Note: Descriptions are shown in the official language in which they were submitted.
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IMPROVED EARTH ANCHOR
RELATED APPLICATIONS:
Applicant hereby claims priority of co-pending Design Application No.:
29/270,187 filed
December 19, 2006.
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention relates to ground anchors, more specifically to pivoting ground
=
anchors.
=
GENERAL BACKGROUND
Ground anchors or earth anchors of the pivoting or tilting type are well known
and generally include a main body portion having a leading edge adapted to be
forced
into the ground, a trailing edge including an outturned lip and a cable or
guide wire
attachment point intermediate the leading and trailing edges generally
positioned from
about the mid point of the overall length of the anchor or towards the
trailing edge so
that upon exerting a force on the cable or attached guide wire after insertion
of the
anchor into the ground, the trailing edge outturned lip will bite into the
earth causing
the anchor to rotate or pivot to a locked position generally at a right angle
to the
withdrawal force. Such anchors have included plate anchors such as shown in
U.S.
Patent 3,969,854, which are generally difficult to drive into the ground.
Those
anchors have more recently been replaced with cylindrical or tubular shaped
anchors
having a bore in the body into which a drive rod can be inserted from the
trailing edge
to a rod abutment point at or adjacent the bottom or end of the bore. Such
anchors, as
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shown in U.S. Patent 4,044,513, employ outtumed lips at the trailing edge
generally
defining an opening into the interior. Such anchors are also shown in U.S.
Patent
4,096,673, both of which are assigned to the assignee of this application.
Anchors of
that type have been sold by the assignee, Foresight Industries, Inc., under
the
trademark Duckbill and generally consist of cast cylindrical bodies having a
cruciform shaped leading edge, a trailing edge with an outtumed lip, a blind
bore, and
a raised rib at a top side remote from the outtumed lip, which has an opening
therethrough for receipt of either a shackle, a cable, or another load
applying device to
initiate rotation and "load locking," i.e. fixing, of the anchor after it is
driven into the
ground by a drive rod, by means of a hammer, jackhammer, hydraulic press, or
the
like. Variations on the general shape of such anchors are shown, for example,
in U.S.
Patent 5,775,037, where the main body may be provided with side edges
extending
outwardly to the side of the central bore beyond the raised rib. A further
variant,
shown for example in U.S. Patent 4,802,317, assigned to the instant assignee,
utilizes
widespread side wings extending laterally of the cylindrical center body
portion
containing the blind bore. Those lateral wings may have sharpened leading
edges and
when the anchor is rotated to the locked position the wings increase the
contact area
between the anchor and the ground providing a wider surface to resist
withdrawal of
the anchor. Such ground anchors are sometimes referred to as wing anchors.
However, the Presence of the wings can, in certain instances, can be
disadvantageous
in that: (a) they provide a much larger area which must be pushed through the
ground
during insertion of the anchor thereby requiring a higher driving force; and
(b) due to
their rather large lateral extent with respect to the central body, the force
necessary to
= pivot and lock the anchor is considerably increased. Additionally, (c)
the wings can
cause a deflection of the anchor during driving. Engagement of an outer reach
of the
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wing with a more drive resistant structure, either a hardened soil structure
such as
hardened clay or with a stone or rock can have the effect of pivoting the
anchor during
its driving, which can cause the anchor to change direction as it is being
driven into
the ground. This can not only result in a mispositioned anchor, it can cause a
bending
of the drive rod, and in extreme conditions can prevent or hinder withdrawal
of the
drive rod after the anchor has been placed.
One approach to increasing the straight line drivability of the winged anchors
and reducing the driving force necessary is illustrated in U.S. Patent
6,237,289 where
the leading edges of the wings are provided with a series of separate chisel
leading
edges that are stepped back one from another axially and extend for short
distances
radially thereby providing the leading edges of the wings with a series of
separate
leading edges that are each longitudinally offset with respect to one another
and
radially offset with respect to the main body. While this serration or
stepping of the
leading edges of large wing anchors is an improvement over prior large wing
anchors,
the necessity for a higher driving force and the difficulties associated with
rotation to
the locked position remain a problem. Such anchors are therefore used
generally only
where high load resistance is required, and the more cylindrical anchors are
used
where lower resistance load levels are anticipated.
The use, however, of cylindrical anchors, with their cruciform driving edges
leaves the anchor, during driving, at risk of wandering or deviating from a
straight
path. Since such anchors are normally driven into the ground at an angle to
the
vertical, which will represent the angle of the application of load after
setting of the
anchor, and since the load application is generally at an angle other than 90
degrees,
particularly where the anchor is used to anchor a guide wire, a fence end or
tree
support or the like, it is sometimes difficult to drive the anchor straight.
Substantially
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cylindrical anchors generally have less holding or load bearing capabilities
than
similar sized winged anchors but are easier to drive and to rotate to a locked
position.
It would therefore be an improvement in the art if generally
cylindrical ground anchors could be provided with a reduced driving
resistance,
with a better straight path driving tendency and with improved load bearing
capabilities.
SUMMARY OF THE INVENTION
The above advantages are achieved in some embodiments of the
current invention by utilizing a substantially cylindrical anchor having a
main body
portion which is provided with a raised rib extending from an upper surface
area of
the cylinder, a first flattened plate-like extension projecting forward of the
main
body terminating in a stepped leading edge, a second generally flat plate-like
extension extending forward of the main body projecting normally to the
leading
edge plate providing guiding surfaces, the second plate terminating at its
leading
end in a series stepped leading edges. The outermost stepped leading edge on
each side of the main body extends beyond the diameter of the main body and
forms a leading edge for a short tapered rib which extends along the length of
the
main body from the rib's leading edge to the trailing edge of the main body
and
has a width projecting from the main body's outer diameter generally no
greater
than its leading edge width, which is substantially the same as the leading
edge of
each step of the guide surface leading edges.
In an embodiment of the invention there is provided an earth anchor
comprising a substantially cylindrical main body having leading and trailing
ends
and a top and bottom, a longitudinal axis, an outturned lip at the trailing
end, a
raised rib extending from a top of the main body portion radially outwardly
thereof
having a leading surface and defining an attachment point for attachment of a
tension member, at least one first generally plate-like member extending from
a
leading end of the main body terminating in the leading edge spaced from the
main body and having top and bottom edge surfaces, the leading edge comprising
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a plurality of individual chiseled edge sections stepped back towards the main
body from an adjacent axially outwardly positioned edge section and extending
substantially normal to the longitudinal axis outwardly from the adjacent edge
section, the stepped back edge sections lying to either side of a plane
parallel to a
longitudinal plane intermediate the top of the main body from which the rib
projects and a bottom of the main body lying opposite the main body from the
rib,
the first generally plate-like member having a top edge surface extending from
the
radially outermost chiseled leading edge back towards the main body aligned
with
a leading surface of the raised rib, at least one rib lying on each side of
the main
body intermediate the top and bottom extending from at least the leading end
of
the main body to the trailing end of the main body, the side ribs being
substantially
V-shaped in cross-section normal to the longitudinal axis and each having a
single
chiseled leading edge.
In an embodiment of the invention there is provided an earth anchor
of the substantially cylindrical body tilting type comprising an anchor body
having
leading and trailing ends with a blind bore extending into the body from the
trailing
end, a portion of the trailing end defining an outturned lip adapted to bite
into the
soil adjacent the trailing end after the anchor has been driven into the
ground
when a tension force is applied to the anchor to withdrawal from the ground,
the
anchor body having a raised rib projecting from it on a side of the anchor
body
opposite the outturned lip, the raised rib defining an attachment point for
attachment of a tension member, the body having a pair of projecting plates
extending forwardly of the leading edge of the body, the plates lying at an
angle to
one another and being joined to one another at an intersection, each of the
plates
having leading edges and each of the leading edges being defined by a series
of
stepped back chiseled edges stepped back from a central chiseled edge to
either
side of the central chiseled edge, an angled surface transition zone between
the
leading end of the body and the leading edges of the plates deflecting
material
from the plates away from the body during insertion of the anchor into the
ground,
ribs on opposite sides of the body extending substantially the length of the
body,
the ribs each having a height from a top to a bottom and a chiseled leading
edge
terminating intermediate the top and bottom and a substantially V-shaped outer
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edge spaced from the body, the ribs projecting from the body to a distance
approximately 20% or less of the width of the body.
It is therefore an object of some embodiments of this invention to
provide a ground anchor having improved drivability requiring the use of
minimal
drive force and having improved straight line drive tendencies.
It is a further object of some embodiments of this invention to
provide a substantially cylindrical or tubular or ground anchor of the
pivoting type
having improved drivability provided by projecting surfaces extending at an
angle
to one another projecting forwardly of the main body of the anchor a distance
of
between 20 and 40% of the overall length of the anchor when measured from the
leading end of the main body portion or 10 to 20% of the overall length of the
anchor when measured from the end of a transition zone between the end of the
main body portion and the projecting surfaces, where the transition zone
consists
of an axially progressive diameter reduction from an outer diameter of the
main
body portion to the projecting surfaces, and where the projecting surfaces
terminate in leading edges which are pointed or chiselled and which comprise a
plurality of leading edge sections which are axially and radially offset from
one
another in a stepwise fashion, the projecting surfaces having generally flat
opposite side surfaces which resist rotation of the anchor about its axis
during
driving.
It is another object of some embodiments of this invention to provide
a generally cylindrical, oval or rectangular body ground anchor having a
leading
edge defined by chiselled surfaces which are spaced axially and radially from
one
another and which are formed at the leading edges of generally flat plates
projecting forward of the main body portion, the plates being positioned at an
angle to one another, and the main body portion having ribs running
substantially
the length of the main body portion on opposite sides thereof, the ribs having
non-
blunt leading edges and generally having a width measured outwardly from the
surface of the main body portion of about 20% or less of the transverse width
of
the main body portion whereby the ribs act to assist in straight driving of
the
anchor without providing significant drag or resistance to rotation.
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It is another, and important, object of some embodiments of this
invention to provide a generally cylindrical anchor having flat plate-like
extensions
extending forward of the main body portion terminating in leading edges, the
leading edges having stepped back chiselled edges, the outermost chiselled
edge
on each side of the main body forming the leading edge of a side rib running
along
the main body to the trailing edge of the main body.
These and other objects will become apparent to those of ordinary
skill in the art from a description of an illustrative embodiment, it being
understood
that this is only one such embodiment of this invention and that many
variations in
shape and dimension are within the scope of this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side view of the anchor of an embodiment of this
invention.
Figure 2 is a top view of the anchor of figure 1.
Figure 3 is a leading edge head-on view of the anchor of an
embodiment of this invention.
Figure 4 is a view of the anchor of figure 1 from the other side.
Figure 5 is a view of the anchor from the bottom.
Figure 6 is a view from the trailing edge head-on.
DETAILED DESCRIPTION
As shown in figures 1 and 2, the anchor 10 of an embodiment of this
invention consists of a generally cylindrical main body portion 11 which may
have
a generally conical leading end 12 and a trailing end 13 formed at an oblique
angle to the longitudinal axis of the main body. The trailing end 13
incorporates at
a bottom 15 of main body 11 an outturned lip 16 which will bite into the soil
surrounding the anchor after it has
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been driven to its desired depth and a withdrawal load is applied. A rib 17 is
formed
on a top 18 of the main body 11, and in the embodiment illustrated, includes a
projecting central section 20 projecting furthest from the top 18 of any
portion of the
main body, that section 20 being provided with an opening 21 extending
transversely
therethrough.
The opening may have a cable threaded through it and clamped back on itself
or may provide a fixture point for a shackle to which a cable or a rod may be
attached.
Numerous other fixture examples for attaching the anchor wire or rod to the
raised rib
are known and can be substituted for the bore 21. These include T-shaped slots
which
can receive a T-shaped head on an anchor rod, or openings extending entirely
through
the anchor from the top surface 18 to the bottom surface 15 having a smaller
opening
in the rib area than at the bottom so that a headed rod may be fed through the
anchor
from the bottom with the rod extending outwardly from the rib and the head
pivotal in
the opening and being retained therein by the smaller opening at the top of
the rib.
These are all matters of design choice and are known to the art.
Similarly the conical shaped leading end of the main body portion may be
formed as flat, sloping surfaces, abrupt end walls or otherwise shaped. A
sloped or
angled wall, whether formed as a portion of the cone or flat triangular
sections having
surfaces at an angle to the longitudinal axis can be beneficial in comparison
to a blunt
radial surface as the anchor is being driven into the ground inasmuch as such
surfaces
will push the soil away from the main body 11 behind them.
Similarly the leading top surface 30 of the raised rib 17 is preferably formed
at
an angle to the longitudinal axis leading from the outer diameter surface of
the main
body portion at its forward end 32 to the central section 20 at an attack
angle
facilitating movement of the soil. The embodiment shown in the figures
provides a
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flat top surface 31 which increases in width from its inter section with the
top leading
end 32 of surface 18 of the main body portion at the start of the conical
section 12, the
increase in width extending backwards to a point forward of the section 20.
The
section 20 is of a smaller width, transverse the longitudinal center line of
the main
body so as to produce an abrupt width reduction at 34 between the leading
portion of
the rib and the attaclunent portion 20. The side wall 35 of the rib extending
from the
flat top 31 may flare out linearly or, as shown in this embodiment, in a more
rounded
fashion, the shape of these surfaces being a matter of design choice.
While I have shown an anchor having a flat surface 31 at the leading face of
the rib, it will be appreciated that an edged surface which rises to a central
peak and
which may extend all the way back from the leading edge point 50 of the anchor
to
the section 20 may be desired to facilitate penetration of the anchor into the
soil.
It is, however, desired that the leading edge of the raised rib be configured
to
direct soil away from the section 20 since the cable, shackle, rod end or the
like may
extend out of the side of the rib section 20 causing a resistance to ease of
passage of
the anchor into the ground.
Because the rib is raised from the main body, and because it provides the
anchoring attachment point for the cable, rod, etc. which will be under
tension when
the anchor is being pivoted and when it is providing its anchoring function,
the rib
must be strong enough to accommodate such load forces without separation from
the
remainder of the anchor. To that end, such ribs are relatively large and are a
factor in
the tendency of the anchor to deviate from a straight course as the anchor is
driven
into the ground. A blind bore 60 extends into the main body from the trailing
edge
and terminates in a driving surface 61 at or adjacent and end of the blind
bore. The
end may be squared as shown or may be radiused to prevent mushrooming of the
tip
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of the drive steel. An elongated drive steel is inserted into the bore 60 and
is used to
drive the anchor into the ground by force application means, which, depending
upon
the size of the anchor, may range from a handheld hammer to a substantial
piece of
machinery similar to a pile driver. Since the depth of insertion of the anchor
into the
ground will be dependent upon anchor size, load to be retained, soil quality,
and the
like, the drive steel may be quite long, be constructed of threaded together
sections
and may not itself be structurally sufficient to ensure that the anchor drives
straight.
While it has been known to provide cruciform projections extending from the
leading end of the main body to assist in penetration of the soil for
substantially
cylindrical rotating anchors, such extensions have not proven to be wholly
satisfactory
in preventing wandering or other than straight line movement of the anchor
during
driving. For winged anchors, which have relatively large side wings projecting
from
the central body, cruciform chiseled projecting edges and sharpened winged
edges
have been utilized such as shown in U.S. Patent 5,031,370. Moreover, such
anchors
have been provided with serrated or stepped leading edges in both the
vertical, top to
bottom, orientation and the horizontal, side-to-side wing-to-wing,
orientation. While
these leading edges have benefits in winged anchors they have not been used on
substantially cylindrical or elliptical bodied non-winged anchors.
This invention provides leading plates 70, 71, 72, and 73, or projecting
surface
members, which extend forward of the main body, which are positioned at an
angle to
one another, generally at right angles, and which provide leading edges 50, 51-
55.
The plate 70 extends forward from the juncture 32 of the raised rib and
terminates in
stepped leading edges 50, 52 and 51, with 51 being centrally located. Each of
the
edges is chiseled forming a piercing tip. The plates 70 and 71 may be
considered as
one plate and the plates 72 and 73 as a second plate, with the two plates
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or, for purposes of description, the plates may be considered as four separate
plates
extending radially from a common junction. A greater or lesser number of
plates can
be provided and although the plates 72 and 73 are shown as having* their
leading
edges 53 spaced axially behind the leading edge 51 of plate 70-71, it will be
understood that the two plates could extend an equal amount forward of the
main
body as shown in figure 4. Preferably the plates provide anti-rotation
surfaces
resisting rotation of the anchor during driving. To this end the plates extend
approximately 1/3 of the overall distance of the anchor when the beginning
point of
the plate is measured from the point 32 representing the forward end of the
main body
11 prior to the conical or transition zone 12. When measured from the end of
the
transition zone 12 the plate will extend approximately 20% of the overall
length of the
anchor. While these percentages may be varied, it is preferred that when
measured
from the point 32 the plates extend between 20 and 40% of the overall length,
and
when measured from the point 33, being the end of the transition, the plates
project
forward from 15 to 25 percent of the length. This provides a sufficient anti-
rotation
surface to aid in straight driving of the anchor. While the top and bottom
surfaces of
the plates 70-73 may be formed parallel to one another, they may also lie at
an angle.
The plate 71 is the mirror image of the plate 70 positioned on the other side
or bottom
side of the anchor, the plates 70 and 71 being separated by horizontal plates
72 and
73, which project similarly from the juncture of the main body portion with
the
conical shaped section 12 and are mirror imaged left and right. The plates 72,
73 may
terminate in setback, chiseled edges 53, 54 or may, if desired, have a more
central
edge extending to the tip 51, although it is my preference to have a single
leading
chiseled edge 51. Although I have shown an X shaped or cruciform shaped
leading
edge consisting of four plates lying at right angles to one another equally
spaced, it
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will be understood that other combinations may be utilized. For example, the
bottom
plate 71 could be eliminated such that the forward projection would be
substantially
T-shaped. It will be appreciated that the plate 70 cannot be eliminated as
easily since
it blends back into the raised rib. Although I have chosen to describe the
forward
extensions as plates, or as plate-like members, this is for descriptive
purposes only
being understood that the entire anchor may be formed as a single casting,
that the
extensions may have a cross sectional curvature to them or may project
upwardly or
downwardly adjacent their outmost edges. It will further be understood that
the top
surface of the plate 70 or the bottom surface of the plate 71 or the sides of
plates 72 or
73 may be chiseled. I use the term chiseled to include all forms of sharpened
edges
including those having a radius at their outermost point. It is not intended
that the
chiseled surfaces by knife sharp and dangerous to handle, however the surfaces
should not be blunt to the full thickness of the plate.
Additionally, at the outer edges of plates 72 and 73 and spaced from the last
setback leading edge 54, ribs 80 and 81 are positioned on each side of the
main body,
the ribs may have substantially triangular shaped chiseled leading edges 55
which
terminate at the' outer edge of the ribs, the outer edge being chiseled or
pointed as
shown at 90, 91 of figure 3. The leading edges 55 and the ribs 80, 81 have a
width
from the outer diameter of the main body which is relatively small, preferably
about
20% of the diameter of the main body 11. These ribs are not designed to act as
wings
such as is found in the winged anchors but instead counteract the tendency of
the
raised rib to turn the anchor from a straight path during driving. By
extending the ribs
80, 81 the full length from before the leading end of the transition section
12 to the
trailing edge 13 of the main body, by maintaining the ribs relatively narrow,
and by
making them V-shaped in cross section, they do not add significantly to the
dtag of
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the anchor as it is being driven into the soil but do act to facilitate
straight driving of
the anchor. It will be appreciated that the force of soil acting against the
leading
surface 30 of the raised rib will have a tendency to cause the anchor to pivot
upwardly
at its front or will push the entire anchor downwardly as it is being driven
into the
ground. The ribs 80, 81 are intended to aid in resisting that tendency without
adding
significant resistance to the driving of the anchor into the ground.
Although I have shown a preferred embodiment having only two ribs which
are aligned with the center line of the longitudinal axis of the anchor and
which start
from the edges of the plates 72, 73, others may choose to use this invention
by
providing, for example, two ribs per side or positioning the rib higher or
lower along
the sides of the main body, therefore not being planer with plates 72, 73.
I have also chosen to use relatively flat plates 70-73 to define the extension
projecting forward of the main body of the anchor since those flat surfaces
also act to
resist wandering of the anchor. Others may decide on different shapes or sizes
for the
projecting features, for example the plates rather than being of uniform
thickness can
be thinner at the front and increase in thickness towards the main body
portion.
Moreover, where I have shown the leading edges 50-54 and 55 to lie at
substantially right angles to the longitudinal axis of the anchor, such edges
may be
angled backwardly if desired.
These and other modifications of this invention will be readily apparent to
those of ordinary skill in the art. For example, although I have shown and
described
the anchors as being substantially cylindrical or elliptical, the anchor body
could be
rectangular, octagonal or otherwise. In general, when I use the term
"substantially
cylindrical" I intend to encompass all such minor shape variations.
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