Patent Publication Number: US-7213718-B2

Title: Vertically aligning slackless drawbar

Description:
FIELD OF THE INVENTION 
   The present invention relates, in general, to certain selected railway type freight car coupling arrangements of the substantially semi-permanent type which are being utilized rather extensively at the present time in the railroad industry to connect the adjacently disposed ends of a pair of such freight cars together in a train consist and, more particularly, the instant invention relates to an improved type of slackless drawbar assembly having vertical aligning means and, still more particularly, this invention relates to an improved vertically aligning slackless drawbar assembly offering a cost effective method of gravity wedge retainment. 
   BACKGROUND OF THE INVENTION 
   Articulated coupling arrangements used for the purpose of connecting adjacently disposed ends of a pair of railway freight cars together in a substantially semi-permanent fashion are well know in the art of railway freight vehicles. These articulated coupling arrangements have to accommodate the longitudinal travel in both directions, as well as the vertical and lateral travel at the coupling as the railway freight cars progress along the rails. The greater loads carried by modern railway cars necessitated articulated coupling arrangements which are capable of maintaining a close-butted relationship between various components to lessen the impact forces on railway cars and the articulated coupling arrangements. As a result, closed buttoned relationships lead to the development of slackless articulated coupling arrangements primarily consisting of couplers and drawbars. The term slackless means that the coupler or drawbar of a particular design is disposed within the center sill in a manner which minimizes longitudinal play or movement. 
   The main advantage of the coupler generally used with the draft gear assembly is that it accommodates the longitudinal travel in both directions, as well as the vertical and lateral travel at the coupling as the railway freight cars progress along the track and, more particularly, enabling such cars to more easily negotiate the curved portion of the track which will be encountered during operation. The primary disadvantage of the coupler is the play or slack in a longitudinal direction increasing the load forces onto a railway freight car. An additional disadvantage of the coupler and the draft gear assembly is the high unit costs due to the complexity of the design and a requirement for a significant number of the components. 
   Lately, the slackless drawbar assemblies have all but eliminated the need for a relatively expensive draft gear assembly used with coupler arrangements. Furthermore, these slackless drawbar assemblies have generally resulted in a desirable overall net decrease in the empty weight of such railway freight cars as well as in overall decrease in unit cost. 
   Each of the slackless drawbar assemblies which are known to be in use at the present time, however, suffer from at least one important and common disadvantage. This common disadvantage is that these slackless drawbar assemblies do not accommodate vertical and lateral travel at the coupling as the railway freight cars progress along the rails and, more particularly, while curving, thus increasing possibility of a flange climb derailment. 
   Additionally, the slackless drawbar may be employed to connect adjacently disposed ends of a pair of a railway freight cars with one car having worn wheels while the other cars have new wheels. Given this condition, the slackless drawbar will then be disposed at an angle in the vertical plane creating an additional vertical force onto a railway freight car having new wheels. This problem is especially magnified when the slackless drawbar is employed to connect adjacently disposed ends of a pair of aluminum lightweight construction coal carrying railway freight cars or an empty weight car. In this application, the slackless drawbar disposed at the angle in a vertical plane may cause the separation of the freight car body from the bolster or it may even cause lifting of the entire fright car from the rail. 
   As of particular significance is a reduction of frictional resistance to side loads to reduce side movement of the connecting adjacently disposed ends of a pair of railway cars and, more importantly, to reduce wheel and rail wear resulting from such side movement and to further minimize the possibility of a flange climb derailment. 
   As it can be seen from the above discussion it is desirable to employ a slackless drawbar which allows for vertical and lateral movement. 
   A common method of providing a slackless arrangement is to utilize a tapered gravity type wedge between a rear wall of a pocket casting (secured in the center sill) and a follower block which rests against the butt end of the coupler or drawbar member. The gravity wedge tends to force the follower block away from the pocket casting end wall and firmly against the butt end of the coupler or drawbar member shank. When component wear occurs subsequently increasing longitudinal clearances between the follower block and the coupler or drawbar member, the clearance or the slack is constantly being taken up by the action of the dropping gravity wedge. 
   In railway freight cars being pushed (buff), the longitudinal forces cause compression of the slackless coupler or drawbar member against the follower, gravity wedge and pocket end wall of the slackless arrangement. 
   When cars are being pulled (draft), the longitudinal forces tending to separate the slackless drawbar or coupler from the pocket end wall creating a condition where the gravity wedge can descend under gravity and lock when the railway freight cars are under the buff load. 
   With the above discussion in mind, attention is now directed to a particular prior art type gravity wedge for a slackless railcar connector assembly. This prior art gravity wedge is taught in U.S. Pat. No. 5,573,126. Disclosed therein is a tapered gravity wedge having a resilient means comprised of an elastomeric or a conventional compression spring disposed within a close tolerance machined bore on one or both faces of the gravity wedge and which protrudes slightly beyond one or both faces of the gravity wedge so that a small, but controlled gap symmetrically remains between the gravity wedge face(s) and the adjacent surface(s). When railcar buff loads are released, the only locked-in force operating on the connector assembly will be that dictated by the compressive load rate of the resilient means. When the buff or compressive load has been released, the gravity wedge will maintain its vertical position as the resilient means “feeds out” and holds the gravity wedge in place, until the next-experienced tensile loading. 
   One of the disadvantages of the gravity wedge of the prior art is the increased cost of the close tolerance machined bores. The other disadvantage is the impact of the environmental factors, such as temperature, humidity, dust and moisture affecting the structural integrity and operation of the resilient means thus enabling descend of the gravity wedge under a draft load condition. 
   Therefore, it is desirable to improve upon retainment of the gravity wedge. 
   SUMMARY OF THE INVENTION 
   The present invention provides a vertically aligning slackless drawbar for connecting adjacently disposed ends of a pair of railway freight cars together in a substantially semi-permanent manner. Such vertically aligning slackless drawbar includes a first member and a second member pivotably and slideably coupled to the first member at one end with a pivot pin. The connection enables vertical movement of the second member in relationship to the first member, thus maintaining such vertically aligning slackless drawbar in a substantially lateral plane and further preventing lifting of the body of such railway freight car from the bolster in a light aluminum railway freight car application. The first member is further secured to a yoke at the other end with the standard “F” pin, and the yoke is secured between the rear lug and a front lug of a center sill of a railway freight car. A pair of tapered gravity wedges compensate for longitudinal slack and are held in place with a pair of leaf springs disposed between the rear lug and the gravity wedge. A predetermined clearance is designed between the adjacent ends of the first and second member to limit lateral movement of the second member in relationship to the first member in order to minimize occurrence of jackknifing. The distal ends of the first and second member incorporate substantially convex surfaces to permit the vertically aligning slackless drawbar and to permit the car to roll with respect to the vertically aligning slackless drawbar. 
   OBJECTS OF THE INVENTION 
   It is an object of the present invention to provide a vertically aligning slackless drawbar that prevents disengagement of the car body with the bolster in a light railway freight car application. 
   It is a further object of the present invention to provide a vertically aligning slackless drawbar that minimizes the occurrence of a flange climb derailment in light weight freight cars. 
   It is another object of the invention to provide a vertically aligning slackless drawbar that offers a lower cost alternative to a slackless coupler in a light railway freight car application. 
   It is an additional object of the invention to provide a vertically aligning slackless drawbar that contains an improved gravity wedge retainment. 
   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 vertically aligning slackless drawbar 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 
       FIG. 1  is a partial planar elevation view of the vertically aligning slackless drawbar of the present invention, partially showing center sills of the adjacent railway freight cars. 
       FIG. 2  is a partial planar lateral view of the vertically aligning slackless drawbar shown in  FIG. 1 . 
       FIG. 3  is a partial planar cross-sectional view of the second member of the vertically aligning slackless drawbar taken along lines  3 — 3  in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION 
   Prior to proceeding with the more detailed description of the invention it should be noted that for the sake of clarity and understanding the invention, identical components which have identical functions have been identified with identical reference numerals throughout the several views illustrated in the attached drawing Figures. 
   Now reference is made, more particularly, to the several Figures. Illustrated therein is an vertically aligning slackless drawbar, generally designated  10 , constructed according to a presently preferred embodiment of the invention. Such vertically aligning slackless drawbar  10  connects the adjacently disposed ends (not shown) of a pair of railway freight type cars (not shown) together in a substantially semi-permanent manner. Such vertically aligning slackless drawbar  10  comprises a first member, generally designated  20 , coupled to a yoke, generally designated  110  and a second member, generally designated  50 , pivotally coupled to the first member  20  with a pivot pin  14 . The pin  14  is retained by a pair of fasteners  42  at each end. 
   As may be seen in the FIGURES, the first end of the first member  20  (partially shown) extends within an open end  102  of a first center sill, generally designated  100 , of a standard construction which is secured longitudinally beneath a railway car (not shown). 
   The first end having a substantially convex surface  22  which fits against a matching substantially concave face  112  of the yoke  110  having a first end  120  and a second end  122  for retainment within the sill  100  between a front lug  104  and a rear lug  106 . It is presently preferred that such substantially convex surface  22  will be convexly shaped in each of a generally lateral direction and a generally vertical direction. A vertically tapered gravity wedge  130  is located between the rear lug  106  of the first center sill  100  and a rear portion  114  of the yoke  110  to remove the longitudinal slack. The rear portion  114  has a first predetermined tapered profile as seen in  FIG. 1 , to cooperate with the second predetermined tapered profile of the gravity wedge  130 . In the presently preferred embodiment, the second predetermined tapered profile of the gravity wedge  130  is substantially equal to the first predetermined tapered profile of such rear portion  114 . First member  20  is secured within the yoke  110  by a standard “F” type pin  98  which is extended vertically through an “F” pin aperture  24  in the first member  20  and through a first pair of vertically aligned concentric apertures  116  disposed within the yoke  110 . The aperture  24  includes a pair of wall surfaces  26  tapered toward the center of the first end at a predetermined angle to aid during such first member  20  rotation. 
   At least one leaf spring  16  of a predetermined force and of a predetermined temper is disposed between the rear lug  106  and the gravity wedge  130  to maintain such gravity wedge  130  in place and prevent the gravity wedge  130  from descending and locking in the draft condition. The advantage of such leaf spring  16  over prior art lies in its higher resiliency to the various environmental factors thus providing consistent retainment of such gravity wedge  130 . 
   The second end of the first member  20  contains a cavity, generally designated  30 , formed by a first side surface portion  32 , a second side surface portion  34 , a top surface portion  36  and bottom surface portion  38 . Both the first side surface portion  32  and the second side surface portion  34  are sloped toward the center of the first member  20  at a predetermined angle. A second pair of vertically aligned concentric apertures  40  are provided within the top surface portion  36  and the bottom surface portion  38  for engagement with the pivot pin  14 . Preferably a pair of sleeve bearings  44  are disposed within each of the second pair of apertures  40  for minimizing frictional forces during rotation of pivot pin  14 . 
   In the alternative embodiment, coupling of the first member  20  to the second member  50  can be accomplished with a threaded fastener and, particularly, a shoulder screw type fastener. To enable this, one of the cavities  40  would be threaded to mate with a threaded portion of such shoulder screw. The shoulder screw type fastener can be either of a commercially available origin or a specialty fastener machined to predetermined dimensions as suitable for a particular application. 
   “Such first member  20  will preferably includes at least one weight-reducing aperture  46 , having a predetermined configuration, formed therethrough intermediate its first and second ends”. 
   The first end of the second member  50  contains a third tapered surface portion  52  and a fourth tapered surface portion  54  mating against the first side surface portion  32  and the second side surface portion  34  of the cavity  30 , respectively. As can be seen in  FIG. 2 , a predetermined clearance  18  is designed between the first member  20  and the second member  50  to limit lateral motion of the second member  50  and minimize the occurrence of jackknifing of the railway freight cars. 
   Preferably, the first end of the second member  50  further contains a sleeve bearing  58  disposed within a pivot pin aperture  56  of a predetermined diameter for minimizing frictional forces during lateral rotation and vertical sliding movements of the pivot pin  14 . 
   The second end of the second member  50  having a substantially convex surface  60  fits against a matching substantially concave surface  202  disposed within a second center sill, generally designated  200 , of an adjacent railway freight car (not shown). It is presently preferred that such substantially convex surface  60  will be convexly shaped in each of a generally lateral direction and a generally vertical direction. A pair of drawbar retainers  70  having a spherical surface  72  are butted against a front lug  204  of the center sill  200 . Such spherical surface  72  is fitted against a mating substantially spherical surface portion  62  of the second end of the second member  50 , best shown in  FIG. 3 . 
   Such second member  50  will preferably include at least one weight-reducing aperture  64 , having a predetermined configuration, formed therethrough intermediate its first and second ends. 
   Those skilled in the art can readily understand that vertical displacement between opposite ends of the adjacent railway freight cars is compensated for in the present invention by the slidable coupling of the pivot pin  14  within the sleeve bushing  58  allowing the second member  50  to move vertically in relationship to the first member  20 . Thus the vertically aligning slackless drawbar  10  of the present invention remains in the substantially lateral plane preventing being vertically displaced and, more importantly, minimizing the occurrence of the disengagement of the car body with the bolster in a light railway freight car application. 
   Lateral movement of the vertically aligning slackless drawbar  10  is enabled by a pivotable coupling of the second member  50  about the pivot pin  14  and further enabled by the convex surface  60  and spherical surfaces  62  to minimize occurrence of a flange climb derailment in light weight freight cars. It will be further understood that the pivotal movement of the second member  50  is limited by the designed clearance  18  in order to minimize the occurrence of jackknifing. 
   Thus, those skilled in the art can readily understand that the vertically aligning slackless drawbar of the present invention offers a lower cost alternative to a slackless coupler in a light railway freight car application by accommodating longitudinal, vertical and lateral travel directions. 
   For the sake of brevity, it should be noted that in the most presently preferred embodiment of the instant invention, the longitudinal slack adjustment of the second member is substantially a mirror image of the slack adjustment of the first member of such vertically aligning slackless drawbar  10 . Accordingly, a detailed description of such slack adjustment will not be repeated here. 
   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.