Note: Descriptions are shown in the official language in which they were submitted.
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Description
GROUND ENGAGING TOOL RETENTION SYSTEM
Technical Field
The field of this invention is ground engaging tools, and more
specifically systems for retaining ground engaging tools on implements.
Background
Many construction and mining machines employ implements to
work the earth. Examples of these implements are rippers, buckets, blades,
etc.
Abrasion and impacts experienced during earthworking can subject the
implements to extreme wear. Implements can be protected against this wear by
including ground engaging tools (GET). GET is typically fashioned as teeth,
edge protectors, sidebar protectors, wear plates, ripper tips, etc. which are
attached to an implement in the area where the most damaging abrasion and
impacts occur. The GET includes sacrificial wear material that will gradually
wear away as it scrapes against the soil and rocks. For example, the cutting
edge
of a bucket can be protected with edge protectors, one type of GET, that wraps
around the edge and shields it from wear.
When the GET is worn, it can be removed and replaced with new
GET at a reasonable cost to continue to protect the implement. It is more
economical to wear out and replace the GET than to wear out and replace an
entire bucket or other implement. Also, easy replacement of GET facilitates
keeping the implement sharp, which can reduce penetration forces and increase
efficiency.
Customers expect GET to remain reliably attached to the
implement during use. Of course, the retention system should not let the GET
fall off of the implement. In most cases the retention system should in
addition
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hold the GET tightly to the implement to avoid excessive movement between the
GET and the implement. Excessive movement between the GET and the
implement may wear the mounting surfaces formed on the implement for the
GET. At the same time, customers expect the GET to be easily and quickly
removed and replaced when it is worn. For most GET, it should preferably be
replaceable in the field, with only a few simple tools, so the machine need
not be
brought to a service shop. The GET retention system performs the task of
reliably holding the GET on the implement during use, and also permitting easy
and quick removal for service.
Many retention systems have been proposed and utilized for
removably attaching GET. One common type of retention system includes a
shear pin which holds the GET onto the implement. An example of this type of
shear pin system is shown in U.S. Patent No. 5,009,017 issued 23 April 1991.
Problems can exist with these known systems. For example,
installing the shear pin may require a hammer to drive the pin into its bore.
On
large GET systems, the hammer required to drive the shear pin may likewise be
very large, and swinging such a large hammer in difficult field conditions can
be
objectionable to the technician. Sometimes the spacing of teeth on the edge of
a
bucket does not provide a comfortable amount of space between the teeth in
which to swing the hammer and drive the shear pins.
As an example of another problem or shortcoming with shear pins,
the pin may "walk" out of its bore and unintentionally release the GET from
the
implement. The retention system must be secure and not permit the GET to fall
off, even when the GET is worn extensively. If the GET falls off, it could be
fed
into a crusher or other processing machine and cause damage. Missing GET can
result in extensive wear and damage of the implement if the missing GET is not
immediately detected and replaced. The known retention systems have not
always held the GET to the implement with adequate reliability.
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One proposed solution to shortcomings of shear pin systems and
other prior art systems is found in U.S. Patent Application Publication No.
2007/0107274 Al, published on 17 May 2007. This solution has some
advantages, yet downsides still exist in this system in some applications. For
example, the pin in this solution only retains one side of the GET to the
implement.
Summary
A GET retention system according to the present invention may
comprise a pin with a threaded bore formed therein, a bolt having a bolt head
and
a bolt shank, the bolt shank being threaded into the threaded bore of the pin,
a
sleeve positioned between the bolt and the pin, the sleeve having a first
counter
bore at a first axial end, the bolt head being at least partially enclosed in
the first
counter bore, and a washer positioned between the sleeve and the pin, the
washer
outside diameter being greater than the sleeve outside diameter.
An implement and GET assembly according to the present
invention may comprise an implement having a nose end, and a recess formed on
an outside surface of the nose end, the recess aligned with a bore formed into
the
nose end, a GET having a pocket, the nose end of the implement, including the
recess, being positioned in the pocket, the GET further having a bore aligned
with
the bore formed in the nose end, a washer positioned in the recess, a pin with
a
threaded bore formed therein positioned at least partially in the bore formed
in
the nose end, a bolt having a bolt head and a bolt shank threaded into the
threaded
bore of the pin, a sleeve positioned at least partially in the bore of the GET
and
the bolt head being at least partially enclosed by the sleeve to protect the
bolt
head from shear loads, and the washer outside diameter being greater than the
sleeve outside diameter.
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Brief Description of the Drawings
FIG. I is an exploded view of GET retention system according to
the principles of the invention with a ripper tip and a ripper shank.
FIG. 2 is a sectional, partially exploded view of the components of
FIG. 1.
FIG. 3 is a sectional view like FIG. 2, but with the retention
system components now fully assembled into a working position.
Detailed Description
The following is a detailed description of exemplary embodiments
of the invention. The exemplary embodiments described herein and illustrated
in
the drawing figures are intended to teach the principles of the invention,
enabling
those of ordinary skill in this art to make and use the invention in many
different
environments and for many different applications. The exemplary embodiments
should not be considered as a limiting description of the scope of patent
protection. The scope of patent protection shall be defined by the appended
claims, and is intended to be broader than the specific exemplary embodiments
described herein.
FIG. I illustrates a GET retention system 100 according to the
present invention, for use on a ripper system. Rippers are known implements
used to loosen hard earth, typically before dozing the material out of the
way, or
before loading the material into a truck with a bucket. A ripper tip 200 is
mounted on a ripper shank 300. The ripper shank 300 may be mounted to a
tractor (not pictured) such as a track-type tractor (also known as a
bulldozer) or
motor grader. The tractor includes means for raising and lowering the ripper
shank 300 into the ground. While the machine is moving, the ripper shank 300
is
lowered into the ground. The ripper tip 200 protects the end of the ripper
shank
300 and provides a sharp edge or point to slice through the ground, fracturing
the
soil or rock to loosen it.
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It will be understood by those of ordinary skill in this art that a
GET retention system according to the principles of this invention could be
used
on other, different types of GET systems and implements. Use of this invention
is not limited to rippers. For example, the illustrated embodiment could
easily be
understood as a retention system for a bucket tip by replacing the picture of
the
ripper shank 300 with an adapter mounted on a bucket of wheel loader or
hydraulic excavator.
The ripper tip 200 includes a pocket 210 that accepts the nose end
310 of the ripper shank 300. The ripper tip 200 includes a front, ground
engaging
portion 201 and an opposite rear portion 202, the pocket 210 being formed into
the rear portion 202 and extending toward the front portion 201. The front
portion 201 includes an edge 203 or point, which provides a relatively sharp
feature for penetration into the earth. The rear portion 202 also includes a
bore
220. Bore 220 is a through bore and passes through left and right walls 204,
205
which surround pocket 210.
The ripper shank 300 includes a bore 320 and associated recess
330. When the ripper tip 200 is mounted on ripper shank 300 in a working
position, bore 220 may align with bore 320 so that they are generally coaxial,
or
at least the two bores 220 and 320 should overlap so a pin can pass through
each
simultaneously. Bore 320 passes through and opens onto a left and a right side
of
ripper shank 300. Recess 330 is formed around and adjacent to one end of bore
320. Recess 330 and bore 320 may be circular in cross section, each with an
axis
which is coaxial with the other, or they may be another shape in cross
section, as
desired.
Retention system 100 is mounted inside of bore 320 and recess
330 of ripper shank 300, and bore 220 of ripper tip 200. Retention system 100
includes a pin 110, a bolt 120, a sleeve 130, and a washer 140.
Pin 110 is elongated in a longitudinal direction and includes a first
end 111 and an opposite second end 112. Pin 110 also includes a central
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threaded bore 113. Bore 113 is formed into second end 112. The axis of bore
113 is aligned with the longitudinal direction of pin 110. Preferably bore 113
is a
blind bore so that in use dirt or other debris cannot enter from first end
111. Pin
110 acts as a shear pin between the ripper tip 200 and ripper shank 300.
Bolt 120 includes a bolt head 121 and a threaded bolt shank 122.
The threads on bolt shank 122 are complementary to threads in bore 113. In the
working, or installed position of bolt 120, bolt shank 122 is positioned
inside and
is threaded into bore 113. In a preferred embodiment, the threads in bore 113
do
not extend all the way from the end of the bore to the second end 112 of pin
110,
and likewise not all of the bolt shank 122 is threaded. Rather, the threads
extend
from the end of the bore 113 only part way to second end 112, and the threads
only cover a portion of bolt shank 122 extending from the distal end of the
bolt
shank 122 part way to the bolt head 121. This allows bolt 120 to thread close
to
the end of bore 113 and allow a length of bolt shank 122 to be strained during
assembly. Providing an appropriate amount of strain in bolt 120 will help
prevent fatigue failure due to any cyclical loading the bolt may undergo, and
help
to prevent bolt 120 from loosening. Bolt 120 functions to hold sleeve 130 and
washer 140 onto pin 110.
Sleeve 130 is substantially formed by a cylinder 131, with a
central through bore 132, a first axial end 133, and an opposite second axial
end
134. In its working, or installed position, sleeve 130 is positioned and
captured
between bolt 120 and pin 110. The central bore 132 passes through each of the
first axial end 133 and the second axial end 134. The cylinder 131 features a
flange 135 which extends radially inwardly into central bore 132. Flange 135
is
also penetrated by bore 132, and includes a first axial surface 136 and a
second
axial surface 137. First axial surface 136 and second axial surface 137 define
opposite axial sides of flange 135, and each is generally a planar surface
normal
to the axis of central bore 132. Flange 135 helps define two counter bores to
central bore 132. A first counter bore 138 whose bottom is defined by first
axial
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surface 136 and whose sides are defined by cylinder 131, opens through the
first
axial end 133. A second counter bore 139 whose bottom is defined by second
axial surface 137 and whose sides are defined by cylinder 131, opens through
the
second axial end 134. Each counter bore 138, 139 can be described as a
widening of the diameter of central bore 132 near each of the first and second
axial ends 133, 134, to a diameter wider than the diameter of central bore 132
where it penetrates flange 135. The sleeve 130 in the illustrated design is
substantially cylindrically shaped on its exterior, yet it could also be other
shapes
as may be beneficial or preferential in different applications.
The function of sleeve 130 is to protect bolt head 121 from wear
and also to react any shear forces that would otherwise be exerted on bolt
head
121. These shear forces will be "blocked" by the sleeve 130, i.e. the sleeve
130
will react those shear forces without transferring them to the bolt head 121.
By
shear force we mean any force which would act on the bolt head 121 in a
direction other than the longitudinal direction of bolt 120.
Washer 140 includes a central bore 141 surrounded by an annular
body 142. In its working, or installed position, washer 140 is captured or
secured
between pin l 10 and sleeve 130. A portion of pin 110 is positioned internal
to
the annular body 142, inside of central bore 141. A reduced diameter portion
114
of pin 110 may be provided which defines a shoulder 115. Reduced diameter
portion 114 is smaller than central bore 141. Shoulder 115 is larger than
central
bore 141 so that annular body 142 of washer 140 abuts against it. The opposite
side of washer 140 abuts against second axial end 134 of sleeve 130. Washer
140
functions to keep the pin 110 and sleeve 130 in their working positions inside
of
bores 220 and 320 by preventing them from sliding axially outward.
In general, washer 140 is larger than sleeve 130 so that washer 140
cannot pass through bore 220 of ripper tip 200 or bore 320 of ripper shank
300,
while sleeve 130 may be positioned in bore 220. The washer 140 has a washer
outside diameter which is defined as the largest diameter of any portion of
the
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annular body 142 measured from the axis of central bore 141. The sleeve 130
has a sleeve outside diameter which is defined as the largest diameter of any
portion of cylinder 131 measured from the axis of central bore 132. The washer
outside diameter is chosen to be larger than the diameter of bore 220 or bore
32o,
or so large that it cannot pass through either bore 220, 320. On the other
hand,
the sleeve outside diameter is chosen to be smaller than the diameter of bore
220,
or so small that it can pass through bore 220. Because the washer outside
diameter is larger than the bore 220 diameter, and the sleeve outside diameter
is
smaller than the bore 220 diameter, it follows that the washer outside
diameter is
therefore greater than the sleeve outside diameter. The washer 140 has a
washer
inside diameter which is the smallest diameter of any portion of the annular
body
142 measured from the axis of central bore 141. The washer inside diameter is
smaller than the sleeve outside diameter so that a portion of the sleeve 130
may
abut against and help capture washer 140.
The second counter bore 139 of sleeve 130 may encompass the
reduced diameter portion 114 of pin 110. In a preferred design, the second
counter bore 139 fits tightly around the reduced diameter portion 114. This
fit
helps shear forces reacted by the sleeve 130 to be transferred to pin 100. To
create this fit and maintain it, bolt 120 may be torqued tightly into pin 110,
driving together the second counter bore 139 and reduced diameter portion 114,
the torque being adequate to hold the fit even under shear loads transferred
between the sleeve 130 and pin 110. To facilitate torquing bolt 120 into pin
110,
the bolt head 121 may include a socket or other exterior shape to engage with
a
wrench or other similar tool, and the first axial end 111 of pin 110 may
likewise
include a socket or other exterior shape to engage with a wrench or other
similar
tool.
While having a second counter bore 139 in sleeve 130 which fits
tightly around the reduced diameter portion 114 of pin 110 is a preferred
design
for some applications, this feature will not be necessary or desirable in
others.
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The second axial end 134 of sleeve 130 and the second end 112 of pin 110 also
have surfaces which abut one another and can transfer shear loads between them
after the bolt 1 20 is torqued tightly into the pin 110. These abutting axial
surfaces will be sufficient to transfer shear loads in some applications,
obviating
the need for second counter bore 139.
The first counter bore 138 substantially encloses the bolt head 121
to protect it and block shear forces from acting on it. In the illustrated
design,
bolt head 121 is substantially within the profile formed by first counter bore
138.
However, it would also be possible to allow some portion of bolt head 121 to
extend from first counter bore 138, but preferably only if the portion of bolt
head
121 which extends out of the counter bore will not be subject to any
substantial
shear forces. Because sleeve 130 protects bolt 120 from shear loads, most of
the
stress due to a shear load is in the sleeve 130 and pin 110, and only a
relatively
small stress increase in the bolt 120 should result from any shear loads.
A substantial portion of sleeve 130 is positioned inside of bore 220
when the retention system 100 is in its installed, or working position. When
ripper tip 200 tries to slide off of nose end 310 of ripper shank 300, the
walls of
bore 220 will interfere with sleeve 130, and ripper tip 200 will not be able
to
disengage from nose end 310. In other words, the second end 112 of pin 110 and
sleeve 130 act together as a shear pin to prevent ripper tip 200 from sliding
off of
nose end 310. When ripper tip 200 tries to slide off of nose end 310, the
force
against sleeve 130 from the surface of bore 220 is one type of shear load
which
the sleeve 130 reacts and absorbs to prevent it from being transferred to bolt
head
121.
Likewise, first end 111 of pin 110 may extend from bore 320 in
the ripper shank 300 into the opposite end of bore 220 in the ripper tip 200
(i.e.
the end of bore 220 opposite from where sleeve 130 is positioned) to also act
as a
shear pin and prevent ripper tip 200 from sliding off of nose end 310.
However,
the extension of first end 1 I 1 into bore 220 is only optional. In an
alternative
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design, bore 320 in ripper shank 300 could be a blind bore, and in that case
the
first end 111 could not extend out of nose end 310 into bore 220. In such an
alternative design, it may be possible to provide two blind bores 320 on
opposite
left and right sides of nose end 310, each with a separate retention system
100
positioned therein. In such an alternative design, it would be necessary to
provide some feature on the ripper shank 300, possibly in bores 320, to
prevent
the pin 110 from spinning in the bore during tightening of the bolt 120 to the
pin
110.
Assembling the GET retention system 100 includes positioning
washer 140 in recess 330 formed on the outside surface of ripper shank 300,
the
washer 140 aligning with through bore 320. Next the nose end 310 of ripper
shank 300 and the washer 140 are positioned in pocket 210 formed in the ripper
tip 200, with bore 220 extending between the pocket 210 and the exterior of
the
ripper tip 200, and aligning with or at least overlapping the bore 320 formed
in
ripper shank 300. Then pin 110 with threaded internal bore 113 is inserted
into
bore 320 of ripper shank 300, through bore 220 of ripper tip 200. Bolt 120 is
next pushed through sleeve 130, and threaded into the bore 113 of the pin 110,
causing sleeve 130 to be captured between the bolt 120 and pin 110, and the
washer 140 to be captured between sleeve 130 and pin 110. Sleeve 130 is now in
place to enclose and protect the head 121 of bolt 120, and to divert any shear
loads which would otherwise act of head 121.
Industrial Applicability
A GET retention system 100, or other GET retention system
designed according to the principles of this invention, finds utility in
retaining
GET on implements such as ripper shanks or buckets, which implements are in
turn used in the construction and mining industries.
