Abstract:
There is disclosed a light weight truck bolster for railway car trucks. Metal has been removed in the compression and tension members of the bolster near the center bowl. One longitudinal rib is located in each end of the bolster arms and a pair of transversely extending vertical ribs are located on opposing sides of the center bowl and extend from the tension member to the compression member. The disclosed light weight truck bolster satisfies the Association of American Railroads (“A.A.R.”) design qualifications for truck bolsters while weighing significantly less than traditional truck bolsters.

Description:
[0001]    This application claims the benefit of U.S. Provisional Application No. 60/073,240, filed Jan. 30, 1998, and is a continuation application of U.S. application Ser. No. 09/238,248, filed Jan. 27, 1999, now U.S. Pat. No. 6,196,134, the entire disclosure of which is incorporated by reference.  
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates generally to railcar trucks and more particularly to a lightweight railcar truck bolster.  
           [0004]    2. Description of the Related Art  
           [0005]    Railcar trucks are the wheeled vehicles that ride on the tracks and support the railcar body. Two trucks are normally used beneath each car body. Each truck includes wheel sets which includes two wheels spaced transversely from each other and joined by a transversely extending axle. Journal bearings are pressed onto each of the axle. Transversely spaced side frames are supported on the wheel sets. The side frames are longitudinally elongated and define longitudinally spaced, downwardly opening pedestal jaws. Bearing adapters are mounted in the jaws and the adapters rotatably receive the wheel set journal bearings. The wheel sets and side frames are mounted together by the bearing adapters.  
           [0006]    Transversely extending between each side frame is a truck bolster. The truck bolster includes a center bowl and two opposed, elongated bolster arms that extend transversely outward from beneath the center bowl. The arms and the bolster overall, are formed of a top plate, also known as a compression member, a bottom plate, also known as a tension member, and two upright structural or side walls. The bolster arms extend outward a length such that in service, the bolster arms extend through bolster arm openings in the side frames. The truck bolster is mounted on helical springs which are also mounted in the bolster arm openings and supported on the side frames. The helical springs support the weight of the railcar and payload and cushion the shock caused by uneven railroad track.  
           [0007]    The Association of American Railroads (“A.A.R.”) sets forth structural requirements for truck bolsters. These requirements include the truck bolster being strong enough to support the weight of the railcar and its payload and also exhibit fatigue resistant capabilities for extended service of the bolster. Because the railcar truck bolsters must exhibit high strength, truck bolsters are conventionally made of cast steel and contribute a significant part of the total weight of the railway car. In the rail line shipping industry, weight limits are placed on shippers of goods for preserving the safety and conditions of the track. Consequently, the quantity of goods that may be placed in or on a railcar is affected by the weight of the railcar body, the trucks and other railcar components. Thus, a reduction in the weight of the railcars, including the truck bolster, will result in an increase in the total capacity of goods shipped by a rail line owner. Therefore, it is highly desirable to reduce the weight of the truck bolster while at the same time maintaining the strength and fatigue resistance capabilities of the bolster.  
         SUMMARY OF THE INVENTION  
         [0008]    Accordingly, an object of the present invention is to reduce the weight of a railway car by reducing the overall weight of the truck bolster. It is another object of the invention to reduce the weight of the truck bolster without a decrease in strength or fatigue resistance.  
           [0009]    Briefly, the present invention involves removing metal from the compression and tension members of the truck bolster and locating a pair of vertical ribs on opposing sides of the bolster center bowl. The vertical ribs extend from the tension member to the compression member. The compression member has a wall thickness that is thinner than conventional bolsters near the center bowl and gradually increases in thickness from the center bowl to the ends of the bolster arms. Likewise, the tension member has a wall thickness that is thinner near the center of the bolster and which gradually increases in thickness toward the ends of the bolster arms. Both the tension and compression members are continuous without lightener holes. To compensate for the loss of material and resulting strength in the compression and tension members, the transversely extending vertical ribs are added on opposing sides of the center bowl to provide the required structural strength to the bolster. Significantly, the disclosed bolster is lighter than conventional truck bolsters, thereby creating an increase in the total capacity of goods that can be shipped by rail line owners. Specifically, the weight of the disclosed bolster has been reduced by over 230 pounds, translating into a weight reduction of over 46,000 pounds for a typical 100-car train. This significant weight reduction, in turn, translates into a significant increase in goods which may be shipped by rail line owners.  
           [0010]    In addition, the disclosed light weight truck bolster is cast from a one-piece bolster core which offers several manufacturing advantages. Traditionally, three to five core pieces were used which led to problems during the pouring process, such as, core shifting. Core shifting, in turn, led to dimensional inconsistencies and greater wall thicknesses which, consequently, led to an increase in the weight of the bolster. These problems are eliminated with a one-piece core. Also with a one-piece core, the bolster wall thickness can be reduced without the possibility of multi-core shifting which, in the past, has created walls that were too thin. Moreover, in addition to the increased manufacturing efficiency with a one-piece core, chaplets which typically were used to support multi-cores are no longer needed to support the cores. Instead, the mold supports the one-piece core. Without the use of chaplets, associated problems, such as, the creation of stress concentrations and removal of chaplet scars in finishing are eliminated. Moreover, significant savings in the costs associated with finishing the bolsters are realized.  
           [0011]    The full range of objects, aspects and advantages of the invention are only appreciated by a full reading of this specification and a full understanding of the invention. Therefore, to complete this specification, a detailed description of the invention and the preferred embodiments follow, after a brief description of the drawings.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The preferred embodiments of the invention will be described in relation to the accompanying drawings. In the drawings, the following figures have the following general nature:  
         [0013]    [0013]FIG. 1 is a side elevation view of the truck bolster of the present invention.  
         [0014]    [0014]FIG. 2 is a half-top plan view and a half-bottom plan view of the invention of FIG. 1.  
         [0015]    [0015]FIG. 3 is a cross-section view of the invention of FIG. 2 taken along lines  3 - 3 .  
         [0016]    In the accompanying drawings, like reference numbers are used throughout the various figures for identical structures.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]    Referring to FIGS.  1 - 3 , there is depicted a preferred embodiment of a light weight truck bolster that meets the A.A.R. structural qualifications for truck bolsters while weighing significantly less than traditional truck bolsters. The preferred truck bolster  10  comprises a center bowl  12 , two opposed, elongated bolster arms  14  and  16  that extend transversely outward from beneath the center bowl. The arms and the bolster overall, are formed of a compression member  18 , a tension member  20 , and two upright structural or side walls  22 . The compression and tension members, and side walls form and define a bolster cavity  23 . To facilitate manufacture, reduce weight and enable mounting brakes and side bearings, lightener holes  24  are located within the side walls  22  on each bolster arm  14  and  16 . The bolster also has a center bore  40  for receiving a king pin to connect the truck to the railcar body. Bolt holes  42  are located near the ends of the bolster arms for mounting side bearings to the bolsters.  
         [0018]    In a preferred embodiment of the tension and compression members, the wall thickness of each has been reduced. Specifically, metal has been removed in the tension member  20  below the center bowl  12  and generally along the entire compression member. As shown in FIG. 1, the preferred thickness of the tension member wall  44  has been reduced to approximately {fraction (15/16)}of an inch. This preferred thickness is constant below the center bowl region and gradually increases from the center bowl region toward the end of the bolster arms  14  and  16  with the maximum thickness being over the turn  26  of the spring seat, a location of high stress concentration. At this turn, the thickness increases to a preferable 1½inches. The preferred thickness of the tension member then gradually decreases toward the end of the bolster arms  14  and  16  to approximately 1{fraction (1/16)}inches.  
         [0019]    Metal has also been removed in the compression member  18  in the area below the center bowl  12 . The preferred thickness of the compression member wall  46  immediately below the center bowl has been reduced to approximately 1¼inches. The preferred thickness has been further reduced in the bolster arms to approximately ¾of an inch. The preferred thickness remains constant along the bolster arms with a gradual increase in thickness toward the turn  26  of the spring seat. At this turn, the thickness increases to a preferable 1{fraction (3/16)}inches. Again, the preferred thickness of the compression wall  46  gradually decreases toward the end of the bolster arms  14  and  16  to approximately ⅞of an inch. Variations to the above preferred thicknesses of the tension and compression members are contemplated and considered within the scope of the present invention.  
         [0020]    Also in a preferred embodiment of the tension and compression members, lightener holes previously in the tension and compression members have been removed. With the removal of the lightener holes, previous metal flow problems, such as the creation of vertices and stress concentrations, are eliminated. The king pin hole and side bearing bolt holes on the compression member are retained.  
         [0021]    In traditional bolsters, two longitudinal ribs were needed and were located within each bolster arm above and below the lightener holes in the tension and compression members, respectively, and running uninterrupted the entire length of the bolster arm. Also with traditional bolsters, transverse ribs were located below the center bowl extending upward approximately 5 inches from the inside of the tension member. A preferred bolster  10  has only one longitudinal rib  48  in each bolster arm end and a transverse rib  30  on each side of the center bowl  12  that extends the full height of the side walls  22 , from the tension member  20  to the compression member  18 . The transverse ribs  30  located on each side of the center bowl are connected by a pair of longitudinal rib connecting walls  31 . As shown in FIG. 3, the rib walls  31  increase in thickness from the tension member  20  to the compression member  18 . Structural cross ribs  33  transverse the rib walls  31  and are located between the transverse ribs  30  and provide structural support for the rib walls  31 .  
         [0022]    The longitudinal rib  48  extends from the tension member  20  to the compression member  18  and the free edge defines a curvature  56 . The curvature  56  allows the rib  48  to form into the tension and compression member eliminating the sharp transition between the rib  48  and the members  18  and  20 . The gradual transition of the rib  48  into the compression and tension members reduces the potential stress concentrations that would typically occur at sharp transitions between adjoining cast members.  
         [0023]    At the junction  32  where the transverse rib  30  forms with the tension member  20 , the rib wall thickness is reduced and small radii  34  are formed between the rib wall and the tension member  20  to prevent shrink in the casting at that junction. The transverse rib  30  has opposite faces  50  and  52 . The face  50  throughout the entire height of the wall, is generally perpendicular to the plane of the compression member. The face  52  throughout the entire height of the wall is angled from the tension member to the compression member. This angled face of the rib wall results in the transverse rib  30  having an increase in wall thickness from the junction  32  to the point at which the rib  30  joins with the compression member  18 .  
         [0024]    The preferred bolster  10  with the longitudinal ribs  48  located near the bolster arm ends and the transversely extending ribs  30  located near the center bowl creates bolster arms that define an empty hollow space  54 , that is, without metal support ribs or gussets in the bolster arms. The empty hollow space  54  is formed by the compression and tension members, the side walls, and the transverse and longitudinal ribs. With the exception of the aforementioned improvements to the truck bolster, the remainder of the bolster is conventional.  
         [0025]    Significantly, with the preferred bolster  10 , a one-piece bolster core is used to manufacture the bolster casting. Traditionally, three to five core pieces were used which led to problems during the pouring process, such as, core shifting, which, in turn, led to casting flaws, offsets and dimensional inconsistencies. Stress concentrations develop at these casting flaws and offsets and are typically a primary reason for metal fatigue. With a one-piece core, the bolster is significantly easier to manufacture, resulting in an increase in production efficiency, and the problems associated with core shifting and resulting stress concentrations are eliminated. In addition, with the one-piece core, no chaplets are needed to support the core. Instead, the mold supports the core eliminating problems such as stress concentrations around the chaplet and chaplet scars or fusion of the chaplets to the casting. In addition, finishing of the chaplet scars is no longer required.  
         [0026]    The preferred embodiments of the invention are now described as to enable a person of ordinary skill in the art to make and use the same. Variations of the preferred embodiment are possible without being outside the scope of the present invention. Therefore, to particularly point out and distinctly claim the subject matter regarded as the invention, the following claims conclude the specification.