Railway rolling stock – Car framing and structure – Freight
Reexamination Certificate
2001-03-12
2003-12-09
Morano, S. Joseph (Department: 3617)
Railway rolling stock
Car framing and structure
Freight
C105S406100, C105S410000
Reexamination Certificate
active
06659017
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to center beam rail road cars.
BACKGROUND OF THE INVENTION
Center beam rail road cars, in cross-section, generally have a body having a flat car deck and a center beam web structure running along the longitudinal center-line of, and standing upright from, the deck. The center beam structure is carried on a pair of rail car trucks. The rack, or center beam structure, has a pair of bulkheads at either longitudinal end that extend transversely to the rolling direction of the car. The lading supporting structure of the beam includes laterally extending deck sheets or bunks mounted above, and spanning the space between, the trucks. The center beam web structure is typically in the nature of an open frame truss for carrying vertical shear and bending loads. It stands upright from the deck and runs along the longitudinal centerline of the car between the end bulkheads. This kind of webwork structure can be constructed from an array of parallel uprights and appropriate diagonal bracing. Most often, a top truss assembly is mounted on top of the vertical web and extends laterally to either side of the centerline of the car. The top truss is part of an upper beam assembly, (that is, the upper or top flange end of the center beam) and is usually manufactured as a wide flange, or wide flange-simulating truss, both to co-operate with the center sill to resist vertical bending, and also to resist bending due to horizontal loading of the car while travelling on a curve. Typically, a center sill extends the length of the car. The center beam thus formed is conceptually a deep girder beam whose bottom flange is the center sill, and whose top flange is the top truss (or analogous structure) of the car.
Center beam cars are commonly used to transport packaged bundles of lumber, although other loads such as pipe, steel, engineered wood products, or other goods can also be carried. The space above the decking and below the lateral wings of the top truss on each side of the vertical web of the center beam forms left and right bunks upon which bundles of wood can be loaded. The base of the bunk often includes risers that are mounted to slant inward, and the vertical web of the center beam is generally tapered from bottom to top, such that when the bundles are stacked, the overall stack leans inward toward the longitudinal centerline of the car.
Lading is most typically secured in place using straps or cables. Generally, the straps extend from a winch device mounted at deck level, upward outside the bundles, to a top fitting. The top fitting can be located at one of several intermediate heights for partially loaded cars. Most typically, the cars are fully loaded and the strap terminates at a fitting mounted to the outboard wing of the upper beam assembly. Inasmuch as the upper beam assembly is narrower than the bundles, when the strap is drawn taut by tightening the winch, it binds on the upper outer corner of the topmost bundle and exerts a force inwardly and downwardly, tending thereby to hold the stack in place tight against the center beam web.
Each bundle typically contains a number of pieces of lumber, commonly the nominal 2″×4″, 2″×6″, 2″×8″ or other standard size. The lengths of the bundles vary, typically ranging from 8′ to 24′, in 2′ increments. The most common bundle size is nominally 32 inches deep by 49 inches wide, although 24 inch deep bundles are also used, and 16 inch deep bundles can be used, although these latter are generally less common. A 32 inch nominal bundle may contain stacks of 21 boards, each 1½ inch thick, making 31½ inches, and may include a further 1½ inches of dunnage for a total of 33 inches. The bundles are loaded such that the longitudinal axes of the boards are parallel to the longitudinal, or rolling, axis of the car generally. The bundles are often wrapped in a plastic sheeting to provide some protection from rain and snow, and also to discourage embedment of abrasive materials such as sand, in the boards. The bundles are stacked on the car bunks with the dunnage located between the bundles such that a fork-lift can be used for loading and unloading. For bundles of kiln dried softwood lumber the loading density is typically taken as being in the range of 1600 to 2000 Lbs. per 1000 board-feet.
It has been observed that when the straps are tightened, the innermost, uppermost boards of the topmost bundle bear the greatest portion of the lateral reaction force against the center beam due to the tension in the straps or cables. It has also been observed that when these bundles bear against the vertical posts of the center beam, the force is borne over only a small area. As the car travels, it is subject to vibration and longitudinal inertia loads. Consequently the plastic sheeting may tend to be torn or damaged in the vicinity of the vertical posts, and the innermost, uppermost boards can be damaged. The physical damage to these boards may tend to make them less readily saleable. Further, whether or not the boards are damaged, if the plastic is ripped, moisture can collect inside the sheeting. This may lead to the growth of molds, and may cause discolouration of the boards. In some markets the aesthetic appearance of the wood is critical to its saleability, and it would be advantageous to avoid this discolouration.
In part, the difficulty arises because the bearing area against the posts may tend to be too small. Further, the join between the upstanding web portion of the center beam and the upper beam assembly can coincide with the height of the topmost boards. This join is not always smooth. Further still, when the posts are fabricated the flanges may not stand perfectly perpendicular to the web, such that one edge of the flange may bear harder against the bundles than another. It would be advantageous to present a larger, smoother, and more homogenous surface to the bundles, or to reduce the force acting at the interface between the bundles and the beam. Use of a roll-formed section, as opposed to a fabricated (i.e., welded) flange assembly may tend to increase the probability that the facing part will be oriented correctly, will tend to have appropriately planar surfaces with smoothly radiused corners, and will tend to present fewer asperities (such as may otherwise arise with distortion and errors in welding) to the lading. Use of smoothly radiused posts, such as can be obtained with roll-formed sections, whether channel or structural tubes for the vertical posts may tend to be advantageous in this regard. Use of a smooth longitudinal beam, whether channel, rectangular tube, or square tube, of somewhat greater outside dimension than the vertical posts may also tend to be advantageous as the quality of the primary bearing surface, namely the longitudinal chord surface rather than the vertical post surface, will be determined by the quality and consistency of the roll-forming process, typically quite high, as opposed to the quality and repeatability of a manual welding process, typically much lower by comparison.
Existing center beam cars tend to have been made to fall within the car design envelope, or outline, of the American Association of Railroads standard AAR Plate C, and tend to have a flat main deck that runs at the level of the top of the main bolsters at either end of the car. In U.S. Pat. No. 4,951,575, of Dominguez et al., issued Aug. 28, 1990, a center beam car is shown that falls within the design envelope of plate C, and also has a depressed center deck between the car trucks. It would be advantageous to be able to operate center beam cars that exceed Plate C and fall within AAR Plate F, with a full load of lumber in bundles stacked 5 bundles high. A five bundle high load of 33 inch bundles requires a vertical clearance in the left and right hand bunks of at least 165 inches. This significantly exceeds the vertical loading envelope of a plate C car.
Increased vertical loading to exceed Plate C, as in a P
Grant Stephen L.
Hahn Loeser + Parks LLP
Jules Frantz F.
Morano S. Joseph
National Steel Car Limited
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