Patent Application
20100126375
The present disclosure relates to railroad freight cars and, more particularly, to hopper cars having through center sills.
To accommodate the widely varying types of cargo that may travel over a railroad, rail cars of many different designs are manufactured, and in some instances a rail car will be specially designed to carry one specific type of cargo. One type of cargo that is often transported via railroad is cargo having bulk fluid properties, meaning commodities that, in bulk, exhibit fluid-like behavior. Examples of such commodities are grain, nuts, and cement, etc. Such bulk fluid cargo is typically transported in a hopper car that is specially designed to carry cargo having bulk fluid properties.
A hopper car usually includes one or more cargo-carrying bins, called cargo wells, which may be filled with grain or other bulk fluid cargo. The cargo is typically poured into the hopper car from the top and discharged from the bottom, through a respective discharge outlet at the bottom of each cargo well. Each discharge outlet is selectively closeable to permit the loading and transporting of the cargo. A discharge outlet is usually located approximately at the center of the cargo well that it empties. When the discharge outlet is opened, the bulk fluid cargo flows from the hopper car. To facilitate the flow of cargo towards these outlets while a hopper car is being emptied, each cargo well will usually include at least one pair of opposed slope sheets, that are slanted downwardly and inwardly towards the respective outlet at the center of the cargo well.
One specific type of hopper car is a through center sill hopper car. A hopper car, like other rail cars, is structurally supported by an undercarriage that includes a center sill extending longitudinally along the center line of the hopper car. A through center sill hopper car has a center sill that runs through the cargo wells of the hopper car, and the cargo in each cargo well thus can surround the center sill. In order to facilitate the flow of cargo around the center sill when the cargo is unloaded, the portion of a center sill within a cargo well is typically covered by a tent-like hood with sloping upper surfaces, so that the bulk fluid cargo does not collect on top of the center sill when the hopper car empties.
The center sill is a primary load-bearing structural member of the hopper car, extending longitudinally between and interconnecting stub sills at the ends of the car to complete a center sill assembly. The center sill is thus the longitudinally central portion of a center sill assembly. The center sill must be of a sufficiently sturdy construction to withstand not only the substantial standing weight of both the hopper car and the cargo it carries, but also the buff and draft forces and various bending and rotational stresses that are applied to the hopper car as it moves along a railroad track as part of a train.
In the past, a center sill was typically constructed of two pairs of opposed, parallel elongate pieces of steel plate or other similarly rigid material, joined as an elongate box beam. These individual members are usually welded together along the right-angle intersections between adjacent members, and are typically fashioned of steel ½-inch thick, or thicker, so as to withstand the aforementioned loads and stresses. Often, the center sill is further reinforced by a plurality of gussets or other reinforcements inside the center sill.
Unfortunately, the size of a traditional center sill previously has substantially added to the weight of the hopper car, and its construction as described above has required a substantial amount of time and labor by skilled welders. What is desired, therefore, is a new center sill structure that is lighter in weight than center sills in existing hopper cars of similar load capacity, and that can be manufactured more easily and economically, yet is able to durably withstand the same loads and stresses as do the center sills of existing hopper cars of similar carrying capacity.
The structures and methods disclosed herein provide answers to some of the aforementioned needs and provide a center sill structure and a method for constructing a center sill as defined by the claims appended hereto.
As a principal feature of a center sill as disclosed herein, a first main structural member defines a bottom cover portion and a pair of parallel upwardly extending laterally spaced side web portions defined by longitudinal bends in a unitary plate, giving the first main structural member a three-sided U-shaped form, and a top cover plate is welded to upper margins of the side web members to form an elongate box beam.
As one feature of the center sill structure disclosed herein, the first main structural member may be of a relatively thin steel plate, conserving weight, and horizontal filler plates of thicker steel plate material may be fastened into place along the bottom cover portion of the first main structural member at each of the opposite ends of the center sill, where such thicker material is desirable in order to carry the higher loads that are expected there.
In one embodiment of a center sill constructed in accordance with the disclosure herein, a doubler plate may be fastened to the filler plate within an end of the box beam portion of the center sill.
In one embodiment of the center sill disclosed herein a doubler plate may be welded to the top cover plate of the center sill in a location where loads are expected to be concentrated.
As one aspect of a method of making a center sill according to the present disclosure a part of the bottom cover portion of the first main structural member may be cut away prior to bending the plate into the U-shaped three sided form.
The foregoing and other features of the structures and methods disclosed herein will be more readily understood upon consideration of the following detailed description of embodiments, taken in conjunction with the accompanying drawings.
Referring first to
The hoppers 32 include slope sheets 34 and 36 whose lower portions are pierced by and connected with the center sill 28, enabling portions of the train load forces to be carried by the portions of the car body 20 adjacent to the center sill 28.
As may be seen in
The top cover plate 58 may extend longitudinally beyond the ends 52, 54, of the webs 46, 48 by a distance 64, such as about 13 inches, so as to be able to be joined to the stub sills 24 and 26 in completing the center sill assembly previously mentioned.
Small locator plates 66 may be welded to the inner side of each of the webs 46 and 48 to support the top cover plate 58 in the desired location spaced upwardly apart from the bottom cover portion 50 as the top cover plate 58 is welded to the webs 46 and 48, as shown best in
A respective reinforcing horizontal filler plate 68 rests atop and is fastened, as by being welded, to the bottom cover portion 50 adjacent to each end 52 and 54 of the center sill 28. A respective horizontal filler plate 68 may extend outward longitudinally from each end 52 and 54 of the center sill 28 to a greater distance 69, such as about 23 inches, than the distance 64 by which the top cover plate 58 extends beyond the ends 52 and 54. The filler plate 68 is provided to carry the heavier loads associated with that part of the bottom of the center sill 28 that is closest to the respective one of the stub sills 24 and 26, and so the horizontal filler plate 68 may have a thickness 70 of, for example, ½ inch, that is greater than the thickness 44.
In order to connect the filler plate 68 to the bottom cover portion 50 parts of the bottom cover portion 50 may be cut away, leaving flanges 71 and 72 and a sinuous end margin 74. A transverse strap 76 may be allowed to remain about 39 inches from the end 52 or 54, interconnecting the flanges 71 and 72 with each other and adding to the length along which a weld joint may be made. The horizontal filler plate 68 is welded to the margins of the flanges 71 and 72, the strap 76, and to the sinuous margin 74 that interconnects longitudinally inboard ends of the flanges 71 and 72.
A longitudinally inboard portion 78 of the horizontal filler plate 68 is narrower than a longitudinally outwardly extending portion 80. The inboard portion 78 may have a length 79 of, for example, about 60⅜ inches, and thus extends a short distance past the flanges 71 and 72 and the sinuous margin 74. The inboard portion 78 is narrow enough to fit closely atop the flanges 71 and 72 and between the side web portions 46 and 48, clear of any curvature of the first main structural member 42 between the bottom cover portion 50 and the webs 46 and 48. The wider outwardly extending portion 80, however, may have a width 82 equal to the separation distance 49 and thus equal also to the width 84 of the top cover plate 58, or may even be wider, depending on the design of the stub sill 24 or 26 to which it is to be joined.
The center sill 28 in the embodiment shown may have dimensions similar to those of a conventionally constructed center sill, with a width 85 of 13⅝ inches and an overall depth of 13⅜ inches, and with a vertical separation 87 of 11¾ inches between the facing surfaces of the top cover plate 58 and the filler plate 68, so as to mate with previously available stub sills 24 and 26. The top cover plate 58, horizontal filler member 68, and side web portions 46 and 48 at the ends 52 and 54 of the resulting center sill 28 can be welded to the stub sills 24 and 26 in substantially the same manner as has been conventionally used to join a center sill to stub sills.
Referring to
As shown in broken line in
As may be seen clearly in
Referring to
At each of the opposite ends 52 and 54 of the center sill 93 a horizontal filler plate 96 is shorter than the horizontal filler plate 68 of the center sill 28. An inboard portion 98 of the filler plate 96 may have a length 100 of, for example, about 44¼ inches. Correspondingly, the flanges 102 and 104 are about 44 inches in length to the sinuous margin 106. The strap 108, corresponding to the strap 76, may be located about 22 inches from the end 52 or 54, near the middle of the lengths of the flanges 71 and 72. For inclusion of a similarly constructed center sill 28 in a longer hopper car having three cargo hoppers 30, there would correspondingly be two more spaced-apart locations where the center sill 28 or 93 is exposed between slope plates of adjacent hoppers, and where the center sill 93 thus would have to carry greater loads because of the lack of support from adjacent structural members of the hoppers to carry train loads.
Similarly, adjacent each end of the center sill 93, a doubler plate 110 is fastened, as by being welded, to the top of the horizontal filler plate 96. The doubler plate 110 may be welded in the correct position on the inner, or top side of the inboard portion 48 of the horizontal filler plate 96 before the filler plate 96 is welded into place. The doubler plates 94 and 110 may be “diamond”-shaped, that is, tapered in each direction longitudinally from a short full-width central portion and having opposite longitudinally-extending pointed ends, so as to extend the connection of each doubler plate 94 or 110 respectively to the top cover plate 58 or the horizontal filler plate 96 over a long enough portion thereof to limit and graduate stress concentrations. The doubler plates 94 and 110 may be of metal plate of a thickness similar to the thickness 44 of the first main structural member, or the thickness 62 of the top cover plate 58.
In assembling the center sill 28 or 93, the horizontal filler plate 68 or 96 is attached by welding along the margins of the flanges 71 and 72 and the sinuous margin 74 entirely on the outer, or bottom face of the horizontal filler plate 68 or 96, preferably with the first main structural member 42 inverted. A fillet weld provides a sufficiently strong joint, between the bottom cover portion 50 of the first main structural member 42 and the filler plate 62 or 96, and can readily be inspected during the life of the car body 20.
With the first main structural member 42 upright, the top cover plate 58 may be placed atop the locator plates 66 and then welded easily and securely to the inner face of the upper margins 60 of the side web portions 46 and 48, which may extend a small distance above the top surface of the top cover plate 58. For example, when the thickness 62 of the top cover plate 58 and the thickness 44 of the side web portions 46 and 48 are both ⅜ inch, a 5/16 inch fillet weld along the entire length of each of the side web portions 46 and 48 may be used to fasten the top cover plate 58 in place.
As will be readily apparent, the process of assembling the center sill 28 is relatively simple by comparison with the conventional assembly of four plates into a box beam for a center sill, and the resulting structure offers the additional solidity of the bends 86 and 88 instead of welds along the bottom longitudinal edges of the center sill 28 or 93. At the same time, the use of slightly thinner plate in the first main structural member 42, with the doubler plates 94 and 110 as reinforcements at critical locations, provides ample strength, yet provides a center sill structure 28 or 93 that is significantly lighter in weight and a car body 20 that is less costly, both to build and to move along a railway.
The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.
