Note: Descriptions are shown in the official language in which they were submitted.
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LOCKING GROUND HOLB COVER
s This invention is in the field of covers for holes, and more
particularly deals with a locking cover for temporary use in
a ground hole such as a post hole or the like.
BACKGROUND
In many situations, such as construction sites or the like,
excavations are undertaken which yield various vertical
tubular holes in the ground. These might be drilled, augered
or hydro-excavated.
The problem of safety presents itself with respect to these
holes, when the construction site needs to be closed up for
the day or the work crew needs to leave the hole unattended
2o for some time and they wish to cover up the hole or close the
hole for safety purposes. In some cases, the construction
site might just be taped or fenced off or the hole covered
with a piece of wood or the like, but these conventional
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methods have their limitations. Firstly, persons or vandals
can uncover these holes and leave them open. The open hole is
a hazard to anyone walking in the vicinity, as the can fall in
the hole and injure a limb, or in the case of small children
they might even fall into a larger hole. Safety regulations
thus require the closure of these holes. A construction crew
working on a series of holes, particularly in close vicinity
to a school or the like, may find that they have to have extra
people on staff to watch the holes or require some method of
1o safely and conveniently locking those holes closed until they
wish to return and complete the work and fill the hole back
in.
Numerous attempts have been made in the art to provide covers
for such holes. United States Patent 5,979,117 to Fuller,
"Hole Locking Device", is one such device. This device is
limited in its utility, however, since the telescoping
cylindrical sections of that device need to be selected to
correspond to the internal diameters of different holes in
2o which the device is to be used. As such, it is difficult to
manufacture a single universal size of that device, and it
will likely take more than one individual to manipulate such
a device into position in a hole.
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Another effort of interest is dlSClosed in United States
Patent 4,101,154 to Kagstrom for a "Locking Device for Well
Covers and the Like". That disclosure relates to a device for
locking the lid or cover in place on a well casing or the
like. That device would be of only limited utility in
anything but a pipe casing, since it is designed to operate
within smooth pipe walls. The locking arms of that device
would not properly handle an uneven hole wall. As well, that
device has other limitations insofar as it allows for the
limited raising of the cover from the top of the hole being
covered. When actuating the Kagstrom device by placing it
into a well, the device does not pull the lid down onto the
hole. This limited degree of play could still allow for
mischief or mishap.
is
There is a need for a secure and simple device to be used to
lock and cover excavation holes, such as fence post holes,
pile holes, hydro-excavation holes, and the like to prevent
people, especially children, from falling in. Ideally, the
apparatus used to lock the cover in place over the hole will
also pull the cover down into the earth such that the hole is
completely locked.
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gLJD~tARY OF THE INVENTION
It is the object of the present invention to provide a
portable locking ground hole cover for use on construction
sites or the like which can be easily installed and removed by
a minimum number of people, and which is easier and less
costly to manufacture than those known in the art.
Further it is the object of the present invention to provide
1o a locking ground hole cover that in addition to locking a
cover plate over a hole by resting it in place on the ground
surface over the hole, the action of locking the ground hole
cover into position also exerts downward force on the cover
adding to the strength of the lock.
The invention, a locking hole cover for use in a hole, the
hole having an opening mouth and walls accomplishes these
objects comprising substantially a cover plate having a lower
surface and an upper surface; a plurality of wall-engaging
2o tensioning arms, each the wall-engaging tensioning arm being
hingably attached to the cover plate at a point below the
lower surface, the unhinged end of each the tensioning arm,
being a wall-engaging end, extending generally away from the
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cover plate; and a spreading apparatus engaging the tensioning
arms such that when the spreading apparatus is moved towards
the cover plate the wall-engaging ends of the tensioning arms
will be forced outwards, and when the spreading apparatus is
moved away from the cover plate the wall-engaging ends of the
tensioning arms will be pulled inwards; and a shaft extending
downwards from the lower surface of the cover plate and
engaging the spreading apparatus such that the movement of the
shaft will cause the movement of the spreading apparatus
1o either towards or away from the cover plate.
Several methods of engagement could be used between the cover
plate, the shaft and the spreading apparatus to ensure the
proper movement of the tensioning arms. In-one embodiment the
shaft is slidably attached through the cover plate and the
spreading apparatus is fixedly attached to the shaft, such
that movement of the spreading apparatus towards or away from
the cover plate is actuated by pulling or pushing the shaft
from the upper surface of the cover plate.
2U
In another embodiment the shaft is rotatably attached to the
cover plate such that the shaft can be rotated from the upper
surface of the cover plate, the shaft engaging the spreading
apparatus such that rotation of the shaft will cause movement
Il
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of the spreading apparatus either towards or away from the
cover plate. Specifically, it is contemplated that the
portion of the shaft engaged by the spreading apparatus
throughout the range of its movement towards or away from the
cover plate is threaded, and engages a corresponding threaded
receptacle passing through the spreading apparatus.
The spreading apparatus might be a rigid member slidably
engaging each tensioning arm. The rigid member could slidably
1o engage each tensioning arm by way of an aperture at each end
of the rigid member through which apertures the tensioning
arms slidably pass. The rigid member might be perpendicular
to the axis of the shaft.
1s Alternatively, the spreading apparatus could comprise a
plurality of spreading arms hingably attached to each other at
one end at which end the shaft will be engaged, and the free
end of each the spreading arm is hingably attached to a
midpoint of a corresponding tensioning arm. The spreading
2o arms might be attached to reflective points on each the
tensioning arm, defining a parallelogram, although that would
not be necessary. Otherwise, the free end of each the
spreading arm could also be hingably attached to a wall-
engaging end of a corresponding tensioning arm.
ii
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The spreading apparatus and the tensioning arms could be
locked in position by locking the shaft in position relative
to the cover plate.
s The tensioning arms could either be attached directly to the
lower surface of the cover plate, or the cover plate might
further include an arm extension extending downwards from the
lower surface of the cover plate the tensioning arms are
hingably attached.
Wall-engaging adapters could be attached at the wall-engaging
ends of the tensioning arms, to increase the traction between
the tensioning arms and the walls of the hole. Various types
of wall-engaging adapters could be used depending upon the
is type of surface of the hole wall. For example, different
adapters could be used for rock, hard soil, clay, sand or the
like. These adapters could be rendered removable so that the
versatility of the device is again improved and the apparatus
can be easily adjusted for different soil conditions.
In order to make the device even more universal, extenders
could be used in place of or as part of wall-engaging
adapters. Extenders could be used to extend the reach of the
tensioning arms away from the shaft so that the device could
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be used in wider holes.
In a situation where the cover plate is not large enough to
cover the mouth of a larger hole, and to increase the
versatility and universality of the device, the device might
also include an adapter plate for placement between the mouth
of the hole and the cover plate, the adapter plate being
larger than the mouth of the hole and having an aperture
extending therethrough, the aperture being smaller than the
to cover plate and large enough to allow the remainder of the
hole cover attached to the cover plate to pass through the
aperture.
Cover plates of various cross-sectional profiles could be
used. In addition to a flat cover plate, it is particularly
contemplated that a convex plate could be used. The outer
edge of the convex cover plate could then bite into the soil
surface around the hole when the cover plate was pulled down
by the remainder of the apparatus as the tensioning arms
2o grabbed the walls of the hole.
The shaft extends through the arm extension, where present.
In such a case, the shaft and the arm extension could be
hingably attached to the lower surface such that the cover
II
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plate has a limited range of movement in directions away from
perpendicular to the remainder of the apparatus, while
maintaining its attachment to the remainder of the apparatus.
DESCRIPTION OF THE DRAWINGS:
While the invention is claimed in the concluding portions
hereof, preferred embodiments are provided in the accompanying
1o detailed description which may be best understood in
conjunction with the accompanying diagrams where like parts in
each of the several diagrams are labeled with like numbers,
and where:
Figure 1 is a side view of one embodiment of the present
invention;
Figure 2 is a side view of another embodiment of the
present invention, wherein the cover plate is convex;
Figure 3 is a top view of the embodiment of Figure 2
further demonstrating the use of an adaptor flange in a
larger hole;
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Figure 4 is a side view of another embodiment of the
present invention; and
Figure 5 shows another alternative embodiment of the
present invention, for use on a sloped ground surface.
DETAILED DESCRIPTION OF THE ILLUSTRATED ENBODI1~NTS:
1o Several embodiments of the present invention will accomplish
the goal of providing a locking ground hole cover which, in
addition to simply locking a cover plate in position over a
hole in the ground, will pull the cover plate down and exert
downward force on the cover plate in the direction of the
15 ground to further strengthen the closure or seal of the hole.
Figure 1 shows a first embodiment of the invention. Firstly,
a hole (1) is shown, the hole (1) having a mouth (2) and walls
(3). Holes of various sizes, and to some extent of various
2o shapes, can be accommodated by the apparatus of the present
invention. It will be understood that insofar as the
apparatus of the present invention can be used in holes of
varying shapes as outlined herein or with any slight
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modifications, the use of such an apparatus with any type of
hole is contemplated within the scope of the present
invention.
s The device itself as shown is a locking hole cover (5) for use
in a hole (1), the locking hole cover (5) having several
elements, including a cover plate (6). The cover plate (6)
has an upper surface ( 7 ) and a lower surface ( 8 ) . In this
particular embodiment, the upper surface (7) of the cover
1o plate (6) is flat. It will be understood that other cross-
sectional profiles could be used for the cover plate (6) . For
example, in later embodiments it will be shown that a convex
upper surface (7) of the cover plate (6) is particularly
preferable. It will be understood that insofar as any cover
15 plate being used accomplishes the goal of covering the hole
(1) and allowing the apparatus to pull said cover plate (6)
down towards the earth and said hole (1), any such cross-
sectional profile is contemplated within the scope of the
present invention.
In addition to the cover plate (6), there is shown a plurality
of wall engaging tensioning arms (15). In this particular
case, two tensioning arms (15) are shown. Each wall engaging
tensioning arm (15) is hingably attached to the cover plate
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(6) at a point below the surface (7) of the cover plate (6).
In this particular case, the tensioning arms (15) are attached
directly to the lower surface (8) of the cover plate (6).
Later embodiments will also show how the tensioning arms (15)
s can be mounted at a point vertically below the lower surface
(8), using an arm extension. The unhinged end (16) of each
tensioning arm (15) is a wall engaging end. The wall engaging
end will be pressed outwards against the walls ( 3 ) of the hole
(1) when the apparatus (5) is locked in position. Generally,
1o however, it can be seen that the tensioning arm (15) and the
wall engaging ends (16) thereof extend away from said cover
plate (6).
The next element of the present invention demonstrated in
15 Figure 1 is the spreading apparatus. A spreading apparatus,
in this case a rigid spreading member (21), engages each of
the tensioning arms (15) such that when the spreading
apparatus (21) is moved towards the cover plate (6), the wall
engaging ends (16) of the tensioning arms (15) will be forced
20 outwards, towards the walls (3) of the hole (1), and when said
spreading apparatus (21) is moved away from the cover plate
(6), the wall engaging ends (16) of the tensioning arms (15)
will be pulled inwards away from the walls (3) of the hole
(1) .
II
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While a rigid spreading member (21) is shown in this
particular embodiment, it will be understood that other types
of spreading apparatus accomplishing the same objective could
be used. For example, others as are shown in subsequent
g embodiments of this detailed description. It will be
understood that any such spreading apparatus accomplishing the
same goal of moving the wall engaging ends (16) of the
tensioning arms (15) towards the walls (3) of the hole (1)
when locking the apparatus in position and releasing them when
1o unlocking the apparatus, while at the same time in the locked
position exerting downward force on the cover plate (6), are
all contemplated within the scope of the present invention.
The final element of the present invention demonstrated in
15 Figure 1 is a shaft (10) which extends downwards from the
lower surface (8) of the cover plate (6) and engages the
spreading apparatus (21) such that movement of the shaft (10)
will cause the movement of the spreading apparatus (21) either
towards or away from the cover plate (6). It will be
2o understood that the shaft (10) or its equivalent is used to
actuate the locking of the device (5) from above the upper
surface (7) of the cover plate (6), while the apparatus (5) is
in place in a hole (1).
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In this particular case, the shaft (10) is slidably attached
through the cover plate (6) and emerges above the upper
surface (7) of the cover plate (6), while the spreading member
(21) is fixedly attached to the shaft (10) at or near its
down-hole end (12). Each of the tensioning arms (15) extends
through an aperture or collar defined at the ends of the
spreading member (21). In order to lock the cover apparatus
(5) of the present invention in place in a hole (1), the shaft
(10) is pulled upwards out of the upper surface (7) of the
to cover plate (6). As can be seen from the diagram, pulling the
shaft (10) upwards will result in the upwards movement of the
spreading member (21), which in turn will force the tensioning
arms (15) and their wall engaging ends (16) out and towards
the hole walls (3). In order to unlock the apparatus (5) of
the present invention, the shaft (10) will be released and
pressed back down into the hole (1) through the cover plate
(6) from outside the hole (1), via the upper surface (7) of
the cover plate ( 6 ) . As can be seen again, pressing the shaft
(10) downwards in such an action will result in the downwards
2o movement of the spreading member (21) and an attendant
collapsing motion on the tensioning arms (15), disengaging the
wall engaging ends (16) of the tensioning arms (15) from the
walls (3) and allowing for the removal of the apparatus (5)
from the hole (1).
ii
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In this particular figure, the apparatus (5) is shown in its
locked position, with the shaft (10) raised and the tensioning
arms (15) forced out against the walls (3) of the hole (1).
The apparatus would be unlocked by releasing the shaf t ( 10 ) to
s move downwards within the hole (1), at which point the
spreading member (21) would pull in the tensioning arms (15)
away from the walls (3) of the hole (1).
Also shown in Figure 1 are wall engaging adaptors (18)
1p attached at the wall engaging ends (16) of the tensioning arms
(15). The wall engaging adaptors (18) might be
interchangeable, since different types of adaptors might work
better in situations where the walls of the hole are of
different consistency or material. For example, one or more
is spikes might be used as the wall engaging adaptor (18) where
the wall of the hole was hard soil or clay, whereas if the
hole was sandy or soft, a cup or some other type of attachment
might be used which would better engage the hole wall. In a
situation where the hole was smooth on the inside, a rubber
20 grip of some type might be used. It will be understood that
in any case, the use of any type of a wall engaging adaptor on
the tensioning arms (15), which adaptor has the purpose and
effect of increasing the grip between the wall engaging ends
(16) and the wall of the hole (3) is contemplated within the
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scope of the present invention.
In operation of the apparatus (5), since the tensioning arms
(15) are actuated from below, the tensioning arms (15) also
exert a downward force on the cover plate (6) as the wall
engaging ends (16) are driven into the walls (3) of the hole
(1). This is another of the main advantages of the apparatus
of the present invention, since in addition to simply locking
the cover plate (6) over the hole (1) in whatever position it
1o is set by the operator, the apparatus (5) will actually pull
the cover plate (6) into a properly locked position.
It is possible to lock the cover plate (6) and the tensioning
arms (15) in their position within the hole (1) by locking the
shaft (10) in position in relation to the cover plate (6). In
this particular situation, the method of locking which is used
is a series of shaft locking holes ( 13 ) within the shaft ( 10 ) ,
through which a locking pin (14), padlock or the like could be
placed once the shaft (10) had been ratcheted upwards to the
point that the cover was satisfactorily locked in position
within the hole (1). It will be understood that any other
method of locking the position of the shaft (10) in relation
to the cover plate (6), from outside of the hole (1), is
contemplated within the scope of the present invention as
ii
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well.
Figure 2 demonstrates a side view of another embodiment of the
present invention. Again, the hole (1) is shown with its
mouth (2) and walls (3). The ground surface (4) around the
hole mouth (2) can also be seen.
The basic concept of the apparatus (5) of this embodiment is
the same as that of Figure 1. There is shown the cover plate
(6), which in this case has a convex side profile.
In this particular case, with the cover plate (6) of a convex
cross-section, the downward pressure exerted on the cover
plate (6) by the remainder of the apparatus (5) when the
tensioning arms (15) are forced into the walls (3) of the hole
(1), will also pull the cover plate (6) in effect down into
the ground surface (4) around the mouth (2) of the hole (1).
The outer edge of the convex cover plate (6) will allow for
this biting action into the soil or onto the surface (4).
The apparatus of Figure 2 displays several other variations
which can be made on the invention as well. Firstly, the wall
engaging tensioning arms (15) are actually attached to the
cover plate (5) at a point below the lower surface (8) of the
i
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cover plate (6) by way of an arm extension (9). The arm
extension (9) extends downwards from the lower surface (8) of
the cover plate (6) and the arm extension (9) is then the
portion of the cover plate (6) to which the tensioning arms
(15) are hingably attached and from which they extend
generally downwards into the hole (1) away from the cover
plate (6). It will be understood that arm extensions of
various types and lengths could be used so long as they
accomplish the objective of placing the attachment point of
1o the tensioning arms (15) a distance down into the hole (1)
away from the lower surface (8) of the cover plate (6). Any
type of a configuration of the arm extension (9) accomplishing
this objective is contemplated within the scope of the present
invention.
The tensioning arms (15) can be seen in this figure as well.
In this case, the spreading apparatus consists of a plurality
of spreading arms (23). The spreading arms (23) are hingably
2o attached to each other at one end (25), at which end the shaft
(10) will also be engaged. The free end (24) of each
spreading arm (23) is hingably attached to a tensioning arm
(15). Since in this particular embodiment the number of
tensioning arms (15) again is two, the number spreading arms
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(23) is also two. It will be understood that the number of
tensioning arms (15) and spreading arms (23) could be varied
in co-ordinating pairs and any such change in the number of
tensioning arms (15) or spreading arms (23) are contemplated
within the scope of the present invention as well.
In this particular embodiment, the attachment ends (24) of the
spreading arms (23) are attached to reflective midpoints (17)
of each tensioning arm (15). It will be understood that the
to spreading arms (23) could engage the tensioning arms (15) at
any point along their length, so long as the hingable
attachment was such that the proper raising and lowering
action of the spreading apparatus (23) still accomplished the
goal of forcing the tensioning arms (15) outwards from the
1s shaft (10) or pulling them inwards to collapse the apparatus.
G~lhile in this case the spreading arms (23) are attached at
reflective points, ie. at points the same distance along each
of the tensioning arms (15), it will be understood that in
2o certain circumstances this may not be the case and insofar as
the apparatus is still functional in the same manner these
changes as well are contemplated within the scope of the
present invention.
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The operation of the shaft (10) is different in this
embodiment as well.
Rather than having the fixedly attached spreading member of
Figure 1, the spreading apparatus (23) is operated differently
in this embodiment - the shaft (10) is rotatably attached to
the cover plate (6) such that the shaft (10) can be rotated
from the upper surface (7) of the cover plate (6). As can be
seen in this particular case, the shaft (10) is rotatably
io attached to the cover plate (6) perpendicular to the lower
surface ( 8 ) of the cover plate ( 6 ) . The engagement of the
spreading apparatus (23) and the shaft (10) can then be such
that rotary action of the shaft (10) causes the movement of
the spreading apparatus ( 23 ) up and down along the shaft ( 10 ) .
In this particular case, the portion of the shaft (10) engaged
by the spreading apparatus (23) throughout the range of its
movement towards or away from the cover plate (6) is threaded.
The threaded portion of the shaft (10) engages a corresponding
2o threaded receptacle passing through the spreading apparatus,
which in this case is the attached plurality of spreading arms
(23). Rotation of the shaft (10) would then result in the
movement of the spreading apparatus (23) up and down along a
length of the shaft ( 10 ) , which in turn would exert outward or
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inward pressure on the tensioning arms (15). In this
particular case, the shaft (10) is attached through the cover
plate (6) such that it can be rotated using a keyed wrench or
other tool and the shaft (10) would not protrude to any
significant degree above the upper surface (7) of the cover
plate (6). This flush nature of the top end of the shaft (10)
in relation to the cover plate (6) would further increase the
safety provided by the apparatus (5) of the present invention.
to It will be understood that this threaded embodiment is simply
another method of demonstrating how the shaft (10) might be
used to actuate the spreading apparatus (23) and any other
such method of attachment in co-operation between the cover
plate (6), shaft (10) and spreading apparatus (23)
15 accomplishing the same goal is contemplated within the scope
of the present invention.
It will be understood that whilst this particular embodiment
demonstrates the preferred method of attachment of the shaft
2o and the cover plate insofar as it leaves a relatively flush
upper surface of the cover plate without a protruding section
of the shaft, another alternative embodiment would be to
thread the entire shaft and have the shaft pass through a
threaded receptacle on the cover plate, and then fixedly
ii
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attach the spreading apparatus to the lower portion of the
shaft, whereby rotation of the shaft would result in the
pulling up or pushing down of the shaft, similar to the
embodiment of Figure 1.
Figure 3 is a top view of an embodiment of the apparatus of
the present invention roughly according to Figure 2. However,
an adaptor plate (27) has been added to show the versatility
and utility of the basic apparatus (5) of the present
1o invention in a larger hole, wherein the width of the mouth of
the hole shown as (29) is wider than the dimension or width of
the cover plate ( 3 0 ) . An adaptor plate ( 27 ) can be used which
is wide enough, the width thereof shown as (31), to cover the
entire mouth (2) of the hole (1). The adaptor plate (27) is
is placed on the ground surface (4) between the mouth (2) of the
hole (1) and the cover plate (6), the adaptor plate (27)
having an aperture (28) extending therethrough, the width (32)
of the aperture being smaller than the width (30) of the cover
plate (6) and large enough to allow the remainder of the
2o apparatus (5) attached to the cover plate (6) to pass through
the aperture. As such, the apparatus (5) can be dropped into
position in the hole (1) through the aperture (28) of the
adaptor plate (27) and the cover plate (6) will then engage
the adaptor plate (27) which, in turn, engages the ground
~,I
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surface (4) around the mouth (2) of the hole (1). The
tensioning arms (15) of the apparatus of the present invention
could then still be levered into position against the interior
walls (3) of the hole (1) either on their own or, as discussed
below, extenders could be added to the ground engaging ends
(16) of the tensioning arms (15).
Where, as in Figure 2, the shaft (10) is attached such that it
can be moved without protruding above the upper surface (7) of
i0 the cover plate ( 6 ) , a removable wrench or other tool might be
used to temporarily attach to the shaft (10) and rotate it.
Another safety feature of the invention could be to provide
for a keyed wrench or the like, such that it would make it
even more difficult for an unauthorized person to unlock the
is device .
It will be understood that any type of an adaptor plate
accomplishing the objects of the present invention, namely to
provide a surface for the cover plate (6) to engage, which
2o surface in turn is engaging the ground surface (4) around the
mouth (2) of the hole (1), is contemplated within the scope of
the present invention.
Figure 4 shows another embodiment of the present invention
ii
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with a different configuration of the tensioning arms (15) and
the spreading apparatus (23).
Again, a convex cover plate (6) is shown, and the arm
extension (9) and shaft (10) are configured the same as those
in the embodiment shown in Figure 2. The major difference
between the embodiment of Figure 4 and Figure 2 is that of the
spreading apparatus of this embodiment.
4~hile the embodiment of Figure 2 is shown in a loose or
released fashion within the hole, the embodiment of Figure 4
is again shown in its locked position with the tensioning arms
(15) and their wall engaging ends (16) fully extended against
the walls (3) of the hole (1).
In this particular case, while the same configuration of
spreading arms (23) is used as in Figure 2, the spreading arms
(23) are attached to the tensioning arms (15) in a different
fashion. Firstly, rather than being attached to any midpoint
of the tensioning arms (15), the spreading arms (23) are
hingably attached at the wall engaging ends (16) of the
tensioning arms (15). In this particular case, a small hinge
plate or attachment plate (26) has been used. Although it
will be understood that with the proper necessary
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modifications, the spreading arms (23) and the tensioning arms
(15) could be directly attached or other methods of attachment
could be used, without departing from the scope and intent of
the claimed invention.
s
Shown attached to the wall engaging ends (16) of the
tensioning arms (15) are extenders (19). Extenders (19) could
optionally be added at the wall engaging ends (16) of the
tensioning arms (15) to extend the reach of the tensioning
1o arms (15) away from the shaft (10) for use in a larger hole.
It will be understood, however, that the use of such extenders
(19) is optional and as such the apparatus of the present
invention both with or without said extenders (19) is
contemplated within the scope of the claimed invention.
1s
Also shown attached at the extreme ends of the extenders (19)
are wall engaging adaptors (18) which again, in this
particular embodiment, are of a spiked configuration.
20 The embodiment of Figure 4 would be operated in the same
fashion as that of Figure 2, namely rotational power would be
applied at the top of the shaft (10) from the upper surface
(7) of the cover plate (6) and the rotation of said shaft (10)
would cause the movement of the spreading apparatus (23) up
~i
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and down along a section of the shaft (10) which would in turn
cause the outward or inward movement of the tensioning arms
(15) and any extenders (19) or wall engaging adaptors (18)
disposed at the ends thereof.
s
Figure 5 demonstrates yet another alternative embodiment of
the apparatus of the present invention, which would lend
itself to use in a hole excavated in a sloping ground surface.
Shown in that diagram is a hole (1), with a mouth (2) and
1o walls (3). The ground surface (4) in which the hole (1) has
been drilled is sloped. This ground surface (4) might be a
hillside or the like. In order to make the apparatus of the
present invention extend fully down into the hole (1) and yet
have the cover plate (6) accommodate the sloping ground
is surface ( 4 ) , the shaf t ( 10 ) and any arm extens ion, shown in
this diagram at (9), could be hingably attached in any number
of methods, such as a ball joint, hinge or the like, to the
cover plate (6) such that the shaft (10), tensioning arms (15)
and spreading apparatus (23) could extend directly down the
2o hole (1) and the cover plate (6) has a limited range of
movement in directions away from perpendicular to the
remainder of the apparatus while maintaining its attachment to
the remainder of the apparatus, such that the tensioning arms
( 15 ) will pull the cover plate ( 6 ) down into s loped conformity
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and lock with the sloped ground surface (4) when the
tensioning arms (15) are forced outwards into the hole walls
(3). It will be understood that many different methods of
hinging the attachment of the shaft and any arm extension
could be used insofar as they all accomplish the same goal of
allowing for a degree of play in the cover plate (6) in its
attachment to the remainder of the apparatus, these different
methods will all be contemplated within the scope of the
present invention.
Shown in Figures 2, 4 and 5, the shaft (10) extends downwards
through the arm extension (9) which arm extension (9) in these
embodiments might comprise a collar or sleeve. It will be
understood that other types of arm extensions (9) could also
be used through which the shaft (10) would not necessarily
have to extend, without departing from the scope of the
present invention.
Thus it can be seen that the invention accomplishes all of its
2o stated objectives. The foregoing is considered as
illustrative only of the principles of the invention.
Further, since numerous changes and modifications will readily
occur to those skilled in the art, it is not desired to limit
the invention to the exact construction and operation shown
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and described, and accordingly, all such suitable changes or
modifications in structure or operation which may be resorted
to are intended to fall within the scope of the claimed
invention.
