Fiberglass railcar roof

RELATED APPLICATIONS

This is a continuation of Applicants' U.S. patent application Ser. No. 08/736,255, which was filed on Oct. 24, 1996, is entitled FIBERGLASS RAILCAR ROOF, now U.S. Pat. No. 5,916,093, and the disclosure of which is hereby incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a roof for a railcar, and more particularly to a composite fiberglass roof for use on standard, high cube, refrigerated and cryogenic railcars.

Today, the four most common types of railcars being used commercially for the transportation of cargo are standard, high cube, refrigerated and cryogenic railcars. A standard railcar, which is approximately 51 feet long, has a storage compartment that is approximately 9 feet high and 9 feet wide, with a storage area of over 4,000 ft

3

. High cube railcars are similar in construction, except they are approximately 17 feet longer and 4½ feet higher than standard railcars. This added size provides a storage area of over 8,200 ft

3

, but also includes a height that requires a shallow roof that only extends above the railcar by a few inches. The exteriors of refrigerated and cryogenic railcars closely resemble standard or high cube railcars, but their interiors are insulated. A refrigerated railcar also contains a mechanical refrigeration system, while a cryogenic railcar includes a false ceiling above which a load of cryogenic material is stored to provide the necessary cooling of the railcar and its cargo.

Each of these railcars has a roof, which is formed of galvanized steel and includes numerous individual panels that extend transverse to the railcar and are riveted, welded or otherwise bolted to each other and to the railcar's sidewalls. Steel roofs have been the industry standard for years, yet they have many disadvantages, as discussed below.

Conventional steel roofs are difficult to install on a railcar. Typically, the roof is formed from numerous individual panels that each have a 3 foot length and a width that is sized to span the distance between the railcar's sidewalls. Furthermore, each panel has an upwardly extending flange extending along both of the panel's lateral edges. Two panels are joined by placing their lateral edges next to each other and welding or riveting the flanges together. The joined flanges form a rib-like support between the panels, which must be subsequently sealed to prevent it from leaking. The roof is formed by repeating this process until enough panels have been interconnected to cover the upper surface of a railcar. This entire structure is next placed on top of a railcar, where it is welded to the railcar. The seam formed between the roof and the railcar must also be sealed. Furthermore, because the installation process can loosen or damage the seals between the individual panels, the roof must be tested to ensure it does not leak after it is installed on the railcar. Typically, the entire installation process is time-consuming and tedious, taking at least 20 man-hours to complete.

The disadvantages of using a conventional steel roof do not end once the roof is installed. An additional problem with steel roofs is that steel is expensive and extremely heavy. A conventional steel roof typically weighs more than 2,000 pounds. When mounted on a railcar, this weight raises the center of gravity of the railcar by approximately 4 or 5 inches. As a result, the railcar is less balanced and more prone to tipping. This added weight also increases the power and fuel necessary to transport the railcar, as well as the time necessary to stop the railcar.

Additional problems with steel roofs arise during their use on a railcar. As discussed, the steel roof panels typically are joined to each other and the railcar through a combination of rivets, bolts and welds, which must be sealed to prevent leakage. Even if the roof is completely sealed when first installed, the extreme vibration and torsion that the railcar and roof undergo during normal use can cause these seals, bolts and/or rivets to loosen and leak. When this occurs, water and other materials can pass through the roof, thereby exposing the railcar's cargo to possible contamination and damage.

A further disadvantage can occur when cargo is loaded into or removed from a railcar with a steel roof. During this process, the railcar's roof can be struck by cargo being loaded or removed, or struck by the mast of a forklift, which is commonly used to load and unload the railcar. Impact from this contact can deform the roof upward. Because the steel roof is inelastic, it does not return to its original position after the impact, but remains permanently deformed. In addition, when the roof is pushed or deformed upward, it may cause the sides of the railcar to collapse inward, thereby distorting the entire railcar. The entire railcar must then be removed from service for repair. Furthermore, contact to the roof of the railcar can also cause the roof to tear or puncture. A tear or puncture is difficult to patch because the roof is formed of galvanized steel. Therefore it is often necessary to remove and replace any punctured or torn roof panels.

Still another problem with conventional steel roofs is that they readily absorb heat from outside the railcar and do not allow light to enter the railcar. When the railcar is used on warm days, the steel construction of the roof quickly heats up and conducts this heat to the railcar's interior. On hot days, it is possible for the interior of a railcar to reach temperatures in excess of 100° F. Furthermore, because no light passes through the rooft external light sources must be brought into the railcar whenever the it is to be loaded or unloaded. Installing external light sources not only increases the time to load or unload the railcar, but also increases the number of obstacles that must, be avoided by workers when loading or unloading the railcar.

When a conventional steel roof is mounted on a refrigerated or cryogenic railcar, an insulating layer must be added beneath an existing steel roof. Installing this layer requires retrofitting a liner beneath the railcar's steel roof. Next, the entire roof assembly must be rigidly braced from beneath the newly installed liner. Finally, holes are drilled through the liner, and insulating material is injected though these holes. Unless the bracing and liner are very thoroughly and carefully installed, the pressure exerted by the injected insulating material is likely to cause the entire subassembly to collapse inward, thereby requiring the railcar to be cleaned and the installation process to be repeated.

In addition to this installation process, cryogenic railcars further require a false ceiling and a cryogenic supply system to be installed beneath this insulating layer. Conventional supply systems are mounted to the steel roof above the false ceiling. The ceiling typically includes individual sections that extend across the width of the railcar and are placed end-to-end beneath the supply system. If it is necessary to repair or otherwise maintain the supply system, these sections must each be removed to gain access to the supply system.

The fiberglass roof of a preferred embodiment of the invention features a composite fiberglass surface, which has a central portion and a peripheral region extending beyond the central portion. The central portion has a cross-sectional configuration that defines a first arc along the length of its cross-section. The roof also includes a plurality of spaced-apart, broad fiberglass ribs that are integrally formed in the central portion and extend both transverse to the longitudinal axis of the fiberglass surface as well as above the central portion. The ribs define a second arc that intersects the first arc. This unique, dual-arc structure, which includes broad elongate ribs, provides a fiberglass roof that is lightweight and simple, yet extremely durable and resilient. Preferably, the ribs form a unitary, seamless expanse with the fiberglass surface, and the entire roof is molded from a single sheet of composite fiberglass material.

In another embodiment of the invention, the fiberglass surface has a central portion with a lower face and a peripheral region extending beyond the central region. In this embodiment, a plurality of spaced-apart ribs are mounted on the lower face of the central portion and extend transverse to the longitudinal axis of the fiberglass surface. The ribs preferably have arcuate cross-sections, providing a fiberglass roof especially adapted for use on high cube railcars, whose height requires a roof that only extends above the railcar's sidewalls by a few inches.

Yet another embodiment of the invention is a fiberglass roof for use on cryogenic railcars. The roof includes a bunker that defines a recess for supporting cryogenic snow. A composite fiberglass surface is mounted on the bunker to enclose the recess, and an insulating layer is disposed between the bunker and the fiberglass surface. The roof further includes a manifold for delivering cryogenic material to the bunker. The manifold has a supply tube disposed below the lower surface of the bunker and a plurality of nozzles that extend from the supply tube through the bunker's lower surface and into the recess for forming cryogenic snow from the cryogenic material and for distributing the cryogenic snow within the recess.

These and other advantages are obtained by the invention, which is described below in conjunction with the accompanying drawings, in which embodiments are disclosed that may satisfy one or more of the above problems of conventional roofs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

shows a side view of the railcar roof mounted on a standard railcar. The roof includes a fiberglass surface and plural elongate fiberglass ribs that extend above the fiberglass surface.

FIG. 2

is a top plan view of the roof of FIG.

1

.

FIG. 3

is an enlarged cross-sectional view of the roof of

FIG. 1

taken generally along the line

3

—

3

in FIG.

1

and showing the roof with a peripheral region that is mounted on a railcar.

FIG. 4

is an enlarged fragmentary side sectional view of the roof of

FIG. 1

taken along the line

4

—

4

in FIG.

2

and showing the peripheral region of the roof mounted on a railcar.

FIG. 5

is an enlarged detail taken generally along the curved line

5

in

FIG. 4

, showing the peripheral region of the fiberglass surface mounted on the railcar with a structural adhesive.

FIG. 6

shows an alternate embodiment of the peripheral region shown in FIG.

5

. As shown, the peripheral region includes a fiberglass portion that is integrally formed with the fiberglass surface and a clip that is coupled to the fiberglass portion and welded to the railcar.

FIG. 7

shows an alternate embodiment of the peripheral region shown in FIG.

5

. As shown, the peripheral region includes a fiberglass portion that is integrally formed with the fiberglass surface and a weldable portion that is at least partially laminated within the fiberglass portion and is welded on the railcar.

FIG. 8

is a fragmentary top plan detail of the peripheral region of

FIG. 7

with a region of the fiberglass portion removed to show details of internal construction.

FIG. 9

shows the roof of

FIG. 1

, as shown in FIG.

4

and including an insulating layer having a ceiling liner and volume of insulating material disposed between the liner and the fiberglass surface and ribs.

FIG. 10

shows an alternate embodiment of the insulating layer shown in FIG.

9

.

FIG. 11

is a side environmental view of an alternate embodiment of the railcar roof, showing the roof mounted on a high cube railcar. The roof includes a fiberglass surface and plural broad fiberglass ribs that extend below the fiberglass surface.

FIG. 12

is a top plan view of the roof of FIG.

11

.

FIG. 13

is an enlarged cross-sectional view of the roof of

FIG. 11

taken generally along the line

13

—

13

in FIG.

11

.

FIG. 14

is an enlarged fragmentary side sectional view of the roof of

FIG. 11

taken generally along line

14

—

14

in FIG.

12

.

FIG. 15

is an enlarged cross-sectional detail taken along the curved line

15

in FIG.

14

and showing the details of internal construction of the ribs and fiberglass surface.

FIG. 16

is an enlarged detail taken along the line

16

—

16

in FIG.

12

and showing a lap joint that connects two halves of the roof of FIG.

11

.

FIG. 17

shows the roof of

FIG. 11

, as shown in FIG.

14

and including an insulating layer having a ceiling liner and a volume of insulating material disposed between the liner and the fiberglass surface and ribs.

FIG. 18

shows an alternate embodiment of the insulating layer of FIG.

17

.

FIG. 19

is a fragmentary isometric view of an alternate embodiment of the railcar roof of

FIG. 1

positioned above the upper surface of a railcar. As shown, the roof is configured for use on a cryogenic railcar and includes a fiberglass surface with elongate ribs, a bunker and an insulating layer disposed between the fiberglass surface and the bunker.

FIG. 20

is a fragmentary top plan view of the roof of FIG.

14

.

FIG. 21

is a side sectional view of the roof of

FIG. 19

taken along line

21

—

21

in FIG.

20

.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A fiberglass railcar roof constructed according to the present invention is shown in

FIGS. 1 and 2

, and is generally indicated at

10

. As shown, roof

10

is mounted on the upper surface of a standard railcar, which is generally indicated at

20

and includes opposed sidewalls and end walls and a door. The sidewalls and end walls have upper edges that are collectively referred to as the railcar's upper surface. This upper surface is indicated generally at

21

in FIG.

1

. Details of railcar

20

and upper surface

21

will differ depending upon the particular manufacturer and intended use of the railcar, and form no part of the invention.

Roof

10

includes a fiberglass surface

12

that covers and extends across the entire upper surface of railcar

20

. Fiberglass surface

12

has a generally rectangular central portion

14

and a peripheral region

16

that extends beyond the central portion. Specifically, peripheral region

16

has a generally planar configuration and extends outward from the entire perimeter of central portion

14

to engage the railcar's upper surface

21

. When used on a standard railcar, central portion

14

is approximately 9 feet wide and over 50 feet long. Peripheral region

16

extends beyond the central portion's entire perimeter by approximately 3 inches.

Roof

10

further includes a plurality of spaced-apart, broad fiberglass ribs

18

. The ribs are elongate and extend transverse to the longitudinal axis of the fiberglass surface, which is generally indicated at

22

in FIG.

2

. The ribs further extend above central portion

14

. Preferably, ribs

18

are integrally formed, or molded, in central portion

14

, thereby producing a roof having a unitary, seamless expanse. As shown in

FIGS. 1 and 2

, ribs

18

are spaced along the entire central portion of fiberglass surface

12

and define intermediate regions

24

of central portion

14

between adjacent ribs. Ribs

18

have inclined sidewalls

23

and flat tops

25

.

As mentioned above, the ribs have relatively broad widths. As shown in

FIGS. 2 and 3

, each rib

18

spans central portion

14

and has a width, measured parallel to the longitudinal axis

22

of the fiberglass surface, that is approximately 22% of rib's length. Furthermore, each intermediate region

24

has a width that is approximately 54% of the width of each rib. Preferably, ribs

18

are approximately 9 feet long and two feet wide, and define intermediate regions that are approximately 9 feet wide and 16½ inches wide. It should be understood, however, that other configurations are possible and are within the scope of the invention. Each rib should have a width that is at least 10% of the rib's length. Additionally, the width of each intermediate region is preferably less than 75% of the width of each rib. This configuration of broad, elongate ribs provides an configuration that can be molded in a single, completely fiberglass unit.

A cross-sectional view of roof

10

is illustrated in FIG.

3

. As shown, central portion

14

has a generally arched or bowed cross-sectional configuration that extends above the peripheral region to define a first arc, which is indicated at

26

and preferably extends along the entire width of the central portion. Ribs

18

each extend above the central portion and define a second arc, which intersects the first arc and is generally indicated at

28

. Preferably, each rib

18

defines a second arc along the entire length of the rib. In the preferred embodiment shown in

FIG. 3

, the first and second arcs have radii of approximately 122 feet, 1 inch and 24 feet, 7 inches, respectively. It should be understood that the degree of curvature on the arcs shown in

FIG. 3

have been exaggerated for purposes of illustration. The arcs intersect proximate the points where peripheral region

16

joins the central portion. This dual-arc configuration provides a roof that is capable of supporting significant loads. Specifically, roof

10

is capable of supporting a 15 lb/ft

2

snow load and a 300 lb point load anywhere across its surface. Furthermore, roof

10

will only deflect downward a maximum of one inch, as mandated in the standards established by the American Association of Railroads.

Preferably, roof

10

includes at least one layer of woven roving fiberglass, forming a generally planar framework of strands extending generally perpendicular to each other. This provides additional strength to the roof in both longitudinal and transverse directions. Even more preferably, the woven roving layer is laminated between additional layers of fiberglass material. One convenient and relatively inexpensive way to provide this construction is to begin with a layer of “Combomat,” which is manufactured by Johnston Materials, Inc. and which contains a layer of woven roving fiberglass material stitched to a layer of chop strand, or randomly oriented, fiberglass material. A second layer of chop strand fiberglass material is then laminated to the exposed woven roving side.

Besides providing significant strength and resilience to the previously described root, the composite fiberglass construction of the roof also significantly reduces the roof's weight when compared to conventional steel roofs. Specifically, the composite fiberglass roof shown in

FIGS. 1-4

weighs approximately 60% to 70% less than a comparable steel roof. In addition, the upper face of roof

10

is preferably covered with a translucent UV-resistant coating, which not only allows external light to pass through the roof to illuminate the interior of an attached railcar, but also reflects heat away from the roof.

A further advantage of the roof's composite fiberglass construction, and especially the roof's woven roving fiberglass construction, is that the roof is extremely resistant to puncturing or tearing. Unlike steel roofs that are prone to tearing or permanent deformation, the unique configuration and woven construction of roof

10

provides a resilient surface capable of deflecting upwards at least 4 or 5 inches without tearing or causing the sides of the railcar to collapse inward. When the impact force that deformed the roof is removed, roof

10

resiliently returns to its prior, unstressed configuration. If the applied force is strong enough and localized enough to pierce the roof, its woven fiberglass construction constrains the tear to a minimal area. Furthermore, unlike galvanized steel roofs, roof

10

may be readily patched with another piece of fiberglass, even while the attached railcar is still in service.

The preferred method of mounting the peripheral region

16

of the roof on the upper surface

21

of the railcar is to use a structural adhesive, such as Lord Adhesives' Lord No. 410/#19 acrylic adhesive or a suitable equivalent. As shown in

FIG. 5

, a layer of adhesive, which is generally indicated at

30

and is enlarged for purposes of illustration, is disposed between the railcar's upper surface

21

and the peripheral region

16

of roof

10

. This adhesive bond between roof

10

and the railcar's upper surface

21

has proven to be extremely strong and reliable. Furthermore, by using a structural adhesive to mount the roof on the railcar, the entire installation procedure can be completed in a just 3 or 4 man-hours, a fraction of the time it would take to install an equivalent steel roof. Another advantage of this method of attachment is that it does not require any additional holes to be drilled into the roof or the railcar. This is preferable because any hole or aperture in the railcar increases the possibility that water or other material can enter the railcar and contaminate the railcar's cargo.

Alternate embodiments of peripheral region

16

are shown in

FIGS. 6 and 7

and are indicated generally at

16

a

and

16

b.

respectively. In these embodiments, the peripheral region includes a fiberglass portion

34

, which is preferably integrally formed with fiberglass surface

12

, and a metallic, or weldable, portion

36

that is coupled to and extends beyond the fiberglass portion. In

FIG. 6

, weldable portion

36

includes a clip

38

, which is preferably constructed of galvanized steel. As shown, clip

38

has a first portion

40

that is welded to the railcar's upper surface

21

. Clip

38

also has a second portion

42

that jackets at least a portion of fiberglass portion

34

and is coupled to this fiberglass portion by a structural adhesive

30

, such as the previously described adhesive from Lord Adhesives.

In

FIG. 7

, another embodiment of weldable portion

36

is shown, as is generally indicated at

36

a.

In this embodiment, weldable portion

36

a

has a generally planar configuration and is constructed of galvanized steel. Weldable portion

36

a

has a first portion

40

a

which is welded to upper surface

21

, and a second portion

42

a

that is at least partially laminated within fiberglass portion

34

. As shown in

FIGS. 7 and 8

, second portion

42

a

includes a plurality of spaced through-holes

44

along its length. Fiberglass portion

34

includes an upper layer

34

a

and a lower layer

34

b

which collectively define a slot

45

for receiving portion

36

a.

During the forming process for fiberglass portion

34

, the second portion of weldable portion

36

a

is inserted between layers

34

a

and

34

b,

where it is subsequently laminated and sealed between these layers. As shown, layers

34

a

and

36

b

each at least partially extrudes into through-hole

44

. Once fully cured, the weldable portion is firmly and permanently united with roof

10

.

It should be understood that weldable portions

36

and

36

a

could be attached to the railcar by methods other than welding. For example, the previously described structural adhesive could be used to bond these pieces together. Additionally, other suitable forums of mechanical attachment, such as rivets or bolts, could be used. Gluing is preferred, however, because it does not introduce additional holes into the roof or railcar and also does not require an additional sealing step.

When roof

10

is to be used on a refrigerated railcar, it is preferable for the roof to include an insulating layer. As shown in

FIG. 9

, insulating layer

46

is positioned beneath the bottom surface formed by ribs

18

and fiberglass surface

12

and is specifically configured to mate with this bottom surface. The layer includes a ceiling liner

48

which is coupled to the peripheral region of roof

10

. The ceiling liner is substantially coextensive with roof

10

and is preferably formed of a fiberglass material. Ceiling layer

48

and the lower surfaces of ribs

18

and central portion

14

define a cavity

50

that is filled with an insulating material

52

. Preferably, insulating material is formed of a closed-cell foam, which resists moisture absorption.

An alternate embodiment of insulating layer

46

is shown in FIG.

10

and generally indicated at

46

a.

In this embodiment, ceiling liner

48

a

extends below upper surface

21

and into the railcar's storage area. As shown, this results in a thicker insulating layer

46

a.

Similar to the first embodiment, insulating material

52

a

completely fills the cavity

50

a

defined between ceiling liner

48

a

and the lower surfaces of ribs

18

and central portion

14

.

The previously described fiberglass roof, with its dual-arc cross-sectional configuration and broad elongate ribs, offers all of the features and advantages discussed above, and throughout this description, while avoiding essentially all manners of drawbacks that characterized conventional steel railcar roofs. Roof

10

is well suited to be used on all standard and intermediate height railcars, and its molded fiberglass construction makes the roof readily adaptable to specific railcar configurations. Nonetheless, when a fiberglass roof is to be used on a high cube railcar, it is often necessary to use an alternate embodiment of the invention because a roof that extends more than a few inches above the railcar would result in the railcar being unable to pass through many existing tunnels. Therefore, an alternate embodiment of roof

10

is needed for use on these high cube railcars.

Indicated at

110

in

FIG. 11

is a fiberglass roof constructed in accordance with the present invention, and particularly suited for use on a high cube railcar. The upper portion of a high cube railcar is indicated at

120

and has an upper surface

121

on which roof

110

is mounted. It should be understood that railcar

120

forms no part of the invention.

As shown in

FIGS. 11-12

, roof

110

includes a composite fiberglass surface

112

with a central portion

114

that extends above a peripheral region

116

and has a lower face

118

. The central portion preferably has a cross-section that defines an arc along its length, as shown in FIG.

13

. Peripheral region

116

extends beyond central portion

114

and preferably has a generally planar configuration that extends outward from the entire perimeter of central portion

114

. As shown, fiberglass surface

112

is very similar in size and materials of construction as the previously described fiberglass surface of roof

10

, except surface

112

is usually longer than fiberglass surface

12

because high cube railcars are typically approximately 17 feet longer than standard railcars. The fiberglass surface is constructed of the same composite fiberglass material as surface

12

and may be formed in one large, unitary expanse. It should be understood that roof

110

is specifically designed for use on high cube railcars, but it may also be used on standard or intermediate sized railcars.

As discussed, roof

110

contains a peripheral region

116

that extends beyond the roof's central portion

114

. Preferably, peripheral region

116

is integrally formed with the central portion of the roof and is mounted on the upper surface of railcar

120

using a structural adhesive, as shown at

123

in FIG.

14

. This method of mounting the roof on a railcar was described in detail with respect to roof

10

and is equally applicable to roof

110

. Additionally, the alternate embodiments of the peripheral region described with respect to roof

10

are also equally applicable to roof

110

.

Roof

110

further includes plural elongate ribs

122

that are mounted on the lower face of central portion

114

and extend transverse to the longitudinal axis of the fiberglass surface, which is indicated generally at

124

in FIG.

20

. Preferably, ribs

122

extend downward from lower face

118

no further than peripheral region

116

and have arcuate cross-sections, as shown in FIG.

14

. On a conventional high cube railcar with a length of approximately 68 feet and a width of approximately 9½ feet, ribs

122

are preferably 9 feet long, approximately 5 inches wide and spaced approximately 4 feet apart from each other. Furthermore, ribs

122

are preferably formed of a composite fiberglass material, such as the woven roving fiberglass construction discussed previously.

This unique configuration provides a durable and resilient roof that is capable of withstanding extreme forces and loads. Roof

110

preferably extends above the upper surface of railcar

120

no further than 3 inches. The unique arcuate composite fiberglass construction of ribs

122

, in conjunction with the resilient nature of fiberglass surface

112

, produces a roof that is resistant to ripping or tearing. When the lower face of the roof is struck by the mast of a forklift or by cargo being loaded into and removed from the railcar, the roof

110

will temporarily deform upward until the force is gone. After this, the resilient nature of roof

110

returns the roof to its original position. Additionally, the resilient, arcuate configuration of ribs

122

causes the mast or cargo that impact the ribs to glance off the ribs rather than firmly engaging the ribs and possibly tearing or otherwise deforming the roof.

Ribs

122

may be integrally formed on the lower face

118

of the roof's central portion

114

. The preferred method of manufacturing roof

110

, however, is to begin with independent, pre-formed ribs are formed of a composite fiberglass material such as the material described previously with respect to roof

10

. Next, fiberglass surface

112

is molded from a similar composite fiberglass material. Before the fiberglass surface completely cures, the pre-formed ribs are positioned in a spaced relationship on the lower face of the fiberglass surface. Because the fiberglass surface is still tacky, the ribs and fiberglass surface adhere to each other and are firmly united once the fiberglass surface completely cures. After bonding the ribs to the fiberglass surface, it is preferred that an additional layer of fiberglass material is placed over at least the regions at which the ribs and fiberglass surface are in contact with each other. This configuration is illustrated in

FIG. 15

, where fiberglass layer

126

overlays and protects ribs

122

and lower face

118

. Other methods of attaching ribs

122

to fiberglass surface

112

are possible and are within the scope of the invention. For example, the ribs could be attached to fiberglass surface

122

using a structural adhesive, such as the previously described adhesive manufactured by Lord Adhesives.

While the fiberglass surface has been described as being formed in one broad unitary expanse, it is often desirable to form this surface in two or more sections that are joined by a lap joint or other suitable form of interconnection. A lap joint is preferred, however, because it does not introduce additional holes to the roof structure. By referring briefly back to

FIGS. 11 and 12

, one can see that roof

110

includes a first section

134

and a second section

136

, which are joined by lap joint

138

. Lap joint

138

is illustrated in greater detail FIG.

16

. As shown, the first section

134

terminates and rests on portion

140

of the second section. Sections

134

and

136

are preferably overlap by approximately 6 inches and are joined by a structural adhesive, which is indicated at

142

in FIG.

16

. It should be understood that the roof shown in

FIGS. 1-10

could incorporate a similar sectional configuration. Nonetheless, the preferred form of roofs

10

and

110

is a single, unitary fiberglass surface. This construction provides the greatest possible strength to the roofs and results in the minimum number of seams or seals in the roofs.

When used on a refrigerated, high cube railcar, roof

110

includes an insulating layer similar to layer

46

described with respect to roof

10

. As shown in

FIG. 17

, the insulating layer is indicated at

146

and includes a ceiling liner

148

disposed beneath ribs

122

and fiberglass surface

112

. The liner is coupled to fiberglass surface

112

adjacent or at the surface's peripheral region

116

and defines a cavity into which insulating material is placed. Preferably, the insulating material is a foamed closed-cell material that is injected into cavity

150

, where is subsequently hardens. As shown in

FIG. 17

, insulating material

152

completely fills cavity

150

, which is bounded by ceiling liner

148

and the surface formed by ribs

122

and fiberglass surface

112

. When a roof is desired that has greater insulating properties than the roof shown in

FIG. 17

, the ceiling liner should extend below the upper surface

121

of railcar

120

and into the railcar's storage area. As illustrated in

FIG. 18

, insulating layer

146

a

includes a ceiling liner

148

a

that extends into the storage area of railcar

120

. This results in a cavity

150

a

with a much greater volume than the cavity shown in FIG.

17

. Cavity

150

a

is preferably completely filled with insulating material

152

a.

A further application of the previously described fiberglass roof is for use on a cryogenic railcar. Cryogenic railcars differ from refrigerated railcars in that they do not include a mechanical refrigeration system. Instead, these railcars have a false ceiling, which defines a bunker into which cryogenic material is stored. Typically, the bunker receives an initial charge of cryogenic material from an external source. This initial charge provides the necessary cooling of the railcar's contents and typically lasts for many days or even weeks.

In this embodiment of the invention, the roof includes either of the previously described roofs

10

and

110

with their respective insulating layers

46

and

146

. For purposes of illustration, the roof is generally indicated at

210

in

FIGS. 19-21

and includes the previously described roof

10

. In addition, to increase the life of the charged cryogenic material, roof

210

is shown incorporating the previously described insulating layer

46

a.

It should be understood, however, that any of the previously described embodiments or their suitable equivalents could be used.

As shown in

FIG. 19

, roof

210

is positioned above the upper surface of a railcar, which is indicated generally at

232

as forms no part of the invention. As shown, the roof includes a composite fiberglass surface

212

and an insulating layer

214

. As discussed, fiberglass surface

212

is shown as being the previously described roof

10

, and insulating layer

214

is the previously described layer

46

a.

In this embodiment, the interconnection and construction of surface

212

and layer

214

are unchanged, and for brevity's sake, will not be repeated. Roof

210

further includes a bunker

216

for supporting cryogenic snow (not shown). Bunker

216

has a lower surface

218

and walls

220

that collectively define a recess

222

within the bunker. Preferably the bunker is generally comprised of a composite fiberglass material, such as the material described with respect to roof

10

. In the preferred embodiment, the lower surface of bunker

216

includes a balsa layer laminated between layers of stitch mat and is arched or bowed upward by approximately 1 inch to have a generally arcuate cross-sectional configuration. This arched, laminated-balsa construction of the bunker's lower surface enables it to support large quantities of cryogenic snow. For example, a cryogenic railcar is typically charged with approximately 16,000 to 18,000 pounds of cryogenic snow. The degree of curvature of lower surface may vary depending on the amount of cryogenic snow the bunker is designed to support.

As shown in

FIG. 19

, the bunker's walls

220

extend upward from lower surface

218

and terminate with a flange-like peripheral region

226

. Preferably, walls

220

are approximately 10 inches high. Peripheral region

226

has an upper surface

228

, which is coupled to insulating layer

214

and fiberglass surface

212

, and a lower surface

230

that is mounted on the upper surface of a railcar. Preferably peripheral region

226

is mounted on this upper surface

232

with a structural adhesive. It should be understood, however, that peripheral region

226

could encompass any of the embodiments described with respect to roofs

10

and

110

. The railcar's upper surface often includes an inwardly extending shoulder

233

on which the bunker's lower surface

218

is seated and supported, as shown in FIG.

21

.

Roof

210

also includes a manifold for delivering cryogenic material to bunker

216

. As shown in

FIGS. 19-21

and indicated generally at

234

, the manifold includes a supply tube

236

, which is disposed below the bunker's lower surface

218

. Preferably, supply tube

236

extends generally parallel to the bunker's longitudinal axis, and nozzles

238

are spaced approximately 2½ to 3 feet-apart along the entire length of supply tube

236

. Additionally, the lower surface of bunker

216

preferably defines a channel

242

that extends upwardly into recess

222

and into which supply tube

236

is received. A generally planar mounting plate

234

is coupled to the bottom face of lower surface

218

to enclose the supply tube within channel

242

. Plate

244

not only supports the supply tube within channel

242

, but it also protects the tube from being struck and/or damaged by cargo or other objects within the railcar. Furthermore, by receiving the supply tube into an upwardly extending channel, the bottom face of the bunker's lower surface retains a generally smooth, continuous configuration. This is preferable because it increases the storage capacity of the railcar and reduces the possibility of the supply tube being damaged while the railcar is in use.

Manifold

234

also includes a plurality of nozzles

238

that are connected to and extend upward from the supply tube through the lower surface of the bunker. Nozzles

238

further extend into recess

222

for forming cryogenic snow from cryogenic material and for distributing the cryogenic snow within the recess. It is preferred that the nozzles may be easily removed from and reattached to the supply tube to allow the nozzles to be cleaned, repaired or replaced, as needed. One suitable way to accomplish this is to use nozzles that have threaded lower portions, which are screwed into the supply tube. Additionally, each nozzle

238

often includes a fastening mechanism, such as a threaded washer or bolt, that is retained on the threaded portion of the nozzle and is used to draw the supply tube into firm engagement with the lower surface of the bunker.

Also seen in

FIGS. 19-21

are a plurality of spaced ports that extend through the bunker's lower surface

218

. Ports

246

further extend upwardly into recess

222

and are each covered with a fine mesh or screen

248

. Each screen

248

is pivotably mounted on its associated port to provide access to nozzles

238

and the inside of bunker

216

from the interior of the railcar. As shown, the ports are selectively spaced along the bunker's lower surface on alternating sides of channel

242

. Preferably, ports

246

are selectively sized and spaced to enable a user to reach through a port to access the nozzles. As shown, ports

246

have generally square configurations, with each side having a length of approximately 12 inches, thereby defining a port with a cross-sectional area of 144 square inches. Furthermore, the ports are spaced so that every nozzle is approximately 18 inches from at least one port. This selective sizing and spacing enables a user to access the nozzles without having to disassemble the roof

To charge bunker

216

with cryogenic snow, supply tube

236

is connected to an external supply, which delivers cryogenic material under pressure to the supply tube. Preferably, at least one end of supply tube

236

extends through one of the railcar's walls, where it can be connected to an external supply of cryogenic material. The other end of supply tube

236

is sealed, as shown in FIG.

19

. Generally, this cryogenic material is liquid carbon dioxide. For purposes of illustration, this charging process is described using carbon dioxide, although it should be understood that other cryogenic material may be used and is within the scope of the invention. The supplied liquid carbon dioxide is transported through supply tube

236

to nozzles

238

, where it is expelled into recess

222

. It should be understood that the pressure external nozzles

238

is significantly less than the pressure at which the cryogenic material is delivered. Therefore, once the liquid carbon dioxide is expelled from nozzles

238

, it “flashes” and instantaneously forms cryogenic snow, namely, solid carbon dioxide (commonly known as dry ice) and carbon dioxide gas. The gaseous carbon dioxide immediately passes through ports

246

into the railcar, where it is vented out of the railcar. The solid carbon dioxide is retained within and fills bunker

216

. Typically, between approximately 50% and 60% of the supplied liquid carbon dioxide is immediately converted to gaseous carbon dioxide and vented from the railcar. The remaining material, now solid carbon dioxide, is retained within the bunker and slowly sublimates (changes directly to gas) over a period of many days or even weeks. During this sublimation process, the solid and gaseous carbon dioxide maintains the railcar's storage area at a cryogenic temperature.

While the invention has been disclosed in its preferred form, the specific embodiments thereof as disclosed and illustrated herein are not to be considered in a limiting sense as numerous variations are possible. Applicants regard the subject matter of the invention to include all novel and non-obvious combinations and subcombinations of the various elements, features, functions and/or properties disclosed herein. No single feature, function, element or property of the disclosed embodiments is essential. The following claims define certain combinations and subcombinations that are regarded as novel and non-obvious. Other combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such claims, whether they are broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of Applicants' invention.