Abstract:
A hatch cover ( 10 ) is engageable with a hatch ( 11 ) on a railroad car ( 13 ). The hatch cover comprises a first rib ( 30 ) and a second rib ( 32 ) running annularly about the under side of the hatch cover and has an associated first coefficient of expansion. A gasket ( 70 ) having an annular shape and a U-shaped cross-section is coupled to the first and second ribs. The gasket forms a seal between the hatch and the hatch cover. The gasket has a second coefficient of expansion which is greater than the first coefficient of expansion. As the railroad car moves through different external temperature environments, the second coefficient of expansion being greater than the first coefficient of expansion allows the gasket to remain coupled to the hatch cover and maintain the seal between the hatch cover and the hatch throughout the various temperatures experienced.

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates in general to railroad cars and, more particularly, to an apparatus for a hatch cover gasket. 
     BACKGROUND OF THE INVENTION 
     Railroad cars are used to transport goods from one location to another. Railroad cars are often loaded with goods through a hatch in the top of the railroad car. A hatch cover is used to cover the hatch. A seal is formed between the hatch cover and the hatch using a hatch cover gasket. Traditional hatch cover gaskets have been coupled to the hatch cover using small tabs or glue to retain the gasket within a channel in the hatch cover. 
     As railroad cars transport goods from one location to another, the railroad cars often experience numerous temperature changes during the journey. The temperature changes cause the hatch cover gasket to expand and contract. The expansion and contraction of the hatch cover gasket often decouples the hatch cover gasket from the associated hatch cover. Hatch cover gaskets also have a tendency to freeze onto the hatch. 
     SUMMARY OF THE INVENTION 
     From the foregoing, it may be appreciated that a need has arisen for a hatch cover gasket capable of remaining coupled to the associated hatch cover when exposed to various temperatures. According to the present invention, a system and apparatus are provided to address the shortcomings of prior hatch cover gaskets. 
     According to one embodiment of the invention, a hatch cover apparatus comprises a body formed with a first rib and a second rib, the body having a first coefficient of expansion, and a sealing element being annularly shaped and formed with a sealing element body, a first leg, and a second leg. The sealing element is engageable with the body and has a second coefficient of expansion greater than the first coefficient of expansion. 
     According to another embodiment of the invention, a system comprises a railroad car and a hatch coupled to the railroad car. The system further comprises a hatch cover engage able with the hatch and having a body, a first rib and a second rib coupled thereto, the first and second ribs having a first coefficient of expansion, and a sealing element having an annular shape and having a body, a first leg, and a second leg, the sealing element being engageable with the hatch cover and having a second coefficient of expansion greater than the first coefficient of expansion. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is best understood from the detailed description which follows, taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a side view of a railroad car having a hatch and a hatch cover; 
     FIG. 2 is a top view of the railroad car hatch cover of FIG. 1; 
     FIG. 3 is a cross-sectional view of the hatch cover along the line  3 — 3  of FIG. 2; 
     FIG. 4 is a detailed view of a portion of the hatch cover of FIG. 3, showing a plurality of channels, a plurality of ribs, and a plurality of flanges of the hatch cover; 
     FIG. 5 is a top view of the underside of the hatch cover of FIG. 1; 
     FIG. 6 is a cross-sectional view of the underside of the hatch cover along the line  6 — 6  of FIG. 5; 
     FIG. 7 is a side view of a gasket for use with the hatch cover according to the present invention; 
     FIG. 7A is a top view of the gasket of FIG. 7; 
     FIG. 7B illustrates the hatch cover engaged with the hatch of FIG. 1; 
     FIG. 8 is a cross-sectional view of the gasket of FIG. 7 coupled to the hatch cover of FIG. 1; 
     FIG. 9 is a side view of a gasket with tapered legs according to an embodiment of the present invention; 
     FIG. 10 is a side view of a gasket with legs having tapered outer walls according to an embodiment of the present invention; and 
     FIG. 11 is a side view of a gasket with legs having tapered inner walls according to an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Railroad cars transport goods inside the railroad cars, protecting the goods from damage and external contamination. The railroad cars may experience varying temperature and environmental conditions when transporting the goods. Railroad cars may include a hatch in the top of the railroad car through which goods may be placed in the railroad car. Railroad cars use a hatch cover to cover the hatch in the railroad car. The hatch cover often includes a gasket coupled to the hatch cover for forming a seal between the hatch cover and the hatch. As the railroad car experiences varying temperature and environmental conditions during transport, the gasket may fail due to repeated expansion and contraction caused by the temperature variations experienced by the railroad car. Specifically, the gasket may disconnect from the hatch cover. The disconnection of the gasket from the hatch cover breaks the integrity of the seal between the hatch cover and the hatch. The disconnection of the hatch cover may also allow the gasket to remain in engagement with the hatch after the hatch cover is removed. Removing the gasket from the hatch is time consuming and reattaching a new gasket to the hatch cover is also time consuming and expensive. The present invention involves a hatch cover gasket that remains coupled to the hatch cover and maintains a seal during temperature variations while avoiding attachment to the hatch during hatch cover removal. 
     FIG. 1 is a side view of a railroad car  13  having a hatch  11  covered by a railroad car hatch cover  10 . Railroad car  13  may be any suitable railroad car for transporting objects. In the illustrated embodiment, hatch  11  is a generally circular opening through which material may be loaded or unloaded; however, other suitable configurations for hatch  11  may be used, including rectangular and irregularly-shaped hatches. Hatch  11  is formed with a periphery  15  on which hatch cover  10  rests. 
     According to the teachings of the invention a sealing device  70  (FIG. 7) is oriented between hatch  11  and hatch cover  10  to form a seal. The coefficient of expansion of sealing device  70  is greater than the coefficient of expansion of hatch cover  10 , resulting in a better seal in varying temperatures than provided by previous systems and methods. 
     Additional details of hatch cover  10  are described below in conjunction with FIGS. 2 through 6. Sealing device  70  and its operation are described in conjunction with FIGS. 7 and 8. FIG. 2 is a top view of railroad car hatch cover  10 . Hatch cover  10  includes a flat portion  12  formed with a plurality of channels  14 . In the illustrated embodiment, hatch cover  10  is a plastic hatch cover; however, hatch cover  10  may be formed from any suitable material. For example, hatch cover  10  may be formed from aluminum or steel. 
     FIG. 3 is a cross-sectional view of hatch cover  10  along the line  3 — 3  of FIG. 2, and FIG. 4 is a detailed view of indicated portions of FIG.  3 . FIGS. 3 and 4 are described together for greater clarity. Hatch cover  10  includes a first flange inner wall  26 , a second flange inner wall  27 , a flange outer wall  28 , a first rib  30 , a second rib  32 , an outer flange  34 , an inner flange  36 , an outer channel  37 , a center channel  38 , an inner channel  39 , a rib outer wall  42 , and a rib inner wall  44 . 
     Outer flange  34  extends downwardly from an outer edge of hatch cover  10  and extends circumferentially around hatch cover  10 . In the illustrated embodiment, inner flange  36  is spaced approximately between three and five inches from outer flange  34  toward the center of hatch cover  10  with inner flange  36  preferably spaced four inches from outer flange  34 ; however, other suitable spacing may be utilized. Each of the outer and inner flanges  34  and  36  respectively include facing flange inner walls  26  and  27 . Outer flange  34  includes flange outer wall  28 . Flange outer wall  28  is disposed on the external side of outer flange  34 . In the illustrated embodiment, flange inner walls  26  and  27  have less than one degree of deflection toward each other; however, other suitable amounts of deflection toward each other may be tolerated. 
     Outer channel  37  is formed between first rib  30  and inner wall  26 . In the illustrated embodiment, outer channel  37  has a width of one inch or less; however, other suitable widths may be utilized. Outer channel  37  extends around the underside of hatch cover  10  and preferably extends around the entire underside of hatch cover  10 . 
     Center channel  38  is formed by inner wall  44  of first and second ribs  30  and  32 . In the illustrated embodiment, center channel  38  is between one and four inches in width and is preferably at least one and one-half inches in width; however, other suitable dimensions may be utilized for center channel  38 . Center channel  38  extends around the underside of hatch cover  10  and preferably extends around the entire underside of hatch cover  10 . 
     Inner channel  39  is formed between the outer wall of the second rib  32  and inner wall  26  of inner flange  36 . In the illustrated embodiment, inner channel  39  is up to one inch in width; however, other widths may be used in other embodiments. Inner channel  39  extends around the underside of hatch cover  10  and preferably extends around the entire underside of hatch cover  10 . 
     Ribs  30  and  32  extend annularly around the underside of hatch cover  10 . Ribs  30  and  32  may alternatively extend around the underside of hatch cover  10  in a manner such that the ribs  30  and  32  are continuous or non-continuous. Ribs  30  and  32  are formed from the same material as hatch cover  10 . Ribs  30  and  32  run generally parallel to each other and to outer flange  34 . Ribs  30  and  32  are tapered such that they decrease in thickness from bottom to top. In particular, a respective base portion of ribs  30  and  32  is coupled to the underside of hatch cover  10 . The respective base portions are thicker than an upper portion of ribs  30  and  32 . Ribs  30  and  32  each have respective facing inner walls  44  with up to two degrees of deflection. The ribs may be between 0.040 and 0.312 of an inch in width and in the illustrated embodiment are between 0.090 and 0.095 of an inch. In the illustrated embodiment, ribs  30  and  32  are spaced approximately 1.5 inches apart from each other, and are spaced approximately 1 inch from outer flange  34  and inner flange  36 ; however, other suitable spacing may be used. 
     In the illustrated embodiment, ribs  30  and  32  are flexible in order to respond to changes in temperature as described in more detail below in association with FIGS. 7-9. 
     FIG. 5 is a top view of the underside of the hatch cover of FIG. 1, and FIG. 6 shows a cross-sectional view of the underside of the hatch cover along lines  6 — 6  of FIG.  5 . FIGS. 5 and 6 are described together for increased clarity. Hatch cover  10  further includes a plurality of reinforcing members  50 , a date wheel  52 , and a hub  58 . Reinforcing members  50  are disposed approximately 45° from each other, but any suitable angle may be used, and are coupled at a first end to inner flange  36  and at a second end to hub  58 . In the disclosed embodiment, reinforcing members  50 , inner flange  36 , and hub  58  are formed integral with each other. Reinforcing members  50  provide structural reinforcement and support to hatch cover  10 . Date wheel  52  may be used to provide an indication of the day and date of when hatch cover  10  was molded. 
     FIG. 7 is a side view of a gasket  70  for use in forming a seal between hatch cover  10  and hatch  11 , according to the present invention. FIG. 7A is a top view of gasket  70 . FIGS. 7 and 7A are discussed together for increased clarity. According to the illustrated embodiment, gasket  70  is made from FDA vinyl 45 to 60 durometer-shore A; however, other suitable materials may be used, including 45-65 durometer-shore A Santaprene. Gasket  70  has a coefficient of expansion that relates how much gasket  70  expands with increasing temperature that is larger than the coefficient of expansion of hatch cover  10 . Gasket  70  may be formed from any suitable flexible plastic, such as polyvinyl chloride, such that the material used to form gasket  70  has a greater coefficient of expansion than the material used to form hatch cover  10 . In particular, advantageous relationships between the coefficient of expansion of gasket  70  is greater than one and less than or equal to twenty times greater than the coefficient of expansion of the hatch cover  10 . Moreover, the coefficient of expansion of gasket  70  is preferably five times greater than the coefficient of expansion of hatch cover  10 . Gasket  70  is operable to remain coupled to hatch cover  10  and sealably engaged with hatch  11  at temperatures between −40 degrees Fahrenheit and plus 140 degrees Fahrenheit, inclusive. 
     Gasket  70  includes a body  71 , a first leg  72 , a second leg  74 , and a channel  76 . Gasket  70  is annularly shaped and has a U-shaped cross-section. Body  71  is the long portion of the U-shaped cross-section of gasket  70  and a bottom surface of body  71  is engage able with hatch  11  to form a seal between hatch cover  10  and hatch  11  as shown in FIG.  8 . 
     As shown in FIG. 9, legs  72  and  74  may be tapered. As shown in FIG. 10, legs  72  and  74  may have outer walls which are tapered, and inner walls which remain unhampered. As shown in FIG. 11, legs  72  and  74  may have inner walls which are tapered and out walls which remain unhampered. 
     Legs  72  and  74  are coupled to body  71 . In the illustrated embodiment, legs  72  and  74  are press fit to body  71 . Legs  72  and  74  may be tapered. Channel  76  is generally U-shaped and is formed by body  71 , and legs  72  and  74 . As shown in FIG. 8, channel  76  interacts with ribs  30  and  32 , and legs  72  and  74  are respectively disposed within channels  37  and  39  to engage gasket  70  with hatch cover  10 . 
     FIG. 7B illustrates hatch cover  10  engaged with hatch  11 . As hatch cover  10  is engaged with hatch  11 , periphery  15  of hatch  11  engages with body  71  and the lip portion presses upwardly on body  71  and forces body  71  into center channel  38 . When hatch cover  10  is in sealing engagement with hatch  11 , periphery  15  extends partially into center channel  38 . The flexibility of gasket  70  allows body  71  to form a seal between periphery  15  and hatch cover  10 . As body  71  is forced into center channel  38 , legs  72  and  74  are pulled inwardly toward center channel  38  by body  71  and are forced to tightly grip respective ribs  30  and  32 . 
     FIG. 8 is a cross-sectional view of the gasket. Gasket  70  is press-fit onto ribs  30  and  32  such that ribs  30  and  32  are engaged with the inner walls of legs  72  and  74 . Gasket  70  is maintained in engagement with ribs  30  and  32  by friction and pressure between ribs  30  and  32  and legs  72  and  74 . At standard temperature, gasket  70  is in a rest state where legs  72  and  74  grip ribs  30  and  32  such that friction and pressure prevent gasket  70  from disengaging from ribs  30  and  32 . Ribs  30  and  32  are flexible and bend sufficiently to allow gasket  70  to firmly grip ribs  30  and  32  in the rest state. For example, ribs  30  and  32  may be formed from polyvinyl chloride or Santaprene. 
     Gasket  70  has a greater coefficient of expansion that the material used for ribs  30  and  32 . The greater coefficient of expansion of gasket  70  allows gasket  70  to remain coupled to hatch cover  10  during temperature changes. For example, in cold temperatures, hatch cover  10  will contract less than gasket  70  causing gasket  70  to press harder on the ribs  30  and  32  because gasket  70  will have contracted more than hatch cover  10 . In hot temperatures, hatch cover  10  will expand to a lesser extent than gasket  70  causing gasket  70  to press against inner walls  26  of flanges  34  and  36  because gasket  70  will have expanded to a greater extent than hatch cover  10 . 
     The present invention provides a number of technical advantages. One such technical advantage is the capability of the gasket to remain coupled to the hatch cover under various temperature conditions. The gasket is capable of maintaining a seal between the hatch cover and the hatch because the gasket does not freeze onto the hatch and does not decouple from the hatch cover. Thus, the gasket according to the present invention disengages from the hatch when the hatch cover is removed and avoids the need to remove the gasket from the hatch as is often necessary with traditional gaskets. Another advantage is that the gasket is press-fit onto the hatch cover, thus avoiding the need to glue the gasket to the hatch cover. 
     It should also be recognized that direct connections disclosed herein can be altered, such that two disclosed components or elements would be coupled to one another through an intermediate device or devices without being directly connected, while still realizing the present invention. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of the present invention, as defined by the following claims.