Yoke for a railway draft gear and method of making

Abstract

Yokes utilized in railway coupling apparatus are designed according to the invention to have improved stress profiles and increased service life. Investment casting techniques used to make the yokes and other components of the coupling apparatus yield improved surface finishes and tighter dimensional tolerances of the parts without requiring hammering, coating or other post-casting treatment.

1 . A method for making a railway car coupling component, comprising the steps of:
 forming a destructible prototype of the component in destructible media;   coating the prototype to form a temporary mold;   removing the prototype from the temporary mold; and   casting the component in the mold in metal; wherein   the component has weight greater than about 70 lbs, and has dimensions within ±3% of a design dimension.   
     
     
         2 . The method according to  claim 1 , wherein the component is a yoke, having a weight greater than about 190 lbs. 
     
     
         3 . The method according to  claim 1 , wherein the prototype is made of wax. 
     
     
         4 . The method according to  claim 1 , wherein the prototype is coated with a ceramic slurry to form the temporary mold. 
     
     
         5 . A railway car coupling component made by the process of  claim 1 . 
     
     
         6 . A knuckle made by the process of  claim 1 . 
     
     
         7 . A method for making a yoke for a railway car coupling apparatus, comprising the steps of:
 forming a destructible prototype of a yoke having a tail portion at one end and two opposed sections parallel along their entire length extending from the tail portion and terminating in a head portion,   the head portion formed from the forward ends of the sections forming opposed top and bottom walls of the head portion and two opposed key slot walls disposed between the top and bottom walls, the key slot walls each having an elongated key slot having a forward surface defined by a first arc,   the key slot walls each having a forward peripheral surface defined by a second arc with a center of curvature coincident with the center of curvature of the first arc, wherein the distance between the front of the key slot and the front of the second arc is less than 3 inches;   coating said prototype to form a temporary mold;   removing the prototype;   casting the yoke in the temporary mold in metal; wherein   the finished yoke weighs more than about 190 lbs and has dimensions within ±3% of a design dimension, without finish grinding.   
     
     
         8 . A yoke made by the process of  claim 6 .