Note: Descriptions are shown in the official language in which they were submitted.
CA 02636445 2008-06-27
RETRACTABLE MONORAIL TARPAULIN SYSTEM
Field of the Invention
100011 The present invention relates to the field of tarpaulin systems. In
particular, it
relates to a retractable tarpaulin system for covering a vehicle bed.
Background of the Invention
[0002] Cargo transportation is a major industry throughout the world, and a
major
concern in the cargo transportation industry is the protection of the cargo
from damage
during transport. The most common type of cargo transport is the trailer
truck, which is
used to deliver cargo to its final destination. While some trailers are based
on enclosed
cargo containers, similar to those used for sea transport, the most common is
the well-
known flatbed trailer. Flatbed trailers are inexpensive and easy to load, but
have a major
drawback in that the cargo on the trailer is exposed and at risk of damage
from the
elements.
[0003] Tarpaulin systems (tarps) are commonly used to cover the cargo area of
a
flatbed trailer attached to a truck or other vehicle for the transportation of
cargo and
goods. An advantage provided by tarps is that they can be removed to
completely
uncover the bed of the vehicle, allowing for faster loading and unloading than
with a
closed-bed vehicle using doors. However, an issue arises in that the tarp must
be capable
of maintaining a certain degree of tension when covering the bed to prevent
damage to
the tarp or the cargo protected by the tarp during transport.
[0004] A particular problem arises in the transportation of glass using a
flatbed
trailer. As the glass must be transported vertically, the trailer is modified
with a centre
wall or series of pillars to provide support for the vertically stacked glass.
However, the
presence of the centre pillar inhibits the ability to cover the trailer
manually with a
tarpaulin. With a standard tarpaulin system, the excessively tall bows
increase the weight
of the system to a point that it is not feasible.
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[00051 Furthermore, as it is preferable to load and unload the glass from the
sides of
the trailer, the bows of the tarpaulin must be retractable to permit side
loading of the
trailer. However, as the known bows in the art are U-shaped frames that extend
along
both sides, it is difficult to fully retract the bows without at least some
interference with
cargo loading.
[00061 There is a need for a tarpaulin system that is suited for covering
vehicle beds
designed for transportation of glass and other, similar sheet materials that
must be
transported vertically.
[00071 It is an object of this invention to partially or completely fulfill
one or more of
the above-mentioned needs.
Summary of the Invention
[0008] The invention comprises a retractable tarpaulin system, comprising: a)
a
headboard attached to a front end of a trailer deck; b) a monorail extending
from the
headboard to a rear end of the trailer deck, said monorail located
substantially along a
centerline of the trailer deck and secured to an A-frame on said trailer deck
via a flexible
slide block to transfer flexion torque away from the monorail to the trailer;
c) a rear bow
attached to and moveable along said monorail, and detachably secured to the
rear end of
the trailer deck; d) one or more intermediate bows, attached to and moveable
along said
monorail between said headboard and said rear bow; and e) a tarpaulin covering
said
vehicle deck and supported under tension by said headboard, said rear bow, and
said
intermediate bows.
100091 The tarpaulin system may further include one or more tensioning buckles
spaced along opposite edges of the tarpaulin, the tensioning buckles operative
to secure
the opposite edges of the tarpaulin to the vehicle deck.
[oolol Preferably, the tarpaulin system includes one or more of the following
features: the intermediate bows attached to the monorail via a plurality of
wheels which
engage corresponding tracks on the monorail; the headboard modified with
angular
features to provide improved aerodynamic performance over a flat headboard;
and spring
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steel woven into the tarpaulin in a direction parallel to the trailer deck
along one or more
sections of the tarpaulin.
[00111 Another embodiment of the invention comprises a retractable tarpaulin
support system for supporting a tarpaulin under tension, comprising: a) a
headboard
attached to a front end of a trailer deck; b) a monorail extending from the
headboard to a
rear end of the trailer deck, said monorail located substantially along a
centerline of the
trailer deck and secured to an A-frame on said trailer deck via a flexible
slide block to
transfer flexion torque away from the monorail to the trailer; c) a rear bow
attached to
and moveable along said monorail, and detachably secured to the rear end of
the trailer
deck; d) one or more intermediate bows, attached to and moveable along said
monorail
between said headboard and said rear bow.
[00121 Preferably, the retractable tarpaulin support system includes
additional
features as described above.
[00131 Other and further advantages and features of the invention will be
apparent to
those skilled in the art from the following detailed description thereof,
taken in
conjunction with the accompanying drawings.
Brief Description of the Drawings
[00141 The invention will now be described in more detail, by way of example
only,
with reference to the accompanying drawings, in which like numbers refer to
like
elements, wherein:
Figure 1 is a perspective view of a trailer incorporating an embodiment of the
inventive tarpaulin system;
Figure 2 is a perspective view of Figure 1 with the tarpaulin removed;
Figure 3 is a close-up perspective view of the front end of the trailer of
Figure 2;
Figure 4A is an underneath perspective view of the trailer of Figure 2;
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Figure 4B is a close-up perspective view of the circled area of Figure 4B;
Figure 5A is a perspective isolation view of an intermediate bow;
Figure 5B is a close-up perspective view of the circled area of Figure 5A;
Figure 6A is a close-up perspective view of the rear end of the trailer of
Figure 2;
Figure 6B is a close-up perspective view of circled area A in Figure 6A;
Figure 6C is a close-up perspective view of circled area B in Figure 6A;
Figure 7A is a side view of the trailer of Figure 1;
Figure 7B is a close-up side view of circled area C in Figure 7A;
Figure 7C is a close-up side view of circled area D in Figure 7A;
Figure 8 is a perspective view of a trailer incorporating an alternative
embodiment
of the inventive tarpaulin system;
Figure 9 is a perspective view of the trailer of Figure 2 with the
intermediate bows
retracted and the tarpaulin removed.
Detailed Description of the Preferred Embodiments
100151 A presently preferred embodiment of a glass transport flatbed trailer
10
incorporating a preferred embodiment of the inventive tarpaulin system is
shown in
Figure 1. The trailer deck 110, and cargo located thereon (not shown), is
covered by a
tarpaulin 120 supported by a headboard 100 and a rear bow 240 (shown in Figure
2) and
held under tension by integrated tensioning buckles 140 attached to webbing
130 built in
to the tarpaulin 120 that secure the sides of the tarpaulin 120 to the sides
of the trailer
deck 100.
[00161 Figure 2 shows the trailer 10 of Figure 1 with the tarpaulin 120
removed. A
series of center pillars 210 and beams 220 forms an A-frame for vertically
supporting
cargo, such as glass sheets, as is known in the art. Coupled to the top of the
A-frame is a
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monorail 250 that runs the length of the trailer 10 from the headboard 100 to
the rear of
the trailer deck 110. A rear bow 240 is secured to the monorail 250 and
detachably
secured to the trailer deck 110 and is used to tension the tarpaulin. Along
the length of
monorail 250 are spaced rigid intermediate bows 230 which extend the width of
the
trailer deck 110 and preferably include a partial vertical extension to
support the sides of
the tarpaulin 120. Preferably, the vertical extension of the intermediate bows
230 extends
less than a quarter of the side length (height) of the tarpaulin.
[0017] Figure 3 shows the mounting of the monorail 250 to the structural frame
115
of the headboard 100 and the A-Frame. The headboard 100 is comprised of a skin
105
covering the structural frame 115. The headboard can also be considered as the
front
bow of the tarpaulin system.
[0018] As shown, the headboard 100 is of an angular shape which provides
improved
aerodynamic efficiency for the trailer 10, particular in combination with the
increased
tension and stability of the tarpaulin resulting from the present inventive
system. While
an aerodynamic headboard 100 is preferably, a conventional flat headboard can
also be
used with the tarpaulin system, albeit without the same degree of aerodynamic
benefit.
[0019] Figures 4A and 4B show a perspective and a close-up view of the
underside of
the monorail 250 and A-frame beam 220. The monorail 250 is secured to the beam
220
by a flexible slide block 400 that enables the trailer 10 to flex under the
weight of the
cargo load without placing undue stress on either the monorai1250 or the beams
220.
[0020] Figures 5A and 5B show a perspective and a close-up view of the center
of a
detached intermediate bow 230, detailing the connection mechanism 500 used to
secure
the intermediate bow 230 to the monorail 250 (shown in Figure 2). The
mechanism
comprises a U-shaped brace 520 with a set of opposing wheels 510 mounted on
the
interior of the brace 520. The wheels engage the monorail 250 along opposing
sides and
the top, securing the intermediate bow 230 an inhibiting any perpendicular
motion of the
bow 230 relative to the monorail 250. The use of wheels 520 enables the bow
230 to
maintain freedom of movement laterally along the monorail 250, allowing the
bows 230
to be collectively moved to the front or rear of the trailer 10 for cargo
loading.
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[00211 Figures 6A, 6B and 6C show the rear bow 240 and the details of the rear
bow
mounting and tensioning assemblies. The base 625 of the rear bow 240 has a
plurality of
wheels 615 that engage a guide rai1610 mounted on the rear of the vehicle deck
110 on a
stanchion base 620. The wheels 615 allow the rear bow 240 to be adjusted
laterally after
the tarpaulin 120 is stretched over the intermediate bows 230 to place the
tarpaulin 120
under tension and lock the tarpaulin 120 and the intermediate bows 230 in
place. As
shown in Figure 6C, tension adjustment is performed using one or more tension
buckles
660 secured to a support stanchion 670 mounted in stanchion base 620.
Stanchions 670
are removable from stanchion bases 620 to allow rear bow 240 to be moved
towards the
headboard 100 and facilitate loading of cargo from the rear end of the
trailer.
[00221 Additional tensioning of the tarpaulin 120 is provided by tensioning
buckles
140 and 145 mounted directly on the tarpaulin as shown in Figures 7A, 7B and
7C. The
tarpaulin 120 has a set of tensioning buckles 140 attached at the ends of
reinforced
webbing sections 130. The buckles 140 are secured to edges of the trailer deck
110 and
tightened, using a ratcheting system or other means as is known in the art, to
place the
tarpaulin 120 under tension. Additional horizontal tensioning buckles 145 are
used to
secure the corners of the tarpaulin 120 to the corners of the trailer deck 110
in the same
fashion. In conjunction with the structural support provided by the
intermediate bows
230, the result is a taut structure with increased stability and reduced wind
resistance, as
well as improved resiliency, as the edges of the tarpaulin 120 will not `flap'
in the wind
during transport, which can damage the tarpaulin, as well as expose the cargo,
possibly
damaging it as well.
100231 Operationally, to load cargo on to the trailer deck 110, the tarpaulin
120 is
retracted by moving intermediate bows 230 along the monorai1250 to collect at
one end,
preferably the headboard end, of the trailer deck as shown in Figure 9.
Additionally, by
removing stanchions 670 from stanchion bases 620, rear bow 240 can also be
moved to
collect at the headboard end with the intermediate bows 230. Cargo, such as
glass sheets,
can then be loaded from both sides of the vehicles deck, using an overhead
and/or level
loading system as is known in the art. Once the cargo is loaded and secured,
the
intermediate bows 230 (And rear bow 240, if moved), along with the tarpaulin
120 are
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extended back over the vehicle deck I 10 (as shown in Figure 1) and secured in
place
under tension by adjustment of tensioning buckles 140 and 145, and rear bow
240 as
described above.
[0024] To assist in maintaining the structure of the tarpaulin 120 during
retraction
and extension, strips 800 of spring steel or a similar material can be woven
into the
tarpaulin 120 along the bottom edges and along the section overlapping the
monorail 250
as shown in Figure 8. The strips assist the tarpaulin in forming a stable
structure when
extended. Then, during retraction, the compression of the spring steel acts as
a lifter to
prevent the tarpaulin from binding in the monorail 250 or the wheels 510 of
the
intermediate bows.
[0025] While the above system has been presented in the context of tarpaulins
for
flatbed deck glass transport trailers, the system is equally applicable to any
tarpaulin and
trailer system.
[0026] This concludes the description of a presently preferred embodiment of
the
invention. The foregoing description has been presented for the purpose of
illustration
and is not intended to be exhaustive or to limit the invention to the precise
form
disclosed. It is intended the scope of the invention be limited not by this
description but
by the claims that follow.
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