Abstract:
E-type and F-type yokes improve the ability of the yokes to be constructed having lighter weight yet function to handle loads from car coupling assembly components, such as, for example, a coupler mounted on the yoke. The E-type and F-type yokes have straps and openings provided in the straps, and are constructed from austempered ductile iron. Embodiments may be constructed with a tail or butt portion that includes sloped walls that form cavities in the butt portion of the yoke, where a supporting structure spans between the yoke rear wall and the draft gear seat wall.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is directed to apparatus for coupling railway cars, and more particularly to E-type and F-type yokes that are constructed to be lighter in weight than current yokes and to provide improved wear resistance. 
     2. Description of Related Art 
     It is common practice in the railroad industry to use coupling components to secure adjacent rail cars together, in particular, freight cars. In general, two adjacent freight cars are joined by heavy shafts extending from each car, known as couplers. The couplers are installed on yokes that are mounted on the underside of the car. Railway couplers, particularly those utilized for railway freight cars or vehicles, have a coupler body which is an integral casting of a coupler head and a shank. The head of the shank may be an AAR Standard Type “E” or “F” Coupler Head. The head also carries a knuckle and includes a lock, a thrower, a pivot pin and an articulated lock assembly. Couplers generally carry a knuckle which is pivotally mounted on the coupler head and is designed to engage with another knuckle carried on an adjacent coupler or another car. 
     The coupler is made from a casting formed from low alloy steel. Although there are AAR standards for couplers, the length of the shank from the butt end of the coupler to the location where the shank joins the head may vary. The coupler is designed to be installed on a draft yoke of a railway vehicle. In the case of the type F coupler shank, the butt end of the coupler shank is a spherical surface and bears against the face of the front follower plate mounted within the yoke. The coupler is pivotally mounted on a yoke with a pin that joins the coupler to the vehicle&#39;s yoke. Generally, each coupler is engaged with a yoke housing a shock-absorbing element referred to as the draft gear. The type-E and type-F couplers are the standard couplers for railway freight cars. As a result of implementation of AAR standards and specifications for production of couplers, such as a type-E coupler, the standard railway car couplers are completely interchangeable, regardless of the manufacturer. In addition, adherence to a standard also promotes uniformity among manufacturers products, so that couplers from any one manufacturer are to able to be readily joined to couplers from any other domestic manufacturer. The Association of American Railroads (“AAR”) has adopted standards for railway couplers, which provide specific geometry and dimensions that allow the coupler to receive standard knuckles that are pivotally carried on the coupler to couple with a knuckle on a coupler of an adjacent railway car. The knuckle must be allowed to freely operate when coupling and uncoupling railway cars. In order to determine whether a coupler meets the AAR standards, gauges may be used, which are applied to the coupler to verify that the coupler dimensions or parameters are within an allowable variation or tolerance range. 
     Each coupler is engaged with a yoke housing a shock-absorbing element referred to as the draft gear. Conventionally, the yoke is an elongated structure having two side sections extending from and joined by a tail portion. The side sections are also known and referred to as “straps”. The side sections or straps are joined at the opposite end by a head portion where the yoke is joined to the coupler with a securing component, such as a key or pin. The yoke generally has a pocket formed by the straps and a rear wall, and a draft gear is positioned between the straps of the yoke, and between the tail portion and the head portion. The best-known yokes are the E-type and F-type. The E-type yoke is governed by AAR standards that include the AAR S-143 Standard, SY 40AE, Y40 or YS93AE, for a 24⅝ inch gear pocket, although there are some tolerances that the pocket may have, as permitted by the standards. A typical E-type yoke has straps that are 5 inches. The F-type yoke is governed by the S-149 standard and the Y45 standard. Although there are other differences between E-type and F-type yokes, a primary difference is the design and orientation of the pin or key used to join the coupler to the yoke. 
     Typical yokes contain apertures in the yoke head portion, which also may be known as the key slots or pin bores by which a coupler is joined to the yoke with the installation of a key or pin through the slot or bore to connect the yoke and coupler. Adjacent railcars, when coupled together and in motion, place tension on the yoke and compressive forces are transferred to bearing surfaces at opposed ends of the yoke where the draft gear is housed. 
     Adjacent freight cars are separated in accordance with standard specifications which includes an allowance for a specified yoke length. In accordance with applicable AAR standards, typically, E-type and F-type yokes, respectively, may have a length of 41⅛″ or 37½″. 
     SUMMARY OF THE INVENTION 
     Lightweight E-type and F-type yokes are provided. The yokes of the invention improve the ability of the yokes to be constructed having lighter weight, yet function to handle loads from car coupling assembly components, such as, for example, a coupler mounted on a yoke. Yokes according to the invention, in addition to being constructed lighter in weight, may also have improved wear properties, such as, for example, in regard to the engaging surfaces of the yoke. 
     According to one preferred embodiment, E-type and F-type yokes are provided having a tail or butt portion that includes angles or sloped walls that form a one or more cavities in the butt portion of the yoke. 
     According to another preferred embodiment, the butt portion of the yoke includes a supporting structure that features a transverse rib or wall that may be less than 2 inches, and preferably an inch or less, and more preferably less than ½ inch. According to some preferred embodiments, the supporting structure is even narrower, and is a transverse rib or wall that has a thickness of about ¼ inch. 
     It is another object of the invention to provide an improved yoke that includes lightening features of apertures in the straps or side walls of the yoke, or combinations thereof. 
     It is another object of the invention to provide an improved yoke that includes lightening features of apertures in the head of the yoke, and particularly in the top and bottom walls of the head. 
     It is another object of the invention to provide an improved yoke that may conserve material used to construct the yoke. In accordance with some preferred embodiments, yokes may be have maximum wall thicknesses of about 1¼ inches. According to some embodiments, some walls or ribs used in the construction of the yoke may have thicknesses as narrow as ¼ inch. In accordance with some preferred embodiments, the keyslot walls may be provided having a uniform or substantially uniform thickness that may be less than the thickness of the straps of the yoke. According to a preferred embodiment, a preferred thickness of the keyslot walls may be about 1¼ inches, and according to a most preferred embodiment, may be less, and may be about 1 inch. 
     It is another object of the invention to provide an E-type yoke that is lighter in weight than traditional E-type yokes, yet is suitably strong and meets or exceeds AAR standards for E-type yokes. 
     It is another object of the invention to provide a type-F yoke that is lightweight and has improved resistance to wear. 
     It is another object of the invention to provide an F-type yoke that is lighter in weight than traditional F-type yokes, yet is suitably strong and meets or exceeds AAR standards for F-type yokes. 
     According to one preferred embodiment, it is a further object of the invention to produce an E-type yoke with opposing keyslot walls having a uniform thickness in their extension beyond the head top and bottom walls. 
     It is another object to accomplish the above objects by providing a yoke with one or more of the above features, including embodiments that contain one or more or combinations of one or more of the features. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of an E-type yoke according to the invention. 
         FIG. 2  is a side elevation view of the E-type yoke of  FIG. 1 , depicted in an orientation in which the yoke is used in operation. 
         FIG. 3  is view looking from the bottom toward the top of a section of the yoke of  FIG. 2 , taken along the section line  3 - 3  of  FIG. 2 . 
         FIG. 4  is top plan view of the E-type yoke of  FIG. 1 , looking overhead at the yoke. 
         FIG. 5  is a rear elevation view of the yoke of  FIG. 1 , shown with the yoke resting on a side. 
         FIG. 6  is a perspective view of an F-Type yoke according to the invention. 
         FIG. 7  is a top plan view of the yoke of  FIG. 6 . 
         FIG. 8  is a right side elevation view of the yoke of  FIG. 6 . 
         FIG. 9  is a sectional view of the butt end portion of the yoke of  FIG. 6 , broken away from the other portions of the yoke, and taken along the section line  9 - 9  of  FIG. 8 . 
         FIG. 10  is a front elevation view of the yoke of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1-10 , exemplary embodiments of a lightweight coupler yoke  10 , 110  are shown. The yokes  10 , 110  are configured to be compatible with existing standard type couplers and knuckles to allow for use of the yokes  10 , 110  in current railway coupling applications. The yokes  10 , 110  preferably are constructed from austempered metal, as discussed herein, and preferably may be constructed having a suitable wall thicknesses to provide suitable strength to withstand force loads that a yoke would encounter during operations, including when in use on a railway vehicle. Preferred embodiments of the yokes also possess suitable strength properties to meet AAR standards or exceed them. The yokes  10 , 110  may be configured as a casting. In operation, the yokes  10 , 110  may be installed on a center sill of a railway vehicle along with a coupler and a draft gear (not shown). 
     According to  FIGS. 1-5  an E-type yoke  10  is shown according to a preferred embodiment. The yoke  10  has a head  11  at one end thereof and a butt portion  12  at the other end thereof. Connected to the butt end portion  12  are top and bottom straps  20 , 21 , respectively, which span to extend to the yoke head  11 . A draft gear seat  13  is shown having a substantially planar surface  13   a . The yoke head  11  includes keyslot walls  15 , 16  which, in the embodiment illustrated, are outwardly divergent from one another. The keyslot walls  15 , 16  span from the front draft gear walls  22 , 23  from which they extend forwardly, to the nose portion  24 , 25 . The draft gear pocket  26  is shown defined between the rear draft gear wall face  13   a , the top and bottom straps  20 , 21 , respectively, and the front draft gear walls  22 , 23 . The keyslot walls  15 , 16  are provided with keyslots  27 , 28 , respectively, which oppose each other, as shown in  FIGS. 2, 3 and 5 . Each keyslot  27 , 28  preferably has a radiused configuration at each end thereof. In addition to the keyslot walls  15 , 16 , the head  11  also is shown having a first wall and a second wall, which may be referred to as a top wall  31  and a bottom wall  32 . 
     The yoke  10  may be configured with standard yoke contour dimensions for E-Type couplers (such as Y40 and Y41). According to preferred configurations, according to one exemplary embodiment, a yoke configured with the Y40 yoke dimension preferably has a draft gear pocket length of 24⅝ inches, and for a Y41 yoke configuration, the draft gear pocket length is 36 inch long. According to preferred embodiments, the draft gear pocket  26  preferably is sized and dimensioned in accordance with AAR specifications and standards to accommodate a draft gear and/or other components that may be installed for the coupling assembly. According to a preferred embodiment, the E-type yoke may have a preferred length of 41⅛. 
     According to a preferred embodiment illustrated, openings  35 , 36  are provided in the respective straps  20 , 21 . The openings  35 , 36  in the straps  20 , 21  preferably oppose each other. According to a preferred embodiment, the openings  35 , 36  are elongated to span across the straps  20 , 21 . The openings  35 , 36  are shown having radiused ends and a straight elongated portion. The straps  20 , 21  may be constructed in accordance with an AAR standard, which in some preferred embodiments is 5 inches in height. The openings  35 , 36  are preferably provided within the 5 inches of strap height. According to a preferred embodiment, the height H 1  of the openings  35 , 36  preferably are up to about one half of the strap height H 2 , as depicted according to a preferred embodiment shown in  FIG. 3 . According to one preferred embodiment, the strap height H 2  is 5 inches and the opening height H 1  is 2½ inches. According to one embodiment, the draft gear pocket  26  may be 25 inches (measured from a plane of the rear surface  13   a  to a plane of the draft gear pocket front walls  22 , 23 ). According to one preferred embodiment, the openings  35 , 36  are provided at a central location of the straps  20 , 21 , relative to the strap height. According to one embodiment, the openings preferably are provided to be located within about 1.5 inches from the edge of a strap wall. 
     Referring to  FIGS. 1, 3 and 4 , the top wall  31  and bottom wall  32  of the head portion or head  11  preferably have wall openings  37 , 38 , respectively, disposed therein. According to a preferred embodiment, the wall openings  37 , 38  are provided to oppose each other, and preferably, the openings  37 , 38  are centrally located in the top and bottom walls  31 , 32 , respectively. According to a preferred embodiment, the top wall  31  and bottom wall  32  have a curved or radiused edges  31   a , 32   a , respectively, which are provided at the front wall end. According to a preferred embodiment, the openings  37 , 38  preferably are provided with a forward portion  37   a , 38   a , which is radiused or curved. According to some preferred embodiments, the radiused or curved forward portion  37   a , 38   a  of the respective top and bottom wall openings  37 , 38  has a profile corresponding with the radius or curve of the top and bottom front wall edges  31   a , 32   a . In a preferred embodiment, the wall openings  37 , 38  have radiused or curved corners. As illustrated the top and bottom walls  31 , 32 , respectively, support the yoke  10  and the keyslot walls  15 , 16  connecting to the respective top and bottom walls  31 , 32 . 
     According to a preferred embodiment, the thickness of the yoke walls preferably may be constructed to be from about 1¼ inches to about ¼ inch. For example, the thickness of the walls forming the straps  20 , 21  may be from about 1 inch to 1¼ inch, with a preferred thickness of about 1⅛ inch. According to some embodiments, the top and bottom walls  31 , 32  of the head portion  11  may have a wall thickness that is similar to the walls of the straps  20 , 21 . Preferably the thickness of the keyslot walls  15 , 16  may be provided to be about 1¼ inches or less, and according to some preferred embodiments, the thickness of the keyslot walls  15 , 16  is about 1 inch. According to a preferred embodiment, the wall thicknesses of the key slot walls  15 , 16 , the straps  20 , 21  and top and bottom walls  31 , 32  may be from about 1 inch to 1¼ inches, wherein each wall or strap pair may have a thickness within this range, which may be a different thickness than the other wall pair or strap pair. According to a preferred embodiment, each strap  20 , 21  preferably may have a uniform thickness along its length between joining locations (which is shown joining with the butt end  12  at one end thereof, where a radiused fillet may be provided ( FIG. 2 ), and joining with the head  11  at the other end thereof, which also may have a radiused fillet at the head portion  11 . 
     According to a preferred embodiment, as illustrated, the yoke  10  has a butt end portion  12  disposed opposite the head portion  11 . The butt end portion  12  is shown having radiused or curved edges  12   b , 12   c , and a pair of pockets  50   a , 50   b  (see  FIG. 3 ) provided in the butt end portion  12 . Referring to  FIG. 5 , the butt end portion  12  is shown having tapered side wall portions  12   e , 12   f  which taper inwardly toward the center of the butt end portion  12 . The butt end portion  12  is shown with a rear wall portion  12   a  formed by the narrowing of the converging side wall portions  12   e , 12   f . Referring to  FIG. 3 , the butt end portion  12  is shown having an inner wall portion  12   g  which preferably is connected with the rear wall portion  12   a . According to a preferred embodiment, the inner wall portion  12   g  connects with the rear wall portion  12   a  by a connecting structure, which in the preferred embodiment illustrated, is shown as a rib or wall  12   h . The connecting rib or wall  12   h  preferably is transversely disposed and is provided at the mid level of the height of the butt end portion  12 , such as, for example, the height of the inner wall  12   g . The inner wall  12   g  according to some preferred embodiments may be formed from the wall that forms the draft gear seat  13  and may be coextensive with it, or formed such that the draft gear surface  13   a  is on one side of the wall and the rear surface of the draft gear seat wall faces into the cavities or pockets  50   a , 50   b.    
     Referring to  FIGS. 6-10 , according to one embodiment, an F-type coupler yoke  110  is shown according to a preferred embodiment. The coupler yoke in the F-type yoke configuration, illustrated as the yoke  110 , is generally oriented vertically when in use, as depicted in the view of  FIG. 6 , where the pin bores  115 , 116  are shown located vertically to receive a connecting member, such as a pin (not shown) to connect with a component of a coupling assembly (e.g., a coupler). The yoke  110  has a head or head portion  111  at one end thereof and a butt portion  112  at the other end thereof. The head portion  111  preferably includes an upper head portion  111   a  and lower head portion  111   b . Connected to the butt end portion  112  are top and bottom straps  120 , 121 , respectively, which span to extend to the yoke head  111 . A draft gear seat  113  is shown having a substantially planar surface  113   a . The yoke head  111  includes pin bores  115 , 116  which are provided in the respective top and bottom walls  117 , 118  of the head  111 . According to a preferred embodiment illustrated, the top and bottom walls  117 , 118  may be outwardly divergent from one another. Preferably, an upper window  122  and lower window  123  are formed in the respective top and bottom walls  117 , 118  through which observation of the draft gear (not shown) may be made when the yoke is installed in an assembly with other coupling components. A front supporting structure, shown including a pair of side walls  124 , 125  is provided, and connects the upper front wall portion or wall  117  with the lower front wall portion or wall  118 . A pocket  126  is shown provided between the draft wall surface  113   a  and the yoke head portion  111 . 
     According to a preferred embodiment illustrated, strap openings  135 , 136  are provided in the respective straps  120 , 121 . The strap openings  135 , 136  preferably oppose each other. According to a preferred embodiment, the strap openings  135 , 136  are elongated to span across the straps  120 , 121 . The strap openings  135 , 136  are shown having radiused ends and a straight elongated portion. The straps  120 , 121  may be constructed in accordance with an AAR standard, which in some preferred embodiments is 5¾ inches in height (as viewed in  FIG. 7 , where a strap height H 4  is represented). The strap openings  135 , 136  are preferably provided within the 5¾ inches of strap height dimension H 4 . According to a preferred embodiment, the height H 3  of a strap opening  135 , 136  preferably is up to about one half of the strap height H 4 , as depicted according to a preferred embodiment shown in  FIG. 7 , showing the strap  135 . According to one embodiment, yoke  110  may have an overall length of 37½ inches, with the draft gear pocket  126  having a length of 24⅝ inches (measured from the rear surface  113   a  to a point 4 17/32 inches behind the center point of the pin or pin bore  115 , 116 ). According to a preferred embodiment, the rear surface  113   a  to the center of a pin bore  115 , 116  is 29 5/32 inches. According to one preferred embodiment, the strap openings  135 , 136  are provided at a location between the butt end portion  112  and the head portion  111 . According to one embodiment, the openings preferably are provided to be located within about 1 inch to 1½ inches, and preferably about 1¼ inches to 1⅜ inches from the edge of a strap wall. According to a preferred embodiment, the straps  120 , 121  may increase in width at the locations near each of the ends of the respective straps  120 , 121 , including, for example, at the strap locations where the front and rear of the openings  135 , 136  begin or end. 
     According to a preferred embodiment, the thickness of the walls of the yoke  110  preferably may be constructed to have thicknesses between about 1¼ inches to about ¼ inch. For example, the thickness of the walls forming the straps  120 , 121  may be from about 1 inch to 1¼ inches, with a preferred thickness of about 1⅛ inches. According to some embodiments, the top and bottom walls  117 , 118  of the head portion  111  may have a wall thickness that is similar to the walls of the straps  120 , 121 . The top and bottom walls  117 , 118  may comprise extensions of the respective straps  120 , 121  and have similar thicknesses or, alternatively, have different thicknesses than the respective straps  120 , 121 . Accordingly, the pin bores  115 , 116  preferably have a depth corresponding with the thickness of the respective top and bottom wall  115 , 116 , or respective top or bottom strap  120 , 121 . According to a preferred embodiment a positioning feature is provided at the yoke head portion  111 . Referring to  FIG. 10 , the positioning feature is shown in accordance with a preferred construction as a plurality of positioning tabs  161 , 162  provided on the inner surface  117   a  of the top wall portion  117 , and positioning tabs  163 , 164  provided on the inner surface  118   a  of the lower wall  118 . The positioning feature facilitates even loading to control and distribute loads, for example, from a coupler shank. The positioning tabs  161 , 162 , 163 , 164  preferably comprise wear surfaces and preferably are constructed from the same composition as the other portions of the yoke  110 . Preferably the positioning tabs, such as the upper tabs  161 , 162  and lower tabs  163 , 164 , are provided in opposing relation to each other so that the upper tabs  161 , 162  face the lower tabs  163 , 164 , with each upper tab  162 , 162 , facing a respective lower tab  163 , 164 . As shown in  FIG. 8 , the tab  162  has a generally flat or substantially flat inner surface portion  162   a  and has tapered sides  162   b , 162   c . Preferably, the other tabs  161 , 163 , 164  also are constructed having a flat or substantially flat inner surface portion and tapered sides. The tabs  161 , 162 , 163 , 164  narrow the opening provided at the head  111  of the yoke  110 . According to one preferred embodiment, the tab pairs  161 , 162  and  163 , 164  are disposed proximate the respective pin bore openings  115 , 116 , with each tab of a pair being provided on an adjacent side of a respective pin bore  115 , 116 . 
     According to a preferred embodiment, as illustrated, the yoke  110  has a butt end portion  112  disposed opposite the head portion  111 . The butt portion  112  is shown having radiused or curved edges  112   b , 112   c , and pockets  150   a , 150   b  provided in the butt end portion  112 . According to preferred embodiments, the pocket arrangement includes a first pocket  150   a  and second pocket  150   b . Referring to  FIGS. 7, 8 and 9 , the butt end portion  112  is shown having tapered side wall portions  112   e , 112   f  which taper inwardly toward the center of the butt end portion  112  (similar to the walls  12   e , 12   f  of the butt end portion  12  shown in  FIG. 5 , in connection with the yoke  10 ). The butt end portion  112  is shown with a rear wall portion  112   a  formed by the narrowing of the converging side wall portions  112   e , 112   f . Referring to  FIG. 9 , the butt end portion  112  is shown having an inner wall portion  112   g  which preferably is connected with the rear wall portion  112   a . According to a preferred embodiment, the inner wall portion  112   g  connects with the rear wall portion  112   a  by a connecting structure, which in the preferred embodiment illustrated, is shown as a rib or wall  112   h . The connecting rib or wall  112   h  preferably is transversely disposed and is provided at the mid level of the height of the butt end portion  112 , such as, for example, the height of the inner wall  112   g . The inner wall  112   g  according to some preferred embodiments may be formed from or be part of the wall that forms the draft gear seat  113  and may be coextensive with it, or formed such that the draft gear surface  113   a  is on one side of the wall and the rear surface thereof faces into the cavities or pockets  150   a , 150   b.    
     According to a preferred embodiment, the front portion of the straps  120 , 121  may be constructed to slightly taper inwardly at the head portion  111 . According to a preferred embodiment, the inwardly taper of the straps  120 , 121  preferably is after the front of the openings  135 , 136 , and the straps  120 , 121  and head walls  117 , 118  that join with straps  120 , 121 , respectively, also may have an inward taper. According to a preferred embodiment, a further inward taper of the front portions of the walls  117 , 118  may be provided, and the inward taper may include a portion of converging wall thickness in the front of each wall  117 , 118 , preferably at each front flange  117   b , 118   b.    
     According to some embodiments, the yoke  110  may be configured with standard yoke contour dimensions for F-Type yokes. According to preferred configurations, a yoke configured with the S-149 yoke dimension preferably has a draft gear pocket length of 24⅝ inches and a length of 37½ inches. The spacing between the straps  120 , 121 , as depicted in  FIG. 8 , preferably, meets or exceeds the AAR standards (including any allowable tolerances) so the pocket  126  formed between the straps  120 , 121  may accommodate coupling components (e.g., a draft gear). According to some preferred embodiments, the yoke height, as shown by reference to the orientation in  FIG. 8 , may have a height of about 11½ inches. The yoke  110  preferably may be configured with dimensions that meet the AAR specifications for F-type yokes including with any permitted tolerances, and, may exceed the specifications. 
     According to a preferred embodiment, the yokes  10 , 110  are constructed from an austempered metal, and more preferably, from austempered ductile iron (ADI). Although other austempered metals may be used, and other grades of ADI, according to a preferred embodiment, yokes may be constructed from Grade 3 ADI. According to a preferred embodiment, the ADI may be Grade 3 ADI in accordance with ASTM A897/A897M for ADI castings. According to some preferred embodiments, yokes  10 , 110  may have properties that meet or exceed the specifications for Grade 3 ADI. 
     The yokes  10 , 110  preferably join with a coupler that carries a pivotally connected knuckle movable between open and closed positions. According to preferred embodiments, the yokes  10 , 110  are constructed from an austempered metal, and more preferably austempered ductile iron. As discussed herein, according to preferred embodiments, the yokes  10 , 110  are constructed from ductile iron that is austempered (austempered ductile iron or “ADI”). According to a preferred embodiment, the yokes  10 , 110  may be constructed from a material that is suitably strong and, according to preferred embodiments, may be used to construct a yoke  10 , 110  which meets or exceeds AAR standards. According to come embodiments, the yokes  10 , 110  may be constructed from Grade E steel or ductile iron, and according to some preferred embodiments, the yokes  10 , 110  may be constructed from an austempered metal, such as for example, austempered steel, austempered alloy steel, as well as other austempered metals, and austempered metal alloys. According to a preferred embodiment, the yokes  10 , 110  are constructed from austempered ductile iron. The ductile iron from which the yoke  10 , 110  is formed, may include austempered ductile iron that comprises ductile iron alloyed with one or more metals selected from the group consisting of nickel, molybdenum, manganese, copper and mixtures thereof. According to preferred embodiments, the metal, such as, for example, according to a preferred embodiment, ductile iron used to produce the yoke  10 , 110 , may be treated by a treatment process, and preferably a process to strengthen the material, and to provide a suitable microstructure in the formed yoke  10 , 110 . According to preferred embodiments, the treatment process preferably involves an austenitizing process, by which the formed yoke  10 , 110  is an austempered material, and more preferably, austempered ductile iron (ADI). For example, the forming of the yoke  10 , 110  may involve applying a suitable austenitizing process to the formed ductile iron yoke, (e.g., a casting, forging, machining or other method of forming the yoke). One preferred method involves heating the yoke casting in a heat extraction composition, such as, for example, a molten salt bath, to austenitizing temperature; and holding the bath at an austenitizing temperature so as to dissolve carbon in austenite, followed by quenching (preferably rapidly done) to avoid pearlite formation, and holding the yoke at an austempering temperature in the molten salt bath. The isothermal transformation to ausferrite preferably takes place to provide an austempered ductile iron yoke  10 , 110 . According to alternate embodiments, austempered ductile iron (ADI) may include ductile iron alloyed with one or more metals, such as, for example, nickel, molybdenum, manganese, copper and mixtures thereof. 
     The ADI or ductile iron is austempered to obtain tensile strength, yield, and elongation properties for the inventive yokes which are suitable to meet or exceed the AAR standards for yokes utilized in coupling systems, including the current standard set forth by the American Association of Railroads (AAR) in AAR Manual of Standards and Recommended Practices, such as current standard M-211, M-205, M-220 NDT and Rule 88 of the AAR Office Manual, the complete contents of which are herein incorporated by reference. Alternatively, according to some alternate embodiments, austempered steel, such as, austempered alloy steel, as well as other austempered metals, such as, for example, austempered metal alloys, may be used to construct the yokes  10 , 110 . 
     According to preferred embodiments, the yokes  10 , 110  may be constructed having wall thicknesses that are reduced compared to current existing yokes. The yokes  10  and  110  shown are preferred embodiments, and other configurations, preferably, yoke constructions meeting the standard geometries of AAR coupler yoke standards may be provided and produced in accordance with the present invention, including constructing the yoke to be lighter in weight and/or have thinner walls or wall portions, having openings in the straps and walls, as well as constructing the yokes from austempered metal, and more preferably Grade 3 ADI. Preferred thicknesses for the yoke walls according to preferred embodiments, are from about ¼ inch to about 1¼ inches. 
     Lightweight yokes according to the invention preferably are compatible with coupling and usage of the prior yokes for connection with and use with prior and existing standard AAR couplers, draft gears, blocks and other standard coupling assembly components. The lightweight yokes of the invention provide a lightweight alternative that may be used in place of prior yokes, wherever the prior yokes have been used or are called for. In addition, although references are made to some preferred dimensions corresponding with AAR standards, the dimensions preferably include tolerances provides by or permitted by the standards. According to alternate embodiments, the yokes may be dimensioned to meet one or more alternative standards. 
     According to preferred embodiments, the coupler yokes may be made from a casting and with the use of cores. 
     It is intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention. Numerous other changes, substitutions, variations, alterations and modifications may be ascertained by those skilled in the art and it is intended that the present invention encompass all such changes, substitutions, variations, alterations and modifications as falling within the spirit and scope of the appended claims.