Abstract:
An improved polymeric knuckle pin with at least one indented area that elastomer rings rest in. The indented area is strategically placed in an area on the shaft of the pin where the coupler-knuckle connection exerts impact, force, and stress on the pin. The elastomer rings in the indented area provide cushion to the pin from the impact, force, and stress, allow the pin to avoid hard contact with the coupler and knuckle, distribute the loads exerted by the coupler and knuckle more evenly, realign the coupler and knuckle positions, and protect the pin itself from surface cuts and scratches. The elastomer rings on the shaft of the pin improve the life of both the coupler-knuckle assembly and the pin.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to railway car coupling systems, and more particularly to an improved polymeric knuckle pin. 
         [0002]    This invention is applicable to any type of coupler that uses a pin to pivotally secure the coupler and knuckle together. The knuckle pin pivotally connects a coupler and a knuckle on a railway car. Such railway knuckle pins are usually comprised of a metal or plastic material. 
         [0003]    Knuckle pins are shown in U.S. Pat. Nos. 5,145,076, 5,630,519, and 5,736,088. Prior known knuckle pins were made of either metal or plastic material. Metal pins are heavy, limiting the number of pins a maintenance worker can carry while checking the coupler-knuckle connection on the railroad cars. Metal pins are also very hard to maintain because they are susceptible to rust and corrosion. Furthermore, as a railway car operates, buff and draft movements cause the coupler-knuckle connection to exert stress, force, and impact on the knuckle pin. The high hardness of a metal pin may cause damage to the coupler or knuckle. The pin may bend and impede coupler-knuckle operation, and in rotator cars, if structurally compromised the pin may drop out and cause damage to the crushers. 
         [0004]    Prior known plastic knuckle pins alleviate some of the damages problems caused by the metal knuckle pins, however, the plastic pins were susceptible to defects caused during the formation process. It was not uncommon for plastic pins to contain air and moisture pockets, making the pins non-uniform in their material matrix. Other plastic pins contained spaced-apart annular relief areas in the shaft to improve the overall uniformity of the plastic material. However, these relief areas significantly compromise the structural integrity of the pin and create multiple stress concentration points causing the plastic pins to break easier. 
         [0005]    The present invention provides an improved, impact and stress absorbing knuckle pin that reduces fatigue in the coupler, knuckle, and knuckle pin. 
       SUMMARY OF THE INVENTION 
       [0006]    In accordance with the present invention, an improved railway car polymeric knuckle pin is provided for use in a railway car coupler assembly. 
         [0007]    The polymeric knuckle pin is comprised of a shaft, a head on one end of the shaft, and a locking mechanism on the end of the shaft opposite the head to secure the pin in position as a pivot point between a coupler and a knuckle connection on a railway car. The knuckle pin contains at least one groove in the shaft. The grove is strategically placed in an area on the shaft of the pin where the coupler-knuckle connection exerts impact, force, and stress on the pin. A single or plurality of elastomer rings is placed in the groove or grooves on the shaft. The elastomer rings in the groove provide cushion to the pin from the impact, force, and stress, allow the pin to avoid hard contact with the coupler and knuckle, distribute the loads exerted by the coupler and knuckle more evenly, realign the coupler and knuckle positions, and protect the pin itself from surface cuts and scratches. The elastomer rings on the shaft of the pin improve the life of both the coupler-knuckle assembly and the pin. 
         [0008]    In another embodiment of the present invention, a polymeric knuckle pin is comprised of a shaft, a head on one end of the shaft, and a locking mechanism on the other end of the shaft opposite the head. The shaft containing at least one groove at a point where the coupler-knuckle connection exerts force on the shaft of the pin. The groove or grooves contain a single elastomer ring or plurality of elastomer rings. The head of the pin is non-round shape. The shaft contains a center area between the head and the locking mechanism where the diameter of the shaft is smaller than the diameter of the rest of the shaft. 
         [0009]    It is an object of the present invention to provide a knuckle pin with elastomer rings that prevent the pin from permanent bending and other damages. 
         [0010]    It is also an object of the present invention to provide a pin with elastomer rings that have a high elasticity and will fully recover to their original position once stress from the coupler-knuckle connection is removed from the pin. 
         [0011]    It is a further object of the present invention to provide a knuckle pin with elastomer rings that will realign the coupler-knuckle assembly. 
         [0012]    It is a further object of the present invention to provide a knuckle pin with elastomer rings that will reduce damage and fatigue on the coupler-knuckle assembly. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a top perspective view of a coupler-knuckle assembly with the improved knuckle pin of the present invention in place; 
           [0014]      FIG. 2  is a front elevational view of the improved knuckle pin of the present invention; 
           [0015]      FIG. 3  is a side elevational view of the improved knuckle pin of the present invention; 
           [0016]      FIG. 4  is a top plan view of the improved knuckle pin of the present invention; 
           [0017]      FIG. 5  is a bottom plan view of the improved knuckle pin of the present invention; 
           [0018]      FIG. 6  is side perspective view of a second embodiment of the improved knuckle pin of the present invention; and 
           [0019]      FIG. 7  is a sectional view of the coupler-knuckle assembly along lines  7 - 7  of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    Referring now to  FIG. 1 , a coupler-knuckle assembly incorporating preferred embodiment the present invention is generally designated  10  and includes a coupler body  12 , a knuckle  14 , and a knuckle pin  16 . In the present assembly, the knuckle  14  is pivotally connected to the coupler body  12  by the knuckle pin  16 . The coupler body  12 , as shown, has its knuckle  14  in the closed position. 
         [0021]    Referring now to  FIG. 2 , the knuckle pin of the present invention generally indicated  16 , includes a shaft  32  with a center region  33 , a top end  35 , and a bottom end  42 . A knuckle-pin head  30  is on the top end  35  of the shaft  32 , and a snap lock locking mechanism  36  is on the bottom end  42  of the shaft  32 . The knuckle pin of the present invention is preferably a solid piece of molded urethane or polyurethane as described below. In comparison to a metallic knuckle pin, the polymeric pin is lighter and more resilient, accepts bending fatigue better, and creates less friction as a pivot point between the coupler and knuckle improving performance of the coupler-knuckle assembly. 
         [0022]    The knuckle pin head  30  of the pin  16  has a dome-shaped top  31 , which is sized diametrically larger than the shaft  32 . The pin head  30  also has a significantly larger diameter than the pinhole in the coupler-knuckle assembly. An annular radius  34  is formed between the top end of the shaft  35  and the pin head  30  to protect against damage to the pin when installing the pin. 
         [0023]    At the bottom end  42  of the shaft  32 , the locking mechanism  36  is comprised of two snap lock tabs  37  and  39 . The snap lock tabs  37  and  39  are compressed together or towards each other as the pin is inserted into the coupler-knuckle assembly  10  and expand when the pin is fully inserted into the coupler-knuckle assembly. The snap lock tabs  37  and  39  secure the knuckle pin in the coupler-knuckle assembly, because once the pin is fully inserted into the assembly, the snap lock tabs expand or snap-out to greater diameter than the pinhole in the coupler body. A cotter pin or other suitable locking mechanisms can also be used. 
         [0024]    The shaft  32  is generally cylindrical in shape and includes at least one indented area, wherein the indented area is diametrically smaller than the shaft  32 . An upper indented area  38  and a lower indented area  38 B are located on the shaft  32  in the coupler-knuckle impact regions  112  and  113  (shown in  FIG. 7 ), but the groove can extend beyond the coupler-knuckle impact regions  112  and  113 . Preferably there are multiple indented areas on shaft  32 . One indented area  38  is located on shaft  32  where the shaft  32  contacts the coupler body  12  and knuckle  14  in the coupler-knuckle top impact region  112 , and the other indented area  38 B is located on the shaft  32  where the shaft  32  contacts the coupler body  12  and knuckle  14  in the coupler-knuckle bottom impact region  113 . Elastomer rings  40  are located on the shaft  32  covering and filling some or all of the indented areas. In the areas of the shaft  32  where the indented areas and the elastomer rings  40  are located, the diameter of the indented area plus the rings  40  are the same as the diameter of the shaft  32  or slightly larger than the diameter of the shaft. The elastomer rings of the present invention are preferably made from thermal plastic polyurethane material, but the rings can be made from any material having a high elasticity and resiliency. The number of elastomer rings varies depending on the length of the indented area and the diameter of the rings, but preferably a plurality of elastomer rings are placed inside each indented area. Placement of the elastomer rings in the indented areas along the area where the coupler-knuckle connection exerts the greatest stress, force, and impact on the knuckle pin allows fatigue on both the coupler-knuckle assembly and the pin to be reduced. The elastomer rings deform elastically absorbing the force and stress from the coupler-knuckle connection and cushion any impact that occurs. 
         [0025]    Referring now to  FIG. 3 , the improved knuckle pin  16  is shown in a side elevational view. The knuckle pin  16  is completely symmetrical except for the locking mechanism  36  on the bottom end  42  of the shaft  32 . The two snap lock tabs  37  and  39  are only on two sides of the knuckle pin  16 . Everything else shown is the same as previously described in  FIG. 2 . 
         [0026]    Referring now to  FIG. 4 , a top plan view shows that in the preferred embodiment of the present invention, the knuckle pin head  30  is circular in shape. As shown, the elastomer rings  40  extend radially outward, slightly beyond the diameter of the shaft  32 . 
         [0027]    Referring now to  FIG. 5 , a bottom plan view of the knuckle pin  16  shows that the pin is completely symmetrical except for the snap lock tabs  37  and  39  on the bottom end  42  of the shaft  32 . 
         [0028]    Referring now to  FIG. 6 , another embodiment of the knuckle pin of the present invention is shown at  60 , including a shaft  66 , wherein the shaft  66  has a top end  67 , a center region  68 , and a bottom end  69 , a knuckle-pin head  62  on the top end  67  of the shaft  66 , and a locking mechanism  76  on the bottom end  69  of the shaft  66 . The indented area  72  and elastomer ring  74  structure is the same as described in  FIG. 2 . In the present embodiment, the knuckle pin head  62  is a non-round shape  64  preventing rotation of the knuckle pin  60  while inserted in the coupler-knuckle assembly  10 . The knuckle pin head  62  as shown has one flat side with the remaining sides round, but any other non-round shapes are contemplated in this invention. The shaft  66  has a reduction in the shaft diameter  70  in the center region  68  of the shaft  66 . Typically during use, very little stress is paced on the center region  68  of the shaft  66 . The reduction in shaft diameter  70  allows the knuckle pin  60  to be lighter because less material is used, while also facilitating the cooling process by allowing the pin to cool faster and more evenly, ensuring the pin has a uniform material matrix after the molding process. The bottom end of the shaft  69  has a bottom extension  78  with a hole  80 . This a non-standard element on most knuckle pins, but it allows a compressed air hose to be tied to the shaft through the hole  80 . 
         [0029]    Referring now to  FIG. 7 , a sectional view including the knuckle pin  16  of the present invention locked into place in a coupler-knuckle assembly  10  is shown. The knuckle pin  16  is inserted into the coupler pinhole  114  that is aligned with the knuckle pinhole  116  until the locking mechanism  76  engages and prevents the pin from coming loose or falling out of the coupler-knuckle assembly  10 . When the knuckle pin  16  is fully inserted into the coupler knuckle assembly  10 , as shown in  FIG. 7 , the indented area  72  containing the elastomer rings  74  are aligned with the coupler-knuckle impact regions  112 . There is a top coupler-knuckle impact region  112  and a bottom coupler-knuckle impact region  113  where the coupler and knuckle components meet. The coupler-knuckle impact regions  112  are where the coupler-knuckle assembly  10  exerts the greatest amount of force, impact, and stress on the knuckle pin  16 . The force and stress exerted on the knuckle pin  16  are caused by the misalignment of the knuckle pulling lugs  100  and the coupler body pulling lugs  106 . The knuckle has two upper pulling lugs  101  and  102 , and two lower pulling lugs  103  and  104 . The coupler body has two upper pulling lugs  107  and  108 , and two lower pulling lugs  109  and  110 . While in use, when uneven force is exerted on the upper and lower pulling lugs of the coupler and knuckle, the coupler knuckle assembly can become misaligned placing force, stress, and impact on the knuckle pin  16 . The elastomer rings  74  deform elastically absorbing the force, impact, and stress exerted on the knuckle pin  16  reducing the fatigue of the pin, and the resiliency of the elastomer rings realign the coupler  12  and knuckle  14 . Once the coupler  12  and the knuckle  14  are realigned in their original and proper position, and the outside stress is removed from the knuckle pin  16 , the elastomer rings  74  fully recover to their original position. 
         [0030]    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.