Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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The invention relates to a removable excavator tooth
tip on a holder fixed to an excavator bucket, and more particu-
larly, to an insert for connecting the tip to the holder.
In one known tip attachment of this kind, as described
in French Patent 22 6~ 140, the apertures in the holder are of a
somewhat oval cross-section. The surfaces, facing the rubber
element, sandwiched between two shaped metal parts, are uniforrnly
flat so that the said element may be compressed to any desired
degree. This means that under the dynamic loading arising in
excavating, the rubber element soon reaches the limit of its
load-carrying capacity, since the rubber no longer regenerates
but loses its resiliency. ~ ~
In the case of another known tooth attachment, as ~i
described in German AS 1,960,411, the holder engages the trans-
verse bolts constituting the connection engaged through an
intermediate resilient layer, leaving between themselves a gap,
the width of which, in the longitudinal direction of the exca-
vator tooth, is less than the thickness of the resilient inter-
mediate layer. This is intended to prevent the resilient
intermediate layer from being overloaded by the dynamic qtresses
arising during excavating. On the other hand, the intermediate
layer must be highly resilient if it is to keep the connecting
element in place. In the case of the known attachment, this is
impossible since dynamic stressing of the resilient intermediate
layer must be taken into account, and the width of the gap,
therefore, does not permit variable compression. Thus, the -~
possible resilient travel of the intermediate layer will be used
only partly when the connecting element is being driven out. If
the gap in this known arrangement were to be enlarged, thus
allowing the resilient intermediate layer to be cornpressed to a
greater degree, then, as in the case of the other tooth attach- ;
ment outlined above, the dynamic loading would soon cause the
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rubber to reach the limit of fatigue in its load-carrying
capacity. The rubber would then no Longer function as a
resilient element. Furthermore, in the case of the known
arrangement, the resilient intermediate layer is compressed only
on one side while the connecting element is being drlven out,
since the said connecting element is driven out on each side
only by means of a cam. As a result of this design, and since
the full resilient travel cannot be utilized while the insert
is being driven out, in the known tooth attachment only a portion ~ '
of the force of the resilient intermediate element is made use
of. Thus, the resistance of the insert to lateral forces is ;~
relatively low, and the tooth tip cannot be secured optimally
to the holder by means of the insert.
It is the purpose of the invention to provide an ~ ~,
attachment for an excavator tooth in which, on the one hand, the ',
rubber element is loaded to its elastic limit while the insert
is being statically driven out and, on the other han~, the
resilisnt rubber element remains resistant to fatigue under the ~,
continuous dynamic loading arising from excavating operations.
In addition to this, when the connecting element is being driven
out, the rubber element is to be stressed uniformly over its ~'
entire length in order to achieve an optimal resilient action,
and the rubber element itself is not to be stressed in shear
while it is being driven out.,' ~'
A construction in accordance with the present invention
includes an insert for removably attaching an excavator tooth
tip, wherein the tip includes a sleeve adapted to fit on a
holder secured to the digging edge of an excavator bucketO
Apertures are provided in opposed portions of the sleeve and '~
adapted to be aligned with a bore in -the holder running parallel ',
with the digging edge of the tooth tip and along a plane
containing the centerline of the tooth. The insert comprises
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a first and second metal member having a resilient element
sandwiched between them which i9 loaded in compression. One
surface of the insert is adapted to bear against the surfaces
facing the cutting edge while the other surface of the insert
is adapted to bear against the surface~ facing away from the
digging edge. The first metal part is U-shaped longitudinally
with the legs of the U-shaped first metal part extending
away from the digging edge of the ~ip and overlapping the ends
of the second metal part. The gap between the end of the U-
shaped legs and the surface of the respective apertures inthe sleeve i9 less than the allowable resilient travel or
tolerable compression travel of the resilient member within
the fatigue limits of the resilient member~ ;
In a more specific embodiment thereof, the metal
parts, and particularly the second metal part, are provided
with projections having camminy surfaces, and the transverse
dimension of the insert in the area of the projections is
greater than the diameter of the aperture in the sleeve portion
but is such that when a force is applied to an end of the insert,
the camming surfaces on the projection will force the second
metal part to compress the re~ilient ~ember again~t the first
metal part beyond the fatigue limit of the resilient member,
thus reducing the transvexse dimension-of the in~ert in th~ area
of the projection, thereby allowing the in~ert to pa~s through
the apertures in the sleeve. In a further embodim~nt, the
first metal part is provided wlth ~loping surfaces ~uch that
when the insert is being driven out, the re~ilient memker is
compressed to its elastic limit by the sloping surfaces in
addition to the camming surfaces.
The advantage of such an attachment is that when
B ~ the insert is being driven out in order to release the tooth
~ tip from the holder, the rubber element is more heavily compressed
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by the cams and the sloping surfaces of the shaped metal parts
until its elastic limit is reached, which is not possible when
it is in operation. The cams and the sloping surfaces of the ~ -
insert and the matching surfaces of the holder and of the
tooth tip, are arranged in such a manner that, when the connecting
element is being driven out. the rubber element is compressed
substantially uniforrnly over its entire length. This ensures
that the spring force of the rubber element is used to its full
advantage for the purpose of locking the cormecting element
and that, even under the heaviest loads, the tooth tips are
securely held in the holdexs.
An example of the emb~diment of the inventiorl i~
described hereinafter in conjunction with the drawings attached
hereto, wherein~
Figure 1 i~ a fragmentary, longitudi~al cross-
~ection taken throu~h an excavator tooth,
and
Figure 2 i9 a fragmentary, transverse cross-section
taken along the line II-II in Figure 1~
Tip 20 of the excavator tooth consists of a cutting
or digging edge 21 and a sleeve 22 by means of which the said tip
is slipped over the holder 23~ Holder 23 defi~es an aperture 24
extending along the centerline parallel with digging edge 21.
The kore 24 is aligned with apertures 25 in sleeve 22 and accom
modates insert 26. ~
The insert comprises U-shaped metal part 27, rubber '
element 28, and shaped metal part 29.
On its outer side, facing the base of holder 23,
shaped rnetal part 29 is fitted with projections 30 having camming
surfaces 30b and 30c respectively. The side of these projections
facing sleeve 22 ri3e more steeply than the side facing holder
23. The latter ha~ corr~sponding sloping surface 31 cooperating
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with sloping ~urfaces 30b of projections 30~
Arranged upon U-~haped metal part 27 are sloping .:
surfaces 27a which cooperate with corresponding sloping
surfaces 23a on holder 23. The surface of part 27 facing
towards the digging edge 21, is provided with a reces~ 32 ~:
for the better definition of sloping surface 23a of holder
23.
The procedure for driving out insert 26 is as
follows: A blow with a heavy hammer on end face 27b of
U-shaped metal part 27 causes shaped metal part 29 to be
carried along by leg 27c of shaped metal part 27. This
causes increasing compression of rubber element 28, on the :
one hand, by sloping surface 27a of U-shaped metal part 27
and sloping surface 23a of holder 23 and, on the other hand,
by cam surfaces 30b and 30c of shaped metal part 29, sloping
surface 31 of holder 23, and qurfaca 33 of sleeve 22~ As
the insert 26 is driven further out, the compression applied
to rùbber element 28 is greater than that applied by the
loads arising during excavating. - :
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