Patent Application
20240359713
This invention relates to the field of railroad freight cars, and, more particularly, to the field of box cars.
In the past, railroad freight cars have had wooden floors to permit lading to be nailed down. Box cars are long known in railroad use in North America. They generally have an underframe structure that is surmounted by a set of walls and a roof that define a housing in which to carry lading. The housing often has doors on the side, although box cars with doors on both ends are also known. In box cars the underframe may include a center sill, a pair of spaced-apart side sills, and a set of lateral support members in the form of cross-bearers and cross-ties that extend between the center sill and the side sills. The cross-bearers and cross-ties often carry longitudinally-running stringers, and a nailable floor is often mounted on top of the stringers. The fabrication of this skeleton structure tends to require a large number of relatively short welds to secure the stringers to the cross-bearers and cross-ties. It may be difficult to maintain a relatively uniform level of welding in these welds, particularly if they are hand welded with not always optimal access for the welder.
The present invention, in its various aspects, provides a railroad box car with a non-nailable floor. In another aspect, a railroad freight car has a floor assembly with both cross-bearers and stringers in which the stringers are mounted below the floor sheet and the floor sheet forms the top flange of the cross-bearers. In another aspect, a railroad freight car has a center sill, cross-bearers, stringers and a floor sheet in which the floor sheet defines the lading bearing surface, and the floor sheet defines the top cover plate of the center sill, the upper flange of the cross-bearers, and the upper flange of the stringers. In another aspect a railroad freight car has cross-bearers and stringers, and the uppermost portions of the cross-bearers and stringers are flush with each other. In another aspect there is a railroad freight car floor assembly in which the outboard ends of the cross-bearer webs are notched, and a lengthwise-running reinforcement channel is mounted in the respective notches. In another aspect there is a method of making a railroad freight car floor assembly in which the floor sheet is placed face down and the assembly is manufactured in reverse order by building at least the stringers and then the cross-bearers on top of the floor sheet.
In an aspect of the invention there is a box car floor assembly. It has a floor sheet having a length and a width; an array of cross-members; and a set of stringers. The set of stringers is oriented to run lengthwise relative to the floor sheet. The set of cross-members is oriented to run cross-wise relative to the floor sheet. The floor sheet has an upper surface that defines the lading surface of the floor assembly. The cross-members have accommodations formed therein through which the stringers pass uninterrupted.
In a feature of that aspect, the floor sheet defines the upper flange of the array of cross-members. In another feature, the floor sheet defines the upper flange of the stringers of the set of stringers. In a further feature, the floor sheet defines the upper flange of the array of cross-members and the floor sheet defines the upper flange of the stringers of the set of stringers. In still another feature, the assembly has a straight-through center sill, and the floor sheet defines a center sill cover plate of the center sill. In an additional feature, the floor sheet defines the upper flange of the array of cross-members and the floor sheet defines the upper flange of the stringers of the set of stringers. In still another feature, the floor sheet is a non-nailable floor sheet.
In another feature, the floor assembly has laterally outboard margins and tie-downs mounted along the laterally outboard margins. The floor assembly has reinforcement rails mounted along the laterally outboard margins to which the tie down fittings are mounted. The cross-members have webs that are located underneath the floor sheet and the cross-member webs have notches formed therein, the reinforcement rails being mounted in the notches.
In another feature, the set of cross-members has a first cross-bearer, the first cross-bearer having a first web and a second web, the first and second webs being spaced apart; the first and second webs of the first cross-bearer having upper edges welded to an underside of the floor sheet. The set of stringers including a first stringer. The first stringer is a first channel having a first leg, a second leg and a back joining the first and second legs. The legs of the channel being welded toes-in to the underside of the floor sheet. In a further feature, a doubler is mounted to the first web of the first cross-bearer underneath the first stringer, and the doubler is welded to the back of the first stringer. In another feature, the legs of the first stringer are splayed apart such that the toes of the legs are separated by a first distance. The back of the first stringer has a width. The first distance is greater than the width.
In a further feature, the floor assembly has a second stringer. The second stringer is a second channel corresponding to the first channel of the first stringer. The first stringer is mounted laterally inboard of the second stringer. The first leg of the first channel of the first stringer is an inboard leg. The second leg of the first channel of the first stringer is an outboard leg. The second stringer has a respective inboard leg and a respective outboard leg. The first channel has toes of the first and second legs thereof that are welded to the underside of the floor sheet, the toes being separated by a first distance. The second channel has toes of its respective inboard and outboard legs welded to the underside of the floor sheet, the second channel being distant from the first channel. There is a second distance between the outboard toe of the first channel and the inboard toe of the second channel. The second distance is in the range of 70% to 130% of the first distance. In a still further feature, the floor assembly has a longitudinal centerline and a set of out-of-plane stems located between the centerline and a laterally outboard margin thereof, two of the out-of-plane stems being defined by the first and second legs of the first stringer, that set of out-of-plane stems dividing the floor sheet into a number of segments, and each of the segments has an unsupported span distance between two adjacent ones of the stems, and each of the distances is in the range of 11/16 to 21/16 of the average of the distances.
In still another feature, the floor assembly has a longitudinal centerline. The floor assembly has a center sill that extends downwardly from the floor sheet. The center sill has a first web that is welded to the floor sheet and extends downwardly out-of-plane relative thereto. The floor assembly has a second stringer. The second stringer is a second channel corresponding to the first channel of the first stringer. The first stringer is mounted laterally inboard of the second stringer. The first leg of the first channel of the first stringer is an inboard leg. The second leg of the first channel of the first stringer is an outboard leg. The second stringer has a respective inboard leg and a respective outboard leg. The first channel has toes of the first and second legs thereof that are welded to the underside of the floor sheet. The second channel has toes of its respective inboard and outboard legs welded to the underside of the floor sheet, the second channel being distant from the first channel. A first segment of the floor sheet is defined between the first web of the center sill and the inboard toe of the first channel. A second segment of the floor sheet is defined between the first and second toes of the first channel. A third segment of the floor sheet is defined between the outboard toe of the first channel and the inboard toe of the second channel. A fourth segment of the floor sheet is defined between the first and second toes of the second channel. Each of the segments has a width in the transverse direction. The widths have an average size. Each of the widths lies within the range of 70% to 130% of the average size. In an additional feature the widths of the segments are substantially equal sized. In a further additional feature, the floor assembly has a marginal edge most laterally distant from the centerline, and a reinforcement channel defined along the marginal edge. There is a fifth segment of the floor sheet between the outboard toe of the second stringer and the reinforcement channel. The first, second, third, fourth and fifth segments are substantially equally sized.
In another feature, the floor assembly has a marginal edge most laterally distant from the centerline, and a reinforcement channel defined along the marginal edge and tie-down fittings are mounted in the reinforcement channel. In an additional features, the reinforcement channel is welded underneath the floor sheet and the floor sheet has cut-outs through which to obtain access to the tie-down fittings.
In another aspect, there is a railroad car floor assembly. It has a floor sheet having a lengthwise direction and a transverse direction. There is an array of cross-members, the cross-members being mounted to extend in the transverse direction; and an array of stringers mounted to the cross-members, the stringers being mounted to run in the lengthwise direction. The floor sheet has an upward facing lading supporting surface. The array of stringers being mounted flush with the array of cross-members.
In still another aspect, there is a railroad car floor assembly. It has a floor sheet having a lengthwise direction and a transverse direction; and an array of cross-members, the cross-members being mounted to extend in the transverse direction; and an array of stringers mounted to the cross-members, the stringers being mounted to run in the lengthwise direction. The floor sheet has an upward facing lading supporting surface. The floor sheet defines an uppermost flange of the cross-members. The floor sheet defines an uppermost flange of the stringers.
In another aspect there is a method of assembly of a railroad car floor assembly, the floor assembly including a floor sheet having a lengthwise direction and a transverse direction, the floor sheet having an upper surface upon which to support lading; an array of cross-members; and an array of stringers. The method includes welding the stringers to an underside of the floor sheet with welds running in the lengthwise direction of the floor sheet; welding the cross-members to the underside of the floor sheet and to the stringers with welds running in transverse to the floor sheet.
In a feature of that aspect, the method includes placing the floor sheet upside-down prior to welding the stringers thereto. In another feature, there is a straight-through center sill having a pair of spaced apart webs and the method includes positioning the center sill in a lengthwise orientation relative to the floor sheet and welding the webs to the floor sheet with welds running in the lengthwise direction. In another feature, the floor sheet is a non-nailable sheet, and the method includes welding the cross-members and the stringers to the floor sheet such that the stringers and the cross-members mount to the floor sheet flush with each other. In another feature, the cross-members have cross-member webs that stand downwardly of the floor sheet and the method has providing the cross-member webs with accommodations to permit the stringers to pass thereacross unobstructed. In another feature, the stringers have a web that stands away from the floor sheet and a flange mounted to the web, the flange standing spaced distantly from and in opposition to the floor sheet, and the method includes providing a doubler plate that mounts to a face of the web of the cross-member, and welding a margin of the doubler to the flange of the stringer distant from the floor sheet.
In another feature, the stringers have a channel shape, and the method includes mounting the channel shape toes-in to the floor sheet. In a further feature, the method includes spacing the stringers cross-wise relative to the floor sheet to leave equal un-supported spans of the floor sheet. In yet another feature there is a first gap distance between the toes of each the stringer, and a second gap distance between the toes of one stringer and the toe of the adjacent stringer. The method includes spacing the stringers such that the first gap distance is in the range of 70% to 130% of the second gap distance.
In another feature, the method of assembly is a method of assembly of a of a railroad box car floor assembly, the floor assembly including a center sill having a pair of spaced apart center sill webs that extend downwardly from the floor sheet; the stringers having a channel shape, the channel shape having toes and a back the channel shape having a first gap between the respective toes. The method includes placing the floor sheet upside-down; welding the webs of the center sill to the underside of the floor sheet with welds running in the lengthwise direction; welding the stringers in a toes-in orientation to the underside of the floor sheet with welds running in the lengthwise direction; dividing the unsupported spans of the floor sheet into a set of segments that have a size in the range of 70% to 130% of the size of the first gap; providing the cross-members with a pair of spaced apart webs that stand away from the floor sheet, and providing the webs with accommodations that permit the stringers to pass uninterrupted through those webs; welding the webs of the cross-members to the underside of the floor sheet with welds running in the transverse direction; welding web separators within the center sill to provide web continuity for the webs of the cross-members through the center sill; welding web doublers to the outsides of the cross-member webs and to the backs of respective stringers; and turning the as welded assembly upside right.
These and other aspects and features of the invention may be understood with reference to the detailed descriptions of the invention and the accompanying illustrations as set forth below.
The principles of the invention may better be understood with reference to the accompanying figures provided by way of illustration of an exemplary embodiment, or embodiments, incorporating principles and aspects of the present invention, and in which:
The description is accompanied by a set of illustrative Figures in which:
The description and the embodiments it describes, are provided by way of example, or examples, of particular embodiments of the principles of the present invention. They are provided for explanation, and not of limitation, of those principles and of the invention. In the description, like parts are marked throughout the specification and the drawings with the same respective reference numerals. The drawings are generally to scale, and may be taken as being to scale unless otherwise noted. The terminology used herein is thought to be consistent with the customary and ordinary meanings of those terms as understood by a person of ordinary skill in the railroad industry in North America. Following from decision of the CAFC in Phillips v. AWH Corp., the Applicant expressly excludes all interpretations that are inconsistent with this specification, and, in particular, expressly excludes any interpretation of the claims or the language used in this specification such as may be made in the USPTO, or in any other Patent Office, other than those interpretations for which express support can be demonstrated in this specification or in objective evidence of record in accordance with In re Lee, (for example, earlier publications by persons not employed by the USPTO or any other Patent Office), demonstrating how the terms are used and understood by persons of ordinary skill in the art.
In terms of general orientation and directional nomenclature, for railroad cars and railroad car trucks described herein, the longitudinal, or lengthwise, direction is defined as being coincident with the rolling direction of the railroad car, or railroad car unit, when located on tangent (that is, straight) track. In the case of a railroad car having a center sill, the longitudinal direction is parallel to the center sill, and parallel to the side sills, if any. Unless otherwise noted, vertical, or upward and downward, are terms that use top of rail, TOR, as a datum. The term lateral, or laterally outboard, refers to a distance or orientation relative to the longitudinal centerline of the railroad car, or car unit. The term “longitudinally inboard”, or “longitudinally outboard” is a distance taken relative to a mid-span lateral section of the car body, or car body unit. Pitching motion is angular motion of a rail car unit about a horizontal axis perpendicular to the longitudinal direction. Yawing is angular motion about a vertical axis. Roll is angular motion about the longitudinal, or lengthwise, axis. When reference is made to the “at rest” condition, it pertains to a car that sits motionless, on track that is straight and level. The common engineering terms “proud”, “shy” and “flush” may be use in this description in relation to parts of components that protrude, that are recessed, or that stand in line with neighbouring items, the three terms being conceptually similar to the conditions of “greater than”, “less than” and “equal to” respectively.
This description discusses railroad box cars and box car components. Several Association of American Railroads (AAR) standard truck sizes are listed at page 711 in the 1997 Car & Locomotive Cyclopedia. As indicated, for a single unit, stand alone, rail car having two trucks, a “40 Ton” truck rating corresponds to a maximum gross rail load (GRL) of 142,000 lbs. Similarly, “50 Ton” corresponds to 177,000 lbs., “70 Ton” corresponds to 220,000 lbs., “100 Ton” corresponds to 263,000 lbs., and “125 Ton” corresponds to 315,000 lbs. In each case the load limit per truck is then half the maximum GRL. Two other types of truck are the “110 Ton” truck for rail cars having a 286,000 lbs. GRL and the “70 Ton Special” low profile truck sometimes used for auto rack cars. The various “40 Ton”, “50 Ton”, “70 Ton”, “100 Ton”, “110 Ton” and “125 Ton” nomenclature for truck sizes presume use in “stand alone” railroad cars. A “stand alone” railroad car is one having a single car body with a pair of first and second trucks at either end, joined to other cars using releasable couplers. A “stand alone” rail car is to be contrasted with a multi-unit rail car. Multi-unit railroad cars are railroad cars that have multiple car bodies permanently joined together.
Given that, leaving aside secondary structure such as safety appliances, the railroad box car described herein may tend to have both longitudinal and transverse axes of symmetry, a description of one half of the car may generally also be intended to describe the other half as well, allowing for differences between right hand and left hand parts. The abbreviation kpsi stands for thousand of pounds per square inch. To the extent that this specification or the accompanying illustrations may refer to standards of the Association of American Railroads (AAR), such as to AAR plate sizes, those references are to be understood as at the earliest date of priority to which this application is entitled. Unless noted otherwise, the underframe structure of the railroad car may be understood to be made of mild steel, and is generally of welded construction. Other materials, such as aluminum, are sometimes used, and components may be assembled by use of rivet or Huck™ bolts. The superstructure of the car is also typically made of mild steel sheet that has been formed and welded together, although aluminum and composite materials have also been used. Mild steel may be considered the default material.
By way of general definition, in general, a cross-bearer is a beam that carries a vertical load and that has a moment connection at which to carry bending moments in a load path into other primary structure, such as the center sill. Where a cross-bearer has a built-in moment connection, as illustrated, either to a center sill or to a side sill, there may be web and flange continuity into or across, or both into and across, that primary structural member. A cross-tie, by contrast, is typically not relied upon to transmit bending moment to other structure, but rather it analyzed as having simply supported ends, most often one end being at a side sill, and the other end being at the center sill. Cross-ties may be, an in the embodiment shown are, of shallower section in the vertical direction than the cross-bearers. A floor stringer may be understood to be a floor-supporting member that is oriented longitudinally, or lengthwise, in the car in the direction of rolling motion of the car, that spans two or more laterally extending structural members such as cross-bearers and cross-ties.
Reference may be made herein to the “floor surface”. The floor has an upper surface upon which people can walk, upon which forklift trucks can be driven, and upon which lading can be placed. This upper surface can be termed the walking surface, the working surface, the lading supporting surface, or simply the floor surface. It is a permanent feature of the car structure. That a box car has a lading supporting surface does not mean that temporary or consumable items such as removable mats or pads, or other items functioning essentially as carpeting cannot also be placed underneath lading as a floor protector between the lading and the lading supporting surface. However, those temporary or intentionally consumable non-permanent items are not to be construed as being the box car floor surface.
In terms of understanding the historical context of the invention, in old-style box cars there was typically a straight-through center sill carried on a pair of trucks. The center sill formed the structural backbone of the car. The car typically had main bolsters that extended laterally from the center sill at the locations of the respective truck centers. A set of cross-bearers were then spaced along the car between the main bolsters. The spacings between the cross-bearers also tended to include cross-ties spaced between the cross-bearers. The ends of the main bolsters, the cross-bearers and the cross-ties terminate at longitudinally running side sills parallel to and spaced laterally outboard from the center sill. The upper flanges of the main bolsters, cross-bearers, and cross-ties tended to be co-planar. Longitudinal stringers were mounted on top of the flanges of the main bolsters, cross-bearers and cross-ties. The stringers usually had an I-beam cross-section. Finally, wooden planks were laid over the stringers to define the box car floor. The top of the wooden planking defined the load supporting floor surface. The use of a wooden floor permitted securement of lading by attachment to the floor, the wooden floors being “nailable”. The basic structure of the box car floor was substantially the same as the structure of a flat car deck. The box car walls, and roof were then analogous to a house or enclosure built on the flat car underframe. Subsequently, box cars have been made with “nailable” floors made of roll-formed steel in place of the wooden planks, with the grooves between the roll-formed floor members admitting nails. The through-thickness of the structure then included (a) cross-bearers; (b) stringers on top of the cross-bearers; and (c) flooring on top of the stringers in a stacked-up arrangement. Moreover, the order of construction was as described, starting with the center sill, main bolsters, cross-bearers and side sills prior to mounting the stringers and floor. While early steel cars were of riveted construction, later it was by welding. The process of manual stick-welding of the stringers to the cross-bearers tended to be a slow, fussy job, prone to inconsistent quality.
Box car 20 has a car body 22 that is carried on trucks 24 for rolling operation along railroad tracks. Trucks 24 are spaced apart from each other longitudinally. Car body 22 may have first and second end sections 26. Each end section 26 has a main bolster 34 that seats on a respective truck 24 at a respective truck center CL. Box car 20 has a center sill 30 having draft sills 28 longitudinally outboard of the Truck Centers, with draft gear and couplers 32 mounted at either end for releasable connection to other railroad cars.
In box car 20, center sill 30 may be, and in the embodiment shown in
A floor sheet, or deck sheet, or deck 60, however it may be called, overlies the array of cross-members 40. Stringers 70 are mounted below floor sheet, or deck sheet, or deck 60. Stringers 70 run lengthwise in box car 20, while cross-members 40 run laterally. Floor sheet or deck 60 functions as a top flange to stringers 70 and as a top flange of main bolsters 34 and cross-bearers 42 of the array of cross-members 40. That is, floor sheet or deck 60 carries longitudinal stresses (i.e., in the x-direction of box car 20) in the context of its load carrying relationship with stringers 70, and transverse stresses (in the y-direction of box car 20) in the context of its load carrying relationship with cross-members 40 (and relative to main bolsters 34, also). As shown, in this embodiment the floor sheet, i.e., deck 60, is located above the cross-members 40 of the underframe and overlying stringers 70.
In contrast to previous box cars 20, floor sheet or deck sheet, or deck 60 however it may be termed is not a consumable surface that is replaced from time to time. It is not a nailable surface, such as wood planking, or a nailable surface such as metal sheeting that can be puncture by nails, and that is intended for such nailable use. On the contrary, tie-down capacity is provided not by a nailable floor, but rather by an array of hard points, or hard-eyes, or attachment fittings 65 mounted in channel rails 64. There are, additionally, hard points or attachment fittings 66 mounted in the sidewalls at the locations that match the longitudinal stations of their vertical stiffeners.
So far, the structure as described could be used in a flat car, or any car having a deck to which lading is secured. As shown, box car 20 is a box car having an upstanding wall structure 100 forming a housing covering, and enclosing, deck sheet 60. It has first and second upstanding side walls 102, 104, and first and second upstanding end walls 106, 108, which co-operate to form a rectangular room. In box car 20, walls 102, 104, 106 and 108 are full-height walls, and are covered by a roof structure or roof assembly 110. Wall structure 100 includes top chords 112 that run along the tops of side walls 102, 104, and along long-side margins of roof assembly 110, i.e., the side walls 102, 104 and roof structure, or roof assembly, 110 are mated together at top chords 112. Wall structure 100 has access through first and second side door openings 114 mounted on either side of the car. Openings 114 are rectangular and have a door sill level flush with the inside floor height of car 20. Access to the inside of car 20 through openings 114 is governed by respective doors 116 mounted to either side of car 20, that are received in openings 114 when doors 116 are closed. As in the embodiment shown, doors 116 may be mounted on sliding tracks on either side of the car (i.e., they are sliding doors), and, when closed, doors 116 may form a sealed plug.
Side walls 102, 104 have sidewall sheets 118 that stand upwardly from side sills 50 and extend to mate with top chords 112. Side walls 102, 104 may have an array of longitudinally spaced stiffeners 122 that stand upwardly from side sills 50 and deck 60. Roof structure 110 overspans deck 60 from side wall 102 on one side of the car, to the side wall 104 on the other side of the car, and from one end wall 106 to the other end wall 108.
Examining this structure, center sill 30 has a pair of first and second upstanding webs 36, a bottom cover plate 38 and a top cover plate 58. They are welded together to form a rectangular box section as seen in
Cross-bearers 42 have a pair of spaced apart webs 46 and a bottom flange 48. In the embodiment of
In this description, floor sheet 60 functions as, and may be thought of as being part of the cross-members 40, namely the upper flange thereof. Likewise, as discussed below, it functions as, and may be thought of as being, the upper flange of stringers 70. As such, it forms a bi-axial tension or compression member for both longitudinal and lateral in-plane stresses that is shared by both the stringers and the cross-members.
Also, floor sheet 60 may be, or may form part of, the upper flange of main bolsters 34. That is, the main bolster has a web, or webs, 52, most often lying in a vertical plane or planes and extending upwardly of a bottom flange 54. There may be an upper flange mounted underneath floor sheet 60, or floor sheet 60 may be mounted directly, as by welding, to the upper margins of web or webs 52. Both cross-bearers 42 and main bolsters 34 have moment connections to center sill 30.
In respect of the connection to center sill 30, cross-bearers 42 have flange continuity as between bottom flange 48 and bottom cover plate 38 of center sill 30. There is also web continuity through center sill 30 provided by internal web separators or web gussets 37. There is flange continuity provided by the mating of floor sheet 60 as seen in the illustrations. Floor sheet 60 may form the top cover plate of center sill 30, as where the upper margins of webs 36 are welded to floor sheet 60, and floor sheet 60 is continuous across car 20.
Webs 46 of cross-bearers 42 each have a lower margin that is joined to bottom flange 48. This may be done by welding. Alternatively, and as in the embodiment shown in the drawing figures, bottom flange 48 and webs 46 may be a channel section in which flange 48 is the back of the channel and webs 46 are the legs or toes of the channel section, with the toes being welded to floor sheet 60. In the embodiment shown the channel is a U-pressing. The use of a U-pressing eliminates several feet of welding between flange 48 and webs 46. There may also be web continuity through center sill 30, and a flange continuity connection between floor sheet 60 which functions as the center sill top cover plate 58. (I.e., As noted above, top cover plate 58 may be part of floor sheet 60, such that floor sheet 60 may be, and as shown is, a continuous sheet from side to side of the car). The use of a single continuous sheet, or a small number of large sheets reduces the number and size of welding fillets required in the manufacture of the car. This both facilitates manufacture and promotes more consistency in manufacture.
Webs 46 have pre-cut accommodations or reliefs 61, 62 and 63 formed in the upper margin of the web. Relief 61 defines a first accommodation, or an inboard accommodation in which to seat a first stringer 70. Relief 62 defines a second accommodation, or an outboard accommodation in which to seat a second stringer 70. When stringers 70 seat in respective reliefs 61 and 62, a doubler or backing plate 68 is welded to the outside face of web 46. The top edge of backing plate 68 is fit up against the bottom side of back 80 of stringer 70 on assembly and welded in place.
Relief 63 is a cutout formed in the upper margin of web 46 at its outboard extremity where is meets side sill 50. Relief 63 defines an accommodation or notch in which to receive a lengthwise-running member such as a structural reinforcement in the nature of either (a) a channel or (b) an L-shaped angle that co-operates with the sidewall sheet to define a channel, as shown, to define a tie-down reinforcement channel rail 64 in which tie-down attachment fittings 65 are seated and secured. It may be noted that the outer margin of floor sheet 60 has corresponding accommodations or cut-outs 67 in corresponding locations to the mounting positions of fittings 65, such that there is access to those fittings when the car is assembled.
Side sills 50 may be, and as illustrated are, formed steel sections. As shown those sections include a first leg and a second leg. The first leg is un upright, or vertical, leg 72 that defines the lower margin or skirt of the sidewall structure to which the lower margin of the side wall sheet is mated in a lap-welded arrangement. Leg 72 also forms an end cap of the lateral cross-members of array 40, namely of cross-bearers 42 (and cross-ties, if any). The outboard margin of floor sheet 60 mates with, and is welded to, the inside face of leg 72. Side sill 50 also includes a flange, or horizontal leg 74 that is formed on the lower margin of leg 72. Horizontal leg 74 is truncated at the location of the first cross-bearer 42 that is longitudinally inboard of main bolster 34 to yield a clearance relief for motion of truck 24. Similarly, cross-members or cross-ties 43 that lie longitudinally outboard of main bolster 34, and that extend between draft sill 28 and the side sills are of shallower vertical depth than cross-bearers 42 to provide greater vertical wheel clearance.
When tie down channel rails 64 are in place, they form a reinforced structural edge along the outboard margin of floor sheet 60. That reinforcement, as assembled, may have the form of a rectangular box. The upper, inboard edge of channel rail 64 is welded to the bottom of floor sheet 60. The upper outboard edge is welded to the outermost extremity of floor sheet 60 and to the inside face of leg 72 of side sill 50. The outside lower edge of rail 64 is also welded to the inside face of leg 72 of side sill 50.
In summary, main bolster 34, cross-bearers 42 and cross-members or cross-ties 43 have laterally outboard ends that mate with side sills 50. Each of side sills 50 has an L-shaped angle form, with a first leg 72 and a second leg 74. First leg 72 is a vertical leg that form the vertical web of side sill 50. Second leg 74 is a leg that extends laterally inwardly from the lower end of the vertical leg.
As noted above, the array of stringers 70 is mounted below floor sheet 60. Stringers 70 have a first leg 82, a second leg 84, and a back 80. In the embodiment shown stringers 70 have the form of a channel section that is welded toes-in to the underside of floor sheet 60, thus forming a closed hollow section. In the embodiment shown, legs 82 and 84 are spaced apart and splayed such that the toes are on a widening taper. From the outboard margin of the center sill web to the inboard margin of the hold-down support rail channel is a lateral span distance, d34. In the embodiment shown, that span is broken into five segments by the four toes of the inboard and outboard stringers 70. More generally, the webs defined by legs 82, 84 and web 36 that are welded to the underside of floor sheet 60 define structural webs or stems that extend out-of-plane relative to the plane of the continuous flange defined by floor sheet 60. Starting from the vertical web 36 of the center sill, as a first web, and going to the inboard web of the reinforcement rail channel as the nth web, there is a set of n−1 segments of floor sheet 60 in which each segment is bounded by an inboard stem and an outboard stem. In general, the number of segments between the centerline of the car and the side wall will be (2n+1) where n is the number of stringers. That is, in the example shown, there is a first segment between the center sill web and the web defined by the inboard leg of the inboard stringer 70; a second segment between the toes of the inboard stringer; a third segment between the outboard toe of the inboard stringer and the inboard toes of the outboard stringer; a fourth segment between the toes of the outboard stringer; and a fifth segment between the outboard toe of the outboard stringer and the inboard web of the tie down support rail. In the embodiment shown the lengths of these segments is approximately equal. That is, the length of the longest is not more than 120% of the length of the shortest segment. In an alternate way of expressing this concept of approximate equality, the length of any one segment is in the range of 70% to 130% of 1/5 of d34. In the embodiment shown the segments are substantially equal.
In conventional construction using I-beam stringers, there were typically three stringers to create four segments, given that the I-beam sections only had a single web. The use of U-pressing channel sections permits the number of stringers to be reduced to two, but the number of segments to be increased to five, each of those segments being smaller than what it would otherwise have been if the segments were 1/4 of d34, rather than 1/5 of d34, for example. This reflects the use of the cars. Most commonly, the cars are loaded with pre-packaged pallets. The pallets are loaded into the cars using fork-lift trucks. It is no longer customary to rely upon the pallets being nailed to the wooden planking of the floor of the box car. Rather, pallets tend now to be secured in place using band clamps or come-alongs that are secured to the steel ring fittings of attachment the side rail attachment fittings, or to the steel rings of the load anchors of the attachment fitting of the side walls of the car. Accordingly, use of a greater number of webs to define a larger number or shorter segments may tend to reduce the unsupported span of the segments of the floor sheet over which the relatively concentrated loads of the wheels of the fork-lift will be applied. An outstanding web mated to a spanning flange has a range of influence of perhaps 40 times the width of the depending stem or leg. Thus, the splayed-leg configuration of stringers 70 as shown and described herein may tend to provide a helpful distribution of stiffening influence.
First leg 82 has an upper end welded to floor sheet 60. Second leg 84 has an upper end welded to floor sheet 60. First leg 82 and second leg 84 stand downwardly from floor sheet 60. Back 80 is attached to and forms a laterally extending flange relative to first leg 82 and second leg 84, and is spaced apart from and parallel to deck or floor sheet 60. Stringers 70 run lengthwise from end to end of car 20, between the longitudinal stations of the respective first of cross-bearers 42 located longitudinally inboard of the respective main bolsters. Those stringers resume as stringers 78 located between the respective end sills 76 and the first of cross-bearers 42 longitudinally outboard of the respective main bolsters 34. Stringers 78 have the form of channel sections that, as with stringers 70, are positioned upside-down and welded toes-up to the underside of deck sheet 60.
In the region immediately adjacent to main bolsters 34, there are obliquely oriented stringers 86 that are spaced and angled to provide clearance for the wheels of trucks 24 as trucks 24 turn relative to car body 22. There are reinforcement shear plates 88 that are mounted between stringers 86 and that have spaced perforations that allow plates 88 to be welded to the underside of, and to act as a local doubler for, floor sheet 60 over the trucks.
In the construction of the floor assembly of car 20, floor sheet may be positioned upside-down. The center sill webs are positioned in place, and welded along the inside and outside fillets at which webs 36 abut floor sheet 60. This welding may be by automated welding machines set to run longitudinally. Stringers 70 may be positioned at the same time as webs 36 or may be positioned after webs 36 have been welded in place. Stringers 70 are positioned facing down onto floor sheet 60 (i.e., in their inverted position). The toes of legs 82 and 84 are then welded to what will be the underside of floor sheet 60. Again, this may be an automated process in which the welding heads run in the longitudinal direction of floor sheet 60. In a multi-headed welder, this may occur at the same time as the center sill webs are being welded. Similarly, the outboard margin tie-down support rails are seated along the outboard margins of floor sheet 60 and welded along their toes to floor sheet 60 with the welding machine again moving in the longitudinal direction of floor sheet 60. This may occur sequentially after the welding of center sill webs 36 and stringers 70, or it may occur at the same time. Where a multi-head welding machine is used, this may be a single operation. The use of an automated process of this nature permits the welds to be long, continuous, and of relatively constant quality. Where the various components have been positioned using a master set of jigs it also permits consistency of positioning and adherence to dimensional tolerances that may be difficult to achieve by manual welding. The laterally extending members are positioned in place. The web separators 37 are located along center sill 30 at the longitudinal stations of webs 46, and webs 46 are also position in place with reliefs 61, 62 and 63 seated relative to stringers 70 and channel rail 64. Welding of web separators 37 and webs 46 to floor sheet 60 then occurs in the lateral, or cross-wise, direction of floor sheet 60. Again, these welds may be machine made. With a multi-headed machine they can be made at one time. Machine welding may again tend to yield a more consistent quality of welding and more predictable adherence to dimensional tolerances. Once this has been done, doublers 68 are welded in position. As may be noted, this is, in general, substantially the opposite sequence of assembly to that of traditional flat car or box car floors.
In the method of manufacture, when floor sheet 60 is mounted to the cross-members, the underframe of car 20, including center sill 30, side sills 50, bolsters 34, and cross-members 40, is turned upside-down and continuous welds can be made by machine along the respective fillets. The assembly is then rotated so that the floor sheet faces upward. The resultant structure is one in which rather than the height of the stringers being added to the height of the cross-bearers, the height of the stringers lies within the height profile of the cross-bearers. The use of floor sheet 60 as the cap of the underframe assembly (as opposed to floor planking) means that the stringers lie flush with the cross-bearers rather than standing vertically proud of them. The upper face of the floor sheet defines the floor surface, or walking surface, or lading support surface (however it may be called) of box car 20. That floor surface is a non-nailable surface. Moreover, given that it does not used wood or a nailable surface of grooves or other material, it may be a surface that may tend to be more easily washable, and that may tend not to soak up and retain liquids. That is, in earlier box car floors the absorbance of the wood floor itself tended to retain liquids that spilled or leaked from the lading. Not infrequently, depending on the nature of the lading, those liquids could be acidic or otherwise corrosive and, over time, hasten corrosion of the underlying steel structure. Even in a nailable steel floor, liquids or drippings of this nature may tend to collect in the grooves or, where the floor is punctured by previous nailing, provides an opportunity to drip through onto the underframe, and, again, to hasten corrosion.
In the example of
Various embodiments of the invention have been described in detail. Since changes in and or additions to the above-described best mode may be made without departing from the nature, spirit or scope of the invention, the invention is not to be limited to those details but only by the appended claims.
This application claims the benefit of U.S. Provisional Patent Application Ser. No. 63/462,653, filed Apr. 28, 2023, the specifications and drawings thereof being incorporated in their entirety herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63462653 | Apr 2023 | US |
