Patent Publication Number: US-6704991-B1

Title: Method for forming a railway car with improved crosstie connections

Description:
RELATED APPLICATIONS 
     This application claims the benefit of previously filed provisional application Ser. No. 60/160,552 filed Oct. 20, 1999 entitled Railway Car with Improved Crosstie Connections. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     This invention relates to a railway car having crosstie connections with improved fatigue life and more particularly to an apparatus and method which reduce or eliminate stress related fatigue cracks in an associated weld between two structural members joined to each other at approximately a right angle. 
     BACKGROUND OF THE INVENTION 
     All railroads have a maximum limit on the total amount of weight which may be safely placed upon the associated railway tracks. The total load carrying capability of railway tracks and railway cars may vary substantially depending upon various design parameters. Since there are other limits as to the total amount of weight which may be safely supported by a pair of tracks, there is a continuous ongoing desire within the railway industry to increase the weight of cargo or lading which may be transported within a railway car while at the same time reducing the unloaded or “light weight” of the respective railway car. Many railway cars used to transport freight often have a railway car underframe defined in part by a pair of side sills and a pair of end sills joined with each other in a generally elongated, rectangular configuration. 
     One or more transverse members may be attached to the side sills and spaced from each other intermediate the end sills. Such transverse members are typically provided to support the side sills and/or cargo carried by the associated railway car. For some applications such as well cars, transverse members which support cargo or lading are sometimes referred to as crossbearers. Transverse members which support associated side sills may sometimes be referred to as crossties. 
     During the past several years, railway cars have been developed for use in transporting various types of containers associated with intermodal transportation systems. Such railway cars often have a depressed floor section disposed between a pair of longitudinally extending side structures and transverse end structures. Such railway cars may sometimes be referred to as well cars. Multiple transverse members or crossties are typically disposed between the longitudinal side structures and spaced from each other intermediate the associated end structures. Some of the transverse members, often referred to as “loadbearing cross members or crossbearers” may be used to support containers or other types of lading carried within such well cars. Other transverse members, often referred to as crossties, may be used to provide structural support for the associated longitudinal side structures and more particularly the associated side sills. U.S. Pat. No. 4,805,539 entitled “Well Car End Structure Having Frameless Radial Truck” and U.S. Pat. No. 5,562,046 entitled “Load Bearing Cross Bearer Connection” provide examples of such well cars and associated transverse members. 
     Well cars may sometimes be described as a flatcar with a depression or opening in the center to allow the load to extend below the normal floor level so that the load will not extend above applicable overhead clearance limits. The configuration of a typical well car generally results in the lading or cargo placing multi-directional loads on the associated side sills. Crossties are often provided to cooperate with the side sills to distribute and transmit loads associated with transporting lading by the well car. These loads typically cause relatively high stresses in the structural components of the side sill and crossties. Often welds are formed between the ends of a typical crosstie and respective portions of the side sills of the railway car. The configuration of the end of a typical crosstie and adjacent portion of a side sill frequently results in notches being formed at the end of one or more welds used to connect the crosstie with the side sill. The notches may function as stress risers which in combination with relative high stresses present in the side sill substantially reduce the fatigue life of the associated weld and compromise the integrity of the connection formed between the crosstie and side sill. 
     Various types of mechanical fasteners, fittings and welding techniques have been used to join a first structural member to a second structural member at an angle of approximately ninety degrees relative to each other. For some applications an appropriately sized end plate has been attached to one end of a first structural member for use in providing a desired connection with a second structural member. 
     SUMMARY OF THE INVENTION 
     The present invention includes an apparatus and method to form a weld attachment between two structural members joined to each other at approximately a right angle and minimizes potential for fatigue cracking of an associated weld. Transverse members of a railway car underframe and associated side sills are examples of such structural members. 
     One aspect of the present invention includes a transverse member or crosstie having end plates incorporating teachings of the present invention secured to opposite ends thereof for use in connecting the crosstie with respective portions of an associated railway car side sills. The end plates are preferably substantially enlarged as compared to the cross section of the associated transverse member to increase the amount of weld contact between the resulting weld attachment and respective portions of the side sills. The configuration and size of the end plates and resulting weld attachment are preferably selected, in accordance with teachings of the present invention, to minimize the effects of any abrupt change in cross section between the transverse member and the side sills. 
     For one embodiment a railway car is provided with a plurality of weld attachments having end plates and respective bolts extending through the end plates and adjacent portions of the railway car. Coupling a respective bolt to the end plate and adjacent portions of the railway car proximate each end of the associated weld attachment substantially reduces or eliminates stress risers, and thus reduces or eliminates any tendency for one or more fatigue cracks to develop in the vicinity of an associated weld. When loads are transferred between a first structural member such as a crosstie and a second structural member such as a side sill, the bolts will preferably absorb or pickup a substantial amount of the load being transferred and reduce peak stresses at the ends of the associated weld. The present invention allows a weld attachment and associated weld to join a crosstie with an associated side sill in a manner that substantially reduces or eliminates any potential for fatigue cracking of the weld. 
     Technical benefits include using an end plate formed as part of a press fitting in accordance with teachings of the present invention to provide a weld attachment or weldment which substantially increases the fatigue life of an associated weld. The end plate may also be formed as a part of a casting or forging to provide a weld attachment or weldment incorporating teachings of the present invention. The present invention allows selecting the optimum configuration and dimensions for an end plate and resulting weld attachment to minimize stress risers and any corresponding tendency of an associated weld to develop one or more fatigue cracks. For one embodiment the pressed fitting is preferably flared along each side to provide increased weld area and to also reduce the effect of any abrupt change in cross section between a first structural member connected to a second structural member at approximately a right angle. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following written description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a schematic drawing showing a plan view of one unit of a railway car incorporating teachings of the present invention; 
     FIG. 2 is a schematic drawing in elevation showing a side view of the unit of the railway car of FIG. 1; 
     FIG. 3 is a schematic drawing in section with portions broken away taken along lines  3 — 3  of FIG. 1; 
     FIG. 4 is a schematic drawing showing an isometric view with portions broken away of a crosstie member having a weld attachment or weldment disposed on one end thereof and connected to a selected portion of a side sill in accordance with teachings of the present invention; and 
     FIG. 5 is an isometric drawing showing an exploded view with portions broken away of the connection between the crosstie member and side sill of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the present invention and its advantages are best understood by referring to FIGS. 1-5 of the drawings, like numerals being used for like and corresponding parts of the various drawings. 
     Railway car  20  incorporating teachings of the present invention is shown in FIGS. 1 and 2. Railway car  20  may be generally described as a “well car” satisfactory for carrying cargo containers (not expressly shown) used in intermodal transportation systems or other types of lading. For some applications railway car  20  incorporating teachings of the present invention may represent one unit of a multiple unit articulated well car. For other applications railway car  20  may represent a single unit well car. Therefore, railway car  20  may include coupling assemblies and railway car trucks appropriate for an articulated railway car or alternatively coupling assemblies and trucks appropriate for a single unit well car. Railway car  20  may be designed to accommodate a single stack or a double stack of cargo containers. 
     For one application railway car or well car  20  may represent one unit of a three unit articulated railway car (not expressly shown) having weld attachments formed in accordance with teachings of the present invention to connect a plurality of crossties with selected portions of associated side sills. For this application well car  20  may be designed to meet the requirements of the Association of American Railroads (AAR) Clearance Plate H plus one inch and associated structural design specifications. Well car  20  may also be designed such that the lowest portion of well car  20  is no closer than two and three quarters of an inch above the top of the associated rails as determined by applicable AAR specifications. 
     Railway car  20  preferably includes end assemblies  21  and  22  with respective side assemblies  31  and  32  attached to and extending longitudinally between end assemblies  21  and  22 . End assemblies  21  and  22  are mounted on respective railway car trucks  24 . Side assemblies  31  and  32  are preferably spaced laterally from each other and extend generally parallel with each other between end assemblies  21  and  22 . Side assemblies  31  and  32  cooperate with end assemblies  21  and  22  to define, in part, cargo carrying space  26  disposed therebetween. A portion of cargo carrying space  26  is depressed or extends below the normal floor level typically associated with a railway car having trucks  24 . The configuration and dimensions associated with end assemblies  21  and  22  and side assemblies  31  and  32  are preferably selected to provide cargo carrying area  26  which is compatible with applicable overhead clearance limits and the type of containers or other lading which will be transported by railway car  20 . 
     Various components of end assemblies  21  and  22  and side assemblies  31  and  32  are attached to and/or from a portion of railway car underframe  28 . Two of these components include side sills  33  and  34 . A plurality of transverse members such as load bearing cross members or crossbearers  36  and crossties  38  are preferably attached to and extend laterally between side sills  33  and  34 . Transverse members  36  and  38  are preferably spaced longitudinally from each other and end assemblies  21  and  22 . The number, size and location of transverse members  36  and  38  is dependent upon the load carrying capacity and applicable AAR specifications for railway car  20 . Crossbearers  36  often include one or more container supports and/or guides (not expressly shown) for securing one or more containers (not expressly shown) at a desired location within cargo space  26 . 
     Side assemblies  31  and  32  are preferably attached to and extend longitudinally along respective side sills  33  and  34 . A plurality of side stakes  40  extend vertically from respective side sills  33  and  34  and top chords  41  and  42 . For some applications, top chords  41  and  42  may be described as hollow, elongated metal tubes having a generally rectangular cross section. For the embodiment shown in FIGS. 1,  2  and  3 , side stakes  40  may also be described as hollow, channels having a generally U-shaped cross section. The length of each side stake  40  is defined in part by the distance between side sills  33  and  34  and respective top chords  41  and  42 . For purposes of describing various features of the present invention, the wall or portion of each side stake  40  immediately adjacent to cargo space  26  has been designated  126 . The wall or portion of each side stake  40  opposite from cargo space  26  has been designated  127 . 
     FIG. 3 is a schematic drawing with portions broken away showing a cross section of side wall assemblies  31  and  32  along with one of the crossties  38 . The number, dimensions, configuration and materials used to form crossties  38  are selected to provide desired structural support for the associated side sills  33  and  34 . Connections or weld attachments  51  and  52  are preferably formed, in accordances with teachings of the present invention, between respective ends of each crosstie  38  and selected portions of side sills  33  and  34 . Connections  51  and  52  on each crosstie  38  preferably have substantially the same configuration and dimensions. Therefore, only connection or weld attachment  51  will be discussed in detail. 
     For the embodiment of the present invention [as] shown in FIGS. 3,  4  and  5 , crosstie  38  may be generally described as a hollow metal tube having a generally rectangular cross section. Respective end plates  50  incorporating teachings of the present invention are preferably attached to opposite ends of crosstie  38 . As discussed later in more detail, each end plate  50  is preferably attached to a selected portion of respective side sills  33  and  34  by mechanical fasteners and at least one weld. 
     First surface or top surface  44  of crosstie  38  extends between selected portions of side sills  33  and  34 . The length of top surface  44  plus the thickness of the associated end plate  50  is approximately equal to the lateral distance between side sills  33  and  34 . Second surface or bottom surface  46  of crosstie  38  is preferably reduced in length to allow respective press fittings  54 , with end plate  50  formed as an integral component thereof to be attached to the end of crosstie  38 . For some applications, end plate  50  may be formed as an integral part of a casting or forging (not expressly shown) having dimensions and a configuration corresponding generally with press fitting  54 . For still other applications, an end plate incorporating teachings of the present invention may be attached to a crosstie using various types of inserts, fasteners and welding procedures associated with the railway car manufacturing industry. 
     For some applications such as those shown in FIGS. 3,  4  and  5 , crossties  38  may be formed from an elongated strip of metal having a generally U-shaped cross section hereinafter referred to as U shaped channel  37 . Cover plate  39  having a length less than the length of the associated crosstie  38  may be attached to the open portion of U-shaped channel  37  to provide second surface or bottom surface  46 . The length of the cover plate  39  is preferably selected to be compatible with attaching respective press fittings  54  to opposite ends of crosstie  38 . For other applications, crossties  38  may be formed from hollow elongated metal tubes having a generally rectangular cross section. For the embodiment of the present invention [as] shown in FIGS. 3,  4  and  5 , the elongated strip of metal used to form U shaped channel  37  may have a thickness of approximately one-quarter of an inch. Cover plate  39  may have a thickness of approximately three-sixteenths of an inch and press fittings  54  may have a thickness of approximately three-eighths of an inch. 
     During the assembly of press fitting  54  with the respective end of crosstie  38 , butt weld  56  is preferably formed between end  47  of cover plate  39  and end  57  of press fitting  54 . See FIGS. 3 and 5. Backup bar  58  is preferably disposed immediately adjacent to ends  47  and  57  to assist in forming butt weld  56 . For the embodiment of the present invention shown in FIGS. 4 and 5, notches  60  are preferably formed in U shaped channel  37  at a location corresponding with the desired location for butt weld  56 . As previously noted various manufacturing procedures and techniques associated with the railway car manufacturing industry may be satisfactorily used to form a crosstie for use with the present invention. The present invention is not limited to crossties  38  as shown in FIGS. 3,  4  and  5 . 
     For the embodiment of the present invention shown in FIGS. 3,  4  and  5 , press fitting  54  may be described as having a generally L-shaped configuration with end plate  50  formed as an integral part thereof. For purposes of explaining various features of the present invention, press fitting  54  may be described as having a first leg  55  and a second leg extending therefrom which corresponds generally with end plate  50 . End  57  of first leg  55  is preferably formed with dimensions corresponding generally with the dimensions of end  47  on cover plate  39  of crosstie  38 . For the embodiment shown in FIG. 5, the width of end  57  of press fitting  54  is approximately equal to the width of the associated crosstie  38 . However, the width of end plate  50 , formed in accordance with teachings of the present invention is substantially larger than the width of the associated crosstie  38 . Also, the width of first leg  55  of press fitting  54  preferably increases substantially between end  57  and end plate  50 . 
     The increased width of first leg  55  results in press fitting  54  having a generally flared configuration extending from crosstie  38 . As a result of flaring the sides of first leg  55  and increasing the width of end plate  50  as compared to the width of crosstie  38 , a substantially larger weld  82  may be formed as part of connection  51 . Also, flaring the sides of first leg  55  reduces or minimizes any effect of abruptness in the change in cross section between crosstie  38  and side sill  33 . These features of the present invention result in increased fatigue life for the associated connection or weld attachment  51 . 
     For the embodiment of the present invention as best shown in FIGS. 3,  4  and  5 , side sills  33  and  34  preferably have a generally L-shaped configuration. For purposes of describing various features of the present invention, the respective legs of side sill  33  have been designated  131  and  132 . The configuration of first leg  55  and end plate  50  of press fitting  54  are preferably selected to be compatible with the configuration of legs  131  and  132  of side sill  33 . 
     Enlargements  64  and  66  are preferably formed on opposite sides of end plate  50  and spaced from the end of crosstie  38 . The dimensions and configuration of enlargements  64  and  66  are preferably selected to be compatible with forming respective holes  78  and  80  therein to receive bolts  68  and  70 . Enlargements  64  and  66  also cooperate with each other to form recessed area  77  extending therebetween. For the embodiment of the present invention [as] shown in FIGS.  3 , 4  and  5 , leg  131  of side sill  33  preferably includes respective holes  108  and  110  which are sized to receive bolts  68  and  70 . Holes  108  and  110  are preferably formed at the selected location for forming connection  51  between crosstie  38  and side sill  33 . 
     After press fitting  54  is attached to the end of crosstie  38  using butt weld  56 , a pair of gussets  72  and  74  are preferably attached to the exterior of crosstie  38  immediately adjacent to end plate  50 . For the embodiment of the present invention [as] shown in FIGS. 4 and 5, gussets  72  and  74  have an irregular configuration which somewhat resembles a triangle. However, gussets having a wide variety of configurations may be satisfactorily used with the present invention. Respective welds  76  may be used to attach gussets  72  and  74  at the desired location on opposite sides of crosstie  38  adjacent to end plate  50 . Gussets  72  and  74  are also preferably spaced from first leg  55  of press fitting  54 . Gussets  72  and  74  cooperate with each other to provide a generally flared or expanded cross section for crosstie  38  adjacent to end plate  50  and side sill  33 . 
     The end of crosstie  38  with press fitting  54  attached thereto, in accordance with teachings of the present invention, is preferably placed on leg  132  of crosstie  38  at the selected location. Mechanical fasteners  68  and  70  may be placed through respective holes  78  and  80  in end plate  50  and holes  108  and  110  in side sill  33 . For the embodiment shown in FIGS. 3,  4  and  5 , mechanical fasteners  68  and  70  are bolts. For some applications, other types of mechanical fasteners such as Huck® fasteners may be used instead of bolts. After end plate  50  has been securely attached to the selected portion of side sill  33 , using mechanical fasteners  68  and  70 , or other satisfactory types of mechanical fasteners, at least one weld  82  may then be formed in recessed area  77  between enlargements  64  and  66  and adjacent portions of side sill  33 . 
     Mechanical fasteners  68  and  70  are preferably located proximate the ends of weld  82  in accordance with teachings of the present invention such that mechanical fasteners  68  and  70  will be subjected to fatigue cycling and loading before such loads are transferred to weld  82 . When loads are transferred between a first structural member and a second structural member, mechanical fasteners  68  and  70  preferably absorb or pick up a substantial portion of the load to be transferred before the load is applied to adjacent ends of weld  82 . Thus, mechanical fasteners  68  and  70  substantially reduce peak stress at adjacent ends of weld  82  during load transfer between the first structural member and the second structural member. 
     The size, location and configuration of holes  78  and  80  are preferably selected such that mechanical fasteners  68  and  70  will be generally aligned with and disposed proximate to opposite ends of weld  82 . Mechanical fasteners  68  and  70  are preferably loaded or torqued such that during movement of railway car  20  loads associated with fatigue cycling of the respective connection or weld attachment  51  will generally be transferred to mechanical fasteners  68  and  70 . Thus, end plate  50  and mechanical fasteners  68  and  70  cooperate with each other to substantially reduce or eliminate fatigue cycling at the ends of weld  82 . Also, the configuration of enlargement  64  and  66  cooperate with recessed area  77  and mechanical fasteners  68  and  70  to minimize any stress risers at the end of weld  82 . The previously described flared or gradual change in cross section between crosstie  38  and adjacent portions of side sill  33  provided by first leg  55  and gussetts  72  and  74  also helps reduce the magnitude of fatigue cycling and increases the life of connection or weld attachment  51 . 
     The present invention has been described with respect to railway car  20 . However, an apparatus and methods incorporating teachings of the present invention may be used with a wide variety of railway cars used to carry freight and is not limited to well cars. Also, methods and apparatuses incorporating teachings of the present invention may be used to form a weld attachment between any two structural members disposed at right angles when loads being transferred between the structural members may result in potential fatigue cracking. 
     Although the present invention and its advantages have been described in detail it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention as defined by the following claims.