Patent Publication Number: US-10766507-B2

Title: Method of manufacturing a multiple axle railcar having a span bolster

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present invention is a Continuation Application of U.S. application Ser. No. 14/770,942 filed on Aug. 27, 2015, which is a national stage filing under 35 U.S.C. § 371 of International Application Number PCT/U.S.2015/028569, filed on Apr. 30, 2015, which claims the benefit of U.S. Provisional Application No. 62/074,124, filed on Nov. 3, 2014, each of which are incorporated by reference herein in their entirety. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a method of making a railcar. More specifically, the invention relates to a method of manufacturing a multiple axle railcar having cambered span bolsters. 
     When a railway transports oversized or heavy cargo, it must account for the loading of each axle supporting the weight of the oversized load. To accommodate the excessive load, railways utilize railcars having additional axles compared to standard-capacity railcars. With the load distributed over a greater number of axles, the weight carried by each individual axle is reduced. However, railcar manufacturers must account for the turning performance of the multiple axle railcar, which can be diminished as the number of axles increases. Typically, multiple axle railcars have groups of truck assemblies connected by a span bolster, with a bolster located at each end of the railcar. The span bolster, in turn, attaches to the rail car at a pivot point near the center of the bolster. In this configuration, a multiple axle railcar is able to perform similarly to a standard railcar with a single pivoting truck at each end of the railcar. 
     An example of such a railcar is a twelve-axle rail vehicle manufactured by Kasgro Rail Corp. and disclosed in U.S. Pat. No. 5,802,981. The twelve-axle railcar has three sets of trucks, or six axles, at each end of the vehicle. The three trucks at each end of the railcar are mounted to a common carrier that distributes the load, otherwise known as a span bolster. The benefit of twelve-axle railcar, in addition to its load carrying capability, is improved turning performance resulting from the fact that one span bolster can pivot independent of the other. 
     The increased load carrying capability of the twelve-axle railcar, or any other railcar having additional axles, is the result of evenly distributing the weight of the cargo to maintain reasonable wheel and axle loadings. While twelve-axle railcars improve loading, situations can exist where there is a significant variance between each of the axles. For example, the center truck of a three truck set will often have a higher loading than each of the outboard trucks as it is located below the attachment point to the rail car body. Having equal loading on each axle provides numerous benefits, such as improved safety of operation and reduced maintenance costs. It would therefore be advantageous to develop a method of manufacturing a multiple axle railcar having a span bolster in a manner that minimizes manufacturing variances and promotes consistent loading across each axle. 
     BRIEF SUMMARY OF THE INVENTION 
     Disclosed is a method of manufacturing a multiple axle railcar having a span bolster capable of evenly distributing a load. The manufacturing method minimizes variances that can be introduced during fabrication or welding operations. The elimination of variances leads to more consistent weight distribution in the completed railcar. Moreover, to improve weight distribution among the multiple axles, the components of the span bolster are fabricated with a camber so that the entire span bolster exhibits a slight arc, with the peak near the point where the bolster attaches to the main body of the railcar. The result of creating a camber is that the span bolster tends to flatten under load, equalizing the load among the axles supported by the bolster. The manufacturing process utilizes a jig, which is adjustable depending on the load rating of the railcar being built, to accurately set the desired camber. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a side view of an inboard truck mounting assembly of a span bolster manufactured according to one embodiment of the present invention. 
         FIG. 2  is a side view of a center truck mounting assembly and receiver of the span bolster. 
         FIG. 3  is a side view of an outboard truck mounting assembly of the span bolster. 
         FIG. 4  shows the receiver at the center truck mounting assembly, viewed along the length of the span bolster. 
         FIG. 5  shows one end of the span bolster as viewed from the outboard truck mounting assembly and along the length of the bolster. 
         FIG. 6  shows an alternative view of the outboard truck mounting assembly. 
         FIG. 7  shows an alternative view of the inboard truck mounting assembly. 
         FIG. 8  shows a top view of the span bolster. 
         FIG. 9  is an alternative view of the span bolster in which the interior components are shown. 
         FIG. 10  is a perspective view of the side of the span bolster. 
         FIG. 11A  is perspective view of a railcar with a cambered span bolster at each end of the car. 
         FIGS. 11B-11C  are alternate views of the railcar with cambered span bolsters at each end of the car. 
         FIG. 12  is a side view of the components of the span bolster at an intermediate stage of the manufacturing process. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The method of manufacturing a railcar having a cambered span bolster  502  begins with fabrication of the span bolster  502 . Construction of the span bolster  502  begins with fabrication of the longitudinal supports  401  and  402 , which are shown in  FIGS. 9-10 . The longitudinal supports  401  and  402 , or stringers, are constructed from flat plate steel which varies in thickness depending on the intended application and expected load of the completed railcar. In the preferred embodiment, the supports  401  and  402  are fabricated from 1 inch thick steel. As shown in  FIG. 9 , when assembled on the bolster  502 , longitudinal supports  401  and  402  taper towards the midline of the span bolster  502  near the outboard truck mounting assembly  301 . The taper of the longitudinal supports  401  and  402  are created in a press or by other methods known in the art. Alternatively, the longitudinal stringers  401  and  402  can remain substantially linear. The height and length of supports  401  and  402  are also dependent on the intended application. 
     In the preferred embodiment, as shown in  FIGS. 8-10 , a span bolster  502  carries three truck assemblies. Two separate span bolsters  502 , each carrying three truck assemblies, is connected to the main body  501  of the railcar. A depiction of this preferred embodiment is shown in  FIG. 11A .  FIGS. 11B and 11C  show close-ups of alternate views of a completed railcar. While the invention is described in reference to this preferred embodiment, a pair of axles or more can be mounted to each span bolster  502  and any number of span bolsters  502  can be used on the rail car. The specific number of axles, trucks, and bolsters  502  is dependent on the particular application and intended load capacity of the railcar being manufactured. 
     To evenly distribute the load on each of the six axles, the span bolster  502  is manufactured with a slight camber. More specifically, area of the bolster  502  near its center (the area of the bolster  502  at the receiver  202 ) is raised compared to the ends of the bolster  502 . That is, the span bolster is fabricated with a slight arc which is convex in shape. It is not necessary for the peak of the camber to be located in the center of the bolster  502 . Rather, load equalization among the axles is realized when the peak is located near the rail car body receiver  202 . Since the load of the railcar is concentrated at the receiver  202 , this area of the span bolster  502  experiences the greatest force and, as a result, the greatest deflection from its unloaded shape. As an example, a bolster  502  without a camber would tend to sag under the receiver  202  as the load-induced deflection causes the receiver  202  area to drop below the horizontal plane of the bolster  502 . 
     The amount of camber required for the span bolster  502  is determined based on the specifications of the railcar, such as the length of the bolster  502 , the number of axles, trucks, and bolsters  502  being used, the size of material used to create the bolster  502 , and the load expected to be carried by the railcar, to name a few. In the preferred embodiment, the camber is ½ inch for a three truck bolster  502  approximately 22 feet long. In this preferred embodiment, the center truck assembly is mounted below the receiver  202  and the two outboard truck assemblies  101  and  301  are mounted towards the end of the bolster  502 . As can be seen in  FIG. 11A , the truck assemblies  101 ,  201 , and  301  are symmetrically arranged on the bolster  502  to even the load carried by each axle. In alternative embodiments, the truck assemblies can be offset from the receiver  202  or asymmetrical. 
     During the fabrication of longitudinal supports  401  and  402 , the pre-determined camber is cut into the profile of each support  401  and  402 . The longitudinal stringers  401  and  402  are beam-like members spanning substantially the length of the bolster  502 , with a height from a few to several inches, depending on the load to be carried. As shown in  FIG. 12 , after the longitudinal stringer  401  is cut, the top surface  405  and bottom surface  406  of the longitudinal stringer  401  is arc shaped.  FIG. 12  shows an exaggerated depiction of the camber; otherwise, the camber would not be perceivable in the drawings. In the preferred embodiment, the top surface  405  and bottom surface  406  have the same profile. That is, the peak of the camber is equal for both surfaces  405  and  406 . In alternative embodiments, the magnitude of the peak for each surface  405  and  406  is different. Such differences can be required in situations where other equipment being mounted to the bolster  502 , for example. 
     Cutting the stringers  401  and  402  can be accomplished by any typical method, such as using a plasma, waterjet, laser, or oxygen fuel cutter. However, in the preferred embodiment, longitudinal supports  401  and  402 , as well as the other components, are cut from flat steel using a computer-controlled cutting machine. As will be appreciated by one skilled in the art, a computer-controlled cutter offers a higher level of accuracy and precision. For example, in the preferred embodiment the tolerance for the peak of the camber is plus ¼ of an inch and the tolerances for other components are plus or minus 1/16 of an inch for lengths and plus or minus ½ of a degree for angles. Over the span of a bolster  502  having a length of 20 feet or more, ¼ of an inch offers very little room for error. 
     Once longitudinal supports  401  and  402  are complete and within tolerances, truck mounting assemblies  101 ,  201 , and  301  are fabricated. A portion of truck mounting assemblies  101 ,  201  and  301  are welded in between longitudinal supports  401  and  402 , where the supports  401  and  402  are arranged in a parallel orientation and run substantially the length of the span bolster  502 . In alternative embodiments, a single longitudinal support or additional supports can be used. The remainder of the truck mounting assemblies is positioned below the longitudinal supports  401  and  402 .  FIGS. 1-3  show a side view of the inboard  101 , center  201 , and outboard  301  mounting assemblies, respectively. The mounting assemblies  101 ,  201 , and  301  are adapted to connect to an axle truck, such as a SWING MOTION® truck assembly manufactured by Amsted Rail. 
     As shown in  FIG. 8 , a receiver  202  is provided and is adapted to attach to the main body  501  of the railcar. In this configuration, which depicts a railcar manufactured according to the preferred embodiment, the weight of load carried by the body  501  of the railcar is placed directly over the center truck, causing a slight sag in the center of the bolster  502 . If no camber were present, this point loading would cause the center truck to carry more weight than either of the exterior trucks. As such, the camber is built into the bolster  502  to counteract the load-induced sag. The practical impact of this camber is that the load causes the bolster to flatten, rather than causing it to sag. As previously stated, the camber is determined based on the anticipated load to be carried by the railcar. For example, in one embodiment, the camber is ½ of an inch for a 290 ton span bolster  502 . 
     As shown in  FIG. 1 , the inboard truck mounting assembly comprises a pair of vertical supports  102  and  103  that span the distance between longitudinal supports  401  and  402 . Supports  102  and  103 , when attached to longitudinal supports  401  and  402 , form a box-like structure around the contact point for the truck assembly. In the preferred embodiment, supports  102  and  103  are welded to longitudinal members  401  and  402  before attaching truck assembly mounting plate  104 . Moreover, truck assembly mounting plate  104  is welded during final assembly, after a truck load adjustment is performed. 
     Plates  206  and  304 , for the center  201  and outboard  301  truck assemblies, are attached in a similar process. As further shown in  FIG. 7 , the inboard truck mounting assembly  101  extends beyond the longitudinal members  401  and  402  and is substantially the width of the axle that will be installed on the bolster. In addition, as will be later discussed, the truck mounting assembly  101  is welded to top plate  403  and bottom plate  404 . 
     The outboard truck mounting assembly is fabricated in a similar manner and is shown in  FIG. 3  with supports  302  and  303 . The supports are installed before truck assembly mounting plate  304 .  FIGS. 5-6  shows alternative views of the outboard truck mounting assembly, viewed along the length of the span bolster. 
       FIG. 2  shows the structure of the center truck mounting assembly  201 . As with the exterior assemblies  101  and  301 , the center assembly  201  has supports  203  and  204  traversing the width of the space between the longitudinal supports  401  and  402 . In the preferred embodiment, center truck mounting assembly further comprises a plurality of supports  205  that are positioned beneath receiver  202 . The weight of the railcar body and the load it is carrying is supported directly by receiver  202 , so additional bracing provides additional rigidity at this location.  FIG. 4  is an alternative view of the center truck mounting assembly  201  and shows the details of receiver  202 . As shown in  FIG. 4 , the receiver is attached to longitudinal supports  401  and  402  and is positioned in an opening of top plate  403 . As will be discussed in further detail, receiver  202  is welded to top plate  403  in a subsequent step. 
     At this stage of the manufacturing process, longitudinal supports  401  and  402  were cut and fabricated. Truck mounting assemblies  101 ,  201 , and  301  were fabricated and attached to supports  401  and  402 . The next step of the manufacturing process is to align and weld the combined truck mounting assemblies and longitudinal supports structure to top plate  403  and bottom plate  404 . 
     As previously indicated, the entire bolster is cambered. As such, bottom plate  404  requires a camber to match the arced profile cut into longitudinal supports  401  and  402 . Bottom plate  404  can be bent in a press to create the required profile. Alternatively, in the preferred embodiment, bottom plate  404 , which is cut from flat stock and still has a flat profile, is placed in a jig  600  that substantially matches the camber of the bottom surface  406  of longitudinal supports  401  and  402 . That is, the jig  600  used with the bottom plate  404  will have a convex shape. The jig  600  has an advantage of keeping the parts in proper alignment during the welding process, which can cause distortion as the metal heats and cools. 
     The jig  600  comprises a series of parallel flat bars that span the width of bottom plate  404 . The bars are constructed of plate steel and are spaced every several inches to every few feet along the length of the bolster. Stated differently, a first bar is located near the inboard truck mounting assembly  101 , a second bar is placed parallel to the first bar a few inches away from the first bar, and additional bars are positioned along the length to the outboard truck mounting assembly  301 . Alternatively, other supports that can support the weight of the components can be used, such as pipes or monolithic forms. In the preferred embodiment, the parallel bars have adjustable heights so that the camber can be adjusted depending on the load rating of the railcar. For a camber of ½ of an inch, the center bar, which aligns with the center truck mounting assembly  201 , has a height of ½ inch greater than the bars on each end of the jig  600 . Intervening bars are have a height lower than the center bar, but greater than the end bar. With a jig  600  of this configuration, the amount of camber and the degree of taper from the peak to the ends can be adjusted prior to placing the bottom plate  404  in the jig  600 . 
     After the jig  600  is set for the appropriate camber and bottom plate  404  is placed in the jig  600 , the combined longitudinal support and truck assembly component is placed on top of bottom plate  404 , which is resting on the jig  600 . The weight of the steel begins deforming the bottom plate  404  to the shape of the jig  600 . However, additional force is often required and can be supplied by additional weight, a press, clamps, or other means. In the preferred embodiment, the jig  600  rests on a table and several chains are positioned across the width of the table. Each chain is anchored to the floor or to the table and a winch tensions the chain. Thus, the chain supplies a downward force to the components. Alternatively, to equalize the pressure of the chain on the components, pulleys are placed at the terminal ends of a bar and the bar is placed across the component. By placing separate chains and winches at several locations along the length of the bolster, the bottom plate  404  is forced into contact with each bar of the jig  600 . After the chains are tensioned, the parts are checked for proper positioning. If aligned correctly, the bottom surfaces  406  of longitudinal support  401  and  402 , which already have been supplied with the truck mounting assembly components, is welded to bottom plate  404 . If the alignment is not correct, shims can be used to force the components into the correct alignment. Typically, welding components together causes heat stress that can lead to warping and other deformations in the components being welded together. However, the method of the present invention alleviates this concern as the components are forced into position and held there until the welding process is complete. By using this method, tight tolerances can be achieved. 
     A second jig with the same structure as the first jig  600  but having a concave shape is prepared in a similar manner. Alternatively, the components can be removed from the first jig  600  and the bars adjusted to a concave shape, wherein the bar aligned with the center truck mounting assembly  201  has a height of ½ inch lower than the bars at the end of the jig. Top plate  403  is placed on the concave-shaped jig. Next, the previously assembled component is inverted and placed on top of top plate  403 . Stated differently, the entire assembly is placed in the jig upside-down, since the longitudinal support structure is attached to the underside of the top plate  403 , with the top surface  405  of the longitudinal members  401  and  402  welded to the underside of the top plate  403 . As a result, the top side of top plate  403  must rest against the jig. 
     A clamping process using chains and winches is again performed. Once the parts are aligned within the tolerances, the top plate  403  is welded to the previously assembly components. The top plate  403  and bottom plate  404  are welded to both the longitudinal supports  401  and  402  as well as each individual truck mounting assembly  101 ,  201 , and  301 . Additionally, receiver  202  is welded around the circumference of an opening in top plate  403 . Alternatively, the sequence in which the top plate  403  and bottom plate  404  are attached to the longitudinal supports can be reversed. 
     Prior to final assembly and depending on the application, weld inspections may be performed by a mag particle or a dye penetrant test. Inspection of the weld between the longitudinal supports  401  and  402  to top plate  403  and bottom plate  404  are most critical. 
       FIGS. 8 and 10  show the completed bolster.  FIG. 9  shows the internal structure of the assembled bolster, with longitudinal members  401  and  402  running the length of the bolster. At this stage, any additional components required for the railcar, such as wiring or braking components, can be attached to the bolster. To complete final assembly of a twelve-axle rail car, a pair of bolsters  502  are positioned beneath a railcar body  501  and attached at receiver  202  on each respective span bolster. Truck assemblies containing two axles each are attached to each truck mounting assembly  101 ,  201 , and  301  on each of the bolsters  502 . 
     While the method has been described in detail and with reference to specific embodiments and examples thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the embodiments. Thus, it is intended that the present disclosure cover the modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.