An articulated door and door guiding track covers storage bays of a beverage body. The articulated door is formed by engaging a plurality of polymeric panel sections into a sequence such that each panel section can be positioned at varying angles with respect to an adjacent engaged panel section. Elastic shock cord runs from the bottom panel section to the top panel section of each articulated door. The shock cord prevents adjacent panel sections from moving laterally with respect to one another and holds the flat outer surface of each panel section flush with the flat outer surfaces of adjacent panel sections. The articulated door is guided between an open position and a closed position by a door guiding track comprised of a left channel facing a right channel across a door opening. The door is slidably positioned in the door guiding track by having a left end of each panel section extending into the left channel and a right end of each panel section extending into the right channel.

BACKGROUND OF THE INVENTION 
The present invention relates to articulated doors. More specifically, the 
present invention relates to an articulated door formed from a sequence of 
engagable polymeric panel sections and held together by elastic shock 
cord. 
Beverage trailers and trucks employing beverage bodies have long been used 
to deliver beverages to various sorts of retailers. Articulated doors are 
typically used on both sides of a beverage body to permit access to 
individual storage bays where the beverages are stored. Under normal use, 
these doors are opened many times during the day as the driver delivers 
beverages to retailers along his route. While a general purpose delivery 
truck may use one roll-up door at the rear of the truck, a typical 
beverage body may use ten or more doors. Therefore, any disadvantage 
associated with a particular door design is multiplied many times when 
that design is employed in a beverage body. 
Beverage bodies have typically employed articulated doors that are formed 
from a sequence of solid aluminum panel sections. These panel sections are 
formed with interlockable edges. Usually an aluminum panel section will 
have a first interlockable edge with an attached cylindrical structure and 
a second interlockable edge opposite the first edge with an attached 
cylindrical structure having a radius larger than the radius of the 
cylindrical structure attached to the first edge. The smaller cylindrical 
structure of a panel section is placed within the larger cylindrical 
structure of an adjacent panel section, thereby forming a joint that 
allows the two adjacent panel sections to be positioned at varying angles 
with respect to each other. The smaller cylindrical structure also 
includes a hollow center in which rollers are inserted. Therefore, every 
joint typically has a corresponding pair of rollers. 
To guide an articulated aluminum door between an open position and a closed 
position, a door guiding track is required. A typical door guiding track 
is comprised of a pair of channels, with each channel having a pair of 
channel members facing each other across a gap in which the rollers are 
inserted. These channel members also may include track liners, often 
formed of stainless steel, to absorb vibrational energy and to reduce 
friction between the rollers and the channel members. 
Several problems arise from using this type of articulated aluminum door in 
a beverage body. When doors of this type are new, they typically work 
fine. However, as the beverage body is used, the door frame can be 
deformed by backing into loading docks and driving over rough roads and 
curbs. When the door frame is deformed, the door guiding track becomes out 
of square and the door will either jam or become very difficult to raise 
and lower. 
As the beverage body is transported over roads with the articulated doors 
closed, the doors vibrate in their tracks. This vibrational energy is 
absorbed by the rollers and channel members as they vibrate against each 
other. This forms flat spots on the rollers and indentations in the 
channel members at the points where the rollers contact the channel 
members. As these indentations grow in size, the space surrounding the 
rollers increases, allowing the vibrations to increase in intensity and 
thereby increasing the rate at which the rollers and channel members 
deteriorate. These indentations also contribute to the door becoming more 
difficult to raise and lower. 
As a door becomes more difficult to raise and lower, the rollers and 
channel members are lubricated. The lubrication eventually picks up dust 
and dirt, which further accelerates the deterioration of the rollers and 
door guiding track. A delivery person will progressively exert more force 
to open and close the door as this deterioration cycle continues. 
Eventually a point will be reached when the delivery person will no longer 
be able to move the door. At this point the beverage body is brought back 
to the warehouse where typically a forklift is used to unjam the door, 
which usually destroys the door. 
Another problem that is exacerbated by the indentations is a buckling, or 
rippling effect apparent when the door is viewed in the closed position. 
Even when an articulated aluminum door is new, the diameter of the rollers 
is smaller than the width of the door guiding track that supports the 
rollers. This causes the door to collapse slightly into the door guiding 
track when the door is in the closed position, with individual panel 
sections tending to alternate. One panel section will lean one way as its 
corresponding roller is pushed to one side of the channel member and the 
next panel section in the sequence will lean the other way as its 
corresponding roller is pushed to the other side of the channel member. As 
the indentations grow in size, this rippling, or buckling effect becomes 
more pronounced. This creates an aesthetically unpleasing effect, 
especially when an articulated aluminum door has been painted with a 
beverage company's logo. 
An articulated door and door guiding track that is constructed from 
self-lubricating materials and does not employ rollers would be resistant 
to deterioration and track alignment problems and would therefore be very 
desirable. In addition, such a door would be less likely to suffer from 
buckling and rippling. 
Because aluminum is not a resilient material, collisions with an 
articulated aluminum door usually result in a partial or complete 
destruction of the door. This can happen in a warehouse, where forklifts 
maneuver around and load beverage bodies, in an on-street accident, or 
from within the beverage body itself if the beverages contained therein 
should tip over. While the door can sometimes be repaired by replacing the 
impacted panel section, often adjacent panels will be deformed from the 
force transmitted through the interlocking edges. 
When using beverage bodies in cold climates, the storage bays must be 
heated to prevent the beverages from freezing. Typically this is 
accomplished by circulating heated engine coolant from the tractor through 
the floor of the beverage body. Because aluminum is a highly 
thermoconductive material, a layer of insulation must be added to the 
inner surface of an articulated aluminum door to retain the heat in the 
beverage body. This adds significant expense, complexity and weight to 
articulated aluminum doors used in beverage bodies. 
Another problem associated with the use of beverage bodies in cold climates 
results from the salt and sand that is applied to road surfaces to melt 
ice and improve traction. The salt and sand work their way into the joints 
that connect adjacent panel sections, where they corrode and wear down the 
aluminum surfaces that form the joint. While the door can be steam 
cleaned, the joint has usually been damaged by the time this is done. 
Eventually the joint will lock up and the affected panel sections must be 
replaced. 
Because of the weight of an articulated aluminum door, a counterbalance 
device is typically used to assist the delivery person in opening and 
closing the door. This device is usually located above the storage bay. 
The counterbalance adds weight and complexity to the beverage body and 
decreases the available space left to transport beverages. 
An articulated door comprised of panel sections formed from a lightweight, 
high insulation, wear resistant, corrosion resistant and resilient 
material would be very desirable. 
SUMMARY OF INVENTION 
The present invention is an articulated door. The articulated door is 
formed from a plurality of polymeric panel sections that are engaged in a 
sequence of panel sections such that each panel section can be positioned 
at varying angles with respect to an adjacent engaged panel section. 
The articulated door of the present invention is provided with at least one 
segment of elastic shock cord that runs through a plurality of panel 
sections. The elastic cord holds the door together by preventing the panel 
sections from sliding apart, and minimizes buckling and rippling, thereby 
providing the door with a more aesthetically pleasing appearance than 
doors of the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention is an articulated door formed from a plurality of 
panel sections. The articulated door of the present invention is provided 
with a segment shock cord that runs through the panel sections. In one 
application, the door is used in a beverage body. 
FIG. 1 is a perspective view of beverage body 10. Beverage body 10 has 
floor 11, roof 13, generally vertical walls 9 intermediate the floor and 
the roof, and a plurality of door openings in which articulated doors 12 
are positioned. Beverage body 10 has an interior that is divided into 
individual beverage storage bays 15, which are accessible when articulated 
doors 12 are open. Articulated doors 12 are formed by engaging polymeric 
panel sections 14 into a sequence. A typical door of this type is 87 
inches tall and 54 inches wide. 
FIG. 2A is a transverse sectional view taken along line 2A--2A of FIG. 1 
showing two articulated doors 12 installed in beverage body 10. 
Articulated doors 12 provide access to beverage storage bay 15 and are 
formed by engaging panel sections 14 into a sequence (this view does not 
show every panel section 14 required to form articulated door 12). A 
bottom panel section 22, located adjacent to floor 11 of beverage body 10 
when articulated door 12 is in the closed position, is formed from 
aluminum and contains seal 23. 
Articulated doors 12 are supported and guided by door guiding track 16. 
Each door guiding track 16 is comprised of a pair of channels 21, which 
face each other across the door opening. In this figure, only one channel 
21 of each door guiding track 16 is visible. Each channel 21 includes 
channel members 18, which face each other across gap space 17, and curved 
segment 19, which is provided to guide articulated door 12 above beverage 
storage bay 15 and along roof 13 when door 12 is moved to the opened 
position. 
FIG. 2B is an enlarged view of the bottom portion of left articulated door 
12 of FIG. 2A. Running through each panel section 14 of door 12 are two 
segments of elastic shock cord 31 (only one segment of shock cord 31 is 
visible in FIG. 2B). Also shown in FIG. 2B is bottom aluminum panel 
section 22. Shock cord 31 is terminated at a hole in aluminum panel 
section 22 by knot 27. Knot 27 prevents cord 31 from retracting into door 
12 and applies a force to aluminum panel section 22 that helps hold door 
12 together. Aluminum panel section 22 includes handle 25, which is used 
for raising and lowering door 12. Aluminum panel section 22 also holds 
seal 23, which contacts floor 11 of FIG. 1 when door 12 is in the closed 
position. 
FIG. 3 is a perspective view of polymeric panel section 14. When a 
plurality of panel sections 14 are engaged in a sequence, they form 
articulated door 12 of FIG. 1. Panel section 14 has curved inner surface 
24 and flat outer surface 26. Curved inner surface 24 has a preferred 
radius of 2.099 inches. This facilitates the movement of articulated door 
12 through the curved section 19 of door guiding track 16 of FIG. 2A. Flat 
outer surface 26 is provided so that articulated door 12 can be easily 
painted with a beverage company's logo using a process such as 
silk-screening. Curved inner surface 24 and flat outer surface 26 are 
connected to each other by a plurality of parallel partitions 28. 
Plurality of parallel partitions 28 divides a space between flat outer 
surface 26 and curved inner surface 24 into a plurality of parallel 
compartments 30. This increases the strength of each panel section 14 
while decreasing the weight of each panel section. Parallel compartments 
30 also improve the insulating properties of the panel sections. An 
articulated door formed from a plurality of panel sections 14 will have an 
insulation value approximately twice that of an insulated aluminum door of 
the prior art. 
In FIG. 3, part of curved inner surface 24 is cut away to reveal elastic 
shock cord 31 and parallel partitions 28. Each partition 28 has a hole 
through which shock cord 28 passes (also note shock cord 31 in FIGS. 2B 
and 4). Shock cord 31 prevents adjacent panel sections from moving 
laterally with respect to one another, thereby holding the door together. 
Cord 31 also pulls adjacent panel sections towards one another, which 
minimizes buckling and rippling when door 12 is in the closed position. 
Panel section 14 has right end 32 and left end 34 (named with respect to 
viewing a panel section 14 in an articulated door 12 from an exterior of 
beverage body 10 of FIG. 1). Right end 32 and left end 34 expose the 
plurality of parallel compartments 30. Panel section 14 also includes top 
hook edge 36 and bottom receptive edge 38, which engage with adjoining 
panel sections 14 to form articulated door 12 of FIG. 1. Ideally, a 
distance between top hook edge 36 and bottom receptive edge 38, i.e., the 
height of panel section 14, is as large as possible. As this distance 
becomes larger, fewer panel sections 14 are required to form articulated 
door 12, thereby decreasing the cost of the door. However, as the height 
of the panel sections increases, so must the radius of curved section 19 
of door guiding track 16 of FIG. 2A. Therefore, the preferred height of 
panel section 14 is 2.430 inches to facilitate an articulated door 12 
formed from an acceptable number of panel sections 14, while maintaining 
an acceptable radius for curved section 19 of door guiding track 16. 
Panel section 14 is formed by an extrusion process using a material that is 
a polymer blend of polyphenylene oxide and high impact polystyrene with 
triarylphosphate esters added to retard fire. Different variants of the 
polymer blend can be used based on the climate where the articulated door 
will be used. After the panel sections are formed, holes are drilled in 
the panel sections to accommodate shock cord 31. Compared to aluminum, the 
polymer blend used in the present invention has a high insulation value 
and is lightweight, resilient, self-lubricating, wear resistant, and 
corrosion resistant. Parallel partitions 28, curved inner surface 24, flat 
outer surface 26, top hook edge 36, bottom receptive edge 38, and other 
extruded walls are formed with a thickness of 0.05 inches. 
FIG. 4 is a view of two of the adjacent panel sections 14 of FIG. 2B 
positioned at an angle with respect to each other. Two adjacent panel 
sections 14 would be positioned in such a way as they move through curved 
section 19 of door guiding track 16 of FIG. 2A. As adjacent panel sections 
move through curved section 19, shock cord 31 is stretched around top hook 
edge 36. Shock cord 31 supplies forces to the panel sections 14, which 
tend to move the panel sections into alignment with each other. 
Accordingly, when a door 12 of the present invention is in the closed 
position, shock cord 31 pulls the door together and ensures that all the 
flat outer surfaces of each panel section 14 are flush with each other, 
thereby eliminating the buckling and rippling effects found is aluminum 
doors of the prior art. This is especially important when a door 12 is 
provided with a beverage company's logo, because buckling and rippling 
degrade the appearance of the logo. 
FIG. 5A shows an articulated door 12 removed from beverage body 10 of FIG. 
1. In this Figure, the door is shown as if it were laid on a flat surface, 
with the exterior of the door facing up. 
In this configuration, articulated door 12 is held together by a single 
segment of elastic shock cord 31, which is shown in phantom in FIG. 5A. 
Shock cord 31 is a commercially available elastic shock cord having a 
diameter of slightly less than one-eight of an inch. Shock cord 31 is 
secured to bottom aluminum panel section 22 by knot 27a. The placement of 
knot 27a within bottom aluminum panel section 22 is shown as knot 27 in 
FIG. 2B. 
Shock cord segment 31 runs from knot 27a, up through all panel sections 14, 
then loops across the top panel section, and down through all panel 
section 14 to knot 27b. The portions of shock cord segment 31 which 
comprise knots 27a and 27b apply an upward force to bottom aluminum panel 
section 22, while the portion of segment 31 which runs along the top panel 
section of door 12 applies a downward force to the top panel section. 
Accordingly, a single segment of shock cord is used to hold door 12 
together. 
The distance between knots 27a and 27b is approximately 23 inches. It has 
been found that a proper amount of tension in shock cord 31 is achieved 
when a segment of loose shock cord is cut to a length equal to twice the 
height of door 12, then stretched by about 25 inches when the door is 
assembled. For example, assume a worker is assembling a door that is 87 
inches tall and 54 inches wide. The worker will cut a piece of loose shock 
cord that is 174 inches long. This piece can easily be measured by laying 
the cord up and down along the length of door to be assembled. When the 
shock cord is inserted into the door, it will be stretched about 25 inches 
due to knots 27a and 27b and the portion which runs along the top panel 
section. 
For assembly reasons, it is preferable to have the two knots 27a and 27b at 
the bottom aluminum panel section 22. However, in another configuration 
the two knots are at the top panel section, with the shock cord looping 
back across bottom aluminum panel section 22. 
FIG. 5B shows an alternate method for holding door 12 together with shock 
cord. In FIG. 5B, door 12 is provided with shock cord segments 31a and 
31b, both of which are shown in phantom. As in FIG. 5A, knot 27a and 27b 
hold the shock cord to bottom aluminum panel section 22. However, shock 
cord segment 31a has a knot 27c which holds segment 31a to the top panel 
section 14 of door 12. Likewise, shock cord segment 31b has a knot 27d 
which holds it to the top panel section 14. 
For assembly reasons, the configuration shown in FIG. 5B is not utilized 
when door 12 is initially assembled. However, if a door 12 should become 
damaged and any of the panel sections 14 need to be replaced, and if that 
damage occurred near the top of door 12, then the segment of shock cord 31 
at the top of door 12 in FIG. 5A can be cut, and the damaged panel section 
can easily be removed. Once the panel section is removed, then the two 
segments 31a and 31b which were formed when segment 31 of FIG. 5A was cut 
can be tied off separately using knots 27c and 27d in FIG. 5B to form the 
configuration shown in FIG. 5B. 
Another method of repairing the door shown in FIG. 5A would be to simply 
tie the two segments together after they have been cut and the door has 
been repaired. However, depending on the tension already existing in the 
shock cord, this alternative may not be feasible. 
FIG. 6A is a fragmentary cutaway view showing panel section 14 and door 
guiding track 16 taken along line 6A--6A of FIG. 1. Door guiding track 16 
includes a pair of channels 21, one of which is shown in this figure. 
Channel 21 includes channel members 18 facing each other across gap space 
17. The distance between curved inner surface 24 and flat outer surface 
26, i.e., the width of panel section 14, is preferably 0.515 inches. 
In this embodiment, track liner 54 is positioned over a channel member 18 
that faces curved inner surface 24 of panel section 14. Track liner 54 is 
formed from a high density ultra-high molecular weight polyethylene 
plastic. This produces a sliding, self-lubricating, plastic-on-plastic 
contact between polymeric panel section 14 and track liner 54. This 
embodiment is used in door guiding tracks that have been converted to the 
present invention from door guiding tracks of the prior art. 
FIG. 6B is a fragmentary cutaway view showing panel section 14 and door 
guiding track 16 taken along line 6B--6B of FIG. 1. Right end 32 is 
positioned in gap space 17 of channel 21. In this embodiment, a 
three-sided integrally formed track liner 56 is placed in channel 21. 
Track liner 56 is formed from a high density ultra-high molecular weight 
polyethylene plastic. This produces a sliding, self-lubricating, 
plastic-on-plastic contact between polymeric panel section 14 and track 
liner 56. This embodiment is used in door guiding track of new 
construction. 
The present invention improves the operation of articulated doors and door 
guiding tracks in beverage bodies by eliminating the rollers required in 
the prior art. The rollers are replaced by a sliding, self-lubricating, 
plastic-on-plastic contact that supports and guides the articulated door 
as it is moved between the open position and the closed position, thereby 
making the door less sensitive to door frame misalignment. The door is 
held together by the hinges formed between adjacent panel sections and by 
the elastic shock cord that runs from the bottom panel section to the top 
panel section in each door. The shock cord prevents adjacent panel 
sections from moving laterally with respect to one another and holds the 
flat outer surface of each panel section flush with the flat outer 
surfaces of adjacent panel sections. 
The articulated door of the present invention will last longer than 
articulated aluminum doors of the prior art. The plastic-on-plastic 
contact in the hinges that connect adjacent panel sections can outwear the 
aluminum-on-aluminum contact in the hinges of the prior art by a factor of 
approximately 6 to 1. Although both plastic and aluminum can be steam 
cleaned, any salt, sand, or dirt that gets into an aluminum hinge will 
take a toll in wear and corrosion before it can be removed. In contrast, 
when a plastic hinge is steam cleaned and the salt, sand and dirt are 
removed, the underlying plastic surfaces of the hinge are left largely 
unaffected because the plastic used in the present invention is highly 
corrosion resistant and wear resistant. 
The articulated door of the present invention weighs less than one-half the 
weight of articulated aluminum doors of the prior art. This results in a 
weight reduction of more than 500 pounds in a typical beverage body. In 
addition, because of the door's light weight, the counterbalance used in 
articulated aluminum doors of the prior art may not be needed, further 
decreasing the cost and weight of the beverage body. 
Compared to aluminum, which is highly thermo-conductive, the plastic used 
to form the articulated door of the present invention has a very high 
insulation value. While an articulated aluminum door of the prior art will 
require a layer of insulation to be attached for use in cold climates, the 
articulated door of the present invention will not require additional 
insulation. 
The articulated door of the present invention is resilient; articulated 
aluminum doors of the prior an are not. The door is much less likely to be 
damaged from impacts and collisions than are aluminum doors of the prior 
art. If the door is impacted, the panel sections probably will not break, 
but instead may pop out of the door guiding track and the hinges that 
connect the panel sections to adjacent panel sections. Most likely the 
panel sections will not be damaged and the door can be reassembled. 
Although the present invention has been described with reference to 
preferred embodiments, workers skilled in the an will recognize that 
changes may be made in form and detail without departing from the spirit 
and scope of the invention.