Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~xcAvArrING TOOTH
BACKGROUND AND SUMMARY OF INVENTION:
This invention relates to an excavating tooth
and more particularly to a novel point portion thereof,
being an improvement on *Patent 4,761,900 which, in
turn, was an improvement on co-owned *Patent 4,353,532.
In the '900 patent, a novel locking system was
provided to replace the U-shaped fastener employed in
the HELII,OK tooth sold throughout the world -- see '532
patent~The '900 system employed a drive through pin
maintained in place by a plug member or keeper which
extended transversely of the adapter length, i.e.,
horizontally so as to be unstressed by impact loads.
The vertical locking pin in the '900 patent was clamped
in place by an ear lug on the point rear cooperating
with a pair of vertically spaced ears on the adapters.
These cooperated to retain the pin which was generally
arched rearwardly, i.e., the convex side faced
rearwardly.
I have determined that a significant
improvement in operation can be achieved by employing a
pair of vertically spaced ear lugs on the point ear,
notwithstanding the pin convexity.
More particularly, the invention provides a
replacement point for an excavating tooth comprising
relatively elongated, unitary body having an earth
engaging edge at the forward end thereof and an adapter
nose-receiving socket in the rear end defined by top,
*U.S. Patent Nos.
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bottom and a pair of side walls. At least one of the
side walls extends rearwardly beyond the top and ~ottom
walls, each oE the sidewalls which extend rearwardly
beyond the top and bottom walls having adjacent the top
and bottom thereof vertically spaced upper and lower ear
lugs aligned to receive a locking pin~
Preferably the ear lugs extend inwardly at
approximately a right angle to the socket and provide an
interrupted generally arcuate, forwardly facing bearing
surface for bearing against longitudinally spaced areas
of a locking pin.
Through employing the spaced ear lugs on the
point, a point and nose assembly configuration providing
improved service life of the nose has been created. In
explanation, the end of service life of any excavating
tooth system nose is determined most commonly by one or
the other of two types of failures:
1. Failure of the nose to retain points,
which has been brought about by a wearing away of the
nose through service to create a fit of points on the
nose that is so loose that the points either fall off or
brea~ off.
2. Structural failure of the nose in a
fatigue mode. The improved nose service life provided
by the inventive point and nose construction results
from reductions in the causes of both types of failures.
With regard to nose wear, the inventive
construction reduces bearing pressures of the point on
the nose by providing a longer bearing surface, thereby
slowing the rate of nose wear and resultant loosening of
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point fits. Also, ic provides for a "rocking" type
bearing of the point retaining pin against the nose to
reduce wear of the pin bearing surface on the nose.
Whereas the '900 pin is caused to rub against the nose
ears through small movements up and down that are
induced by the point under loading, the spaced ear
lugs of the inventive point permit a pin
configuration that can absorb -the point induced
: - 2a -
movement through rocking. This rocking movement equates to a
slower rate of wear on the pin bearing surface of the nose in
comparisOn to the ~900 construction, as with the simple analogy
of the rolling wheel versus the sliding block. Further the
inventive construction provides that the rear sidewalls of the
point completely protect the nose pin bearing surface and ~he
pin itself from all external wear, ~hat is, wear from abrasive
soil and rock which the tooth system is excavating.
It is axiomatic that a tight f it is desired to keep the
point in place on the adapter -- this notwithstanding the fact
that under high impact loads there is movement of the point
relative to the adapter nose (see U.S. Patents 2,919,506 and
3,079,710), tightness is relative. The basic HELILOK tooth
system of U.S. Patent 4,335,543 is capable of supporting and
retaining points on the nose after a considerable amount of
looseness has developed from nose wearO It is superior to other
tooth systems in this respect, as are the '900 tooth system and
the inventive tooth system. Yet, there is a threshold of
looseness, which will vary inversely with the severity of
application, beyond which a given tooth system will not be
capable of supporting and retaining points. It is the extension
of the amount of service before this threshold is reached toward
which the inventive tooth is directed.
With regard to nose fatigue failures, the use of spaced
apart ear lugs on the point permits elimination of projecting
ears on the nose. Such projecting ears can be a source of
stress concentration. Hence their elimination provides greater
.
nose fatigue strength as well as allowing a longer bearing
surface. These two advantages more than compensate for the
slight loss of material in the nose to provide the groove for
the new side lock pin.
The principal advantages reside in the achievement of
heretofore unrealizable tighter fits throughout the adapter life
and the avoidance of stress concen~rations at the critical
juncture of the nose with the shank portion of the adapter while
achieving a greater point to nose bearing length.
10Points with vertically spaced rearwardly extending
ear-like portions have been used previously, as in my prior U.S.
Patent 4,326.348 where the ear function was for stabilization in
cooperation with a ear cap.
The prior art does not teach the advantageous function
of the spaced-apart rearwardly extending ear means in confining
the locking pin in original locked position.
The invention is described in conjunction with the
accompanying drawing, in which
FIG. 1 is an exploded perspective view of Patent
2~4,335,532;
FIG. 2 is an exploded perspective view of Patent
4,761,900;
FIG. 3 lS an exploded perspective view of the tooth
parts of the instant invention;
25FIG. 4 is a top plan view of the assembled elements of
the instant Inv-n=ion;
.
.
FIG. 5 is a side elevational view, partially broken
away and in section of the assembly of FI~. 4 with the section
corresponding to the view along line 5-5 of FIG. 4;
FIG. 6 is a sectional view such as would be seen along
the sight-line 6-6 as applied to FIG. 4;
FIG. 7 is a fragmentary side elevational view of the
nose with the point shown in non-impact and impact conditions; *
FIG. 8 is a side elevational view of the adapter nose
portion of the embodiment of the invention depicted in FIGS.
lo 3-7;
FIG 9 is a view similar to FIG. 8 but of another
embodiment of the invention wherein the surface of the nose
bearing against the pin is arcuate;
FIG. 10 is a perspective view of the nose of FIG. 8 as
seen from the left rear;
FIG. 11 i~ a perspective view of a modified form of the
inventive point wherein only one side wall is equipped with
rearwardly extending ear means; and
FIG. 12 is a fragmentary side elevational view
partially in section of a modified tooth assembly embodying
teachings of the invention.
DETAILED DESCRIPTION
Referring to FIG. 1, the HELILOK~ tooth of the '532 is
pictured. This conslsts of a point A, an adapter having a nose
portion B, and a U-shaped lock C. This tooth construction was
especially advantageous in providing a stronger nose because of
the a~sence of any locking pin opening.
*As shown with:FIG. 4.
_ 5
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However, there has been difficulty on occasion in
removing the U-shaped lock C which was o~ercome by ~he use of
the drive-through pin C' of the '900 paten~ - see FIG. 2. An
especially advantageous feature of the '900 patent construction
was the use of an unstressed keeper or ~ransverse plug D. The
tooth point of FIG. 2 is designated A because it is identical to
that of FIG. 1. However, the adapter nose of FIG. 2 was changed
from that of FIG. 1 and therefore is designated B'. As
indicated above, the lock was changed also and therefore the
drive-through pin of FIG. 2 is designated C'.
According to the instant invention, I have changed all
of the point, adapter nose and pin lock, these being designated
A', B'' and C'' -- the keeper being unchanged and therefore
designated D.
The invention is based on the discovery that the pin
normally moves with the point when the latter is under impact
loading. This can be appreciated from the diagramma~ic showing
in FIG. 7. There, the adapter nose is shown in solid line and
is designated 20. The locking pin is also shown in solid line
~ and is designated 21 in the non-impact condition. The tooth
point, however, lS shown in dashed line, designated 22 and also
is in the non-impact or static condition.
An impact load or stress -- directed downwardly as
schematically indicated at 23 -- causes the point to pivot on
the nose to the dotted line configuration designated 22'. The
pin likewise pivots to the dotted line position designated
21'. This illustrates the rocking or rolling action referred to
- 6 -
previously -- and which provides thP advantage of not wearing
the surface 24 of the nose groove that bears on the intermediate
portion of the pin 21, see also FIG. 5.
To take advantage of the discovery that the pin moves
with the point in the system under construction, I made several
changes in the locking mechanism, an important one being the
provision of spaced-apart pin bearing surfaces on the point.
POINT LUGS BEARING ON PINS
These can be first appreciated from a consideration of
10 FIG. 3. In that embodiment the sidewalls of the point A' are
extended rearwardly beyond the socket 27 to provide ears 25 and
26. At their rearward ends, these ear portions or means are
equipped with integral lugs 28, 29 for the ear 25 and 30, 31 for
ear 26. The lug 29 can be seen in the lower right-hand portion
of FIG. 4 and the lug 31 is seen in the upper right-hand portion
of that view. All of these lugs are also designated in FIG. 6.
These lugs are inwardly projecting and by that I refer to
extending at approximately a right angle to the length of the
socket 27, i.e., the interior of the tooth.
~0 From FIG. 6, it can be seen that the vertical distance
between the top 33 of the upper lug 31 and the bottom 32 of the
lower lug 30 is approximately the length of the rear diameter of
the socket 27 which has a circular cross-section at its rear
end, i.e., in the "nose cone" surface at E in FIGS . 1-3 .
This relationship is advantageous in that it permits
adequate size of the inte~ral lugs from the standpoints of
structural strength and bearing area.
,
In explanation, the inward surfaces 34 and 35 of the
lugs 30 and 31 as seen in FIG. 6 (and cor~spondingly on the
lugs 28 and 29) are partly bevelled surfaces located for minimum
clearance around the nose cone surface E in FIG. 3. This can be
seen most clearly in FIG. 6, where the surfaces E' are
extensions of the nose cone rearward to the region of FIG. 6.
In the twisting assembly and disassembly of the point on the
nose, these inward, beveled surfaces of the lugs must clear the
nose cone and extension surfaces, E and E'. By combining the
flat tall point ears of FIGS. 3-7 with the circular socket/nose
cone cross section, I arranged for space outside of this inward
boundary for point ear lugs of adequate size.
In the specific invention, the inward beveled surfaces
34, 35 of the ear lugs actually are arcuate, but satisfactory
function could be achieved with straight bevels.
Referring to FIG. 5, in the preferred construction, the
pair of forwardly facing lug walls 36 and 37 together are
portions of an arcuate surface for tightening engagement with
longitudinally spaced areas of the concave rear edge 38 of the
~ pin ~1. Only one pair of lugs engage the pin on any given
assembly, the other pair being for the purpose of allowing
installation of the point in 180 turned orientation. This
practice of turning~points when they are about half worn out is
sometimes practiced when a very sharp digging configuration is
required.
Prior to assembly, the radius of the concave rear edge
38 of the pin 21 is smaller than the radius of the arc surfac~
-- 8 --
pairs 36, 37 or those corresponding pairs on lugs 28 and 29.
Therefore, if the pin 21 is placed in contact with the lug 21
arc surface 36, 37, but not in assembly on a nose, the contact
is locally near the ends of the lug surfaces as at 32 and 33.
With assembly of the pin into a point and nose assembly, this
contact of the pin on the lug arc surfaces becomes more
distributed because the pin is caused to flex through the
contact of its forward convex edge 39 with the forward wall 24
of the nose groove 40 -- see FIGS. 5, 8 and 10. Finally, under
operating loads received on the point during service, the pin is
able to flex still more so that the radius of its concave rear
edge 38 essentially matches that of lug arc surfaces 36, 37 for
full surface contact~
It, of course, is the flexing of the pin that creates a
tightening assembly force.
Driving of the pin into the point/nose assembly is
facilitated by a bevel interruption of the forwardly facing lug
wall 36 as at 41 in FIG. 5. As the entry end of the pin 21
passes over this bevel 41, the pin is caused to deflect, or
flex, in order ~o arrive at the forwardly facing lug wall 36.
NOSE BEARING ON PIN
Instead of usin~ the ears 42 of FIG. 2 for bearing on
the new pin C ", I employ the forward wall 24 of the nose groove
40 -- see FIGS. 4 and 5. The nose bearing surface is planar as
at 24 in FIG. 8 or slightly arcuate as at 124 in FIG. 9 relative
to the groove 140. Nominallyi the pin.bears on the nose
surfaces at 24, 124 near the longitudinal mid-plane of the nose,
_ g _
but during impact stress the bearing shifts above and below the
mid-plane.
The groove 40 in the nose is defined insofar as its
rear wall is concerned by an integral ledge 43 -- compare FIGS,
3 and 4. This ledge merges top and bottom into the nose as can
be appreciated from the showings at 44 and 45 in FIGS. 3 and 8
and at 144 and 145 in FIG. 9 relative to the ledge 143. The
arcuity of the forward wall 124 of FIG. 9 can be appreciated
from the fact that at its mid point, it is tangent to the keeper
opening 146 -- as contrasted to the relationship of the wall 24
to the keeper opening 46 in FIG. 8. There, the wall 24 has a
groove 47 to accommodate insertion of the keeper -- see also
FIG. 10.
The ledge 43 (or 143) also serves as a guide during
locking pin installation. In this connection I prefer to use a
single ear point construction of FIG. 11 with the nose of FIG. 9
this tooth is used primarily for dredging and does not have to
be reversib~e. Here the construction of the lugs 28 and 29 is
identical to that of FIG. 3 -- only the ear means providing the
?0 lug portions 30, 31 being omitted.
LOCKING PIN
As indicated previously, the pin C'' differs from the
pin C' (compare FIGS. 2 and 3) in that the pin used with the
inventive point has a forward curvature, i.e., is normally
bowed. This facilitates the desired rocking action that
minimizes nose wear at the area 24.
An alternative construction of locking pin 221 is shown
in FIG. 12. The point ears of this construction again are o~
approximately the sam~ length as the rear diameter of the point
-- 10 -
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socket 27, but the forwardly facing lug walls 236 and 237 are
not arcuate Rather these lug walls are flat and parallel for
use with a sandwich type pin. Thi.5 sandwich pin, as has been -
used for many years in the industry, is a laminate of steel
plates 248, 250 confining a rubber core 249. This construction
does not offer the advantage of rocking engagement with the nose
lock groove wall 224 but it would be suitable for light duty
applications, and as such, would provide the advantage of
operating without a plug D. The pin's retention in assembly is
provided by the engagement of the rearward projection 251 on the
rear steel laminate 248 with the inward edges 236, 237 of the
lugs 228 and 229. Here, it will be appreciated that
corresponding lugs are normally provided on the opposite sides
of the point, as is a corresponding groove on the nose.
While in the foregoing specification a detailed
description of the invention has been set down for the purpose
of explanation, many variations in the details hereingiven may
be made by those skilled in the art without departing from the
spirit and scope of the invention.
