Patent Publication Number: US-6336411-B1

Title: Lightweight boxcar roof

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention is directed to a lightweight roof for a railroad boxcar which is formed of larger sheets of galvanized steel than have been conventionally used in the industry for boxcar roofs. 
     An object of this invention is a boxcar roof having fewer but larger roof sheets than prior boxcars to reduce the cost of installation of the roof. 
     Another object of this invention is a boxcar roof that is more resistant to leakage because fewer seam caps and thus fewer seam cap rivet passages are provided. 
     Yet another object of this invention is a lightweight roof assembly in which stronger roof panels are provided over the side door openings of the boxcar. 
     Still another object of this invention is a lightweight roof for a boxcar that is considerably lighter than conventional boxcar roofs. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 an orthographic view of a portion of the roof assembly of this invention with portions broken away; 
     FIG. 2 is a top plan view of the roof assembly portion shown in FIG. 1; 
     FIG. 3 is a cross sectional view taken along line  3 — 3  of FIG.  2  and exaggerated in a vertical direction; 
     FIG. 4 is an enlarged, cross sectional view taken along line  4 — 4  of FIG. 2; 
     FIG. 5 is an enlarged, end elevational view of a corrugation and pleats of a typical roof panel; 
     FIG. 6 is an enlarged, cross sectional view taken along line  6 — 6  of FIG. 2; 
     FIG. 7 is an exploded view of a portion of the roof panel of FIG. 1; 
     FIG. 8 is an enlarged view taken along line  8 — 8  of FIG. 2 showing an end of a seam cap supported top side plate of a boxcar; and 
     FIG. 9 is an enlarged, partial, top plan view of a seam between adjacent roof panels prior to the installation of a seam cap. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 of the drawings shows a portion of one longitudinally extending side of a boxcar roof  21  embodying the novel aspects of this invention. Such a roof  21  may be installed on boxcars of standard lengths, which in North America range from 40 to 86 feet. For clarity and conciseness of explanation, the novel aspects of the invention will be illustrated and described as they are embodied in a railroad boxcar  23  which is 60′ in length. With suitable modifications, a roof incorporating the novel aspects of this invention may also be installed on boxcars which are longer or shorter than 60′ in length. 
     The lightweight roof  21  of this invention consists of thirteen rectangular panels of galvanized steel. These panels include two rectangular end panels  25  each approximately 42⅝″ wide and formed of 12 gauge steel. The roof also includes six rectangular intermediate panels  27  each approximately 72¾″ wide and formed of 14 gauge steel. Additionally, the roof includes five rectangular door overlying panels  29  each approximately 41″ wide and formed of 14 gauge steel. The dimension of each panel, which is described as its width, extends longitudinally of the railroad car when a panel is installed as part of the roof on the boxcar. All of the panels have the same length, approximately 110 inches before forming and shearing, for a boxcar of nine feet, six inches inside width. 
     The panels  25 ,  27  and  29  are arranged starting from one end of the boxcar to the opposite end (from the right hand side to the left hand side as viewed in FIGS. 1 and 2) in the following order: an end panel  25 , three intermediate panels  27 , five door overlying panels  29 , three intermediate panels  27  and one end panel  25 . 
     Each of the panels  25 ,  27  and  29  is formed with oppositely spaced longitudinally and laterally located edges with the longitudinal edges of the panels supported on top side plates  31  (FIG. 8) which in turn are fastened to side walls  33  of the boxcar  23 . Because the longitudinally and laterally located edges of each of the three sizes of panels  25 ,  27  and  29  are similar in shape to permit the connection of contiguous panels and the support of one edge of each end panel  25  on the end walls of a boxcar, only the seam connection between an end panel  25  and an intermediate panel  27  will be shown and described in detail but it should be understood and appreciated that identical seam connections are made between contiguous panels  25 ,  27  and  29  making up the lightweight roof  21  of this invention. 
     The end panels  25  have longitudinally located edges  41  and laterally located edges, one of which  43  is flat and is supported on a top end plate  45  of the boxcar as shown in FIG.  3  and the other edge  47  is upturned as shown in FIG. 6 to form part of a roof seam  49 . Each of the intermediate and door overlying panels have a pair of upturned laterally located edges  47  which become parts of roof seams  49 . 
     Each roof seam  49  includes a seam cap  51 , shown in the exploded view of FIG. 7 of the drawings, which view depicts an upturned edge  47  of an end panel  25  prior to attachment to an upturned edge  47  of an intermediate panel  27 . The attachment between panels is made by lowering the seam cap  51  over the abutting upturned edges  47  of the panels  25  and  27  as shown in FIG. 9 to the assembly stage shown in FIG. 6 where barrel shaped roof pins  53  hold the seam cap  51  in position for the installation of cold squeeze rivets  55 . These rivets are inserted into aligned passages  57  formed in the blade portion  59  of the seam cap and the upturned edges  47  of the end panel  25  and intermediate panel  27  as shown in FIG. 7 of the drawings. Similar roof seam assemblies  49  are made between contiguous panels of the roof  21  whether the panels are of the same width or of different widths and weights exhibited by the three types of panels  25 ,  27  and  29 . 
     Novel aspects of this invention also reside in the selection of material for and the formation of the roof panels in order to obtain maximum strength and durability with minimum weight, low cost of assembly and resistance to leakage. The end panels  25  and the seam caps  51  are formed of 12 gauge galvanized steel while the panels  27  and  29  are formed of 14 gauge galvanized steel. The end panels  25  and door overlying panels  29  are each formed with two pyramidal type corrugations  61  while the intermediate panels  27  are formed with four corrugations  61 . The corrugations are of the type conventionally used for reinforcing roof panels in the railroad car building industry. Located between each pair of corrugations  61  and positioned near the longitudinally located edges of the panels are pleats  63  which take up excess metal at the edges of the panel occasioned by the forming of the corrugations  61 . 
     Formed adjacent each upturned edge  47  of a panel is a formed portion called a marginal panel  65  which blends into the upturned edge  47  of the panel as is shown most clearly in FIGS. 7 and 9. An additional pleat  63  is formed adjacent each marginal panel to absorb the excess metal. 
     As can be best seen in FIGS. 7 and 9, the longitudinally located edges of the panels are sheared at  67  to form a rectangular cutout or cope  69  between the panels. The provision a cope  69  permits the edges  47  to be bent upwardly without distorting the metal at the outer edge of each adjacent panel. A rectangular filler of  14  gauge metal  71  is welded to the undersurface of the panels and fills the rectangular cope  69  before the seam cap  51  is secured in position. The filler extends approximately ¼″ outwardly of the longitudinally located edges of the panels. The provision of a filler  71  at the outer edges of each roof seam  49  prevents the seepage of water beneath the seam cap and through the roof seam. 
     To complete the assembly, the seam caps  51  are placed over the upstanding edges  47  of the contiguous roof panels and the barrel pins  53  are inserted through the passages  57  to force the seam cap against the roof panels. The rivets  55  are then installed first in the passages  57  without roof pins. After the initial rivets are installed, the barrel pins  53  are removed and rivets are installed in the remaining passages  57 . Because of the use of intermediate panels  27  which are wider than roof panels previously used for the roofs of railroad boxcars, fewer roof seams  49  are required in the roof  21  of this invention. The use of fewer roof seams and fewer seam caps  51  results in fewer passages  57  through which water may seep.