Note: Descriptions are shown in the official language in which they were submitted.
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WEAR ASSEMBLY FOR AN EXCAVATING BUCKET
Field of the Invention
[01] The present invention pertains to a wear assembly for protecting the
digging edge of an excavating bucket or the like.
Background of the Invention
[02] Excavating buckets are typically subjected to harsh conditions. Wear
members are usually provided to protect the digging edges from premature wear.
Such wear members have taken many different forms. For example, wear members
have been secured to the lip of a bucket through the use of Whisler-style
locking
arrangements such as used in U.S. Patent No. 4,570,365. These locks, however,
require through-holes to be formed in the lip and the use of large hammers to
drive
the wedges into place. Wear members have also been secured to a lip of a
bucket
by a T-shaped base and a hammerless lock such as disclosed in U.S. Patent Nos.
5,088,214 and 7,080,470. While these systems offer improvements over past
systems, improved stability, strength, manufacturability, and value in a wear
assembly are desirable.
Summary of the invention
[03] The present invention pertains to an improved wear assembly with a
wear member for protecting the front digging edge of excavating equipment,
which is
highly stable, is strong, experiences reduced wear, is easy to use and
manufacture,
safe, streamlined, and involves less discarded material at the end of its
life.
[04] In one aspect of the invention, the wear assembly includes a
replaceable wear member that includes a pair of legs to straddle the lip (or
sides) of
an excavating bucket. One of the legs is provided with a hole for receiving a
lock to
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secure the wear member to the lip, while the other leg includes an upstanding
rib
along its inner surface. The rib extends axially rearward to be slidingly
received into
a slot of a base fixed to the lip for support.
[05] In another aspect of the invention, one of the legs of the wear member
includes a rib having a rear end formed with a support surface that is free of
the leg
and faces away from the other leg. The support surface engages a holding
surface
of the base so as to hold the rear end of the rib between the base and the lip
(or
side) for support under load.
[06] In another aspect of the invention, the wear member includes an
interior surface that faces and overlies the lip (or side) of the bucket. The
interior
surface has a front portion formed with a generally uniform curvature to wrap
around
the lip and a plurality of spaced apart stabilizing surfaces. The stabilizing
surfaces
extend generally parallel to the central axial plane of the lip for a unique
combination
of enhanced stability and reduced stress.
[07] In another aspect of the invention, the wear member and the base are
formed with a tongue and groove coupling wherein the base is formed with a
central
groove and the wear member with a central tongue to fit within the groove. The
tongue and groove each includes cooperating rails to secure the wear member to
the
base. The groove opens forwardly through the front end of the base to receive
the
tongue. This construction provides a stable, secure, and strong connection
between
the components that is easy to use.
[08] In one other aspect of the invention, the lock to secure the wear
member to the bucket includes a body provided with a passage, a movable latch,
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and a wedge received into the passage to move the latch to its holding
position to
maintain the lock in the assembly during use.
[09] In another aspect of the invention, the lock includes a threaded wedge
which is received into the lock body to move a latch to a position to retain
the lock in
the assembly. The latch is movable between a retaining position where the
latch
prevents unwanted loss of the lock and a release position where the latch
permits
removal of the lock.
[10] In one other aspect of the invention, a threaded wedge is provided
with a resilient material that is compressed by the complementary threaded
surface
to resist loosening of the threaded wedge. In one preferred embodiment, the
resilient material is a strip of an elastomer fixed within the helical groove
of the
threaded wedge.
Brief Description of the Drawings
[11] Figure 1 is an exploded perspective view of a wear assembly in
accordance with the present invention that is to be secured to a bucket lip.
[12] Figure 2 is a partial, perspective view of a bucket lip where a wear
assembly of the present invention has been omitted.
[13] Figure 3 a perspective view of the wear assembly with an axial cross
section exposed.
[14] Figure 4 is a top perspective view of a base of the wear assembly.
[15] Figure 5 is a bottom perspective view of the base.
[16] Figure 6 is a front perspective view of a wear member of the wear
assembly.
[17] Figure 7 is a rear perspective view of the wear member.
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[18] Figure 8 is a perspective view of the assembled wear member and
base.
[19] Figure 9 is an exploded front perspective view of a lock of the wear
assembly.
[20] Figure 10 is an exploded rear perspective view of the lock.
[21] Figure 11 is a partial cross-sectional view of the wear assembly of the
invention.
[22] Figure 12 is a partial cross-sectional view of the wear assembly with
an alternative lock.
[23] Figure 13 is a perspective view of the alternative lock.
[24] Figure 14 is a perspective view of a body of the alternative lock.
[25] Figures 15 and 16 are perspective views of a latch included in the
alternative lock.
[26] Figure 17 is a perspective view of a threaded wedge for use in the
alternative lock.
[27] Figure 18 is a cross-sectional view of the alternative threaded wedge.
Detailed Description of the Preferred Embodiments
[28] In accordance with the present invention, a wear assembly 1 is
provided for attachment to excavating equipment such as a bucket. The
invention is
discussed below in terms of the attachment of a shroud to the lip of a load-
haul-
dump (LHD) bucket. However, the invention is not limited to the attachment of
a
shroud or an LHD bucket. For example, the present invention could be used to
secure shrouds to a different kind of bucket, mount shrouds between spaced
apart
teeth, and/or secure other kinds of wear members (e.g., wings or adapters).
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Although one kind of lip is illustrated in the drawings, the invention could
be used
with other kinds of lips having other formations and cross sections. Moreover,
wings
mounted along the sidewafls of the bucket adjacent the lip can have the same
or
similar construction. For purposes of this application the digging edge of the
bucket
will be deemed to include the front edges of the bucket sides where the wings
are
mounted as well as the front edge of the lip. Further, the invention is at
times
discussed in relative terms, such as up, down, front, rear, vertical,
horizontal, etc., for
the sake of easing the description. These terms are to be considered relative
to the
orientation of the elements in Figure 1 (unless otherwise noted), and are not
to be
considered limitations on the invention. As can be appreciated, the wear
assembly
can be used and oriented in a variety of ways.
[29] Wear assembly 1 includes a wear member 3, a base 5, and a lock 7 to
releasably secure the wear member (Figs. 1 and 3). The wear assembly fits over
and
is secured to a lip 12 of a bucket or the like. Lip 12 includes an inside face
14, an
outside face 16, and a front edge 17 (Fig. 2). Scallops or recesses 18 are
preferably
formed along the front edge 17 to accommodate passage of lock 7. Scallops 18
are
each preferably formed to have a uniform, continual, arcuate surface 19 with a
curvature that extends no more than about 180 degrees about an axis extending
generally perpendicular to the lip to be easily manufactured and provide a
robust
base to resist the applied loads. Nevertheless, the scallops could be formed
to have
a non-uniform curvature, a discontinuous or angular shape, and/or be formed to
have full or partial closure. In some circumstances, the scallops could be
omitted
with the boss extending farther forward from the lip.
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[301 A base 5 is fixed to lip 12 over each scallop 18 (Fig. 1). While bases 5
are preferably welded to the lip, they could be cast as an integral part of
the lip or
secured by mechanical means. In addition, the bases could each be formed as a
multiple of parts, which are integral or spaced apart, although a one-piece
member
is preferred for simplicity and strength. Each base 5 has a pair of legs 21,
22 that
straddle lip 12 (Figs. 1 and 3-5). A first or inside leg 21 sets along inside
surface 14
of lip 12 while a second or outside leg 22 sets along outside surface 16.
Outside leg
22 is longer than inside leg 21 to interlock with base 5. However, the legs
could be
the same length or the inside leg longer. In addition, the base could have the
opposite orientation with first leg 21 extending along outside face 16 and
second leg
22 along inside face 14. Legs 21, 22 are interconnected by a front end 20.
[31] The second leg 22 includes a central, axial groove 26 provided with a
pair of inwardly projecting rails 24 along its opposite sides 23 (Fig. 4).
Rails 24
define holding surfaces 25 that are spaced from and facing outside face 16.
Rails
24 cooperate with complementary rails 27 of wear member 3 to prevent the
movement of leg 22 away from the lip. In some circumstances, for example,
lower
stress environments, the rails could be omitted entirely (not shown) so that
the slot
provides lateral support. A brace 30 is preferably provided at the rear end of
second
leg 22 (Figs. 4 and 5), though it could be omitted. In this construction,
groove 26
extends into brace 30 to define an opening 31, which is between brace 30 and
outer
wall 16 when the base is welded to lip 12. While a closed opening 31 is
illustrated,
as a closed pocket groove 26 could extend entirely through brace 30 to define
an
opening that is open on both ends. The opening could also be defined in leg 22
without the addition of the brace. In either case, opening 31 receives a
support
33 of the wear member 3 to
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strengthen and resist breakage of the wear member under heavy loading. Groove
26 also opens forwardly through the front end 20 of base 5 and is generally
aligned
with scallop 18.
[32] Brace 30 also preferably extends transversely beyond leg 22 to define
a front wall 34 to abut the rear end 35 of shroud 3 and thereby reduce the
rearward
shifting of the shroud under load, which in turn, reduces the stress and
wearing of
wear member 3 on base 5. Brace 30 also preferably has an equal or greater
depth
than leg 22 to maximize the surface area in abutment with shroud 3, and to
function
as a deflector for earthen material when the movement of the bucket is
reversed. A
deflector face 36 inclined forward from outer face 16 is preferably formed
along the
rear side of brace 30 to direct the earthen material away from the assembled
base
and shroud. Leg 22 is preferably formed as an open framework with openings 37
to
reduce the amount of needed steel and to facilitate welding of the base to the
lip.
[331 The front end 20 of base 5 wraps around front edge 17 of lip 12 such
that the interior surface 40 of the base (i.e., the surface that faces lip 12)
is shaped
to generally conform to the shape of the particular lip to which it is fixed
(Figs. 1, 4
and 5), although derivations are possible. In this case, interior surface 40
includes
an upright face 41 to set against front edge 17, an upper face 42 to set
against
ramp 43 of inside face 14, and a lower face 44 to set against outside surface
16. If
the front of the lip had a curved or other shape, interior surface 40 would be
changed to accommodate the shape of the lip. The front end 20 of base 5
preferably has a curved front bearing surface 48 to minimize stress
concentrations
and wearing between the wear member and the base. In a preferred construction,
front surface 48 has a generally uniform curvature, though other
configurations are
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possible. A recess 51 is formed in first leg 21 in vertical alignment with
groove 26
for receiving lock 7.
[34] Stabilizing surfaces 49 are formed in front end 20 proximate both legs
21, 22 to engage complementary stabilizing surfaces 50 on wear member 3 (figs
1,
4 and 5). Stabilizing surfaces 49 are preferably limited in size so that front
surface
48 is predominantly an uninterrupted generally uniform curved surface as it
wraps
around the front edge of the lip. The stabilizing surfaces are also preferably
along
the side 93 of base 5 for stability but could be provided at other locations.
Also, the
upper and lower stabilizing surfaces 49 are generally aligned vertically by
each side
93 such that the upper and lower stabilizing surfaces 49 by the one side 93
are
generally aligned with each other, and the upper and lower stabilizing 49 by
the
other side 93 are generally aligned - though other positions are possible.
Stabilizing
surfaces 49, 50 are preferably planar and horizontal, he., parallel to the
central axial
plane P of lip 12.
[35] Wear member 3, which is a shroud in the illustrated construction, has
a front working portion 66 that tapers to a narrowed front edge 68, and a rear
mounting portion 70 that is bifurcated to define a first or inside leg 72 and
a second
or outside leg 74 (Figs. 1, 3 and 6-8). The wear member is configured to set
over
base 5 with legs 72, 74 straddling lip 12. In a preferred construction, wear
member
3 fits over lip 12 with first leg 72 overlying inside surface 14 and second
leg 74
overlying outside surface 16. Nevertheless, the legs could be reversed so that
first
leg 72 is the outside leg and second leg 74 is the inside leg. Wear member 3
has an
interior surface 80 that faces and overlies the lip. The interior surface 80
includes
inner face 83 of outside leg 74, inner face 84 of inside leg 72, and the inner
corner
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surface 86 at the intersection of legs 72, 74. Inner face 83 of leg 74
overlies leg 22
and outside face 16, and inside face 84 of leg 72 overlies leg 21 and inner
face 14.
Interior surface 80 along inner corner surface 86 has a central portion 88 and
side
portions 90. Central portion 88 generally matches front face 48 of base 5 and
abuts
against it during use. Central portion 88 is recessed relative to side
portions 90 to
form sidewalls 91 juxtaposed to sides 93 of base 5 for increased lateral
support.
[36] In a preferred construction, interior surface 80 along central portion
88 defines a curved bearing surface 85 (preferably having a generally uniform
curve)
that opposes and abuts front bearing surface 48. The lack of edges on the
front
bearing surfaces of the wear member and the base reduces stress concentrations
in
the parts, i.e., the generally uniform matching curvature of the two surfaces
at the
front bearing surface reduces the concentration of stress that can occur in
the
corners of other parts as the wear part tends to shift on the base during use.
[371 At times, heavy vertical loads (i.e. the loads with vertical components)
are applied to the front working end 66 of wear member 3. It is desirable to
resist
such loads with surfaces that are substantially horizontal, i.e., generally
perpendicular to the vertical component of the load. In the present invention,
a front
end 89 of interior surface 80 forms the uniform curved surface 86 and a pair
of
stabilizing surfaces 50 (Fig_ 7) proximate each of the legs 72, 74 and central
portion
88 to engage stabilizing surfaces 49 on base 5 (Figs. 4 and 5). The
stabilizing
surfaces 49, 50 provide better resistance and greater stability to wear member
3
under vertical loading. To avoid the creation of long edges, the stabilizing
surfaces
49, 50 are limited to discrete locations, preferably extending only a small
portion
across the front ends of the wear member 3 and base 5 (collectively no more
than
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half), and are preferably located at the sides of bearing surfaces 48, 86 for
increased stability. In this way, the benefit gained by the curved bearing
surfaces is
not lost by the use of the stabilizing surfaces 49, 50. Transition surfaces
81, 87 are
provided to ease contact between stabilizing surfaces 49, 50 and to avoid
sharp
corners where stress may concentrate.
[38] A rib 82 is provided upstanding on the inner face 83 of leg 74 in an
axial orientation for receipt within groove 26 (Figs. 1, 3 and 6-8). Rib 82
includes
rails 27 that cooperate with rails 24; i.e., rails 27 are received between lip
12 and
holding surfaces 25 of rails 24 to support wear member 3 under certain loads.
While rib 82 with rails 84 preferably has a T-shaped configuration, other
shapes,
such as dovetail, could be used. Alternatively, there could be no rails in
certain
situations such as low load environments. Rib 82 preferably extends over at
least
half of leg 22, and most preferably over substantially the entire length of
inner
surface 83, for receipt within groove 26 to maximize the support available.
Alternatively, the groove could be formed on wear member 3 and the rib on base
5.
When shroud 3 is installed, it is slid over base 5 and lip 12 such that inside
and
outside legs 72, 74 straddle base 5 and lip 12. Rib 82 is slid into the open
front end
75 of groove 26 in an easy to use manner so that rails 27 cooperate with rails
24 to
hold leg 22 to lip 12.
[391 In a preferred construction, rib 82 extends beyond the rear end of leg
74 to define a support 33 that is received in opening 31 beneath brace 30,
although
other kinds of rearward supports could be used. For example, support 33 could
be
forward of the rear end of leg 74 provided it included a holding surface 95
free of the
leg and facing away from the lip to engage a complementary support surface
(like
CA 02663881 2011-10-26
94) of leg 74. Support 33 is held between a support surface 94 and lip 12 for
enhanced support of the wear member 3. The cooperation of support 33 and brace
30 supplements the resistance provided by rails 24, 27. By providing such a
support
at the rear end of leg 22, bending of the legs can be reduced, which in turn,
lessens
the risk of breaking the part. For example, as upward vertical loads are
applied to
front portion 66, shroud 3 tends to shift clockwise around front digging edge
17.
This shifting causes outer leg 22 to pull away from outer wall 16 of lip 12.
This
action of pulling away from wall 16 places a large amount of stress in inside
leg 72
which tends to resist the shifting. While this bending is resisted by rails
24, 27,
pulling can still generate heavy loading of the leg. By including a support 33
at the
rear end of leg 22, the stresses produced in the leg pulling outward under
load are
substantially reduced, thus, lowering the risk of breakage under heavy loads.
As an
alternative construction, particularly in low load environments, rails 24, 27
can be
omitted so as to rely solely on support 33 in opening 31. As alternatives, the
rear end
of the entire outer leg 74 could be received under brace 30, or other
supports, and
not as extensions of rib 82.
[40] Wear member 3 is assembled over base 5 with a direct, continuous
rearward sliding motion where rib 82 is slid through open end 75 and into
groove 26.
The rearward movement of wear member 3 over base 5 is continued until inside
corner surface 86 abuts front face 48 of, base 5 (Figs. 3 and 11). At this
juncture,
rear wall 35 of outside leg 74 is preferably placed in close proximity to
front wall 34,
also referred to as stop surface 34. With cast parts, it is not practical for
inside corner
surface 86 and rear wall 35 to simultaneously abut front face 48 and stop
surface 34,
respectively. However, by placing rear wall 35 in close proximity with stop
surface 34,
the two surfaces will
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typically abut under certain loads and after a period of time as wear develops
in the
parts. While it is not preferred, stop surface 34 could be the primary bearing
surface
that first abuts rear wall 35, with inside corner surface 86 abutting front
face 48
second.
[411 Inside leg 72 of wear member 3 includes a hole 96 adapted to receive
lock 7 (Figs. 6-8 and 11). Lock 7 includes a body 101 with a front face 103
and a
rear face 105, and a movable latch 107 (Figs. 9 and 10). In use, lock 7 is
inserted
into hole 96 such that front face 103 opposes a rearwardly facing abutting
wall 111
in recess 51, and rear face 105 opposes rear wall 113 in hole 96 and front
wall 115
of rib 82 (Figs. 1 and 3)_ Although the use of rib 82 to form front wall 115
is
preferred, this wall could be formed by another projection or by an opening in
leg 22.
When inserted, lock 7 passes through opening 96, scallop 18, and groove 26. In
this
position, lock 7 bars the removal of wear member 3 from lip 12. As an
alternative,
base 5 and wear member 3 could extend forward farther than shown to permit
insertion of lock 7 without scallop 18.
[42] In a preferred construction, front and rear faces 103, 105 converge
toward each other as they extend toward the bottom or insertion end 109 (Figs.
9
and 10). Likewise, the collective surfaces of walls 113, 115 preferably
coverage
toward abutting wall 111. In this way, the lock can be pried into and out of
the
assembly 1. Latch 107 includes a rigid part 121 preferably composed of steel
provided with a locking projection 122, and a resilient part 123 preferably
formed of
foam, rubber or other elastomer. The bottom end of rigid part 121 defines a
fulcrum
130 to fit within recess 132 to form a pivot axis about which latch 107 moves.
The
resilient part preferably includes detents 125 for receipt within matching
grooves
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127 in body 101 to retain the latch in cavity 129, but could be secured by
other
means.
[431 During insertion of lock 7, latch 107 is pressed rearward against the
bias of resilient part 123 by its engagement against wear member 3. A curved
slope
131 eases the latch rearward into cavity 129 during insertion. Once locking
projection 122 clears stop 133, the resilient part 123 biases rigid part 121
outward
such that projection 122 engages beneath stop 133 to retain lock 7 in wear
assembly 1. To remove lock 7, a pry tool is inserted along the curved slope
131 to
retract latch 107 into cavity 129 until stop 133 is released. The pry tool
can,
through engagement with ledge 137 of latch 107, pull lock 7 from passage 54.
When latch 107 is retracted, the top face 139 of rigid part 121 abuts top wall
141 of
cavity 129 to enable the lock to be pried out through engagement with the
latch. Pry
slot 126 is also preferably formed on rear face 105 to engage either a second
pry
tool or an alternative pry location to help remove lock 7 from passage 54. A
hole
128 in the back of the lock allows rock fines to be pushed out of cavity 129.
A notch
117 is formed on top wall 119 to accommodate the receipt of a pry too during
installation. Other means for inserting or removing the locks, or the use of
other
locks are possible.
[44] An alternative lock 200 can be used to secure wear member 3 to lip
12 (Figs. 12-18). In general, lock 200 uses a threaded wedge 202 such as
disclosed
in U.S. Patent No. 7,171,771, instead of the
elastomer as used in lock 7. Threaded wedge 202 has a rounded exterior 208
that
tapers from the trailing end 210 to the leading end 212 (Fig. 17). A helical
groove
213 preferably extends the entire length of the wedge, though some portions of
the
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wedge could remain unthreaded. A tool-engaging formation 240 for receiving a
wrench or other tool is defined in trailing end 210 for turning of the wedge.
(45] Lock 200 also includes a body 204 and a latch 206 that are similar to
the body and latch in lock 7 (Figs. 12-16). Body 204 is formed with a channel
230
that receives latch 206 and threaded wedge 202 (Fig. 14). A hole 232 is formed
in
top side 234 to define an inlet end for receiving threaded wedge 202 into
channel
230. A trough 236 with threads 238 in the form of at least one helical ridge
segment and preferably a plurality of helical ridge segments 238a is
preferably
provided along the rear wall 239 of channel 230 to engage the helical groove
213
on threaded wedge 202. A recess 218 is formed at the bottom of channel 230 to
receive and form a pivot support for fulcrum 220 of latch 206.
[46] Except for rear side 216, latch 206 has essentially the same
construction and function as latch 107; i.e., latch 206 has a locking
projection 218,
a fulcrum 220, a ledge 222 and a top face 224 (Figs. 12, 15 and 16). However,
unlike latch 107, rear side 216 includes a recess 226 adapted to receive a
front
portion of threaded wedge 202 (Fig. 16). Retainers, preferably in the form of
elastomeric brakes 228 or the like, may be optionally provided to press
against
wedge 202 and resist its loosening during use. As another alternative, a
resilient
material 229 may optionally be provided within helical groove 213 of threaded
wedge 202 to engage ridges 238 and thereby resist loosening of the wedge (Fig,
18).
The resilient material 229 is preferably a strip of rubber, foam, or other
elastomer
which is fixed within helical groove 213 by an adhesive. The resilient strip
229
preferably extends the entire length of groove 213, but could be formed only
along
part of the groove. The resilient strip 229 could be used alone or in
combination
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with brakes 228. The threaded wedge 202 with resilient strip 229 can also be
used
in other wear assemblies such as disclosed in U.S. Patent Nos. 6,986,216 and
7,174,661 and U.S. Patent No: 7,536,811, filed June 13, 2007.
[47] In use, lock 200 is inserted into assembly 1 like lock 7 (Fig. 12). Lock
200 is preferably inserted into wear assembly 1 with threaded wedge 202
partially
inserted into channel 230, butthe wedge could be installed after body 204 is
placed
into the assembly. Threaded wedge 202 is then threaded farther into channel
230
to force latch 206 forward so that locking projection 218 engages stop 133 to
retain
lock 200 in the assembly during use. A tool-engaging formation 240 is
preferably
provided at trailing end 210 of wedge 202 to facilitate its turning.
