Abstract:
An improved coupler-knuckle assembly is comprised of a coupler body, a knuckle, and at least two knuckle retainer plugs. The knuckle has an internal coring geometry that increases the cross-sectional area of the throat portion of the knuckle compared to previous designs. The present invention&#39;s knuckle design includes a top and a bottom tapered holes in the knuckle with a locking groove at the bottom of each tapered hole for the knuckle retainer plugs to snap into. The knuckle retainer plugs are inserted through the coupler body and into the tapered holes in the knuckle. The improved coupler-knuckle assembly of the present invention reduces fatigue on the coupler, knuckle, and knuckle pin, prevents misalignment of the coupler-knuckle assembly, and prevents knuckle pin breakage.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates generally to railway car coupling systems, and more particularly to an improved cast metal coupler-knuckle assembly. 
     This invention is applicable to Association of American Railroads (AAR) Type E, F, and H couplers. In a standard railway coupler-knuckle assembly, a knuckle pin pivotally connects a coupler body and a knuckle. Both the coupler body and the knuckle have a pinhole that allows a single knuckle pin to pivotally secure the coupler and the knuckle together. 
     In the coupler-knuckle assembly design that is currently used in the railway industry, the knuckle&#39;s weakest section is in the throat area around the hole for the knuckle pin. The hole is 1 21/32 inches in diameter and goes completely through the coupler and the knuckle. The pinhole reduces the cross-section area of the knuckle&#39;s throat area, which is a highly stressed location in the coupler-knuckle assembly. Because of this weakness in the throat area of the knuckle, the current AAR cast metal coupler-knuckle assembly design does not consistently meet the AAR&#39;s newly adopted M-216 fatigue test for a coupler-knuckle assembly. 
     The current single style knuckle pin designs are either metallic or non-metallic. When in use, the knuckle pin can get loaded due to the misalignment of the pulling lugs and pinholes located both on the coupler body and the knuckle. The misalignment causes both the knuckle pin and the coupler-knuckle assembly to fatigue during use, and can cause damage or break the pin or assembly. 
     The present invention provides an improved railway coupler-knuckle assembly that strengthens the coupler-knuckle assembly and reduces fatigue on all components of the coupler-knuckle assembly. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, an improved railway car metal cast coupler-knuckle assembly secured by two knuckle plugs instead of a single knuckle pin is provided for use. 
     The coupler-knuckle assembly is comprised of a coupler body, a knuckle, and at least two knuckle retainer plugs. The knuckle has an internal coring geometry that removes the knuckle pinhole that protrudes entirely through the knuckle in previous knuckle designs. The present invention&#39;s knuckle design includes a top tapered hole and a bottom tapered hole in the knuckle with a locking groove at the bottom of each tapered hole for the knuckle retainer plugs to snap into. 
     The knuckle retainer plugs have a top end and a bottom end, with a head on the top end, and a taper on the bottom end. On the tapered bottom end are locking tabs that snap into the locking groove at the bottom of the tapered hole in the knuckle, ensuring the knuckle is securely attached to the coupler body. The knuckle retainer plugs have relief cutouts on the head of the plugs to allow easy removal from the coupler-knuckle assembly. 
     It is an object of the present invention to provide a coupler-knuckle assembly with a greater cross-sectional area in the knuckle that is stronger through the knuckle throat area and consistently passes the AAR M-216 fatigue test. 
     It is another object of the present invention to provide a coupler-knuckle assembly with a knuckle that couples with a standard E, F, or H-type coupler, 
     It is another object of the present invention to provide a coupler-knuckle assembly utilizing a multi-knuckle plug design wherein the plugs are independent of each other allowing for uniform alignment of the top and bottom pulling lugs, thus, reducing fatigue on both the coupler-knuckle assembly and knuckle plugs. 
     It is another object of the present invention to provide a coupler-knuckle assembly utilizing a multi-knuckle plug design that eliminates knuckle pin loading and prevents bending and breakage of the knuckle pin. 
     It is a further object of the present invention to provide a coupler-knuckle assembly utilizing a multi-knuckle plug design that allows the knuckle plugs to remain unloaded and the coupler and knuckle pulling lugs to remain uniformly aligned during use. 
     It is still a further object of the present invention to provide a multi-knuckle plug coupler-knuckle assembly that can be used in current OEM coupler production or for field replacement when knuckles need to be replaced in a current revenue service. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top plan view of a standard E-type coupler-knuckle assembly known in the prior art; 
         FIG. 2  is a side elevational view of a standard coupler-knuckle assembly known in the prior art; 
         FIG. 3  is a sectional view of a standard coupler-knuckle assembly known in the prior art along lines  3 - 3  of  FIG. 1 ; 
         FIG. 4  is top plan view of the coupler-knuckle assembly of the present invention; 
         FIG. 5  is an end elevational view of the coupler-knuckle assembly of the present invention; 
         FIG. 6  is a side elevational view of the coupler-knuckle assembly of the present invention; 
         FIG. 7  is a sectional view of the coupler-knuckle assembly of the present invention along lines  7 - 7  of  FIG. 4 ; 
         FIG. 8  is a top perspective view of the knuckle retainer plug of the present invention; 
         FIG. 9  is a side elevational view of the knuckle retainer plug of the present invention; 
         FIG. 10  is a top plan view of the knuckle retainer plug of the present invention; and 
         FIG. 11  is a bottom plan view of the knuckle retainer plug of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 1-3 , an E-type coupler-knuckle assembly known in the prior art is generally designated  10  and includes a coupler body  11 , a knuckle  22 , and a knuckle pin  32 . The coupler body  11  comprises generally a coupler head  12  and a coupler shank  14  which is adapted to be mounted on a railway car (not shown). The coupler-knuckle assembly  10  serves to transfer buff and draft loads that are exerted on the assembly  10  during use, from the knuckle  22  to the coupler body  11 , without damaging knuckle pin  32 . 
     The coupler head  12  has a knuckle side  16  and a guard arm side  18 . Coupler head  12  has a front face  24  including a throat portion  26  extending towards the knuckle side  16  in a curved manner toward upper pivot lug  28  and lower pivot lug  30 . Coupler head  12  includes outwardly protruding flange sections  34  and  36  from the top surface  38  of upper pivot lug  28  and the bottom surface  64  of lower pivot lug  30  respectively. Along with pulling and buffing loads on a coupler head  12  during use, a bending load is present which acts to pull upper pivot lug  28  away from lower pivot lug  30 . The flange sections  34  and  36  provide the necessary strength to prevent pivot lugs  28  and  30  from bending away from each other. 
     The knuckle  22  is inserted between upper pivot lug  8  and lower pivot lug  30 , with the upper and lower pinholes  50  and  52  in the upper and lower pivot lugs  28  and  30  respectively, aligned with pinhole  54  in knuckle  22 . The knuckle  22  is pivotally secured in place by knuckle pin  32 , that is inserted through pinholes  50  and  52  in the upper and lower pivot lugs respectively, and through pinhole  54  in the knuckle  22 . Pinholes  50  and  52  in the upper and lower pivot lugs  28  and  30 , and pinhole  54  through knuckle  22  generally have a circular cross-section that is greater than the cross-sectional area of the knuckle pin  32 . 
     Knuckle pin  32  comprises a longitudal cylindrical member having a length greater than that of the distance between the upper and lower pivot lugs  28  and  30 , allowing a bottom portion  42  of knuckle pin  32  to extend beyond lower pivot lug  30 . A cotter pin  46  or other locking mechanism secures knuckle pin  32  in place in the coupler-knuckle assembly  10 . The cotter pin  46  prevents knuckle pin  32  from unintentional upward removal during use, and allows knuckle pin  32  to rotate. At the end opposite the bottom portion  42 , knuckle pin  32  has a head  44  which is diametrically larger than upper pinhole  50 , preventing knuckle pin  32  from moving downward during use. The head  44  also allows a maintenance worker to issue downward blows on the knuckle pin  32  during installation of the knuckle pin  32  into the coupler-knuckle assembly  10  without damaging the knuckle pin  32 . 
     As a result of buff and draft movements during use, force and stress is exerted on the top pulling lugs  60 ,  62  and the bottom pulling lugs  64 ,  66  of the knuckle  22 , causing them to contact with top pulling lugs  68 ,  70  and bottom pulling lugs  72 ,  74  of the coupler body  11  respectively. While in use, when uneven force is exerted on the top and bottom pulling lugs of the coupler and knuckle, the coupler-knuckle assembly can become misaligned as the rigid single knuckle pin only allows one set (either the upper pulling lugs or the lower pulling lugs) of pulling lugs on the coupler and knuckle to contact. This places unwanted force on the coupler, knuckle, and knuckle pin. This force causes the knuckle  22  to move with respect to the coupler body  11 , exerting force on knuckle pin  32 , as well as the knuckle  22  and coupler body  11 . The area of the knuckle  22  that experiences the most stress from the misalignment of the coupler and knuckle is the throat area  76 . The throat area  76  of the knuckle  22  is the internal area of the knuckle  22  immediately surrounding the knuckle pinhole  54 . The use of a single knuckle pin  32  places a load on knuckle pin  32  when the pulling lugs become misaligned, causing fatigue and damage to the coupler, knuckle, and knuckle pin. 
     Referring now to  FIGS. 4-7 , a coupler-knuckle assembly embodying the improved design of the present invention is generally designated  100  and includes a coupler body  102 , a knuckle  112 , and two knuckle retainer plugs  122 ,  124 . The knuckle and knuckle retainer plug design can be used in current OEM coupler production or for field replacement when knuckles need to be replaced in current revenue service. The improved knuckle couples with any Type E, F, or H couplers. 
     The coupler body  102  of the present invention includes the same components and is the same design as the prior art coupler body  11  Shown in  FIGS. 1-3 . Thus, the coupler body  102  includes a coupler head  104  and coupler shank  106 . The coupler head  104  has a knuckle side  108  and a guard arm side  110 . Coupler head  104  has a front face  114  including a throat portion  116  extending towards the knuckle side  108  in a curved manner toward upper pivot lug  118  and lower pivot lug  120 . All parts of coupler body  102  function the same way as described previously for prior art coupler body  11 . 
     The knuckle  112  of the present invention contains a top tapered hole  130  and a bottom tapered hole  132  that extend into the knuckle and towards each other, but do not connect. The tapered holes  130  and  132  are symmetrical, and contain a top locking groove  138  in the top tapered hole  130  and a bottom locking groove  140  in the bottom tapered hole  132  at the bottom of each respective hole. Both locking grooves  138 ,  140  are identical. The locking grooves  138 ,  140  pivotally secure the knuckle  112  into the coupler body  102 , and ensure the knuckle plugs  138 ,  140  remain in place during use. A hollow shaft  142  that is diametrically smaller than the tapered holes  134 ,  136  connects the top tapered hole  134  and the bottom tapered hole  136 . The hollow shaft  142  allows the internal coring geometry  144  of knuckle  112  to have a greater cross-sectional area in the throat portion  145  of the knuckle  112 . This internal coring geometry change leads to added strength and less fatigue endurance on the knuckle during use, while still making the knuckle light enough for installation purposes. 
     The knuckle  112  of the present invention is inserted between upper pivot lug  118  and lower pivot lug  120  of coupler head  104 , and secured into place by an upper retainer plug  122  and lower retainer plug  124 . The retainer plugs  122 ,  124  include a longitudal member that serves to lock the knuckle  112  into the coupler body  102  and allow the knuckle  112  to pivotally move with respect to the coupler body  102 . Upper retainer plug  122  is inserted through the top plug hole  130  in upper pivot lug  118  and into top tapered hole  134  of knuckle  112 , and lower retainer plug  124  is inserted through bottom plug hole  132  in lower pivot lug  120  and into bottom tapered hole  136 . Upper retainer plug  122  and lower retainer plug  124  are secured in place by top locking groove  138  and bottom locking groove  140  respectively. The knuckle retainer plugs  122 ,  124  are snapped into place by exerting pressure on the retainer plugs  122 ,  124  driving it into the knuckle, with the locking tab  208  ( FIG. 8 ) of the knuckle retainer plugs  122 ,  124  secured into the place by the locking grooves  138 ,  140  in the knuckle  112 . 
     After knuckle  112  is secured in place by upper and lower retainer plugs  122 ,  124 , the top pulling lugs  146 ,  148  and the bottom pulling lugs  150 ,  152  of knuckle  112  are aligned with top pulling lugs  154 ,  156  and bottom pulling lugs  158 ,  160  of coupler body  102  respectively. 
     During use, when uneven force is exerted on the top pulling lugs of the coupler and knuckle, the coupler-knuckle assembly can become misaligned placing force on the coupler, knuckle, and knuckle pin. The inventive coupler-knuckle assembly utilizing the retainer plug design allows the retainer plugs to move independently of each other ensuring contact between both the upper pulling lugs of the knuckle and the upper pulling lugs of the coupler, and the lower pulling lugs of the knuckle and the lower pulling lugs of the coupler. Both sets of pulling lugs (upper and lower) on the coupler and knuckle remain in alignment, allowing the knuckle retainer plugs to remain unloaded during use, preventing breakage of the knuckle retainer plugs, and ensuring even load distribution during buff and draft movements. 
     Referring now to  FIGS. 8-11 , a knuckle retainer plug of the present invention designated  200  includes a shaft  202  with a bottom tapered end  204  and a top end  206 . The knuckle retainer plug  200  can be made of a metallic or plastic material. The shaft  202  is a longitudal member with a circular cross-sectional area that is smaller than that of the plug holes  130 ,  132  in the pivot lugs  118 ,  120 . On the bottom tapered end  204  there are locking tabs  208  that allow the knuckle retainer plug  200  to lock into the locking grooves  138 ,  140  of knuckle  112 . The locking tabs  208  ensure that the knuckle is securely attached to the coupler body in the open, closed, or rotated positions, while still allowing the knuckle to rotate. On the top end  206  of the shaft  202  is a head  210 . The head  210  is dome-shaped and generally has a circular cross-sectional shape having a cross-sectional area greater than that of the shaft  202  and the plug holes  130 ,  132  in the pivot lugs  118 ,  120 . It is also contemplated that the present invention can have a head  210  that is a non-circular shape. The head  210  includes at least one relief or cutout  212  that allows a person to easily remove the knuckle retainer plug  200  with a pry bar, standard slotted screwdriver, or any other shaft-like tool. To remove the knuckle retainer plug from the coupler, the tip of the removal tool is inserted into the relief area beneath the head of the knuckle plug, and the removal tool is forced against the coupler body forcing the plug to unsnap from the locking groove in the knuckle. The removed knuckle retainer plug can be reused and reinserted into another coupler-knuckle assembly. The shaft  202  of the knuckle retainer plug  200  also contains relief areas  214 . These relief areas  214  allow the shaft to use less material in the molding process and allow the knuckle retainer plug  200  to cool faster after the molding process is complete. 
     While particular embodiments of the present knuckle pin have been described herein, it will be appreciated by those skilled in the art that changes and modifications may be made thereto without departing from the invention in its broader aspects.