Abstract:
The present invention increases the capacity and resistance to closure of the draft gear assembly wherein a portion of the lug supporting plates, usually the tapered plates, within the friction cushioning device is tapered or angled to increase the side force on the movable plates which increases the draft gear assembly&#39;s resistance to closure and increases the capacity of the draft gear assembly. Additionally or alternatively a tapered or angled top surface on the housing&#39;s third horizontal rib may be provided in the area that contacts or supports the bottom surfaces of the tapered plates. Providing a taper on the third horizontal lug which mates or cooperates with an angle on the bottom edge surface of the tapered plates increases the side force on the movable plates during the application of a buffing shock to the draft gear assembly.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from provisional application Ser. No. 60/561,048, filed Apr. 8, 2004. This application is also closely related to U.S. patent application Ser. No. ______, entitled “Taper Under Taper Plate to Increase Side Force On the Movable Plate”, filed concurrently herewith. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates, in general, to draft gear assemblies for use in cushioning both buff and draft shocks normally encountered by railway rolling stock during make-up and operation of a train consist on a track structure and, more particularly, the present invention relates to a draft gear assembly having plates, particularly the tapered plates, wherein a portion of a lugs supporting the plates is tapered or angled to increase the side force from the wedge shoe to the movable plate which, in turn, increases the draft gear assembly&#39;s resistance to closure and increases the capacity of the draft gear assembly.  
       BACKGROUND OF THE INVENTION  
       [0003]     Draft gear assemblies which utilize friction-type clutch mechanisms to absorb heat energy generated during service have been in widespread use in the railroad industry for many years to absorb both buff and draft shocks applied to the railway rolling stock. Many of such draft gear assemblies which were in use, prior to the present invention, are taught in U.S. Pat. Nos. 2,916,163; 3,178,036; 3,447,693; and 4,645,187. Each of the above-identified patents is owned by the assignee of the present invention. The teachings of each of these patents are all incorporated into the present application by reference thereto.  
         [0004]     These draft gear assemblies are designed to receive coupler forces and dissipate them without damage to the car structure and lading. The assemblies are disposed within an elongated opening located in the center sill member of the railway car along the longitudinal axis thereof and behind the shank, or innermost end, of the railway car&#39;s coupling mechanism. In this position, these friction clutch type draft gear assemblies will absorb at least a relatively large portion of both the buff and draft forces generated during service. Such buff and draft forces encountered by such railway cars are usually being applied in an alternating manner to the center sill member during normal car operation on the track.  
         [0005]     It is well recognized in the art that these draft gear assemblies must be provided with the capability of maintaining at least a certain minimum shock absorbing capacity both during making up a train consist and in-track service. Such minimum capacity has been specified by the Association of American Railroads (AAR) and is defined in the standards issued by the AAR. For example, friction clutch type draft gear assemblies have a specified absolute minimum capacity rating of at least 36,000 foot pounds. Any draft gear assembly with a capacity rating which is determined to be below 36,000 pounds will not receive approval from the AAR for service on any railroad car which may be used in interchange.  
         [0006]     It is, likewise, important to note that the heat energy absorbing action of the friction clutch mechanism must enable this minimum capacity rating to be readily achieved without exceeding a specified maximum 500,000 pound reaction force, or pressure, being exerted on the center sill member of the railway car during both such make-up and operation of such train consist. It has been found that such maximum reaction pressure is required to enable these high energy shocks to be readily absorbed without upsetting the end of the coupling member shank and/or damaging other critical car components and/or lading that is being transported by such railway car.  
         [0007]     In order for the manufacturers of such friction clutch type draft gear assemblies to meet the requirements of the railroad industry, with the ever increasing load carrying capacity of their modern day railroad cars, it has become of extreme importance to enhance the overall rated capacity of the friction-type draft gear assemblies as much as possible. This higher capacity rating being found necessary in order to minimize any damage to such cars and/or the lading due to the increased forces being exerted on the center sill member of the cars by the heavier loads such cars are now carrying.  
       SUMMARY OF THE INVENTION  
       [0008]     It is therefore an object of the invention to produce a draft gear assembly having an increased capacity and resistance to closure.  
         [0009]     It is a further object of the invention to provide a draft gear assembly wherein an additional side force is applied to the movable plates from the tapered plate.  
         [0010]     It is still yet a further object of the invention to provide the lugs supporting the tapered plate with a tapered portion to increase the side force on the movable plate which increases the draft gear assembly&#39;s resistance to closure and increases the capacity of the draft gear assembly.  
         [0011]     It is still yet a further object of the invention to provide a draft gear assembly wherein an angle is provided on the portion of the lug supporting the tapered plate which cooperatively contacts the third housing rib so as to increase the side force on the movable plate, increasing the capacity of the draft gear and providing a greater resistance to closure.  
         [0012]     It is yet a further object of the invention to provide a draft gear assembly having tapered plates wherein a portion of a horizontal housing rib supporting the lugs of the tapered plates is tapered or angled to increase the side force on the movable plate which increases the draft gear assembly&#39;s resistance to closure and increases the capacity of the draft gear assembly.  
         [0013]     It is an additional object of the invention to provide tapered lugs supporting plates in split wedge draft gears in order to increase the side force from the friction wedge means to the friction plate which increases the draft gear assembly&#39;s resistance to closure and increases the capacity of the draft gear assembly.  
         [0014]     Briefly, and in accordance with the forgoing objects, the invention comprises a draft gear assembly comprising a housing closed at one end and open at the opposed end and having a rear portion adjacent the closed end and a front portion adjacent the open end, a compressible cushioning element centrally disposed within the rear portion abutting the housing end and extending longitudinally there from, a seat means abutting the opposite end of the compressible cushioning element during application and release of a force on the draft gear assembly, and a friction cushioning means positioned at least partially within said front portion of said housing for absorbing energy during a compression of said draft gear assembly. The friction cushioning means includes a pair of laterally spaced outer stationary plates having an outer surface for engaging the housing and an opposed inner friction surface, a pair of laterally spaced movable plates having an outer friction surface for movably engaging the outer stationary plates, an inner friction surface and at least one substantially flat edge intermediate the outer friction and inner friction surfaces for engaging the seat means. The friction cushioning means also includes a pair of laterally spaced tapered plates having lugs for supporting the tapered plates within the housing. The lugs of the tapered plate are tapered or angled to increase the side force on the movable plate. The tapered plates have an outer friction and an inner friction surface wherein the outer friction surface movably and frictionally engages the inner friction surface of the movable plate. The friction cushioning means further includes a pair of laterally spaced wedge shoes having an outer friction surface for movably and frictionally engaging an inner friction surface of the tapered plate and a center wedge having a pair of matching predetermined tapered portions for engaging the tapered portion of the wedge shoe to initiate frictional engagement of the friction cushioning means and thereby absorb energy. The housing includes three horizontal ribs for positioning and/or holding the components of the cushioning means. A spring release means is provided which engages and longitudinally extends between the seat means and the center wedge for continuously urging the friction cushioning means outwardly from the compressible cushioning means to release the friction cushioning element when an applied force compressing the draft gear is removed.  
         [0015]     The present invention increases the capacity and resistance to closure of the draft gear assembly wherein a portion of the lug supporting the tapered plates is tapered or angled to increase the side force on the movable plate which increases the draft gear assembly&#39;s resistance to closure and increases the capacity of the draft gear assembly. Additionally or alternatively a tapered or angled top surface on the housing&#39;s third horizontal rib may be provided in the area that contacts or supports the lugs of the tapered plates. Providing a taper on the third horizontal rib which mates or cooperates with an angle on the lugs of the tapered plates increases the side force on the movable plates during the application of a buffing shock to the draft gear assembly.  
         [0016]     The present invention is also applicable to split wedge draft gears wherein the lugs, which support the plate means positioned on either side of the friction plate, are tapered to increase the side force transferred from the wedge means to the friction plate.  
         [0017]     Although a number of objects and advantages of the present invention have been described in some detail above, various additional objects and advantages of the draft gear assembly of the present invention will become more readily apparent to those persons who are skilled in the art from the following more detailed description of the invention, particularly, when such detailed description of the invention is taken in conjunction with both the attached drawing figures and with the appended claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a longitudinal cross-sectional view of a draft gear assembly of the invention incorporating one form of a presently preferred embodiment of a cushioning element for the draft gear assembly.  
         [0019]      FIG. 2  is a longitudinal cross-sectional view of a draft gear assembly of the invention incorporating an alternative embodiment of a cushioning element for the draft gear assembly.  
         [0020]      FIG. 3  is a longitudinal cross-sectional view of a draft gear assembly of the invention incorporating an alternative embodiment of a hydraulic cushioning element for the draft gear assembly.  
         [0021]      FIG. 4  is a perspective view of the draft gear housing illustrating the first, second, and third horizontal rib including the inventive tapered surface on the third rib.  
         [0022]      FIG. 5  is a cross-sectional view of a split wedge draft gear with a center friction plate.  
         [0023]      FIG. 5A  is a plan view of one of the barrier plates of the friction cushioning means of a split wedge draft gear.  
         [0024]      FIG. 6  shows a schematic view of the taper on the lugs of the draft gear. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     The draft gear assembly, according to the present invention, is installed in alignment with a railroad car center sill between a front and a rear draft gear lug. A vertical yoke is connected to a coupler shank by a draft key with a coupler horn spaced from a striking plate and with a front follower member within the yoke which is positioned adjacent to the front lugs, all substantially in accordance with the prior art conventional practice as illustrated in the aforementioned U.S. Pat. No. 2,916,163.  
         [0026]     Prior to proceeding to the more detailed description of the various embodiments of the instant invention, it should be pointed out that, for the sake of clarity, identical components which have identical functions have been identified with identical reference numerals throughout the several views that have been illustrated in the drawings.  
         [0027]     Now reference is made, more particularly, to drawing  FIGS. 1-4 . Illustrated therein are the essential components of a draft gear assembly, generally designated  10 , used in a railway car (not shown). The assembly  10  includes a housing, generally designated as  12 . The housing  12  is open at one end and has a rear portion  14  adjacent a bottom wall  16  which closes the other end of housing  12 . Rear portion  14  is provided for receiving therein a compressible cushioning means, generally designated as  26 . Housing  12  includes a front portion  18  adjacent the open end. Front portion  18  is in open communication with the rear portion. As illustrated in  FIG. 4 , housing  12  additionally includes first, second, and third horizontal ribs  20 ,  22 , and  24 . The third horizontal rib  24 , which supports several of the plates of the friction cushioning means  40 , including lugs  63  of the tapered plates  56 , has a tapered top surface  25  in the area that supports or contacts the lugs  63  of the tapered plates  56 .  
         [0028]     The compressible cushioning element  26  is centrally disposed within the rear portion  14  and has one end thereof abutting at least a portion of an inner surface  28  of the bottom wall  16  of housing  12 . The compressible cushioning element  26  extends longitudinally from bottom wall  16  where the opposite end is placed into abutting relationship with at least a portion of one surface  30  of a seat means  32 . Seat means  32  is positioned within the housing  12  for longitudinal movement therein for respectively compressing and releasing the compressible cushioning element  26  during application and release of a force on the draft gear assembly  10 .  
         [0029]     As shown in  FIG. 1 , the compressible cushioning element  26 , according to one embodiment of the invention, comprises at least one and preferably at least two springs  34 ,  35 .  FIG. 2  shows an alternative embodiment for a compressible cushioning element  26  which comprises an outer coil spring  36  and an inner rubber spring  37 .  FIG. 3  shows another alternative embodiment of the invention in which the compressible cushioning element  26  is a hydraulic unit  38  such as taught in U.S. Pat. No. 3,447,693.  
         [0030]     A friction cushioning means, generally designated as  40 , is positioned at least partially within the front portion  18  of the housing  12 . The friction cushioning means  40  absorbs energy during application of a force sufficient to cause a compression of the draft gear assembly  10 .  
         [0031]     The friction cushioning means  40  includes a pair of laterally spaced outer stationary plates  42  having an outer surface  44  and an opposed inner friction surface  46 . The outer surface  44  engages the housing  12 . A pair of laterally spaced movable plates  48  of substantially uniform thickness is also provided. Movable plates  48  have an outer friction surface  50  and an inner friction surface  52  and at least one substantially flat edge  54  intermediate the outer friction surface  50  and the inner friction surface  52  which edge  54  engages the seat means  32 . At least a portion of the outer friction surface  50  movably and frictionally engages the inner friction surface  46  of the outer stationary plate  42 . A pair of laterally spaced tapered plates  56  is provided. The tapered plates  56  include an outer friction surface  58  and an inner friction surface  60 . The outer friction surface  58  movably and frictionally engages at least a portion of the inner friction surface  52  of the movable plate  48 . As shown in  FIG. 6 , the tapered plates  56  include an angled or tapered lug  63  intermediate the outer friction surface  58  and the inner friction surface  60 . The laterally spaced outer stationary plates  42  and the lug  63  of the tapered plates  56  sit on the third horizontal rib  24  of the housing  12 . This angled or tapered lug edge  63  of the tapered plates  56  is in the area where the tapered plates  56  contact the tapered top surface  25  of the third horizontal rib  24 . Friction cushioning means  40  further includes a pair of laterally spaced wedge shoes  64  which have at least a portion of an outer friction surface  66  movably and frictionally engaging at least a portion of the inner friction surface  60  of the tapered stationary plate  56 . Wedge shoes  64  have at least a portion of one edge  68  engaging seat means  32  and a predetermined tapered portion  70  on an opposed edge thereof. A center wedge  72  is provided which has a pair of matching tapered portions  74  for engaging the tapered portion  70  of the wedge shoe  64  to initiate frictional engagement of the friction cushioning means  40 .  
         [0032]     It has been discovered that providing an angle or taper  25  on the top surface of the third horizontal rib  24  and correspondingly providing an angle or taper on the lug  63  of the tapered plates  56  in the area that contacts this tapered top surface  25  of the third horizontal lug  24  of the housing  12 , results in a greater side force being applied to movable plates  48  by enhancing the force transfer from the wedge shoes  64  to the movable plates  48 . Thus, the capacity of the draft gear and its resistance to closure is increased. A spring release means  76  engages and extends longitudinally between the seat means  32  and the center wedge  72  for continuously urging the friction cushioning means  40  outwardly from the compressible cushioning means  26  to release the friction cushioning means  40  when an applied force compressing the draft gear assembly  10  is removed.  
         [0033]     The present invention may also be applied to a split wedge type draft gear having a center friction plate such as shown in  FIG. 5 . This type of draft gear is discussed in detail in U.S. Pat. No. 4,735,328. The disclosure of which is incorporated into the present application by reference thereto.  
         [0034]     As shown in  FIG. 5 , the split wedge draft gear assembly includes a housing  24   a  closed at one end  76  and open at an opposed end, generally indicated as  78 . The housing has a rear portion adjacent the closed end and a front portion adjacent the open end. The front portion is in open communication with the rear portion. At least one horizontal rib  74  having a top and bottom surface is provided within the housing  24   a . A compressible cushioning means, such as a spring system means  30   a , is centrally disposed within the rear portion with one end thereof abutting at least a portion of an inner surface of the closed end of the housing. The compressible cushioning means extends longitudinally from the one end. A seat means  46   a  is provided having at least a portion of one surface thereof abutting the opposite end of the compressible cushioning means  30   a  during application and release of a force on the draft gear assembly.  
         [0035]     A friction cushioning means, generally indicated as  80  is positioned at least partially within the front portion  78  of the housing for absorbing energy during a compression of the draft gear assembly. The friction cushioning means includes a friction plate means  22   a  centrally disposed within the front portion of the housing. The friction plate means  22   a  has a first end which extends out of the housing  24   a  and a second end which contacts the seat means  46   a . A first and second barrier plate means  48   a  and  50   a  are disposed one on either side of the friction plate  22   a . The first and second barrier plate means  48   a ,  48   b  include lugs  98 , as shown in  FIG. 5A  for contacting at least one horizontal rib  74  within the housing for supporting the barrier plate means within the housing. At least a portion of the lugs  98  included an angled portion  102  which comes into contact with a top surface of the at least one supporting rib within the housing so as to increase the side force applied to the friction plate means  22   a  and increase the capacity of the draft gear.  
         [0036]     The friction cushioning means further includes first and second friction wedge means  18   a  and  18   b . The first friction wedge means  18   a  is disposed on one side of the first barrier plate means  48   a  and the second friction wedge means  18   b  is disposed on one side of the second barrier plate means  48   b . A first and second shoe means  60   a  and  60   b  are provided wherein the first shoe means  60   a  is disposed on one side of the first friction wedge means  48   a  and the second shoe means  60   b  is disposed on one side of the second friction wedge means  48   b . The friction cushioning means also includes first and second wear liner plate means  68   a  and  68   b . The first wear liner plate means  68   a  is disposed on one side of the first shoe means  60   a  and the second wear liner plate means  68   b  is disposed on one side of the second shoe means  60   b . In addition to the angled lug  98  of the barrier plates, at least one horizontal rib contacting the angled portion of the lug can be cooperatively angled.  
         [0037]     Thus, the present invention has been described in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same. It will be understood that variations, modifications, equivalents, and substitutions for components of the specifically described embodiments of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims.