Note: Descriptions are shown in the official language in which they were submitted.
LIVESTOCK BARRIER
The present invention relates to livestoc~ control systems and in
particular to a novel portable LIVESTOCK BARRIER which permits ~ehicular and
pedestrian access to areas in which livestock, such as cattle etc. are
confined.
Back~round of the Invention
Traditionally, livestock have been contained by gates and the like
which generally must be manually operated and are difficult to maneuver
through, especially if an unassisted driver must move heavy equipment
through a gate in an enclosure used to confine a large group of animals.
The "cattle grid", sometimes called a "Texas Gate", was invented to permit
unattended free access to an enclosure while confining animals. The
conventional cattle grid comprises an open grid construction which is
installed over an open-topped, generally rectangular pit in the ground. The
pit, which is commonly about a half meter deep, is excavated in a path or
roadway in place of a traditional gate. The spaces in the open grid
construction are preferably wider than the length of the hooves of the
animals to be confined. Animals are therefore unable or afraid to maneuver
their way across the barrier, while vehicles and people are readily capable
of crossing the grid over the top of the pit.
Although the conventional cattle grid provides distinct advantages over
gates and the like, there are several drawbacks which render it undesirable
in certain situations. First, a large pit must be excavated, the walls
retained, the pit drained and the excavated earth disposed of. The
construction of a cattle grid is therefore an expensive and time-consuming
operation. In addition, once the structure is built, it is permanent in
nature. In order to remove it, the open grid construction must be removed,
the pit refilled and the surface of the road or path repaired. Access to
the area is, of course, impossible during either the construction or removal
of a traditional cattle grid.
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In order to overcome the disadvantages of the traditional cattle grid,
pitless cattle grid structures were invented to contain livestock while
permitting ready access to an area by vehicular and pedestrian traffic. Two
known alternatives are described in United States Patent Number 4,708,515
entitled STOCK BARRIER which issued to Davies on November 24, 1987 and
French Patent Application Number 2,573,621 which was filed by Grospiron on
November 29, 1984.
The STOCK BARRIER to Davies describes a cattle grid which comprises a
plurality of rigid metal panels of open grid construction that are arranged
to lie in a normal operational position at an angle to the ground to thus
form a pair of back-to-back ramps across which stock will not cross but
which can be flattened to the ground against a resilient return force when a
vehicle is driven across. Although this apparatus represents an improvement
in some respects over the traditional cattle grid, it has several
disadvantages which detract from its desirability. First, the structure is
not portable. It requires a pair of opposed sturdy support posts which must
be set in concrete or the like to support the structure, so it is relatively
expensive to install. Second, in order to permit the opposed side edges of
the open metal work panels to flatten against the ground when a vehicle
embarks the stock barrier, a very firm level surface must be provided. This
means that the cattle Brid must be installed over an asphalt or concrete
surface and runners must be installed under certain portions of the grid to
provide for its reliable operation. Finally, because of the construction of
the cattle gird, it is potentially hazardous for vehicles with a very long
wheelbase as the V-shaped grid could be pulled upward by the return springs
when the front wheels leave the grid, causing damage to the undercarriage of
the vehicle due to contact between the undercarriage and the top of the
V-shaped grid.
French Application Number 2,573,621 describes a barrier for livestock
with cloven hooves. The barrier comprises a rectangular array of Y-shaped
sculpted plates which are interlocked to form a planar grid having equally
spaced Y-shaped projections which prohibit such animals from crossing the
array in one direction due to pain inflicted in their distal hoof ligament
by the projections. The advantage of the structure is that it theoretically
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permits the one-way passage of animals across the barrier. It also permits
vehicular traffic over the barrier in either direction. The disadvantage of
the structure is that the interlocking plates are preferably set in a bed of
S wet concrete. The barrier is, therefore, a permanent structure which
requires a relatively lengthy and expensive installation. Besides, it only
prevents the circulation of animals with cloven hooves and then in only one
direction. It further appears to be an expensive alternative in that each
element of the array must be precisely manufactured to relatively exacting
tolerances.
Certain industries such as the oil exploration industry, for example,
often reguire access to fenced cattle ranges for an indefinite term. In
order to facilitate access to a fenced area while minimizing the risk of
having cattle escape from the area, cattle grids of the traditional pit type
are generally installed. Such installations contribute to operating
expenses of exploration and generally slow the progress of opening new
areas. There, therefore, exists a need for a reusable, portable livestock
barrier which is quickly and easily installed with a minimum of time and
effort.
It is an object of the present invention to overcome the problems of
known prior art cattle grids.
It is a further object to present invention to provide a livestock
barrier wh~ch is readily portable.
It is yet a further ob~ect of present invention to provide a livestock
barrier which does not require special support surface preparation for its
installation and use.
SummarY of the Invention
In accordance with the present invention, there is provided a livestock
barrler comprising:
a flat open grid construction across which livestock will not pass when
it is supported in a normal operational position above and parallel with the
ground;
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a frame for supporting the flat open grid construction;
resilient means disposed between the frame and the flat open grid
construction for supporting the flat open grid construction in a normal
operational position so that lt is tiltable with respect to said position
and depressible by the weight of a vehicle to lie flat against the ground
when the vehicle crosses the barrier; and
flexible connectors having opposite ends which are respectively
connected to the frame for supporting the flat open grid construction and a
peripheral edge of the flat open grid construction so that an edge thereof
cannot be tilted higher than the normal operational position.
The livestock barrier in accordance with the invention includes a flat
open grid construction which is supported above and parsllel with the ground
surface. The open grid is preferably a rectangular structure constructed
from straight rigid parallel spaced-apart members. When such a structure is
supported in a normal operational position above and parallel with the
ground, farm livestock refuse to cross it because they fear leg injury due
to the height and spacing of the open grid. The open grid is supported in
its operational position by a resilient suspension which is affixed to a
simple frame that preferably surrounds the outer edges of the grid. In
accordance with a preferred embodiment of the invention, the open grid is
supported by either of an opposed pair of vehicle suspension airbags of the
type used in the suspension system of semitrailer tractor bodies or an
opposed pair of compression coil springs of the type used in pickup truck
suspension systems.
Brief Description of the Drawin~s
The preferred embodiment of the invention will now be explained by way
of example only and with reference to the following drawings wherein:
FIG. 1 is a plan view of a portable livestock barrier in accordance
with the invention;
FIG. 2 is a side elevational view of the livestock barrier shown in
FIG. l;
FIG. 3, which appears on page 3 of the drawings, is an end elevational
view of the livestock barrier shown in FIG. l;
FIG. 4, which appears on page 2 of the drawings, is a cross-sectional
view of the flat open grid construction shown in FIG. 1, the cross-section
being taken along lines 4-4 of FIG. l;
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FIG. 5 is a partial cross-sectional view o~ the supporting frame for
the open grid construction shown in FIG. 1, the partial cross-section being
taken at lines 5-5 of FIG. l;
FIG. 6 is an end view of the supporting frame shown in FIG. l; and
FIG. 7 is an end elevational view of an alternate constructlon of the
livestock barrier shown in FIG. 1.
Detailed Description of the Preferred Embodiment
As shown in FIG. 1 of the drawings, the portable livestock barrier in
accordance with the invention generally referred to by reference 20,
includes an outer support frame 22 and a flat rectangular open grid
construction 24 which serves as a livestock barrier. The open grid 24 is
preferably assembled from square steel box beam stock in order to maximize
rigidity while minimizing weight. Pipe, I-beam, H-beam, channel and other
rigid materials made from steel or aluminum may alternatively be used to
assemble the open grid. The actual structure of the open grid is not
important so long as it provides a surface which, when elevated above the
ground, inhibits livestock from attempting to traverse it. The preferred
construction, as shown in FIG. 1, is a rectangular grid of parallel
spaced-apart box beams 26 which are welded on their opposite ends to a box
beam header 27. The outer support frame 22 is likewise preferably
constructed of steel box beam stock which is welded together to form
rectangular frame. Experimentation has shown that 2" x 2" High Stress Steel
(HSS) extruded box-section beam provides adequate strength while minimizing
the weight of the structure.
FIGS. 2, 3 and 7 illustrate the portable livestock barrier 20 in its
normal operational position wherein the open grid construction 24 is
supported in a raised position parallel with the ground. A resilient
support is required so that the grid may be forced flat onto the ground by a
vehicle passing over the barrier. The preferred resilient support is one of
a suspension airbag unit 28 of the type used for the suspension system of
semitrailer tractor bodies and a compression coil spring 29 of the type used
in the suspension systems of pickup trucks (see FIG. 7). One airbag unit
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known to be satisfactory for this application is an unit manufactured by the
EUCLID* Company, Part No. E2B09-200. One coil spring known to be
satisfactory for this application is a spring manufactured by the MOOG
Company, Part No. CC213. Reference made hereinafter to the airbag unit 28
applies equally to compression coil spring 29. The airbag 28 is affixed on
its base to a flat shelf 30, constructed of steel plate which is welded to
outer frame 22 and reinforced by a pair of triangular brackets 32. Each
suspension airbag 28 is in turn affixed on its top end to a support bracket,
generally referred to by reference 34 (see FIG. 4) which includes a top
plate 36 and two trapezoidal side plates 38 which are welded to the opposite
longitudinal edges of the top plate 36 as may be seen in FIG. 3. Support
bracket 34 is welded along its inner edge to the top surface of the open
grid 24.
The support bracket rides inside a control frame 40 which prevents the
longitudinal and lateral displacement of the open grid 24. Control frame 40
is likewise welded from steel box beam stock and loosely surrounds the
support bracket 34. The support bracket 34 is further provided with an
opposed pair of short laterally projecting box beam sections 42 which ride
up and down along the outer side edges of control frame 40 to prevent the
longitudinal displacement of the open grid 24.
As is apparent from the above description, the open grid 24 is
supported on a horizontal pivot formed by the opposed suspension airbags
28. The open grid 24 is free to tilt, ~ithin restricted limits, about that
horizontal pivot. Short lengths of chain 44, or similar flexible
connectors, are welded or otherwise affixed to each corner of open grid 24
and a corresponding point on an end of the support frame 22 to limit the
tilting movement of the open grid 24. The chains 44 thereby prevent the open
grid 24 from damaging the undercarriage of a vehicle when the vehicle
embarks or disembarks an edge of the open grid 24, because a free edge of
the open grid 24 cannot tilt higher than the normal operating position of
the open grid.
The portable livestock barrier in accordance with the invention further
includes two posts 46 (see FIG. 2) for connecting fencing material to the
ends of the barrier. The posts are likewise preferably constructed from
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steel box beam stock and simply slide into a box beam bracket 48 of larger
cross-section that is welded to the top of each control frame 40 (see FIG.
6). Each post is equipped with three or more islets 50 which are
conveniently half chain links or the like, welded to the post. A similar
link 52 on bracket 48 provides an additional attachment point for fencing
(FIG. 5).
In use, the portable livestock barrier is transported to a location
where it is required and a relatively level installation site is selected.
If the area is fenced, the fence must be cut in order to accommodate the
barrier. If the surface is not level, minimal levelling must be
accomplished before the barrier is installed. If the installation is to be
permanent or long-term, a solid or woven synthetic plant growth barrier
should be installed before the livestock barrier is set in its working
position to prevent grass and weeds from growing up through the structure.
Once a surface is prepared, the barrier is simply set in position and
secured to the ground with anchor rods 54 (see FIGS. 3 and 7) driven through
the holes in anchor brackets 56 (see FIG. 1). Anchor rods 54 are
conveniently concrete rebar with a large flat washer 58 welded onto their
top ends, or a similar substitute which has adequate strength to secure the
outer support frame 22 to the ground. The length of the anchor rods 54 will
depend on the surface to which the portable livestock barrier is to be
anchored. For loose sandy soil, anchor rods of up to 4 feet (1.2 meters)
are recommended. For hard compacted surfaces, anchor rods which are much
shorter in length may be adequate.
After the portable LIVESTOCK BARRIER has been positioned and anchored
to the ground, the airbags 28 are inflated with enough air pressure to raise
the open grid construction 24 to its normal operating position shown in FIGS
2 and 3. Generally about 8 lbs of air pressure per square inch is required,
however, the actual pressure required depends upon the size and weight of
the open grid 24. The airbags 28 have an advantage over coil springs, for
instance, because they are infinitely adjustable over a predetermined range
in the return force they provide. Airbags may therefore support practically
any size of open grid 24. Coil springs, on the other hand, are by nature
fixed in their resiliency and must be balanced with the weight of the open
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grid construction 24. Although the airbags are preferred for their
adjustability, coil springs are preferred for their economy and with minimal
experimentation a suitably si~ed spring can readily be found for any given
size of open grid construction.
In use, a vehicle approaches either side of the portable livestock
barrier 20. As the vehicle is driven onto the outer support frame 22, the
edges of the tires engage a side of the open grid 24. The pressure of the
advancing tires pivots that edge of the open grid 24 downwards to the
ground. As the vehicle advances, the opposed airbags 28 (FIG. 3~ or coil
springs 29 (FIG. 7) are compressed and the open grid 24 is forced flat
against the ground. When the vehicle's advancing tires approach the
opposite side of open grid 24, the free side of the grid once more pivots
upwardly until it is restrained by chains 44. The chains 44 prevent the
open grid from pivoting high enough to contact the undercarriage of the
vehicle and thereby cause damage. The preferred operational position of the
open grid 24 is approximately 4 inches (10 cm) above the ground.
Experiments have shown that a 4 inches (10 cm) elevation is adequate to
prevent livestock from crossing the barrier while being low enough to permit
practically any vehicle to cross safely.
Those skilled in the art will also readily appreciate that minor
modifications to control frame 40 and support bracket 34 would permit the
use of a tension spring in lieu of airbags 28 or compression coil springs
29. The means for supplying the open grid 24 is not important so long as it
is supported in its normal operational position so that it may be tilted
with respect to that position and forced flat against the ground when a
vehicle crosses it.
It will be readily understood by those skill in the art that changes
and modifications may be made to the preferred embodiment described
hereinbefore without departing from the spirit of the invention whose scope
is intended to be limited solely by the appended claims.
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