Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
TENSIONING DEVICE
TECHNICAL FIELD
[0001] The invention relates to a tensioning device.
BACKGROUND OF THE INVENTION
[0002] Details of the background of the invention are available in
commonly-
owned United States Patent No. 9,610,883.
[0003] A tensioning device is used to tighten a chain, cable, strap or
similar
material. There are several types of tensioning devices, including but not
limited to load
binders and turnbuckles.
[0004] Load binders are tools used to secure cargo or loads to trucks,
ships, vessels
or other types of load carriers. Cargo or load is a generic term and is used
in the broadest
sense possible, including but not limited to crates, boxes, logs, pipes, rods,
and
containers. A load binder is an apparatus for tensioning a chain, cable, strap
or similar
material to secure a load. Typically load binders secure loads to the carrier
during
transport or movement.
[0005] The three-point hitch referred to in this application is known
and has been
in use for nearly a century, with one of the first U.S. patents being No.
1,379,399 issued
to Harry Ferguson in 1919.
SUMMARY OF THE INVENTION
[0006] Load binders are tensioning devices generally having two
attachment
points which according to the invention are also points where various other
end effectors
may be affixed. The inventive load binder is of generally longitudinal
structure and
includes at least one extensible member such that the length or distance
between the two
attachment points can be varied. Especially as a tensioning device, cargo
straps, wire
rope, cable, or chains can be attached to the two attachment points while
slack, and then a
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mechanism offering great mechanical advantage can retract the extensible
member,
shortening the length or distance between the attachment points, and thereby
draw the
cargo straps, wire rope, cable, or chains taut.
[0007] Although the tensioning device of the invention is very suitable
for
securing cargo for transport, its mechanism of generating mechanical advantage
is useful
in other applications including but not limited to attachment, leveling, and
safe and
statically determinate positioning of ponderous agricultural implements by
means of the
standard three-point tractor hitch.
[0008] Furthermore, the great mechanical advantage of the invention can
generate
large compression forces as well as in tensions, allowing this device, when
fitted with
appropriate end effectors, to operate as a jack or other lifting device or
support
underlying a ponderous object.
[0009] In one aspect, the invention provides a safer and easy method to
securely
stabilize ponderous objects by means of cargo straps, chains, or the like. It
is especially
advantageous that large forces for securing these objects can be developed
even by users
of modest physical strength.
[0010] It is also important that the mechanical advantage provided
within the
tightening mechanism does not operate in reverse of its own accord; for
example, if the
pitch of a threaded member is selected such that the angle of its helix is
steep enough, the
tension developed to secure the load will overhaul the mechanism instead, that
is, the
threaded member will pull out while forcing the complementary, threadably
coupled
member to which it is mated to rotate. Multiple threads are particularly
susceptible to this
unwanted effect. Thus, in another aspect, the invention affords sufficient
friction so that
once its components are tightened under load, the tension developed is
preserved until the
user loosens the device.
[0011] In a further aspect, the invention provides a linkage adjustable
in length by
means of great mechanical advantage wherein light or easy forces arising from
human
muscles, hand tools, or hand-held power tools can be translated into large,
effective
forces in tension or compression, for securing loads for transport, or for
positive,
statically determinate positioning of heavy agricultural attachments as part
of a multiple-
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link hitch system, or for positioning and alignment, and coupling of the
mechanically
complementary portions of a trailer and the tractor or draft vehicle to pull
the trailer.
[0012] Another aspect of the invention is to implement the same
mechanism used
to derive tension forces at great mechanical advantage so that it can also be
used at other
times to generate and maintain similarly large forces in compression.
[0013] A further aspect of the invention, as opposed to the operation of
over-center
latching means, is that during use, the magnitude of operating force remains
proportional
to the securing load developed by the invention while a load is being secured
or
positioned by the invention. This proportional relationship of forces provides
good
physical feedback to users having less physical experience with the required
forces of the
job at hand. The rise and fall of force required to operate an over-center
device can
surprise inexperienced users or people of modest strength and become a source
or root
cause of accident or other unsafe condition. Thus, another objective of the
invention is
improved safety and reduced opportunity for worksite accidents, especially
pinching or
crushing injuries in the immediate proximity of ponderous objects being
positioned,
adjusted or secured.
[0014] Various modifications and additions can be made to the
embodiments
discussed without departing from the scope of the invention. For example,
while the
embodiments described above refer to particular features, the scope of this
invention also
includes embodiments having different combination of features and embodiments
that do
not include all of the above described features.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] A further understanding of the nature and advantages of
particular
embodiments may be realized by reference to the remaining portions of the
specification
and the drawings, in which like reference numerals are used to refer to
similar
components. When reference is made to a reference numeral without
specification to an
existing sub-label, it is intended to refer to all such multiple similar
components.
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FIG. 1 shows an exploded view of a tensioning device in accordance with the
invention.
FIG. 2 shows an exploded view of an embodiment according to the invention
adapted for
operating in compression as a lifting jack.
FIG. 3 shows the assembly of an embodiment according to the invention adapted
for
operating in compression as a lifting jack.
FIG. 4 shows the assembly of an embodiment according to the invention adapted
for
operating as a top link of a three-point hitch.
FIG. 5 shows an exploded view of an embodiment according to the invention
adapted for
operating as a top link of a three-point hitch.
DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS
[0016] While various aspects and features of certain embodiments have
been
summarized above, the following detailed description illustrates a few
exemplary
embodiments in further detail to enable one skilled in the art to practice
such
embodiments. The described examples are provided for illustrative purposes and
are not
intended to limit the scope of the invention. In the following description,
for the purposes
of explanation, numerous specific details are set forth in order to provide a
thorough
understanding of the described embodiments. It will be apparent to one skilled
in the art,
however, that other embodiments of the present invention may be practiced
without some
of these specific details. Several embodiments are described herein, and while
various
features are ascribed to different embodiments, it should be appreciated that
the features
described with respect to one embodiment may be incorporated with other
embodiments
as well. By the same token, however, no single feature or features of any
described
embodiment should be considered essential to every embodiment of the
invention, as
other embodiments of the invention may omit such features.
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[0017] In this specification reference numerals are enclosed by square
brackets,
and punctuation marks such as commas or periods are placed inside the brackets
and
adjacent to the numeral character. (Similarly, punctuation marks for
parenthetical phrases
reside adjacent to the text characters and inside the parentheses.) This style
differentiates
between written English prose as opposed to lines of computer code or machine
readable
instructions.
[0018] The introductory description is presented in the parent
application in its
description of Figs. 1, 2, and 3 of that application. In this application Fig.
1 also shows a
specific description of the invention. It is a tensioning device comprised of:
a gear box
[21,] a barrel [22] which is tubular shaped having an external diameter and a
rotational
axis along a length of the tube, a barrel gear [30] affixed to the exterior of
said barrel with
the barrel gear encircling the barrel perpendicular to the axis of the
barrel's length, and
guide [33] inside of said gear box with a stub extending out of the guide. The
gear box
has two holes of which the first hole is situated opposite from the second
hole, and these
two holes are sized to allow the barrel to pass through the gear box and are
sized such
that the barrel is able to rotate along its rotational axis. The guide also
has two holes on
its own sides, with the first hole is opposite from the second hole and sized
to allow the
barrel to pass through the guide holes as well, with the barrel able to rotate
freely along
the barrel's rotational axis.
[0019] The gear box is assembled such that the barrel passes through the
two holes
in the gear box and the two holes of the guide with the barrel gear located
inside the gear
box but outside the guide. The barrel gear 30 is attached to the barrel by
means of a roll
pin [40.] A drive gear [32] has a socket wrench receptacle placed over the
stub, and the
drive gear engaged with the barrel gear forms a bevel gear.
[0020] The guide has a stub [41] that extends out one side of the guide.
The gear
drive and socket wrench receptacle sit over the stub and are rotatably coupled
to it, and
the stub is located such that when the gear box is assembled the drive gear
and barrel gear
are engaged and the gears' teeth are mutually meshed for transmission of
torque from the
drive gear to the barrel gear.
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[0021] A cover [21] encloses the drive gear inside the gear box, and the
cover has
a hole through which the socket wrench receptacle can pass through for
rotating the
socket wrench receptacle. A cover [37] and four screws [38] securing said
cover to the
gear box are shown as well.
[0022] In a preferred embodiment, the first end of the barrel includes
right-hand
threads within the first end of the barrel, while the second end of the barrel
includes left-
hand threads. Threadably coupled to these threaded members are two shafts,
with the first
shaft [25] having right-hand threads at one end, and the second shaft [26]
having left-
hand threads at one end. The first shaft is threaded coupled to the end of the
barrel having
the right-hand threads, and the second shaft is threadably coupled into the
end of the
barrel having the left-hand threads.
[0023] It is known that unwanted rotation between a mated pair of
threadably
coupled components (one having internal and the other having external threads)
can be
arrested by driving an additional internally threaded component to bear
against the first
internally threaded component. A simple example of this is that a nut located
at a
predetermined location along a threaded shaft can be locked into that position
by driving
a second nut into it from either axial direction. Double-nutting as this is
sometimes
called, is often employed in environments having moderate vibration such as in
transport
or shipping.
[0024] Threaded load tighteners similar to nuts or threaded washers,
often having
an eccentric perimeter or lobe or tab extending radially away from its
internally threaded
hole, are they used in the same manner as doubled nuts to lock turnbuckles and
load
binders against unwanted rotation after the device has taken up a tensile,
axial load. It is
similarly contemplated within the scope of the invention to include load
tighteners
threaded onto the threaded sections of shafts [25] and [26.]
[0025] The other ends of the first and second shafts have end effectors,
which is a
term including any of various means for connecting chain, cable, strap or
similar
material, or attachment points of ponderous objects to the shaft for operation
in tension.
In the embodiment shown in Fig. 1, the shaft ends not threadably inserted into
the barrel
terminate with eyes [28.] A link [36] and hook [39] are attached to each eye
bolt for
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attaching to chain, cable, or attachment points on machinery to be secures,
such as lifting
rings or tow points on vehicle frames.
[0026] Other end effectors are designed to withstand and transmit
compression
forces into the shafts. An embodiment according to this aspect of the
invention and
adapted for jacking or lifting a load is shown in an exploded view in Fig. 2.
The
aforementioned cover [37] and four screws [38] securing said cover to the gear
box [33]
are seen here, as are the drive gear [32] and barrel gear [30] driven by it.
The barrel gear
is affixed to the barrel by a roll pin [40.]
[0027] The barrel [22] of this embodiment has a first end having
external threads
[50] and second end opposite the first having a lifting pad [51] which in a
best mode is
knurled, grooved, cross-cut, or waffled to provide a positive, non-slip
contact with the
load to be raised. Although in this embodiment the lifting pad is integral to
the barrel and
may be a single forged part for strength, other preferred embodiments
contemplated
within the scope of the invention include those having the lifting pad as a
separate
component swivelably coupled to the barrel end or threadably coupled to the
barrel for
fine height adjustment and mate-up of the lifting pad to the load. The
rotational coupling
between the barrel and the lifting pad allows barrel rotation during lifting
or lowering
without deleteriously forcing the lifting pad to rotate at its contact
interface with the load
in its lifting or lowering motion.
[0028] The threads of the first end of the barrel threadably insert into
female
threads [53] a footpad [52] It is generally preferred that the area of the
footpad be larger
and wider than the area of the lifting pad for improved stability and safety,
although this
area relationship is not strictly necessary. The double-headed, sigmoid-shaped
arrow [55]
in the figure illustrates that the in assembly the threaded end of the barrel
passes through
the barrel gear when coupled to the footpad.
[0029] Lastly of note in this figure, the guide may be constructed so as
to
completely encircle the barrel, or in accordance with this figure, the guide
[41a] further
comprises at least one cylindrical surface complementary to an external
diameter of the
barrel, and may need only extend partway around the barrel to adequately
locate and
stabilize it within the gear box. The roll pin being inserted transversely
through the barrel
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extends beyond the outer diameter of the barrel at both its ends, and these
ends insert into
two holes in the barrel gear so as that rotation of this gear by the driving
action of the
drive gear forces the same rotation upon the barrel. In this configuration, a
guide [41a]
extending partway around the barrel and as a best mode extending halfway
around the
barrel is sufficient to stabilize the barrel during its rotation. In this
embodiment, the
cylindrical surface of the guide further comprises a substantially semi-
circular cross
section.
[0030] Fig. 3
shows the assembly of the embodiment adapted for jacking or lifting.
Here the socket wrench receptacle pq has a square pocket or aperture [60] and
a
polygonal outer perimeter [61] which in this embodiment is a hexagon. The
socket
wrench receptacle [34] is shown and can be rotated by whichever tool an
operator might
use as the means for rotating the drive gear and barrel gear. When operating
as a jack, an
appropriate sized impact or socket wrench is inserted into the receptacle and
the
receptacle is rotated to raise or lower the load. The contours of the aperture
[60] and the
outer perimeter [61] are shaped and sized to accept standard square-drive
socket
wrenches or hexagonal sockets mounted on socket wrenches. Additionally, air
tools,
electric or cordless drills may be affixed with drive bit which engage either
or even both
of these two features. Many other tools or means for rotating the drive gear
are known or
can be readily improvised by those skilled in the art, and it is not the
intention of the
inventor to limit the invention by use of the socket wrench receptacle. Also,
rather than
the square aperture as illustrated, a socket wrench receptacle having a
hexagonal aperture
is also contemplated within the invention, so that it can be driven by Allen
wrenches at
great mechanical advantage. Besides socket wrenches or Allen wrenches, the
socket
wrench receptacle may be driven by a crank with and end of the crank having a
cross
section shape able to be received into the aperture of the socket wrench
receptacle, or
able to grasp the outer perimeter for positive rotation of the socket wrench
receptacle. An
embodiment also exists wherein the crank is permanently connected to the
socket wrench
receptacle. This connection can be rigid or may include at least one
articulated joint or
similar connection, so that the crank can be conveniently folded away or
collapsed when
not in use.
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[0031] Yet other end effectors can operate either in compression or in
tension so
that the invention can form a useful component in many different applications
where
multiple linkages operate in concert, especially but not limited to three
point hitches used
in agriculture and four-bar linkages used in general industrial machinery.
[0032] Thus, another embodiment in accordance with the invention is
configured
as a top link for a three point hitch. Fig. 4 shows an assembly of this
configuration.
Similar to the eyes [28 in Fig. 1] of the parent invention, the end effectors
of the top link
embodiment are ball sockets sometimes also called ball ends, which comprise an
external
ring [71] having a concave spherical interior surface, which grips around the
girth of a
spherical journal member [72.] The hole passing though the journal member of
the ball
end can accept clevis pins or cotter pins and the like for coupling to
attachment points on
agricultural implements or other machinery.
[0033] Fig. 5 shows the same device as shown in Fig. 4, but with the
components
exploded. Here as previously detailed are seen the screws [38] and cover [37,]
the drive
gear [32,] barrel gear [30,] and roll pin [40,] the barrel [22] and gear box
[21,] and a
guide [41a] which embraces only halfway around the barrel. The internal
threaded
apertures [70] at the ends of the barrel receive externally threaded shanks
[73] of two ball
ends which have external rings [71] encircling spherical journal members [72.]
The pair
of ball ends are oppositely threaded, one left-hand thread and the other right-
hand thread,
as are the threaded apertures in the ends of the barrel. Thus, rotation of the
barrel when
the ball ends are constrained from axial rotation will cause the center to
center distance
between the ball end journals to extend or retract and generate great force
while in
motion. Employed as a top link or similar mechanical linkage of adjustable
length, this
configuration of the invention offers great utility in coupling agricultural
implements to
tractors, wherever linkages in assembly must endure heavy axial forces. These
forces can
be developed during installation or adjustments to coupled machinery with
ease, speed,
and greatly improved safety, especially when the forces applied to operate the
drive gear
originate from power tools or levers such as socket wrenches because users'
hands and
arms are relieved from having to apply or withstand heavy forces used to
secure said
machinery or implements.
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[0034]
Furthermore, although the pairs of gears in the illustration appear to have
equal or nearly equal numbers of teeth, it is also contemplated within the
scope of the
invention that the driver gear may have a different number of teeth than the
barrel gear,
providing that all other gear design parameters are met for the gears' teeth
to intermesh
properly, i.e. pressure angle of tooth profiles, addendums, dedendums,
diametral pitch,
and so forth. It is especially contemplated that an additional stage of
amplification of
mechanical force can be created with a drive gear having fewer teeth than a
barrel gear.
[0035] Further
contemplated within the scope of the invention is that rather than
using a roll pin, the barrel and barrel gear may be parts of a single, unitary
component
and especially a forged component where forging can add great strength and
toughness to
the barrel and teeth for improved safety, positive transfer of driving torque
to the barrel,
and extended wear life.
[0036] While certain features and aspects have been described with
respect to
exemplary embodiments, one skilled in the art will recognize that numerous
modifications are possible. Further, while various methods and processes
described
herein may be described with respect to particular structural and/or
functional
components for ease of description, methods provided by various embodiments
are not
limited to any particular structural and/or functional architecture.
[0037] Hence,
while various embodiments are described with or without certain
features for ease of description and to illustrate exemplary aspects of those
embodiments,
the various components and/or features described herein with respect to a
particular
embodiment can be substituted, added, and/or subtracted from among other
described
embodiments, unless the context dictates otherwise. Consequently, although
several
exemplary embodiments are described above, it will be appreciated that the
invention is
intended to cover all modifications and equivalents within the scope of the
following
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