drawback with the use of a grinding wheel
assembly and grinding teeth such as disclosed in Bowling is that the
holes bored in the wheel to receive the bolts are exposed to the risk
of damage due to impact forces imparted to the teeth, which can be
communicated, through the bolts to the holes bored into the wheel.
This can cause the holes bored into the wheel to become deformed
and otherwise compromised. Consequently, the fit and/or
orientation of replacement grinding teeth will not be optimal, and
replacement grinding teeth may wear prematurely and/or become
more readily dislodged from the wheel.
[Para 8] Yet another drawback with the use of the grinding wheel
assembly and grinding teeth such as disclosed in Bowling is that the
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side surfaces of the wheel are exposed to the risk of damage due to
impact forces translated through the grinding teeth. The impact
force imparted to the tooth can cause the at least one substantially
flat surface of the mounting base in direct contact with the wheel to
dent, gouge or otherwise create surface imperfections in the wheel.
Once the surface of the wheel has been damaged, it can be very
difficult to properly mount replacement grinding teeth to the wheel.
In addition, moisture can wick between grinding tooth and the
wheel, which can promote rust and/or corrosion of the wheel,
grinding teeth and/or bolts.
BRIEF SUMMARY OF THE INVENTION
[Para 9] The present invention is directed to tree stump grinding
teeth for use in tree stump grinding wheel assemblies and to tree
stump grinding wheel assemblies that comprise one or more of such
grinding teeth. In a preferred embodiment of the invention, the tree
stump grinding tooth comprises a mounting base having a
substantially flat surface from which one or more cleats project.
The cleats are adapted to be received in corresponding bores
formed in the wheel. A resilient impact pad is positioned between
the mounting base of the grinding tooth and the wheel. The
resilient impact pad protects the surface of the wheel from impact
forces applied to the grinding tooth.
[Para 10] The foregoing and other features of the invention are
hereinafter more fully described and particularly pointed out in the
claims, the following description setting forth in detail certain
illustrative embodiments of the invention, these being indicative,
however, of but a few of the various ways in which the principles of
the present invention may be employed.
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BRIEF DESCRIPTION OF THE DRAWINGS
[Para 11] FIG. 1 is a partially exploded perspective view of one
preferred embodiment of a tree stump grinding wheel assembly
according to the invention showing several grinding teeth, impact
pads, bolts and a portion of a wheel.
[Para 12] FIG. 2 is a side elevation view of one of the grinding teeth
shown in FIG. 1.
[Para 13] FIG. 3 is a top view further illustrating the grinding tooth
shown in FIG. 2.
[Para 14] FIG. 4 is a side elevation view of another one of the
grinding teeth shown in FIG. 1.
[Para 15] FIG. 5 is a top view further illustrating the grinding tooth
shown in FIG. 4.
[Para 16] FIG. 6 is an exploded front elevation view of the grinding
teeth, impact pads and a portion of the wheel shown in FIGS. 1-5.
[Para 17] FIG. 7 is a side elevation view of another one of the
grinding teeth shown in FIG. 1.
[Para 18] FIG. 8 is a top view further illustrating the grinding tooth
shown in FIG. 7.
[Para 191 FIG. 9 is a side elevation view of another one of the
grinding teeth shown in FIG. 1.
[Para 201 FIG. 10 is a top view further illustrating the grinding tooth
shown in FIG. 9.
[Para 21 ] FIG. 11 is an exploded front elevation view of the
grinding teeth, impact pads and a portion of the wheel shown in
FIGS. 1 and 7-10.
[Para 22] FIG. 12 is an exploded front elevation view of an
alternative embodiment of a tree stump grinding wheel assembly
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according to the invention showing several grinding teeth, impact
pads, bolts and a portion of a wheel.
[Para 23] FIG. 13 is a front elevation view of one embodiment of an
impact pad according to the invention.
[Para 24] FIG. 14 is a front elevation view of another alternative
embodiment of an impact pad according to the invention.
[Para 25] FIG. 15 is a front elevation view of yet another alternative
embodiment of an impact pad according to the invention.
[Para 26] FIG. 16 is a front elevation view of yet another alternative
embodiment of an impact pad according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
[Para 27] Referring now to the drawings, wherein like reference
numerals have been used for similar elements throughout, FIG. 1
shows a partially exploded perspective view of one preferred
embodiment of a tree stump grinding wheel assembly 10 according
to the invention. This view shows a portion of a substantially
vertical, rotatable wheel 20, a plurality of grinding teeth 30A, 30B,
30C, 30D, a plurality of impact pads 40A, 40B, 40C, 40D and a
plurality of fasteners 50. The grinding teeth 30A, 30B, 30C, 30D are
fastened in pairs to the wheel 20 using the fasteners 50, with the
impact pads 40A, 40B, 40C, 40D positioned between the grinding
teeth 30A, 30B, 30C, 30D and the wheel 20.
[Para 28] The tree stump grinding wheel assembly 10 according to
the invention is adapted to be mounted to a stump grinding
machine (not shown) that rotates the wheel assembly 10 at relatively
high speed in a forward direction relative to the stump grinding
machine (i.e., in the direction shown by arrow 25 on the peripheral
edge of the wheel 20 in FIG. 1). An operator of the grinding
machine moves the rotating wheel assembly 10 in plunging and
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sweeping motions relative to a tree stump to be removed, which
causes cutting bits 60 mounted to the grinding teeth 30A, 30B, 30C,
30D (and other cutting bits not shown), to make contact with the
tree stump. The cutting bits 60 cut or otherwise pummel the tree
stump into small chips, chunks or pieces until the tree stump is
removed (typically until the stump has been ground away below the
grade of the surrounding soil).
[Para 291 Fasteners 50 are used to fasten the grinding teeth 30A,
30B, 30C, 30D to the wheel 20. In the preferred embodiment of the
invention, the fasteners 50 are made of medium carbon alloy steel,
and are in the form of socket head cap screw bolts. The bolts
should be strong enough to securely fasten the grinding teeth to the
wheel during stump grinding operations. Bolts having a diameter of
from about 0.5" to about 1.25" and a Rockwell hardness of from
about 33 to about 39 are typically sufficient. For smaller wheels
(e.g., wheels having a diameter of 24" or less), a bolt diameter of
about 0.625" is usually suitable. For larger wheels (e.g., wheels
having a diameter of greater than 24"), a bolt diameter of about
0.875" is usually suitable. A variety of fasteners could be used
within the scope of the invention, provided such fasteners exhibit
sufficient strength to secure the grinding teeth to the wheel.
[Para 301 FIGS. 2 and 3 show a side elevation view and a top view,
respectively, of grinding tooth 30A shown in FIG. 1. Grinding tooth
30A includes a mounting base portion 70A and a head portion 80A.
Preferably, the mounting base portion 70A and the head portion
80A are integrally formed with one another and thus comprise a
one-piece construction that is produced by metallic forging or
casting. In a preferred embodiment, a metallic forging is made from
AMS 4140 steel, but other metallic alloys having suitable mechanical
properties are envisioned to be within the scope of the present
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invention. Forging is currently preferred over casting due to the
ability to consistently produce grinding teeth of superior strength
and durability.
[Para 31] As previously noted above, grinding tooth 30A further
includes a cutting bit 60A, which is fixedly attached to the head
portion 80A. The cutting bit 60A is preferably made of tungsten
carbide, but alternatively may be made of other metallic alloys
having comparable hardness and mechanical strength. The head
portion 80A includes a seat 90A, which is milled in an inner surface
of a distal end 100A of head portion 80A. The cutting bit 60A is
preferably soldered to the seat 90A so that the distal end 100A
supports the cutting bit 60A. Alternatively, the cutting bit 60A may
be attached to the seat 90A with known industrial adhesives, or may
be welded or brazed to the seat 90A. The transition between the
mounting base portion 70A and the head portion 80A defines the
proximal end 1 10A of the head portion 80A.
[Para 32] With particular reference to FIG. 3, the mounting base
portion 70A of grinding tooth 30A includes an outer surface 120A
and a substantially flat inner surface 130A. In the illustrated
embodiment, the outer surface 1 20A and inner surface 1 30A are
substantially parallel to one another. However, it will be appreciated
that the outer surface 1 20A of the mounting base portion does not
need to be planar, and does not need to be substantially parallel to
the substantially flat inner surface 1 30A. For example, the outer
surface 120A could be semi-hemispherical in shape, if desired.
[Para 33] The mounting base portion 70A of grinding tooth 30A
further includes an edge portion 1 40A that extends between and
interconnects the outer surface 120A and the inner surface 130A.
The edge surface 140A generally defines a perimeter of mounting
base portion 70A. In the illustrated embodiment, the perimeter of
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the mounting base portion 70A is generally circular in shape.
However, it will be appreciated that the shape of the perimeter of
the mounting base portion 70A is not critical, and that a shape
other than generally circular (e.g., rectangular) could be used, if
desired.
[Para 34] At least one and more preferably two or more cleats 150A
project from the substantially flat inner surface 130A of the
mounting base portion 70A of the grinding tooth 30A. The cleats
1 50A are preferably formed integrally with the mounting base
portion 70A, but could be joined as separate components to the
mounting base portion 70A, if desired. The cleats 150A are
preferably cylindrical in shape, and are adapted to be received
within corresponding cylindrical bores 1 60A (shown in FIG. 6)
formed in the wheel 20.
[Para 351 The outer diameter "D" and the height "H" of the cleats
150A (as measured from the inner surface 1 30A) is not per se
critical. An outer diameter "D" of about 0.5" to about 2.0", and
more preferably about 0.75" to about 1.5", is typically sufficient. A
height "H" of 0.25" to about 0.75", and more preferably about 0.5",
is also typically sufficient. Spacing between cleats 1 50A is not
critical. A spacing distance of 1.5" to about 2.5" as measured
between the centers of adjacent cleats 150A is presently deemed to
be sufficient.
[Para 36] As noted in greater detail below, in some embodiments of
the invention, the fasteners are configured to pass through an
opening formed through the center of the cleat (sometimes referred
to herein as a "concentric" fastener arrangement). In other
embodiments of the invention, the fasteners do not pass through
the center of the cleats (sometimes referred to herein as an
"eccentric" fastener arrangement). It will be appreciated that the
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outer diameter of cleats in concentric fastener arrangements will
generally need to be larger than the outer diameter of cleats in
eccentric fastener arrangements to accommodate the diameter of
the fasteners.
[Para 37] An impact pad 40A is adapted to reside between the
inner surface 130A of the grinding tooth 30A and a side surface
170A of the wheel 20. The primary function of the impact pad is to
absorb and dissipate impact forces imparted to the grinding tooth
30A during stump grinding operations, so that such forces are not
translated through the grinding tooth 30A directly to the side
surface 1 70A of the wheel 20. The use of an impact pad 40A
protects the side surface 1 70A of the wheel from damage, thereby
extending the life of the wheel 20.
[Para 38] Preferably, the impact pad 40A is slightly compressible.
Thus, as the fastener 50 is tightened to secure the grinding tooth
30A to the wheel 20, the impact pad 40A compresses and forms a
seal between the inner surface 130A of the grinding tooth 30A and
the side surface 1 70A of the wheel 20. This prevents moisture from
wicking between the inner surface 130A of the grinding tooth 30A
and the side surface 1 70A of the wheel 20, and thus prevents
corrosion. The slight compressibility of the impact pad 40A also
aids in the removal of the grinding teeth during servicing of the
wheel assembly 10.
[Para 39] In the presently most preferred embodiment of the
invention, the impact pad 40A is made of a polyurethane rubber
having a Shore A hardness of from about 60 to about 100, and more
preferably from about 70 to about 90. When this material is used,
the thickness of the impact pad 40A is preferably from about
0.0625" to about 0.25", and most preferably about 0.125".
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[Para 40] It will be appreciated that the impact pad 40A can be
made of other materials that are "softer" than the steels used to
manufacture the wheel 20 and grinding teeth 30A. For example, it
may be possible to manufacture impact pads from light metals (e.g.,
aluminum or copper) or woven materials. However, in view of cost
and performance, impact pads formed of synthetic polymers are
preferred.
[Para 41] The impact pad 40A is preferably a separate and distinct
component apart from the grinding tooth 30A. Thus, if the impact
pad 40A should become damaged or should wear out, it can be
replaced separate from the grinding tooth 30A (and vice versa). It
will be appreciated, however, that one could apply a compressible
coating to the inner surface 130A of the grinding tooth 30A and/or
to the side surface 170A of the wheel (e.g., by dipping, brushing or
spraying) to provide the same function of the impact pad 40A. This
arrangement, while possible, is not preferred.
[Para 42] In the embodiment of the invention shown in FIGS. 1-6,
the impact pad 40A is configured to cover the cylindrical side
portion 1 75A of the cleats 150A and a portion of the bottom end
1 80A of the cleats 150A to prevent any portion of the cleats 1 50A
from contacting the cylindrical bores 160A formed in the wheel 20.
This arrangement protects the cylindrical bores 1 60A from
becoming damaged due to impact forces imparted to the grinding
tooth 30A during tree stump grinding operations. Forces translated
through the grinding tooth 30A to the cleats 1 50A are absorbed and
dissipated by the impact pad 40A.
[Para 431 As noted above, the grinding teeth 30A, 30B are
preferably mounted to the wheel 20 as matched pairs. In the
embodiment shown in FIG. 2, grinding tooth 30A is provided with
two spaced apart clearance holes 190A, which are formed in the
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outer surface 1 20A and are substantially perpendicular to a plane
defined by the substantially flat inner surface 130A. The clearance
holes 1 90A extend through the entire thickness of the mounting
base portion 70A and the height H of the cleats 150A. The
clearance holes 1 90A are circular in shape, and have a diameter 200
which is sized so as to provide a small annular clearance around the
shank portion of a fastener 50 passing through mounting base
portion 70A. In this embodiment, the clearance holes 1 90A are
concentric with the cleats 150A.
[Para 44] Mounting base portion 70A also includes a pair of
counterbores 210A, which are formed in the outer surface 1 20A.
The counterbores 210A are circular, have an inner diameter 220,
and are substantially perpendicular to the plane defined by the inner
surface 130A. Each counterbore 210A is concentric with a
corresponding one of clearance holes 1 90A and extends only
partially through the thickness of mounting base portion 70A. As
shown in FIG. 3, the inner diameter 220 of counterbore 210A is
larger than the diameter 200 of clearance holes 1 90A, thus making
the counterbores 210A effective for engaging the head portion 230
of a fastener 50 (shown in FIG. 1) used to attach the grinding tooth
30A to the wheel 20.
[Para 45] FIGS. 4 and 5 show grinding tooth 30B, which together
with grinding tooth 30A, forms a mating pair of grinding teeth 30A,
30B for attachment to opposing side surfaces 1 70A, 1 70B of the
wheel 20. Grinding tooth 30B is substantially a mirror image of
grinding tooth 30A, except that grinding tooth 30B is not provided
with clearance holes 1 90A and counterbores 210A. As with
grinding tooth 30A, grinding tooth 30B includes a mounting base
portion 70B and a head portion 80B, which are preferably integrally
formed with one another and are made of a one-piece construction
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comprising a metallic forging which is preferably made from AMS
4140 steel. Other than being formed as a mirror image relative to
grinding tooth 30A, the only other substantial structural difference
between grinding tooth 30A and grinding tooth 30B is that grinding
tooth 30B includes a pair of spaced apart tapped holes 240B instead
of a pair of clearance holes 190A and counterbores 210A. Tapped
holes 240B extend completely through the cleats 1 50B and the
thickness of the mounting base portion 70B and therefore extend
through the outer surface 1 20B and the inner surface 1 30B. Tapped
holes 240B are substantially perpendicular to the plane defined by
the inner surface 130B, and are concentric to the cleats 1 50B. The
tapped holes 240B are preferably tapped with a thread for receiving
the threads 250 on the ends of fastener 50. Thread size is not per
se critical, but a thread size of 14 threads per inch class 2A is
presently most preferred. It will be appreciated that other tapped-
hole sizes and thread sizes may be used.
[Para 46] An impact pad 40B is adapted to reside between the inner
surface 1 30B of grinding tooth 30B and the side surface 170B of the
wheel 20. Preferably, the impact pad 40B positioned between the
inner surface 1 30B of grinding tooth 30B and the side surface 1 70B
of the wheel 20 is identical in all respects to the impact pad 40A
that is positioned between the inner surface 1 30A of grinding tooth
30A and the side surface of the wheel 1 70A. It will be appreciated,
however, that impact pad 40B could be different in configuration to
i m pact pad 40A.
[Para 471 With reference to FIG. 6, a stump grinding wheel
assembly 10 according to the invention is assembled, in part, by
positioning an impact pad 40A between grinding tooth 30A and the
side surface 170A of the wheel 20. An impact pad 40B is also
positioned between grinding tooth 30B and the opposite side
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surface 1 70B of the wheel. The cleats 1 50A, 150B of grinding teeth
30A, 30B are inserted into the appropriate cylindrical bores 1 60A,
160B formed in the wheel 20, which aligns the grinding teeth 30A,
30B in the optimal orientation. The threaded end 250 of a fastener
50 is inserted through one of the clearance holes 1 90A in grinding
tooth 30A, such that it passes entirely through the thickness of the
mounting base portion 70A, through a hole 260A in the impact pad
40A positioned between grinding tooth 30A and the wheel 20,
through a hole 270 in the wheel 20, through a hole 260B in the
impact pad 40B positioned between grinding tooth 30B and the
wheel 20 and is threadingly received into one of the tapped holes
240B in grinding tooth 30B. A second fastener 50 is inserted
through the other one of the clearance holes 1 90A in grinding tooth
30A in the same manner. The fasteners 50 are tightened to
securely fasten grinding teeth 30A, 30B to the wheel 20.
[Para 48] It will be appreciated that the thickness of the mounting
base portion 70A of grinding tooth 30A will be determined based
upon considerations of the strength required to withstand repeated
impact forces imparted on the cutting bits 60A contacting the tree
stump, and to accommodate at least a portion of the head 230 of
fastener 50, which is preferably completely recessed within
counterbore 210A below the outer surface 1 20A of the mounting
base portion 70A, as well as a portion of the shank of fastener 50,
which extends through clearance hole 1 90A. The thickness of the
mounting base portion 70B of grinding tooth 30B is preferably the
same as the thickness of the mounting base portion 70A of grinding
tooth 30A, but may be of any thickness that is sufficient to grip the
threaded end 250 of fastener 50.
[Para 49] The head portions 80A, 80B of grinding teeth 30A, 30B
are curved relative to the mounting base portion 70A, 70B so that
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the head portions 80A, 80B extend away from the side surface
170A, 1 70B of the wheel 20 when the grinding teeth 30A, 30B are
fastened to the wheel 20. When viewed from a top perspective (e.g.,
FIGS. 3 and 5), the longitudinal axis of the head portion 80A, 80B
angle away from a plane defined by the inner surface 130A, 130B of
the mounting base portion 70A, 70B at an angle 0, which is greater
than 0 but less than about 75 , and is preferably between about 30
and about 60 , and most preferably about 45 .
[Para 50] FIGS. 7 and 8 show a side elevation view and a top view,
respectively, of grinding tooth 30C shown in FIG. 1. FIGS. 9 and 10
show a side elevation view and a top view, respectively, of grinding
tooth 30D shown in FIG. 1. FIG. 11 shows an exploded front
elevation view of grinding teeth 30C, 30D, impact pads 40C, 40D
and a portion of a wheel 20. The grinding teeth 30C, 30D shown in
FIGS. 7-1 1 are the same as grinding teeth 30A, 30B shown in FIGS.
2-6, except that when viewed from a top perspective (e.g., FIGS. 8
and 10), the longitudinal axis of the head portion 80C, 80D is
parallel to the plane defined by the inner surface 130C, 1 30D of the
mounting base 70C, 70D.
[Para 51 ] It will be appreciated that if desired, the longitudinal axis
of the head portion could angle away from a plane defined by the
inner surface of the mounting base portion 70 at a negative angle
(not shown), provided the grinding tooth is fastened to the wheel
proximal to its peripheral edge. This arrangement would provide a
cutting bit at the periphery of the wheel, which can improve plunge
cutting efficiency.
[Para 52] In the preferred embodiment of the invention, at least
one, and preferably a plurality of pairs of grinding teeth 30C, 30D
are fastened to opposing side surfaces 1 70A, 170B of the wheel 20
proximal to the peripheral edge 280 (see FIG. 1) such that the head
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portions 80C, 80D thereof extend beyond the peripheral edge 280
of the wheel 20. At least one, and preferably a plurality of pairs of
grinding teeth 30A, 30B are fastened to opposing side surfaces
170A, 1 70B of the wheel 20 in radially inward locations in a swirled
pattern. Thus, when the wheel 20 is rotated, a cutting bit 60A, 60B,
60C, 60D of one or more of the grinding teeth 30A, 30B, 30C, 30D,
is in position to make contact with a tree stump on the entire outer
periphery and both sides of the wheel 20.
[Para 53] FIG. 12 illustrates an alternative embodiment of the
invention wherein the cleats 1 50E, 1 50F project from the inner
surface of the grinding teeth 30E, 30F at points other than where
the bolts pass through. In other words, unlike the grinding teeth
30A, 30B, 30C, 30D, shown in FIGS. 1-1 1, in which the clearance
holes 1 90A, 190C and tapped holes 240B, 240D are concentric to
the cleats 150A, 1 50B, 1 50C, 1 50D, in the embodiment shown in
FIG. 12, the clearance holes 190E and tapped holes 240F are
eccentric to the cleats 150E, 150F. And, in the embodiment shown
in FIG. 12, the impact pads 40E, 40F cover the entire cleat 1 50E,
150F. The grinding teeth 30E, 30F, impact pad 40E, 40F and wheel
20 arrangement illustrated in Fig. 12 is presently most preferred.
[Para 541 FIGS. 13, 14, 15 and 16 illustrate alternative
embodiments of impact pads 41, 42, 43 and 44, respectively. In
FIG. 13, the impact pad 41 is configured to cover the cylindrical side
walls of the cleat and a portion of the end thereof, but is provided
with an opening 261 through which a concentrically disposed
fastener 50 can pass. In FIG. 14, the impact pad 42 is configured to
cover the entire cylindrical side wall of the cleat, but not the end
thereof. In FIG. 15, the impact pad 43 is configured to cover only a
portion of the cylindrical side walls of the cleat (and not the end
thereof). In Fig. 16, the impact pad 44 is configured to cover the
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entire cleat. Impact pad 44 also includes an opening 262 through
which an eccentrically disposed fastener can pass.
[Para 55] In operation, a wheel assembly according to the invention
is mounted to a suitable stump grinding machine. The stump
grinding machine rotates the wheel assembly (in the direction 25
shown in FIG. 1) at relatively high speed. The operator moves the
rotating wheel assembly in plunging and sweeping motions with
respect to a tree stump to be removed. When the cutting bits
contact the tree stump, they grind, tear, chip or otherwise pummel
the tree stump into small chunks, chips or pieces. The operator
moves the rotating wheel assembly into contact with the tree stump
until it is sufficiently ground away, typically to a point where no
portion of the tree stump remains above the grade of the soil
surrounding the tree stump.
[Para 56] The impact forces caused by the cutting bits striking the
tree stump are translated through the head portion of the grinding
teeth to the mounting base portion. However, because an impact
pad is positioned between the inner surface of the mounting base
portion and the side surface of the wheel, such forces are not
directly communicated to the side surface of the wheel, where they
could damage the wheel. Instead, the impact force and shock is
translated to the impact pad, which absorbs and dissipates at least a
portion of the energy. This prevents the grinding tooth from
damaging the side surface of the wheel.
[Para 57] In addition, the cleats serve to help align the grinding
teeth in the appropriate orientation on the side surface of the wheel.
In addition, they provide a mechanical lock between the grinding
teeth and the side surfaces of the wheel. Thus, it takes far greater
force than necessary to shear the bolts to separate the grinding
teeth from the wheel.
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[Para 58] Additional advantages and modifications will readily
occur to those skilled in the art. Therefore, the invention in its
broader aspects is not limited to the specific details and illustrative
examples shown and described herein. Accordingly, various
modifications may be made without departing from the spirit or
scope of the general inventive concept as defined by the appended
claims and their equivalents.
