Note: Descriptions are shown in the official language in which they were submitted.
2 ~ 4 B fi ~ 3 ~
~uKvlTT~R EXCAVATION ~K~'L WITH FINE
GRADING SCOOP
Field of the Invention
This invention relates in general
to excavation buckets and relates in
particular to a backhoe or excavator bucket.
Background of the Invention
Excavation equipment with
excavation buckets for digging and grading
has been known for many years. The buckets
themselves have been developed and refined
over the years to increase the
,~
2 2146613
digging efficiency of such devices. Excavation buckets
are typically adapted to backhoes. A backhoe is a type of
excavation equipment which includes, generally, a tractor
and an articulatina, hinged arm assembly attached to the
tractor. The arm assembly is mechanically
interconnected at one end to the tractor and at its
opposing end to an excavation bucket. In use, the bucket
is extended away from the tractor, engaged with the
material being excavated, and then drawn toward the
0 tractor to scoop the material into the bucket.
A typical excavation bucket comprises,
generally, a pair of spaced-apart side plates and a bottom
plate joined along edge portions of the side plates to
define a material-containing volume therein. A leading
edge of the bucket, defined by the leading edge of the
bottom plate, may be provided with a plurality of teeth
for improved digging action. The rear of the bucket is
provided with mounting plates defining holes for
mounting the bucket onto the arm of a backhoe.
In this conventional configuration, the
bottom plate of the bucket is a continuous plate extending
from the front of the bucket to the rear of the bucket. The
profile of the bottom plate is typically arcuate, defining a
varying radius of curvature along different portions of the
bottom plate. During use, the bucket is rotated by the
backhoe arm while the leading edge of the bucket is
forced into the material being excavated. The
configuration of the bottom plate, and of the bucket
generally, is such that the bottom plate slides relative to
the material and provides little resistance to movement of
the bucket. The leading edge of the bucket, at which the
teeth are located, is typically the widest transverse
portion of the bucket and the portion of the bucket that
extends deepest into the trench. This configuration
insures that there will be little or no interference between
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the bucket side plates and the sidewalls of the excavated
trench or ditch.
B ackhoes are particularly effective for
digginv trenches and ditches. However, the conventional
S backhoe bucket becomes difficult to operate when
working near building foundations or other locations
where buried building service conduits and pipes may
extend from the building near the location of excavation.
For example, electrical cables, either direct-buried or
0 disposed in buried conduits, water mains, and gas lines,
are often buried in the ground adjacent building
foundations. When excavating with a conventional
bucket near locations known or suspected to include
buried objects, it becomes necessary to remove only
1S shallow layers of material as the depth of the trench
approaches the buried depth of the buried object. Failure
to excavate with caution near the buried object could
result in the excavation bucket snagging, rupturing, or
otherwise damaging the structure, possibly with
catastrophic consequences.
Further, when laying pipe or other conduit in
exca- ated trenches, the final grading of the trench must
be carefully and precisely made to ensure proper slope
and foundation for the pipe or conduit. This type of
operation is difficult to perform with a conventional
backhoe bucket because the toothed leading edge of the
bucket is not designed to remove shallow layers of
excavation material or to permit fine-grading of material
to be excavated.
Summary of the Invention
Accordingly, an object of the present
invention is to provide an improved excavation bucket,
particularly an improved backhoe bucket.
4 21~661'3
Another object of the present invention is to
prv~ide an excavation bucket with a scoop forrned into
the bottom thereof to ~llow fine-grading with the
excavation bucket.
A further object of the present invention is
to provide an excavation bucket that can be used in one
mode for digging, and in another mode for 8rading.
Another object of the present invention is to
provide an excavation bucket with a scoop formed in a
o bottom plate thereof, which is capable of fine-grading
adjacent buried objects, particularly cylindrically shaped
objects buried in the excavation path, without disturbing
or ~l~m~ging the buried object.
Stated generally, the excavation bucket
according to the present invention utilizes a conventional
configuration modified with a scoop provided on the
bottom portion of the bucket. This configuration allows
the bucket to be utilized in a conventional manner for fast
digging in a first mode, and in a novel manner for fine-
grading with the scoop in a second mode.
Stated in greater detail, the scoop is formed
in the bottom plate of the excavation bucket by providing
front and rear bottom plate portions which are attached to
the side plates to form an elongate scoop slot extending
2S from one side plate to the other side plate. The slot is
defined by edges defined along adjacent edges of the
front and rear bottom plate portions. The bottom plate
edges are displaced such that the edge along the rear
bottom plate is lower, relative to the bucket opening, than
the edge along the front plate. This configuration is fixed
and allows the scoop to excavate up to a maximum depth
into the material to be excavated. An outer surface of the
front bottom plate supports the bucket on the material
durina fine-grading and positions the slot edge of the rear
bottom plate at a fixed depth below the surface. The
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e,~ca~ ation depth can be varied by chan~ing the attitude
of the engagement of the outer surface of the front
botlom plate in relation to the material to be e:~cavated.
In one embodiment of the present invention
the front and rear bottom plate portions are arcuate. In
another embodiment of the present invention the front
bottom plate portion is substantially planar and the rear
bottom plate portion may be arcuate or planar or
comprise planar and curved portions. The type of
0 material to be excavated and the excavation conditions
may dictate or suggest which configuration of bottom
plate portions to use.
The bucket may be provided with bucket
guide plates disposed in engagement with and
substantially co-planar to the side plates. The bucket
guide plates define guide edges that extend slightly past
the outer surface of the front bottom plate portion from
the front portion of the bucket adjacent the teeth to the
rear bottom plate edge defining the scoop slot. The guide
edocs of the guide plates are effective to prevent the rear
slot edge from engaging buried objects, including
conduits and pipes. The guide edges act as guide
surfaces that will engage a buried object as the bucket
approaches the buried object. As the bucket is drawn
closer to the tractor the guide edges ride along the buried
object, thrusting the bucket in an upward direction. As
the scoop draws closer to the buried object the guide
surfaces continu~ to ride along the object causing the
rear slot edge to disengage the buried object and pass
over it. After the rear slot edge has passed the buried
object the guide surfaces no longer engage the buried
object and the rear slot edge drops down and resumes
fine-grading the material.
The scoop is located so that the bucket will
3s retain a substantial amount of material while digging and
6 21~6~1~
remo~ing in the conventional manner without material
e citing through the scoop slot. Specifically, the scoop is
located along the bottom of the bucket so that there exists
a substantial fillable bucket volume behind the scoop.
s Thus, the rear bottom section and the side plates provide
an interior bucket volume that can retain material to
~llow complete excavation and removal by the bucket.
The performance of the bucket according to
the present invention can be improved by providing a
closure for the scoop slot to prevent material that has
entered the bucket, during either regular excavation or
fine-grading, from exiting through the scoop slot. It is
possible to provide a control valve or the like at the scoop
for selectively controlling the movement of material
through the scoop slot. However, such a closure would
tend to be complex and not durable enough to withstand
hea~y dig_ing. Thus, a passive one-way valve such as a
resilient flap is particularly suitable for use in the present
mventlon.
A resilient flap, for example, made of a
molded rubber composition, is optionally provided to act
as a one-way valve for material passing through the
scoop into the bucket while preventing material flow in
the opposite direction. The resilient flap is preferably
mounted within the scoop to prevent damage thereto
during operation of the bucket. The flap can be mounted
to extend downwardly from a trailing edge of the front
bottom section of the bucket, or can be mounted to
extend upwardly from a leading edge of a rear bottom
section of the bucket. The free end of the resilient flap
must contact and cooperate with other structure inside the
bucket acting as a stop to prevent its rotation when
operating in the excavation mode to prevent material
flow from the bucket.
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The wear characteristics of the bucket can be
enhanced by providing wear plates and guides at
appropriate positions on the bucket. For example, a wear
plate can be provided either above or below, or both,
relative to a leading edge of the rear bottom section at the
scoop. This prevents wear of the leading edge of the rear
bottom section. The wear plates can be mounted to be
replaced, or removed and repaired, as required.
Likewise, a lower wear plate can be provided at the
0 trailing edge of the front bottom section.
The wear plate(s) and combination of wear
plates can be provided for changing or modifying the
configuration of the scoop slot. Specifically, the wear
plates can be added to make the scoop slot effectively
larger or smaller. Further, the leading edges of the wear
plates can be selected to carry out various functions, for
example, a beveled cutting edge.
The leading edge of the rear bottom section
can be beveled to provide a cutting edge. Further, the
wear plate(s) can be provided with a beveled cutting edge
at the leading edge thereof. The wear plate(s) can be
positioned to provide a double or triple cutting edge, or
can be positioned to provide a continuous cutting
edge/surface with the beveled cutting edge of the rear
bottom section of the bucket.
Brief Description of the Invention
Fig. l is a pictorial view of an excavation
bucket according to a first preferred embodiment of the
present invention.
Fig. 2 is a side elevation view of the bucket
as shown in Fig. 1, together with a fragmentary showing
a conventional arm and operating cylinder for supporting
the bucket.
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Fig. 3 is a side elevation view of the bucket
shown in Fi._. 2 indicating the configuration of the side
plates.
Fig. 4 is a lengthwise cross-section view of
the bucket shown in Fig. 2.
Fig. S is a front elevation view of the bucket
as seen from the right side of Fig. 2.
Fig. 6 is a lengthwise cross-section view of
the bucket shown in Fig. 4, modified with the addition of
0 a closure for the scoop.
Fig. 7 is a pictorial view of another
embodiment of the bucket according to the present
in~ ention.
Fig. 8 is a pictorial view of another
embodiment of the bucket according to the present
invention.
Fig. 9 is a lengthwise cross-section view of
the bucket shown in Fig. 8.
Fig. 10 is an illustrative view of the bucket
of Fig. 8 shown fine-grading material from a trench and
engaging a buried object.
Detailed Description of Preferred Embodiments
The present invention is directed to
excavation buckets, in particular backhoe and excavator
buckets for trenching. However, the present invention
~ can be applied to other types of buckets such as front
loaders and other types of excavation equipment.
A first preferred embodiment of an
excavation bucket according to the present invention is
shown in Figs. 1-6 and is designated generally by the
numeral 10. The excavation bucket 10 comprises a pair
of upstanding side plates 12 and 14 connected together
by a rear bottom assembly 16 and a front bottom
assembly 18. Edges defined alona portions of the side
~14~613
pla~s 12 and 14 and along portions of the rear and front
bottom assemblies 16 and 18 are joined together, by
welding for example, to forrn a structure having an upper
opening O for material introduction, and to define a
bucket material volume therein. In the excavation bucket
10 the side plates 12 and 14 have a generally D-shaped
con~l~uration as shown in Figure 3.
The excavation bucket 10 further includes a
pair of connector plates 44 attached to one end of the rear
0 bottom assembly 16 and used for connecting the
excavation bucket to other excavation equipment, such as
a tractor. Each connector plate 44 defines a mounting
aperture 46 and articulation apertures 48 and S0.
Referring to Fig. 2, the bucket 10 is illustrated as attached
to a support arm 21 and hydraulic cylinder H of a
backhoe (not shown) in a conventional manner. The
hydraulic cylinder H, which includes a telescoping rod R,
is attached to the support arm 21. A distal end 23 of the
rod R connects to an articulation assembly 25. The
articulation assembly 25 attaches pivotally to the bucket
throug,h a spindle 27, and rotates the bucket 10 counter-
clockwise or clockwise around the mounting aperture 46
as the rod R is extended from the cylinder C, or retracted
into the cylinder.
2s Looking now at Fig. 4, the rear bottom
assembly 16 comprises an arcuate rear plate 29 and a
grading plate 32. The grading plate 32 defines edges 33
and 34. Edge 33 of the grading plate 32 engages the rear
plate 29 and is secured thereto by conventional means,
including welding. The edge 34 is a beveled edge which
provides a cutting edge 36 to facilitate fine-grading. In
the embodiment shown in Fig. 4, the grading plate 32 is
thicker than the rear plate 30 which gives the grading
plate 32 greater strength, longevity and robust
perforrnance.
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~o
- The front bottom assembly 18 includes an
arcuate front bottom plate 31 and a transverse plate 30.
Th. front bottom plate 31 defines a trailing edge 22,
which engages the transverse plate 30, and a leading edge
38 to which is mounted a plurality of teeth 40 by supports
42 welded to the front bottom plate 31 adjacent the
leading edge 38.
The transverse plate 30 defines edges 35 and
37. The forward edge 35 of the transverse plate 30 is
0 welded to edge 22 of the front bottom plate 31. The
transverse plate 30 is also welded, at its ends, to the side
plates 12 and 14. The rearward edge 37 of the transverse
plate 30 is elevated above the edge 34 of the grading
plate 32 to provide a scoop 19 defining a scoop slot
1~ oper~ing 20. More particularly, the scoop slot openin_ 20
is defined by the rearward edge 37 of the transverse plate
30, by the beveled edge 34 of the grading plate 32, and
by the triangular notched portions 26 and 28 disposed in
the side plates 12 and 14. The triangular notched
~0 portions 26 and 28, shown in Fig. 5, expose forward
facing surfaces 26a and 28a, respectively, of the side
plates 12 and 14. The grading plate 32 is spaced relative
to plate 30 in substantially co-planar orientation and at a
distance T apart as shown in Fig. 3. The distance T
2S defines the maximum thickness of material removable by
the scoop 19 in a single pass of the bucket 10 used in a
fine-~rading mode. The orientation of the grating plate
32 relative to the transverse plate 30 may be varied as
required for particular bucket configurations.
The excavation bucket 10 can be provided
with optional features, as shown in Fig. 6. The grading
plate 32 can optionally be provided with an upper wear
plate 52, or a lower wear plate 52', or both. The wear
plate(s) can be secured to the grading plate 32 by one or
more threaded fasteners 54, or by other conventional
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Il
me~ns. The application of the wear plate(s) 5~ and 52'
modifies the dimensions and configuration of the scoop
openin_ 20 to be larger or smaller as desired for a
particular application. The wear plates 52 and 52' can be
fabricated and positioned so that the beveled cuttin~
edges 34 are continuous and, thus, maintain the bevel
angl- of bevel edge 34. Alternatively, the effective bevel
angle of the edge 34 of the grading plate 32 can be
modified by changing the angle of the leading edge of the
lo lower wear plate 52'.
The transverse plate 30 can optionally be
pro~ ided with a lower wear plate 56. The wear plate 56
can be secured to the transverse plate 30 by one or more
threaded fasteners 58, or by other conventional means.
The application of the wear plate 56 modifies the
dimensions and configuration of the scoop opening 20 to
be smaller as desired for a particular application.
Further, the angle of the upper leading edge of the scoop
can be modified by simply changing the angle of the
~0 leading edge of the wear plate 56.
The wear plates 52, 52', and 56 described
abo~ e can be replaced, or removed and repaired, when
worn or ~m~ged. Further, various combinations of wear
plates can provide numerous configurations tailored to
particular applications.
The scoop 19 can be provided with a
resilient flap 60, shown in Fig. 6, to allow material to
enter the bucket 10 through the scoop opening 20, and to
prevent material, once in the bucket, from undesirably
exiting the bucket 10 through the scoop opening 20. The
resilient flap 60 can be fabricated or molded to a variety
of different configurations suitable to accomplish this
task. For example, the resilient flap 60 can have an
upside-down L-shaped configuration. A metal strip 62
secured by one or more threaded fasteners 64 can
I~ 2i~6613
secur~ly fasten the resilient flap 60 to the trans~erse plate
30.
In the embodiment shown in Fig. 6, the
resilient flap 60 is connected adjacent to edge 37 of the
transverse plate 30, and extends downwardly blocking
the scoop opening 20. The resilient flap 60 is of
sufficient len~th that it contacts an upper surface 65 of
the gradin~ plate 32 to prevent portions of the flap 60
from being expelled out of the scoop opening 20 under
0 the force of excavated material within the bucket 10.
Alternatively, the resilient flap 60 may be
attached to the grading plate 32 so that the flap 60
extends upwardly therefrom and seals against edge 37 of
the transverse plate 30.
A second embodiment of a backhoe bucket
according to the present invention is shown in Fig. 7 and
is generally designated by the numeral 10'.
The bucket 10' includes a flat front bottom
assembly 100 and upstanding side plates 12' and 14'. The
sides 12' and 14' are provided with C-shaped notches 102
and 104 exposing surfaces 102a, 102b, 102c, 104a~ 104b,
104c. A transverse face 106 is exposed in the entrance of
the scoop 20'. The transverse face 106 can be used for
grading when the backhoe bucket 10' is moved away
from the excavation equipment while the cutting edge 36'
is used for grading when pulling the backhoe bucket 10'
toward the excavation equipment.
A third preferred embodiment of the
excavation bucket of the present invention is shown in
Figs. 8-10 and is generally designated by the numeral
210. The bucket 210 comprises upstanding side plates
212 and 214, and a rear bottom assembly 216 and a front
bottom assembly 218 secured between the side plates 21
and 214. The bucket 210 further includes a pair of
connector plates 244, attached to one end of the rear
~146613
13
bottom assembly 216, for connectin_ the bucket 210 in
supported and articulating engagement with a backhoe
arm 21, shown in Fig. 10, in a conventional manner. The
bucket 210 also includes upper and lower bucket guide
plates 215 and 217, respectively, secured to each of the
side plates 212 and 214. The bucket guides 215 and 217,
which are described in greater detail hereinbelow, are
effective to cause the bucket 210 to ride over objects
buried in the material to be excavated when the bucket
o 210, disposed in the scoop grading mode, engages the
object. These buried objects include, for example,
electrical conduits and gas and water service pipes buried
below grade.
The rear bottom assembly 216 includes an
arcuate rear plate 229 and a grading plate 232 attached to
the forward edge of the rear plate 229. The grading plate
232 defines substantially parallel transverse edges 233
and 234. The rear transverse edge 233 of the gradin;,
plate 232 engages the forward edge of the rear plate 229
and is secured thereto by conventional means, including
welding. The front transverse edge 234 may be provided
with a bevel 236 to facilitate fine-grading.
The front bottom assembly 218 includes a
planar front bottom plate 240 and a tooth mounting and
reinforcing plate 246. The front bottom plate 240 defines
an outer support surface 241 and includes parallel
~ transverse edges 247 and 248 and side edges 249 and
250. A lower portion of the tooth mounting and
reinforcing plate 246 overlays, and is welded to, a por~on
of the front bottom plate 240 adjacent the upper edge 247
so as to reinforce the front bottom plate 240. A plurality
of tooth supports 42, each mounting a tooth 40, is
attached to an upper edge 255 of the tooth mounting and
reinforcing plate 246.
21~G613
14
The upper bucket guide plates 215 are
atta.hed to the side plates 212 and 214, adjacent the
buc~et opening O, and tend to reinforce the side plates
212 and 214. Each of the upper bucket guide plates 215
includes an upper guide edge 258 that extends past the
tooth mounting and reinforcing plate 246 a prescribed
distance and at generally right angles to the tooth
mounting and reinforcing plate 246. The upper guide
edge 258 defines an upper guide surface 260 on each side
0 of the bucket 210.
The lower bucket guide plates 217 extend
downwardly from the forward ends of the upper guide
plates 215 to the grading plate 232, and attach by welding
to the side plates 212 and 214, the opposed ends of the
grading plate 232, and the side edges 249 and 250 of the
fron~ bottom plate 240. Each lower bucket guide plate
217 includes a longitudinal lower guide edge 259 that
exterlds past the front bottom plate 240 a prescribed
distance and substantially perpendicular thereto. The
lower guide edge 259 thus defines a lower guide surface
261 ~ hich extends from the upper bucket guide plate 215
to the edge 234 of the grading plate 232. The lower
guide surface 261 extends coincident to or slightly
outu-ard of the edge 234 of the grading plate 232. The
lower bucket guide plate 217 also includes a clearance
edge 264 which extends from the grading edge 234 to the
grading plate edge 233 and slightly below the grading
plate 232.
The edge 248 of the front bottom plate 240
is disposed in spaced-~part relation to the edge 234 of
the ~rading plate 232 a distance T. The front bottom
plate edge 248, the grading plate edge 234 and the lower
guide edges 259 thus provide a scoop 270 defining a
scoop slot opening 272. The distance T defines the
.
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ma~imum thickness of material that is removable in a
single pass of the scoop 270 throuoh the material to be
e.~cavated.
Operation
The backhoe bucket 10 is capable of beino
used for digaing trenches and the like in a conventional
manner in a first digging mode and for fine-grading
material in a second digging mode. In the first digging
mode the teeth 40 of the bucket 10 are forced into the
material to be excavated and then the bucket 10 is rotated
and drawn toward the backhoe tractor, filling the bucket
10 with dislodged material. The bucket 10 is emptied in
a conventional manner.
At some point the backhoe operator may
desire to fine-grade the bottom of the trench or suspects
that a buried object is near the bottom of the trench. The
operator changes the bucket operation to the second
digoing mode whereby the operator rotates the bucket 10
so that the grading plate edge 34 engages the trench
bottom surface and the teeth 40 are spaced above and out
of contact with the trench bottom surface. As the bucket
10 is drawn toward the tractor, the grading plate edge 34
planes beneath the trench bottom surface, due to the
bevel edge 36, and continues deeper into the trench
bottom until the front bottom plate 31 engages the trench
bottom surface and supports the bucket 10 relative to the
trench bottom as the bucket 10 is drawn toward the
tractor. A uniform layer of material having a thickness T
is removed from the trench as the bucket 10 is drawn
ever closer to the tractor. The fine-graded material
passes through the scoop opening 20 and accumulates in
the bucket 10. The accumulated material is disposed of
in a conventional manner.
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16
The oper~tion of the backhoe bucket 210 as
sho~ n in Figures 8-10 is described in detail below.
The backhoe bucket 210 is used as described
above for conventional excavation of material during
trenching operations. When the backhoe operator desires
to fine-grade the trench bottom the operator rotates the
bucket 210 so that the grading plate edge 234 enga2es the
trench bottom surface and the teeth 40 are spaced above
and out of contact with the trench bottom surface. As the
o bucket 210 is drawn toward the tractor, the grading plate
edge 234 planes beneath the trench bottom surface, due
to the bevel edge 236, and continues deeper into the
trench bottom until the outer support surface 241 of the
front bottom plate 240 engages the trench bottom surface
and supports the bucket 210 relative to the trench bottom
surface as it is drawn toward the tractor. At this point a
uniform layer of material having a thickness T is
removed from the trench as the bucket 210 is drawn ever
closer to the tractor. The fine-graded material passes
through the scoop opening 272 and accumulates in the
bucket 210. The accumulated material is disposed of in a
conventional manner.
In Fig. 10 there is shown the bucket 210
fine-grading a trench and engaging a buried object P
2~ lying in the excavation path. The object P is a
cylindrically shaped object such as a pipe and is disposed
transverse to the movement of the bucket 210. It should
be understood that the efficacy of the bucket 210 to fine-
grade near buried objects is not limited to only
cylindrically shaped buried objects. The bucket 210 is
capable of fine-grading near other tubular structures
having non-circular transverse cross-section shapes. As
the bucket 210 approaches the object P the lower guide
surface 261 of the lower bucket guide plate 217 contacts
the object as shown in Fig. 10, causing the bucket to be
l7 21~6613
thrust in an upward direction, while still fine-_radina
material as the bucket 210 is drawn toward the tractor.
As the bucket 210 continues to be drawn horizontally
to~-ard the tractor, the point of engagement of the object
P along the lower guide surface 261 adv~nces towards
the point at which the lower guide surface 261 is adjacent
to the trading plate edge 234. Because the lower guide
surface 261 extends coincident to or slightly outwardly of
the edge 234, the edge 234 is unable to engage the object
lo P sufficient to damage or excavate the object P as the
edge 234 passes over the object P. As the bucket 210
advances even further horizontally, the bucket 210
remains supported above the object P along the clearance
edge 264 of the lower bucket guide plate 217 and then
resumes fine-grading when the object P disengages the
clearance edge 264. Advantageously, an upper portion of
the outer surface of the object P becomes visible to the
operator.
