Freight accommodation on freight carrier – Particular article accommodation – Cylindrical article accommodation
Reexamination Certificate
2000-12-15
2003-06-17
Gordon, Stephen T. (Department: 3612)
Freight accommodation on freight carrier
Particular article accommodation
Cylindrical article accommodation
C410S047000, C410S143000, C410S144000
Reexamination Certificate
active
06579048
ABSTRACT:
FIELD OF INVENTION
This invention relates to the field of railroad cars having multiple troughs for transporting heavy cylindrical objects such as, for example, coils of rolled sheet metal.
BACKGROUND OF THE INVENTION
Railroad coil cars are used to transport coiled materials, most typically coils of steel sheet. Coils can be carried with their coiling axes of rotation (that is, the axes of rotation about which the coils are wound) oriented longitudinally, that is, parallel to the rolling direction of the car. The coils are generally carried in a trough, or troughs, mounted on a railcar underframe. The troughs are generally V-shaped and have inwardly inclined surfaces that support the coil. The troughs are typically lined with wood decking to provide cushioning for the coils. When a coil sits in a trough, the circumference of the coil is tangent to the V at two points such that the coil is prevented from rolling.
A coil car may have single, double or triple longitudinally extending troughs. The use of multiple troughs allows any single car to carry either a load of large coils in the center trough or a load of relatively smaller diameter coils, or coils of various diameters such that lading more closely approaches maximum car capacity during a higher percentage of car operation. Additionally, some coil cars have been provided with trough assemblies that can be shifted to permit conversion between different trough modes. An example of a coil car that can be converted from a single to a double trough mode can be found in U.S. Pat. No. 3,291,072, issued to Cunningham on Dec. 13, 1966. Similarly, conversion of a coil car from a single or triple trough arrangement to a double trough mode is shown in U.S. Pat. No. 4,451,188, issued to Smith et al., on May 29, 1984. The general object is to provide versatility such that overall car utilisation is improved. Hence, the car is more economically attractive to a user.
Historically, coil cars have been constructed on a flat car underframe having a through-center-sill, that is, a main center sill that runs from one end of the rail car to the other. In this type of car the center sill serves as the main structural member of the car and functions as the primary load path of the car both for longitudinal buff and draft loads from coupler to coupler, and for carrying the vertical load bending moment between the trucks. The trough structure, or bunk, is mounted on the flat car deck. In such a car the cross-bearers carry loads into the main center sill. The side sills tend to be relatively small, and serve to tie the outboard ends of the cross-bearers together. Conventionally, the center sill is box-shaped in cross-section. That is, it is rectangular and has a constant depth of section. The top and bottom flanges of the main center sill tend to be very heavy in such cars, since they are relied upon to carry the vertical bending load.
Alternatively, another way to construct a coil car having a triple trough arrangement employs a central trough supported by a main center sill and an array of laterally extending cross-bearers and cross-ties that are angled upward and outward in a V-shape. At their distal end the cross-bearers and cross-ties meet, and are tied together by, relatively small side sills in a manner generally similar to a flat car. A central trough extends longitudinally above the center sill with side troughs lying outboard of the central trough. The side troughs are formed using slanted decking and are mounted above the cross-bearers at about the same height as the central trough relative to top of rail. In this arrangement the center sill is still relied upon to carry the great majority of the bending load.
Coil cars can also be fabricated as integrated structures. One way to do this is to employ a deep center sill, elevated side sills, and substantial cross-bearers mounted in a V between the center sill and substantial, load bearing side sills. The cross bearers and trough sheets carry shear between the side sills and the center sill. In this way the structural skeleton of the car acts in the manner of a deep V-shaped channel with flanges at each toe, namely the side sills, and at the point of the V, namely the center sill. In this arrangement, under vertical bending loads, the side sills are in compression, and the main sill is in tension.
In the cases of either a V-shaped integrated structure, or even a traditional flat car based structure, it may be beneficial to employ a “fish belly” center sill. A fish belly center sill is a center sill that is relatively shallow over the trucks, and has a much deeper central portions in the longitudinal span between the trucks. It is advantageous to have a deeper section at mid-span where the bending moment due to vertical loads may tend to be greatest.
Another way to achieve a greater depth of effective section in an integrated structure, so that a higher sectional second moment of area is obtained, is to employ deep side sills, in a manner akin to a well car. The deep side sills act as longitudinal beams. A longitudinal cradle, namely the trough structure, is hung between the side sills. In this kind of car, the main longitudinal structural members are the side sills which carry the great majority of the bending load. The cradle itself may have a center sill to tie the cross-bearers together at mid-span between the side sills. A center sill of modest proportions is sufficient for this purpose. The side sills carry the load back to main bolsters, and then into the draft gear mounted longitudinally outboard of each truck.
Where deep side sills are used, the minimum height of the bottom chord of the side sill is determined by the underframe portion of the design envelope prescribed by the AAR, such as for AAR plate B, plate C, or such other plate as may be applicable. At lower heights, the allowable width of the car diminishes, so the overall width of the car measured over the side sill bottom chords needs to be relatively narrow as sectional depth increases. Conversely, to accommodate the largest possible load width, it may tend to be desirable for the top chords of the side sills to be spread as far as possible within the allowable car width of 10′-8″. Thus it may be beneficial to locate the bottom chord closer to the car centerline than the top chord.
It may be desirable to be able to carry steel coils in a side-by-side arrangement. If three troughs are provided, it is advantageous for the center trough to be carried at a different height, relative to top of rail (TOR), than the outboard, or side, troughs. This may be beneficial for at least several reasons.
First, the total width of lading that can be carried by a coil car at one time is limited by the allowable car width envelope. If three identically sized coils are mounted such that the axes of the coils are carried at the same height relative to top of rail, then the sum of the diameters of the coils, plus the necessary clearance between coils, is limited by the maximum allowable coil car lading width. However, if the coiling axis of rotation of one coil is higher than an adjacent coil of equal or lesser diameter, then it may be possible to carry the coils in a partially encroaching, or overlapping, arrangement. That is, a greater sum of diameters may be accommodated than would otherwise be possible within the nominal maximum loading width. As a result, lading can include a combination of larger coils than might otherwise be possible, thus tending to improve car capacity utilisation.
Second, it is desirable that the point of maximum width of the load be carried at a height that is greater than the height of the uppermost extremity of the top chord members of the side sills. Once again, the advantage of this is that, generally, this will allow the vertical projection of the outboard coil to encroach more closely to the inner edge of the top chord, and so permit a larger coil to be carried in the outboard trough. This condition may be reached when the car is carrying two coils in excess of 40 inches in diameter side by side, wi
Al-Kaabi Mohammed
Coslovi Ilario A.
Grant, Esq. Stephen L.
Hahn Loeser & Parks LLP.
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