Abstract:
A housing for a railroad car draft gear is disclosed. The draft gear housing has an axially elongated tubular portion comprised of layers. At least one of the layers of the draft gear housing is formed from a filament wound structure or composite material, and an additional layer may be steel.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a draft gear, and more particularly, to the housing for the draft gear which carries an energy absorption spring package. The draft gear housing is comprised of a layer or layers of a filament wound composite material and, in a preferred embodiment, steel. 
     2. Prior Art 
     Draft Gears from there invention in the late 1800s, have included some kind of frame or housing. These frames or housings have, for the most part, been constructed of steel or malleable iron via a semi-sophisticated manufacturing process. Because of various problems, the number of qualified suppliers of castings in the U.S.A has been dwindling and customers have been forced to seek sources of supply overseas and/or pay higher prices in the domestic market. Irrespective of where the steel or malleable iron castings are sourced, because of their material composition, they tend to be heavy and difficult to manufacture. That is, even when manufactured correctly, they add weight to the finished rail car and the shipping costs of the castings themselves tend to be high. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disabilities of the prior art by providing a draft gear housing which includes a relatively small amount of cast steel or wrought steel or malleable iron, is lightweight and does not require sophisticated manufacturing techniques. In accordance with the present invention there is included a housing having a closed end, and an open end which is axially spaced from the closed end of the housing. Along the length thereof, the draft gear housing includes a series of tubular layers, at least one of which is a filament wound composite material, and another, in certain embodiments, which is steel. The steel layer can be cylindrical in shape or slightly barrel-shaped and can extend either substantially the entire length of the housing or just a portion of the axial length thereof. 
     Thus, an object of this invention is to provide a draft gear having a housing which includes a filament wound composite material and a minimal amount of steel. 
     Still a further object of this invention is to provide a draft gear housing which is constructed of a filament wound composite material arranged around a barrel shaped steel cylinder. 
     An additional object of this invention is to provide a draft gear housing whose bore needs not be only round or rectangular in shape but can be tailored to the particular application. 
     Another object of this invention is to provide a lightweight draft gear housing which is constructed of fiberglass filament and epoxy resin wrapped around a plastic frame. 
     Yet another object is to provide a draft gear housing that employs metal, which is cheap, easy to manufacture and which is readily commercially available. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Other features and advantages of the invention will become apparent in the following description of the preferred embodiment taken in conjunction with the drawings, in which: 
     FIG. 1 is a longitudinal cross-sectional illustration of a draft gear housing wherein the steel cylinder extends only part of the length of the bore; 
     FIG. 2 is a top elevation view of the draft gear housing of FIG. 1; 
     FIG. 3 is a second embodiment of a draft gear housing wherein a steel tubular member extends substantially the full length of the draft gear housing. 
     FIGS. 4,  5 ,  6 ,  7 ,  8  and  9  illustrate that the draft gear housing bore can take a number of different shapes; 
     FIG. 10 is a side perspective of a fiberglass filament and epoxy resin matrix wrapped around a composite plastic liner; and 
     FIG. 11 is a side perspective of a steel cylinder prior to the addition of the fiberglass and epoxy resin matrix which is barrel-shaped. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention, as illustrated in the drawings, and particularly in FIG. 1, concerns a draft gear  10  which includes a housing  12  having one end  14  closed by a fixed end wall or plate  16  and an open end  18 . The housing  12 , carries for reciprocating movement within the open end  18 , a plunger  20 . The plunger  20  is acted upon by a follower plate  22  in a manner as is well known in draft gear technology. The plunger  20  acts upon a spring assembly arranged within the housing  12  In one form, the spring assembly includes an elastomeric pad stack  24  in a manner well known in the art as disclosed in U.S. Pat. No. 4,566,678. In order to maintain the elastomeric pad stack  24  in a straight column, a guide spike  26  is employed. The guide spike  26  is held stationary at all times by virtue of a head portion  28  of the guide member  26  being fixed to the plate  16 . During a work cycle, a pilot hole  30  in the elastomeric pad stack  24 , along with a center bole  31  in the plunger  20 , allow for the compression of the pad stack while the guide spike remains stationary. The spike can also be captured between the pad and the rear wall. 
     As often the case, the pad stack  24  may be subjected to a pre-load, in which case a force is exerted against the plunger  20  in a vertical direction. In order to lock or keep the draft gear assembly  10  together, a ring or key  32  is secured to the housing  12  once all the elements have been assembled. The key  32  abuts the ledge  34  of the plunger  20  thereby preventing escape of the elements from the housing  12 . The key also functions as part of the solid stop when the draft gear  10  is subjected to a load which goes beyond the load carrying ability of the elastomeric pad stack  24 . This condition is called bottoming out and results when excessive energy is transmitted through the bottom  36  of the follower plate  22  to the key  32  and the housing  12 . In practice, the excessive energy is transmitted into the housing  12 , some of which is dissipated as heat. Whatever is left passes through the plate  16  and then into the body of the rail car. 
     The housing  12  itself is comprised of at least one layer of a filament wound composite, which in a preferred embodiment is fiberglass filament and epoxy resin. However, it is understood that many other composite materials may be used with the present invention, such as carbon fiber and epoxy resin, or any other composite material. In one embodiment there is a 43 degree wind angle given to the fiberglass which is a compromise between competing radial and longitudinal forces and manufacturability and is known in the art. 
     Referring now to FIG.  1  and to the housing  12  which in this embodiment employs first  38  and second  40  steel liners that are in a side-by-side relationship. As shown, the two steel liners do not extend the full length of the housing  12 , that is, from the open end  18  to the plate  16 . In part, this is due to the guide spike  26  which ensures that the elastomeric pad will not contact the inner wall  42  of the housing during a work cycle. The end  14  of the housing  12  is fixed to the end wall  16  by being inserted into a groove or channel  43  and then secured. As is apparent, any suitable means for fixing the end  14  to the end wall  16  is acceptable. The remainder of the housing  12  is a matrix of fiberglass filament and epoxy resin  44 . Although not shown, it is contemplated that the housing  12  could be constructed entirely of a matrix of fiberglass filament and expoxy resin. Additionally, contemplated is the substitution of a composite plastic for any steel items. 
     Referring now to FIG. 3 wherein another embodiment of the invention is shown. In this embodiment the elastomeric pad stack  46  is not provided with a guide spike such as  26 , but rather has a single steel liner  46  which extends the entire length of the housing  48 . In the event of a bottoming out of the draft gear  50 , the steel liner  46  will bear the majority of the load. Another way to dissipate the energy in a bottoming out situation is to employ a liner which changes some of the longitudinal forces into hoop forces against the fiberglass matrix, such as the barrel-shaped steel liner  52  shown in FIG.  11 . 
     The steel liner  52  shown in FIG. 11 is not only barrel-shaped, it is provided with relief means such as slits  54  extending generally parallel to a longitudinal axis of the liner  52 . The liner, with or without relief means, can take many shapes but is designed to translate energy from a horizontal direction extending substantially parallel to a longitudinal axis of the draft gear housing  12 , such as in a bottoming out situation, into a direction extending generally normal to the longitudinal axis of the of the draft gear housing  12  and radially against a filament wound composite or structural matrix which is wrapped thereabout. In practice, and as schematically illustrated in FIG. 11, the bottoming out energy is imparted to the liner  52  in the direction of arrow  56  whereby causing the liner  52  to compress against an end wall, such as  16 . Because of the shape of the liner and the relief means, in this embodiment slits  54 , the axial length of the liner is compressed while simultaneously bulging outwardly in the direction of arrow  58  against the surrounding filament wound composite or structural matrix (not shown in FIG. 11) where such energy is converted into heat and dissipated. The steel liners, shown in FIGS. 3 and 11, are but two embodiments and any liner having relief means and/or barrel shapes or whatever, that while captured converts input energy moving in a direction extending generally parallel to the longitudinal axis of the draft gear housing  12  into output energy moving in a direction extending generally normal to the longitudinal axis of the draft gear housing  12  (90 degrees out of phase relative to the input force energy direction) will be equally satisfactory. 
     FIGS. 4-9 are but other examples of the different shapes that the draft gear housings  60 ,  62  and  64  may take because of the versatility and draft housing design freedom allowed or yielded by forming at least a lengthwise portion of the draft gear housing from filament wound composite or structural matrix constructions. This freedom allows the tailoring of the housing of the draft gear to fit the available space constraints in the rail car. It should be noted that in these particular embodiments, the filament wound composite or structural matrix  66 ,  68 , and  70  forming an integral part of the draft gear housing was formed around a mandrill without either a steel or composite plastic liner. 
     FIG. 10 is still another embodiment wherein a filament wound composite or structural matrix  72  has been formed around first and second composite plastic liners  74  and  76 . As stated above, composite plastics may be substituted for steel, but in the event standard friction draft gear elements were to be incorporated into a filament wound composite or structural matrix draft gear housing, a steel liner would preferably be used in combination therewith. 
     While embodiments of this invention have been shown and described, it should be understood that this invention is not limited hereto except by the scope of the claims. Various modifications and changes may be made without departing from the scope and spirit of the invention as the same will be understood by those skilled in the art.