Patent Publication Number: US-7908975-B2

Title: Hollow railroad car structure

Description:
FIELD OF THE INVENTION 
     This invention relates to the field of railroad freight cars, and, in particular to a structure for an hollow railroad car such as a covered hopper car. 
     BACKGROUND 
     There are many kinds of railroad cars for carrying particulate or granular material. These materials are not liquid, yet may in some ways tend to flow in a somewhat liquid-like manner. Many of those cars have an upper opening, or accessway of some kind, by which the particulate is loaded, and a lower opening, or accessway, or gate, by which the particulate material exits the car. 
     Consider, for example, a hopper car for transporting an almost powder-like material, such as flour or cement. Flour and cement tend to self-pack during motion of the car, such that the lading may not necessarily leave the car when a bottom gate is opened. One approach to the shipment and unloading of flour is to employ an air flow. Air is introduced at the gate to permeate the load, such that the load behaves like a fluidized bed, and hence is inclined to flow out the gate. Second, a jet of air is used to induce flow of the powder substance along an outflow conduit, much in the nature of an ejector pump. The powder leaving the gate is entrained in the airflow, and is carried to the desired destination. Railroad cars used for this purpose may have pressure vessel bodies. That is, the hatches seal, and, during unloading, the car may be modestly pressurized to perhaps 10 or 15 psi. 
     Although these cars are made of steel, the external shell may be thought of as a membrane. For example, the cars may have an overall width of 128 inches, and a wall skin thickness of roughly 3/16″, giving an aspect ratio on the order of 700:1 The length of the car may vary depending on the density of the lading for which the car is built, but, typically may be of the order of 30-40 ft between truck centers, and perhaps 40 to 50 ft over the strikers. 
     SUMMARY OF THE INVENTION 
     In an aspect of the invention there is an internal reinforcement for a covered hopper car. It has a peripherally extending, substantially planar frame, the frame having a first portion and a second portion. The first portion of the frame defines a laterally extending member having a thickness, a depth, a first surface and a second surface. The depth is greater than the thickness, and may be at least 4 times the thickness. The first surface defines a planar land against which to mate an upper vertex of a first discharge slope sheet of the covered hopper car. The second surface defines a planar land against which to mate an upper vertex of a second discharge slope sheet of the covered hopper car. The second portion has first, second and third sectors, each sector having a thickness and a depth of section, The depth of section is greater than the thickness, and may be at least 4 times the thickness. The first sector has an external profile to which a first side sheet of the covered hopper car conforms. The second sector has an external profile to which a second side sheet of the covered hopper car conforms. The third sector has an external profile to which a roof sheet of the covered hopper car conforms. The frame has an internal opening formed therethrough, the internal opening having a periphery. The frame having an overall width. The internal opening periphery has an overall width. The overall width of the internal opening periphery is at last 80% of the overall width of the frame. 
     In another aspect of the invention there is a covered railroad hopper car. It has a lading containment shell carried on railroad car trucks. The lading containment shell has at least first and second hopper discharge sections, each having respective first and second slope sheets. The shell has an external skin. The shell has a shell periphery reinforcement located between the first and second hopper discharge sections. The shell periphery reinforcement being substantially planar. The shell periphery reinforcement has a first, cross-wise extending portion having first and second surfaces to which the first and second slope sheets mate. The shell periphery reinforcement has a second portion having sidewall and roof sheet profile defining portions. The shell has respective sidewall and roof sheets conforming to the profiles. The first and second portions of the shell periphery reinforcement combine to define a ring frame having an open interior portion. 
     In a different aspect of the invention, there is a covered railroad hopper car that has at least one hopper discharge outlet section having a generally four sided inlet, and a round outlet. There are a first and second side sill assemblies, each side sill assembly including a longitudinally extending channel section and a hopper discharge side sheet member, a portion of the hopper discharge side sheet portion mating with the longitudinally extending channel section to form a closed section beam. A pair of slope sheets extend cross-wise to the side sill assemblies, the pair of slope sheets being co-operably mounted relative to the side sheet members to form a four-sided pyramid opening. 
     These and other aspects and features of the invention may be understood with reference to the description which follows, and with the aid of the illustrations of a number of examples. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The description is accompanied by a set of illustrative Figures in which: 
         FIG. 1   a  is a general arrangement, isometric view of a railroad freight car such as may incorporate the various aspects of the present invention; 
         FIG. 1   b  is a side view of the railroad car of  FIG. 1   a;    
         FIG. 1   c  is a top view of the railroad car of  FIG. 1   a;    
         FIG. 1   d  is an end view of the railroad car of  FIG. 1   a;    
         FIG. 2   a  is a sectioned perspective view of the railroad car of  FIG. 1   a;    
         FIG. 2   b  shows a sectional view of the railroad freight car of  FIG. 1   a  taken on section ‘ 2   b - 2   b ’ of  FIG. 1   d , along the longitudinal centerline of the car; 
         FIG. 2   c  shows a transverse sectional view of the railroad freight car of  FIG. 1   a  taken on section ‘ 2   c - 2   c ’ of  FIG. 1   b , through the central discharge section at mid-span; and 
         FIG. 2   d  shows an enlarged view of a detail of  FIG. 2   b.    
     
    
    
     DETAILED DESCRIPTION 
     The description that follows, and the embodiments described therein, are provided by way of illustration of an example, or examples, of particular embodiments of the principles, aspects or features of the present invention. These examples are provided for the purposes of 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 unless noted otherwise. 
     The terminology used in this specification is thought to be consistent with the customary and ordinary meanings of those terms as they would be 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, to confine the rule of broadest reasonable interpretation to interpretations that are consistent with actual usage in the railroad industry as understood by persons of ordinary skill in the art, or that are expressly supported by this specification, the inventor 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, or by way of expert evidence of a person or persons of at least 10 years experience in the railroad industry in North America or in other territories or former territories of the British Empire and Commonwealth. 
     In terms of general orientation and directional nomenclature, for railroad cars described herein the longitudinal 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 top chords. Unless otherwise noted, vertical, or upward and downward, are terms that use top of rail, TOR, as a datum. In the context of the car as a whole, the term lateral, or laterally outboard, or transverse, or transversely outboard refer to a distance or orientation relative to the longitudinal centerline of the railroad car, or car unit, or of the centerline of a centerplate at a truck center. The term “longitudinally inboard”, or “longitudinally outboard” is a distance taken relative to a mid-span lateral section of the car, or car unit. Pitching motion is angular motion of a railcar 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 axis. Given that the railroad 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. In this description, 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. 
       FIG. 1   a  shows an isometric view of an example of a railroad freight car  20  that is intended to be representative of a wide range of railroad cars in which the present invention may be incorporated. While car  20  may be suitable for a variety of general purpose uses, it may be taken as being symbolic of, and in some ways a generic example of, a covered flow through car, in which lading is introduced by gravity flow from above, and removed by discharge through gated or valved outlets below. Covered flow through, or center flow cars may include open covered hopper cars, grain cars, plastic pellet cars, and so on. In one embodiment car  20  may be a pressurized discharge car for the carriage of bulk commodities in the form of a granular particulate such as cement or flour, and discharge may occur through a system of pipes. That discharge may be assisted by a fluid flow, such as an injected airflow. Other than ancillary fittings, the structure of car  20  may tend to be symmetrical about both its longitudinal and transverse, or lateral, centerline axes. 
     By way of a general overview, car  20  may have a car body  22  that is carried on trucks  24  for rolling operation along railroad tracks. Car body  22  may typically be of all welded steel construction, but this need not necessarily be so. For example, aluminum construction may also be considered. Car  20  may be a single unit car, or it may be a multi-unit car having two or more car body units, where the multiple car body units may be connected at an articulated connector, or by draw bars. Car body  22  may have a lading containment vessel, or structure, or shell  26 . Shell  26  may include a generally upstanding wall structure  28  which may include a pair of opposed first and second end walls  30 ,  32 , that extend cross-wise, and that may be, or may include, inclined end slope sheets  31 ,  33 ; a pair of first and second side wall assemblies, that may be identified as side walls  34 ,  36  that extend lengthwise; and a roof sheet or roof sheet assembly  38  that extends cross-wise between the upper portions of sidewalls  34 ,  36 . The end walls  30 ,  32  and side walls  34 ,  36  co-operate to define a generally rectangular form of peripheral wall structure  28 , when seen from above. Wall structure  28  may include top chords  40 ,  41  running along the top of sidewalls  34 ,  36 , and side sills  42 ,  43  running fore-and-aft along lower portions of side walls  34 ,  36 . In some instances car  20  may have stub center sills  44  at either end, in which case side walls  34 ,  36  may act as deep beams, and may carry vertical loads to main bolsters that extend laterally from the centerplates. Alternatively, or in addition to deep side beams, car  20  may include a straight-through center sill, running from one end of the car body to the other. In the case of a single, stand alone car unit, draft gear and releaseable couplers may be mounted at either end of the center sill. In a center flow, or flow through car, the upper portion of the car may typically include means by which to admit lading whether under a gravity drop or other system. For example, car  20  may include hatches  46  mounted in roof sheet assembly  38 . Typically, hatches  46  may be mounted along the car centerline and may tend to be equal in number to the number of hopper discharge sections, although this need not necessarily be so. In the case where car  20  is a pressurized discharge car, hatches  46  may be sealed pressure hatches. A pressurizable car may also include pressure relief valves, as at  47  to prevent over pressurization. 
     Car body  22  includes intermediate slope sheets  51 ,  53  and internal reinforcement members of internal reinforcement assemblies that may extend between the sidewalls of the car, in a manner such as may tend to divide the internal space of car body  22  into two or more sub-compartments, sub-volumes or subspaces indicated generally as  50 ,  52  and  54  in this example, and which may be referred to as hoppers. Clearly, in some embodiments there may be one single hopper, in others two hoppers and in others three, four, or more hoppers. Each hopper has a discharge section or discharge assembly  60  that includes converging sloped members and an outflow. Each discharge section may tend to have the general shape and appearance of an upside-down pyramid. In the example of a pressurized discharge car that outflow may be substantially round at its outlet and may give onto outflow piping. That outflow piping may include air jets by which air may be introduced into the lading to cause the powdered lading to fluidize, and may include piping and air nozzles for entraining the outflow, and may include means by which to pressurize the car. 
     Each discharge section or assembly  60  may be bounded on the sides by side slope sheets  56 ,  57  that are downward and inward extensions of the skins of the sidewalls of the car; and on the ends by either (i) end slope sheets  31 ,  33  or (ii) internal slope sheets  51 ,  53 . The lower portions of the side slope sheets may have a generally triangular shape when laid flat. Where there is a transition from a generally rectangular hopper to a round outlet there may be formed corner transition sheets or members  58  as well. Not atypically, each pair of fore-and aft opposed slope sheets, be they end sheets or internal slope sheets, may be inclined at equal and opposite angles, and the angles of those sheets may be selected to be somewhat steeper than the free slope angle, or natural angle of repose, of the lading for which the car is designed. Car body  22  may have relatively large end slope sheets which may tend to extend to a height relatively close to top chords  40 ,  41 . That is, taking either the coupler centerline height or the center sill cover plate upper surface as a datum, slope sheets  31 ,  33  may terminate at a height that is at least half way to the top chord, and which may, in some embodiments, extend more than ⅔, ¾ or ⅘ of that distance, as may be. 
     Side slope sheet members  56 ,  57  may be steel plates, and may be positioned to co-operate with slope sheets  31 ,  33  to define a converging, or funnel-like passageway, or conduit, leading to an opening, indicated generally as  70 , at which an exit, or port, or gate  62 , however it may be termed, is defined. In the car shown, upper regions  64  of the sheets that form the side slope sheets of the hopper discharge also form one of the walls of the closed section of the side sill, and have an end extremity, or marginal edge  66 , that extends somewhat beyond the juncture with U-pressing  68  which forms the other walls of the side sill. U-pressing  68  has an outer vertical leg, a substantially horizontal leg, a lower upwardly bent leg, and au upper inwardly bent leg. The slope sheet upper portion, or region,  64 , runs across the ends of the inwardly and upwardly bent lower leg and the upwardly and inwardly bent upper leg, and, when welded thereto, a hollow pentagonal box section side sill is formed. Items  64  and  66  co-operate to form a single assembly on manufacture. The lower marginal edge  72  of the elliptic side sheet then overlaps, and mates with the upper region  64  of the side slope sheet in a lap joint, the lower edge of the upper sheet lying inboard of the upper edge of the lower sheet. The side sheets are then formed, or wrapped on the reinforcements  80 , (discussed below) in a relatively simple assembly procedure. There is, in essence, slope continuity, or very close to slope continuity, at the lap joint at the side sill such that tensile forces induced in the side sheet under pressure (whether by the lading or otherwise) may tend to be passed into the slope sheet wall of the side sill without the generation of a significant bending moment at the welded joint. The side sheet may then be a continuous web, or skin, from the lap joint at the side sill to the junction at the top chord and roof sheet. The formation of the side sill and side slope sheet as a single assembly may tend also to avoid or reduce fit-up problems on assembly. That is, when seen in section, the sidewall is made up of only two sheets—namely the predominantly elliptic skin and the mating discharge section side slope sheet. 
     To the extent that the side slope sheets and end (or intermediate) slope sheets fit together and mate at their upper extremities (indicated generally at  74 ), the joining of the slope sheets and the rings to the side sill assemblies occurs before the installation of the side and roof sheets. The combined side sill assemblies and reinforcement ring assemblies (i.e., items  80 ) then form, in effect, a large self-jig on which the skins are mounted. The set of four transition members  58  are mounted along the corners of the converging sections of the longitudinal and side slope sheets. These transition members are, in effect tapered conic sections that provide the transition from the generally square or rectangular upper inlet region of the hopper discharge to the round outlet at pressure hatch  76  to which outlet ducting or piping  98  is connected. The tip or point of transition member  58  is located in, and forms, the valley between the respective pair of end and side sheets pointing upwardly. Transition members  58  are welded along one edge to the side slope sheets, along the other edge to the longitudinal slope sheet (be it an internal slope sheet or an end slope sheet), and, along the base of section, form a quarter of a circle on assembly, such that the four members form a circle to which the circular hatch assembly of pressure hatch  76  can mount. 
     Car  20  may include a fitting or fitting assembly, or reinforcement  80  mounted midway between the centers of two adjacent hopper discharge section outlets. Reinforcement  80  may lie in a vertical plane bisecting the apex where the planes of two adjacent slope sheets (e.g.,  51 ,  53 ) would otherwise meet at a line of intersection. That is, to the extent that car  20  has a longitudinal centerline, vertical planes may be constructed through the centerlines of the hopper discharges perpendicular to the longitudinal centerline. Reinforcement  80  may be a substantially planar reinforcement that lies in a vertical plane perpendicular to the longitudinal centerline of the car and between, and equidistant from the plane constructed through the centers of the adjacent discharge sections. 
     In the past, hoop stiffeners have been used in hopper cars. However, they have tended to include hat sections or other out-of-plane formed members whose juncture with the intersection apices of the fore-and-aft inclined slope sheets has been problematic in the view of the present inventor. Relatively complex fitting arrangements have been used to mate these various parts. It is the very complexity that is a disadvantage in the view of the present inventor. Their fabrication and installation tends to be fussy and expensive, and may in the end be poorly done notwithstanding. By contrast, the present inventor has employed reinforcement  80 . Reinforcement  80  may tend to be free of out of plane bent sections. Reinforcement  80  has a first portion  82  that runs cross-wise between the side sheets at a level at or near the height of the side sills. For the purposes of this description, if the side sills have an overall section depth (or height) h, “at or near” in the preceding sentence may be taken as meaning within twice h of the side sills. As such the first, or lateral base portion  82  of reinforcement  80  functions as a ridge plate having first and second surfaces against which the upper end vertices of the respective adjacent slope sheets  51 ,  53  mate at a clean, relatively easily made fillet weld. This may tend to avoid the fit-up problem associated with trying to weld the two vertices together. As may be noted, lateral base portion  82  extends a considerable distance above, and a clear distance below the ideal locus of intersection of the planes of the adjacent inclined slope sheets so that there is, in effect, a jig fitting or backing member that extends both above and below the joint, and that provides a surface to which a good, clean fillet weld can be made. 
     Reinforcement  80  also includes a second portion  84 , which has the general shape of an inverted horseshoe. This horse-shoe, or bulging shape may be thought of as having three portions or sectors, those portions or sectors being a first sector  86 , a second sector  88  and a third sector,  90 . First sector  86  may be thought of as being associated with the first sidewall  34 , and extending between the first side sill and the first top chord. Similarly, the second sector,  88  may be thought of as being associated with the second sidewall  36 . The third sector  90  may be thought of as being associated with roof assembly  38 . The outer edges of these respective sectors each have an external profile, and the skins of the structural shell, being identified as  92 ,  94  and  96  respectively, conform to the profiles of these sectors. The sectors also have an internal profile. It may be, as in the embodiment illustrated, that this internal profiled edge may generally follow the same shape as the outside edge, such that the leg length L 64  (i.e., the distance from the outside edge to the inside edge, taken perpendicular to the local tangent to the curve) is roughly constant, although this is not necessarily so. The inner profile edge may be a smooth curve without slope discontinuities, and may have corresponding circular and elliptic portions. The three sectors (and, indeed, reinforcement  80  in its entirety) may be fabricated by being cut as a monolith from a single piece of rolled sheet. However, in the embodiment illustrated these sectors are cut from sheet, and butt welded together, as indicated in  FIG. 2   c.    
     In contrast to a solid partition sheet, reinforcement  80  is in essence a planar ring, albeit a generally D-shaped ring since it has one substantially straight side, namely that of the ridge plate defined by first portion  82 . The ring has a large internal opening, indicated generally as  100 . This ring serves three or more functions. First, it acts as a frame or former, or jig, during construction of the car. The jig facilitates installation of the upper vertices of the adjacent slope sheets. The jig also functions as a former that compels the skins of the sidewalls and the roof assembly to take on their arcuate shape, as do the corresponding curved outer edges of the obliquely inclined end slope sheets. The fabrication of these flat planar sections, and their installation, is simpler than the formation and installation of the previous hat-shaped sections, and avoids the sometimes problematic join where the hat sections formerly met the upper edge caps of the slope sheets. Second, each of (i) the side sheets and (ii) the roof sheet acts as a shear web between flanges of a beam of deep section. In the case of the roof sheet, the beam is formed by the co-operation of the two top chords and the roof sheet, and resists lateral loads. In the case of the sidewalls the deep beam is defined by a top chord, a side sill and a side sheet. In all three cases, the frames (however many there may be) deter out of plane deflection of the shear web (i.e., the curved skin). Thirdly, the rings may tend to act as a forcing node in buckling. That is, the car shell can be considered to approximate a thin-walled tin can, in which the wall thickness, as noted above, is of the order of 1/700 th  of the width of the car. The rings and the slope sheets both tend to have an influence in the local adjacent structure to prevent local wrinkling of the membrane, and also to force global buckling of the structure into a higher mode according to the number of nodal points so defined. The rings may also tend to prevent or discourage the tendency of the sidewalls to bulge outwardly when the car is pressurized. That is, where a car has flat side walls, or flat sidewall portions, the skin, behaving in the manner of a web, may tend to oil-can outward when pressurized. However, a skin formed on a forced curvature may tend to carry the pressure in the form of a tensile stress in the skin and may resist this kind of grossly discernible deflection. 
     Each ring acts as the inwardly extending leg or stem of a section, where the flange of the section is defined by the skin of the shell. As opposed to a formed hat section, the leg has a solid rectangular section having a thickness and a depth. This depth may vary about the periphery. Fillet welds are made about the outer periphery of the leg on both sides. The region of influence of the leg is a function of the proportions of the leg (i.e., the stem of the section defined by the depth of the ring and its through thickness) and of the skin. Although it need not necessarily be so, it is convenient for the thicknesses of the three sectors of the horseshoe portion of the ring to be of the same thickness, and also convenient for the base or straight wall portion to be of that same thickness. The length of the leg (i.e., the depth of the section) is greater than the thickness, such that a long thin stem is formed that influences the adjacent regions of the skin, thus forming, in effect, a T-section. That thickness may be of the order of half an inch, while the leg depth may be of the order of 5 inches. The skin thickness of the wall may be of the order of 3/16″. Inasmuch as the thickness of the leg is more than twice the thickness of the skin, and the depth of the leg is more than 8 times its own thickness, (i.e., it is about 10:1 to 12:1) its own local stiffness is substantially greater than the neighboring skin. Its effective influence may tend to extend 20 to 30 times the skin thickness to either side into the adjacent skin. At the same time, removing a large amount of material from reinforcement  80 , by virtue of the large aperture, permits a savings of weight and prevention of pressure differential between the hopper sections. 
     The roof sheets may be formed on a circular arc with a substantially constant radius of curvature. In the embodiment illustrated, the side sheet skins (following the correspondingly curved profiles of reinforcements  80 ) have a predominant portion extending upwardly from the lap joint at the side sill that is formed on an elliptic curve. The use of an ellipse in this instance permits the car to retain a large internal volume while avoiding, or minimizing, the employment of large flat side sections, and provides the desired curvature at the side sill. The upper portion of the skins of the sidewalls runs on a tangent, that tangent portion forming an inner wall of the closed section of the top chord. As may be noted, the roof sheet is both welded at the intersection with the sidewall sheet tangential extension and at the locus of intersection of the roof sheet with the upper leg of the top chord. 
     As noted above, the ring may have a depth of section that is at least 4 times its thickness, and that is not formed in a hat shape or other out-of plane shape. Rather it may be formed by profile cutting a flat sheet or flat bar. The aspect ratio may be more on the order of about 10:1 to 12:1. The overall width of said internal periphery of the ring may typically be being at least ¾ or ⅘ of the overall outer width of the frame. Expressed differently, the reinforcement  80  has an overall width measured across the second portion, and has the form of a hollow ring having a D-shape. The first portion forms a straight back of the D-shape. The second portion forms a continuously arcuate bulging portion of the D-shape. Reinforcement  80  has a wall depth (or leg length) of the arcuate portion that is less than 1/10 of the overall width of reinforcement  80 . Expressed somewhat differently again, the car has a longitudinal centerline. A first area is defined in a vertical plane extending perpendicular to the longitudinal centerline. The hopper car has longitudinally extending side sills. The side sills having an uppermost extremity at the upper margin of the side slope sheets. There is a first area being bounded by an inside face of said skin above said uppermost extremities of the side sills. The open interior portion of the reinforcement has an open area equal to at least 60% of the first area. Expressed differently again, the covered railroad hopper car has a shell that is a pressure vessel. The pressure vessel has an overall width W. The second portion of the ring reinforcement has a leg length to thickness ration of greater than 8:1. There is a thickness ratio of the skin to the reinforcement of less than 1:2. The open area of the interior portion of the reinforcement has an hydraulic diameter of at least ⅗ W where the hydraulic diameter is defined as D h =4A/P, where A is the area and P is the length perimeter. 
     The external skin of the shell includes at least one skin sheet having a thickness t skin , and the second portion of the ring frame has a leg extending in a plane perpendicular to said skin sheet, the leg having a length greater than 10 times the skin thickness t skin . In one embodiment the leg length may be of the order, on average, of about 25 or 30 times the skin thickness. The leg has a thickness that is more than 50% greater than the skin thickness t skin . In one embodiment the leg thickness may be more than double that thickness, and may be 2½ to 3 times that thickness. 
     Various embodiments have been described in detail. Since changes in and or additions to the above-described examples may be made without departing from the nature, spirit or scope of the invention, the invention is not to be limited to those details.