Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND AND S~RY OF INVENTION:
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This invention relates to an earth working tooth
with wear cap and, more particularly, to a uniquely contoured
and constructed wear cap that promotes longer life of the
tooth. The tooth with which the instant invention is concerned
includes an adspter which is designed to be fastened so as
to proJect forwardly from the leading edge of earth working
equipment, i.e., buckets, dippers, etc. At the projecting
forward end of the adapter, a nose ~s normally provided which
is received within the socket of the replaceable point, the
two being fastened together by means of ~ removable lock.
Normally, 5 to 10 replaceable points are used during the life
span of the adapter.
Starting about 25 years ago, efforts were made to
extend even further the life of the adapter -- it being appreci-
ated that this i8 a relatively heavy element and that consider-
able down time of valuable equipment may be required for its
replacement. One such effort i8 geen in Peklay U. S. ~atent
2,896,345 wherein the wear cap was provided on the top surface
of the sdapter and held in place by means of the cooperation of c
tongue and groove connection slong the sides of the wear cap and
adapter and the projection of the top wall of the point. This
proved inadequate because the constant flow of material over
the wear cap wore away the metal, particulsrly along the sides
of the top of the cap. This threatened the central dovetail
connection and led to the improvement set forth in Hill u. s. Pat-
ent 3,082,555.
An important distinction in the Hill patent '555
was the enthickening of the cap along the sides in an attempt
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to prolong the wear life of the cap. This also proved un-
successful so the Hill construction was modified to eliminate
the angled bottom sides of the cap and to extend the depending
tongue the full length of the cap so as to provide for rever-
sibility -- the thought being that the live could be effectively
extended by reversing the cap after the dovetail connection
at the forward end had become threatened. This reversible
dification of the Hill '555 construction has been widely
utilized for the last 15 years or 80.
Even though the reversible feature provided the
advantage of a somewhat extended wear life, it maintained
the disadvantage of the Hill construction over the Pecklay
constructlon in continu$ng to expose the connection between
the cap and adapter at the cap forward end. This meant that
material flowing rearwardly over the tooth had the opportunity
of entering into the space between the surfaces providing the
dovetail connection and creating wear which could lead to
looseness and premature failure.
Furthermore, in the oft-repeated event of inadequate
maintenance -- as where these wear caps were not replaced soon
enough, th~ forward end of the wear cap dovetail became partially
worn away. This proved catastrophic to the service life of
the adapter because it would no longer retain wear caps.
This has been avoided by the insta~t invention which,
in a sense, is a partial return to the Pecklay '345 construction
by virtue of having a closed forward end on the wear cap 80
as to protect the bearing surfaces constituting the connection
between the cap and adapter. ~owever, two significant
differences characterize the invention over Pecklay '345.
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lrst, the bearing surfaces of the cap/adapter connection
are no longer dovetailed but are "horizontal", i.e., parallel
to each other on the opposite sides of the cap and, more
particularly, a massive section has been added at the very
front of the cap which is characterized by forwardly extending
side pro~ections. These projections effectively extend the
life of the cap by installing more wear metal at the point
of crucial wear, i e., ~ust forward of the side rail connection.
Thus, it will take correspondingly longer before flowing
earth which can be quite abrasive, can enter into the spaces
between the bearing surfaces of the connection. Additionally,
the parallel bearing surfaces provide effective retention of
wear caps even where their forward end has worn when a wear cap
has been allowed to wear through. Here it should be appreciated
that close fits between interconnected parts are impossible
not only because of the production of these parts by casting
but also because the interconnected parts may have different
degrees of wear.
The provision of the forward projections on the cap
generated ~n additional benefit in the fact that the generally
cup-shaped forward contour generated by these projections
provided a barrier which induced buildup of material on
the top of the point in the crucial central rear area ~bout
the pin lock. This i6 the location o f incipient failure
because of the removal of material for the pin lock and
also because of the repetitive stresses which are localized
in this area.
Although the concept of providing a barrier at the
rear of the point to develop a buildup is not new -- ~ stratton u. c.
Patent 2,987,838, it has not been utilized in commercially
available excavating teeth. More particularly, when Stratton
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attempted to provide th~s function through the use of a wear
cap, he provided no forward pro~ections, no closed forward
end and utilized the inferior dovetail connection between the
cap and adapter.
It should also be appreciated that wear caps having
parallel 8iae r8ils or wing~ to enter into grooves on the side
of the ad~pter have also been known for a substantial period --
~ Petersen U. S. Patent 2,968,880. However, this construction has
also failed to reach commercial significance not only
because of the flimsiness of the sheet metal cap but, more
importantly, the fact that the cap was not closed at the
front so as to protect the important connect~on along the
8idcs of the cap and adapter.
In one broad aspect~ the invention pertains 'o a
wear cap for an earth working tooth which cap comprises a
unitary metal member having a central front facing wall flank-
ed by divergent forwardly extending side projections, to
provide a concavity facilitating build-up on the tooth of
earth being worked. The wear cap has sidewalls extending rear-
wardly from the projections with inwardly extending wlngs
along the bottom edges of the sidewalls for mounting the
wear cap on the tooth.
The invention further pertains to an earth-working
tooth comprising an elongated adapter having a point-receiving
part at its forward end and means at the rear end for securiny
the adapter to earth working equipment. A wear cap is remov-
ably mounted on a generally horizontally extending surface
of the adapter with a point removably mounted on the adapter
part to maintain the wear cap in place on the adapter. The
wear cap has a central forwardly facing wall flanked by
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forwardly extending projections along the cap sides. Rail
lock means interconnecting the cap and adapter are rear-
wardly aligned with the projections, and include parallel
recesses in the sides of the adapter adjacent to but spaced
vertically of the adapter surface and also provide parallel
generally horizontally extending bearing surfaces. The
wear cap has parallel side wings received in the recesses,
with the wings providing parallel bearing surfaces arranged
to contact the recess bearing surfaces. The wear cap
projections diverge forwardly from the forwardly facing
wall.
DETAILED ~ESCRIPTION OF THE INVENTION:
The invention is described in conjunction with the
accompanying drawing, in which --
FI~ a perspect$ve ~iew of a fragment of theexcavating tooth of the instant invention, only a portion of
the adapter being shown and that portion of the tooth above
the horizontal mid-plsne;
FIG. 2 is a showing similar to FIG. 1 but with
th~ wear cap in worn condition ~ust prior to replacement;
FIG. 3 is an exploded perspective view of the
showing of FIG. l;
FIG. 4 is a side elevational view of the adapter
employed in the invention along with the point and wear cap
shown in dotted line;
FI~. 4A is a fragmentary top plan view of the
front portion of the wear cap;
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FIG, 5 is.a front elevational view of the wear cap
of FIGS. 1-4;
FIG. 6 is an exploded perspective view of a
modified form of inventive tooth;
FIGS. 7 and 8 are, respectively, top plan and side
elevational views of the wear cap of the assembly of FIG. 6;
FIG, 8A is a fragmentary side elevati~nal view
showing the vertical curvature of the wear cap forward wall
with dimensional figures indicated thereon; and
FIG. 9 is a s~de elevational view of the adapter of
the assembly of FIG. 6 again with the wear cap and point shown
in dotted line.
Turning to the first drawing sheet, FIG. 1 illustrates
in exploded fashion, the principal parts of the earth wor~ing
or excavating tooth generally designated 20. The numeral 21
designates the adapter which is of the Whisler type (see
particularly FIG. 4) having a split shank so as to straddle the
leading edge of a bucket or other earth receiving device. The
wear cap i8 designated 22 and the point 23. The point is
equipped with aligned openings 24 and 25 adapted to receive
a pin 26 which extends through a further aligned opening
27 in the adapter and bears against a plug 28 positioned within
an enlarged portion 27a of the adapter opening 27. The pin,
plug and openings can be seen in greater detail in u. s. Patent
3,126,654.
The adapter 21 adjacent the top thereof is equipped
with recesses 29 and 30 opening to the adapter sides and which
provide bearing surfaces therein -- on the parallel upper
(i.e., downwardly facing) surfaces thereof 29a and 30a.
This is developed by the general T shape having an upper bar
31 providing side flanges for the imposition of stress fro~
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the inwardly facing, parallel wings 32 and 33 on the wear
cap -- the wear cap providing parallel upwardly facing surfaces
32a and 33a on the wings thereof (see FIG. 5). Thus, any
force having an upward component on the wear cap brings the
rail iock surfaces 32a, 33a into contact with the flange
surfaces 29a, 30a to resist the dislodging force.
The cap 22 i8 characterized by a relatively massive
8ection 34 (see FIG. 4) along its top, particularly in the front
portion thereof. This massive section extends rearwardly from
the central front-facing wall 35 (see FIG. l). The front-
facing wall 35, in the illustration given in FIGS. 1-5, has
an inclination relative to the horizontal of at least about
75 so that the same is generally vertical. The wall 35 is
flanked by forwardly extending, integral pro~ections 38 and
39 (see FIG. 1) which, in combination with the wall 35 and
the forwardly sloping wall 37, d~velop a cavity generally
designatet 36. Thus, the entire front of the cap 22 is closed
to protect the confronting surface~ of the cap and adapter --
see particularly FIG. 4,
As indicated previously, the pro~ections 38 and 39
serve to place atditional wear metal forward of the crucial
side rails or wings 32, 33 and slots or recesses 29, 30. As
can be appreciated from a consideration of FIG 2, remnants
of the pro~ections still remain even after a substantial
portion of the front massive section has been worn away -- see
the irregular shaped aperture W, indicating a complete wear-
through of the cap in this area. This provides a visual
indication that cap replacement is necessary.
As indicated above and best seen in FIG. 1, concavity
36 is defined by integral forwardly extending portions 38
and 39 w~ich diverge in proceeding forwardly (see FIG. 4A).
The portions 38, 39 are developed by walls 30, 41 that extend
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forwardly from the central vertical wall portion 37 at an
angle of at least about 25. As the cavity providing walls
40, 41 extend further forwardly, their angularity or cup-
shape become m3re pronounced, especially adjacent the upper
parts of the portions 38 and 39 (see FIG. 4A). This provides
a unique operation in protecting both the cap 22 and the
point 23 particularly in the area of the pin lock 26.
For example, earth is forced to flow both inwardly
and rearwardly by virtue of encountering the projections 38,
39. This results in an earth build-up in the cavity or cup-
shape 36 -- the earth flow being resisted by the massi~e section
34. Because of their lateral tapering nature, the projections
38, 39 (see FIG. 1) offer increased protection to the side means
28, 29, 32, 33 for folding the cap on the adapter -- all
while still providing a flow of earth that in effect, has "dirt
wearing on dirt".
The arrangement depicted in FIGS. 1-5 is particularly
suited for teeth made in accordance with U. S. Patent 2,919,506.
For a later generation tooth (see U. S. Patent 4~23l~l73)aglightly
modified form of cap is provided but which utilizes the
teachings of the invention heretofore set down -- the
modified form i8 shown on the second drawing sheet.
Reference is now made to the second sheet of the
drawings wherein like numbers are employed to designate like
parts, but with the addition of 100. Thus, in the exploded
view of FIG. 6, the numeral 120 designates the tooth
generally and which is made up of an adapter 121, a wear cap 122,
and a point 123. The various elements making up the releasable
lock for the point on the adapter are identical to those
previously designated by the numerals 24-28 and are omitted
from this embodiment for clearness of pr~sentation.
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In this embodiment, the cap 122 is moun~ed in
precisely the same way on the adapter 121 as previously
described, i.e., parallel wings 132 and 133 on the cap are
installed within recesses 129 and 130 on the adapter sides.
Likewise there i5 a massive section 134 at the top of the cap
122, The differences between this embodiment and the one
previously described stem primarily from the difference in
the points 23 and 123. The point 123, for example,
has rearwardly extending tongues on the top, bottom and
sides thereof which are normally received within correspond-
ing recesses in the adapter 121. Further details of the point
and adapter of this embodiment can be seen in the above-
mentioned Patent 4,231,173 and the disclosure of that patent
is incorporated herein by express reference.
In this embodiment, as before, the wear cap is
retained in place against forward movement by the interference
or overlap with the rear end of the point. Because the point
in this embodiment is equipped with the rearwardly extending
tongues, a slight change in the forward or front contour of the
wear cap is indicated. Por example, the central vert~cal wall
portion 137 pro~ects downwardly between the forwardly divergent
portions 138 ant 139 to provide this overlap or interference
and the forwardly divergent portions 138, 139 (which develop
the concavity or cup-shape) are extended further forwardly 80
as to completely overlie the portions of the adapter which
otherwise would be exposed -- due to the function of ac-
commodating the various rearwardly extending tongues 120a on
the point. Other than in these specific structural differences,
the wear caps 22, 122 function in the same way of directing and
confining earth to protect the cap rail lock and point pin
lock.
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This is achieved by providing that portion of the
central forwardly facing wall above the point at least twice
as high as the vertical thickness of the wings 32, 33. For
example, the overall height of one size of wear cap is 111 mm.
The portion of this height above the point is 90 mm. whereas
the thickness of the wings 32, 33 i8 about 25 mm. In this
regard, the underside of the wear cap 120 is the same as
that o wear cap 20 and the rear elevation for this embodiment
i8 analagous to that seen in FIG, 5.
Through the provision of the wings and recesses,
bearing surfaces are provided as indicated at 29a, 30a and
32a, 33a so that both the portion of the cap above the wing
bearing surfaces and the flange portions of the adapter
above the recess beari~g surfaces have to be worn away
before earth passing over the wear cap can engage both sets
of bearing surfaces and cause dislodgment of the wear cap.
Well before this occurs, the massive section at the front
of the wear cap (the side wings extending only part way from
the rear of the cap to develop this ~ass~ve section) will
hsve been worn away in the fashion indicated at W in PIG. 2
through the earth-directing function of the pro~ections 38,
39 to provide a visual indication that the cap needs
replacement. This is true irrespective of the forward
contour of the wear cap, either that of the embodiments of
FIGS. 1-5 wherein the cap has a generally box-shape in side
elevation or the embodiment of FIGS 6 to 9 wherein the central
: front facing wall 135 is extended below the bottom of the cap
to provide a depending flange 137a (see particularly FIG. 8).
It will also be noted that in the embodiments of FIGS. lOa,
the vertical thickness of the wings 32, 33 is the same as that
of the adapter flanges above the bearing surfaces 29a, 30a.
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It will be appreciated that, dependent upon the cir-
cumstances, wear caps can be used either on the top or bottom
surface of the adapter, or both. For example, there is merit in
employing a wear cap only on the bottom where the structure such
as a shovel dipper i8 sub~ect to wear particularly on its
bottom surface. The arrangement is precisely as pictured
wherein the parts cooperate to prevent inadvertent dislodgment
of the wear cap.
It should be appreciated that where the terms "top"
and "bottom" are employed, these are directed to the generally
horizontally extending surfaces of the adapter or like structure
when the s~me iB in the position for penetrating material.
In both embodiments, the forwardly facing cavity (as
at 36 in FIG. 1) is concave generally in the vertical plane --
compare, for example, FIGS, 4 and 8. This results from angling
the upper and lower portions of the central front facing wall
(as at 35 in F~G. 1) and which i8 illustrated schematically
relati~e to the ~econd embodiment in FIG, 8A. It will be seen
there that the concavity has a depth d which is substantially
less than the chordal length c. Advantageously, the depth shoult
be at least about 5% of the chordal length.
While in the foregoing specification, the invention
has been discribed in detail, many variations may be made in
those details without departing from the spirit and scope
of the invention.
