Abstract:
A truck body with geometric features that improve material flow while the truck body is being tilted and the payload is being dumped. These geometric features influence the discharge of the material in the truck to better empty the truck body during dumping and lessen the risk or effect of carryback. The truck body geometry results in less dribble, less hang up, and less carryback. The overall discharge time is also often reduced.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to truck bodies (also called “truck trays”), e.g., for hauling material in the mining industry. More specific aspects of this invention relate to truck bodies having improved material flow characteristic when dumping their loads and reduced carryback (i.e., material undesirably retained in the truck body after dumping). 
       BACKGROUND OF THE INVENTION 
       [0002]    Mining trucks are used in mining applications to carry material from the pit to a different location where the material is dumped. Truck bodies (or trays) are mounted to the trucks to hold the material during transit. These truck bodies are tilted upward to dump the material (see  FIG. 1 ). Truck bodies of this type are commonly loaded using cable shovels, face shovels, hoe buckets, loaders, and the like. 
         [0003]    In many applications, material tends to stick to the inside of the truck body when the operator tilts the truck body to dump the material. The material that remains within the truck body after it has been dumped is called “carryback” (e.g., because the truck body is not fully unloaded and this stuck material is “carried back” to the dig location with the otherwise empty truck body). This carryback problem can be exacerbated when the material being hauled has a high moisture content, oil content, and/or a high clay content. Interactions between the material being hauled and the truck body interior also can result in sticking or carryback problems. 
         [0004]    Carryback is undesirable for several reasons. First, significant carryback reduces the capacity of the truck body for its next run or runs (which can increase the overall number of truck trips required to move the necessary material). Carryback also may form an uneven and/or sticky contact surface that may provide an origination site for adhesion of additional hauled materials on later truck runs (i.e., the amount of carryback may grow at a given origination site over time and over multiple hauls), thereby even further reducing truck body capacity. When the carryback content becomes significant enough, the truck may be temporarily taken out of service so that the carryback can be removed (which increases costs, labor, and time involved). This carryback material can be difficult to remove, and removal risks damaging the truck body, also causing the truck to be temporarily taken out of service for repairs. Moreover, any damage to the truck bed surface (e.g. from chisels, hammer, bucket teeth, etc.) can form sharp edges, corners, or other surface irregularities, which can serve as an origination site for additional carryback in the future. Carryback also leads to increased fuel cost and tire wear due to hauling unwanted material. 
         [0005]    Mining operations have taken several steps in an effort to combat carryback. As one example, some truck operators will try to rapidly start, stop, and/or change direction of the moving truck and/or truck body while dumping in an effort to shake the material out more quickly and/or to dislodge any stuck material. This action, however, can be hard on the truck, particularly the hydraulics used to hoist the truck body and/or the structural framework of the truck. 
         [0006]    Other countermeasures have been taken in an effort to deal with carryback problems. As another example, some mining operations have attempted to prevent or limit carryback by applying release agents and/or using special truck body liner materials. The success of release agents is contingent on mine site conditions and requires continued application. Liners can also be effective, but can significantly increase the weight of the truck body. 
         [0007]    As another carryback countermeasure, in some truck structures, diesel exhaust from the truck engine is routed through channels defined in various areas of the truck body. The diesel exhaust heats the truck bed (which is typically made from steel), which can help cause the release of stuck on materials. 
         [0008]    While these methods can be helpful, for some materials and/or at some mine sites, additional countermeasures are often needed to combat carryback and improve dumping performance. Accordingly, there is room in the art for improvements in the structure and construction of truck bodies to help reduce or eliminate carryback problems and/or to more efficiently empty the truck bed. 
       SUMMARY OF THE INVENTION 
       [0009]    Aspects of this invention generally relate to improvements in truck body designs that utilize, at least in part, geometry and geometric features of a truck body to manipulate material flow while the truck body is being tilted and the payload is being dumped. Aspects of this invention utilize geometric features of the truck body that influence the discharge of the material in the truck to better empty the truck body during dumping and lessen the risk or effect of carryback. The inventive geometry results in less dribble, less hang up, and less carryback. The overall discharge time is also often reduced. 
         [0010]    Truck bodies include a front wall, two side walls and a floor to form a payload bed for receiving and hauling materials. Truck bodies (also called “truck trays”) in accordance with this invention include one or more of the following features to improve dumping of a load:
       (a) a front transition surface extending between the floor and the front wall over at least a portion of their width, which in some examples have a radius of curvature of at least 500 mm, and in other examples is a surface outside of a space defined by the adjacent surfaces and an equiangular diagonal reference line with a midpoint 120 mm from the intersection of the planes of the adjacent surfaces;   (b) a corner transition surface between the front wall and an adjacent side wall over at least a portion of their heights, which in some examples has a radius of curvature of at least 300 mm, and in other examples is a surface outside of a space defined by the adjacent surfaces and an equiangular diagonal with a midpoint 120 mm from the intersection of the planes of the adjacent surfaces;   (c) a side transition surface between the floor and an adjacent side wall along at least a portion of their lengths, which in some examples has a radius of curvature of at least 300 mm, and in other examples is a surface outside of a space defined by the adjacent surfaces and an equiangular diagonal with a midpoint 120 mm from the intersection of the planes of the adjacent surfaces;   (d) a tail or rear floor portion that extends rearward and upward in relation to a front portion of the floor, which in some examples the rear floor portion extends upward from a front floor reference line defined as a rearward extension of the front floor portion and along or above a rear floor reference line that is angled to the front floor reference line within a range of about 1° to about 20°, in other examples above 10°, in other examples within a range of about 10° to about 17.5°, and in one specific example at an angle of about 15°.   (e) a curved front wall (i.e., with a radius of curvature rearward of the front wall), which in some examples has a radius of curvature of at least about 2500 mm rearward of the front wall, and in other examples has a radius of curvature within a range of about 2500 mm to about 5000 mm, in other examples within a range of about 3000 mm to about 4500 mm, and in other examples within a range of about 3500 mm to about 3950 mm.   (f) a vertical side wall taper (i.e., side walls diverging away from one another in a bottom-to-top direction) over at least a portion of their overall height, which in some examples are inclined within a range of 0° to about 10° for each wall, in other examples about 5° to about 10°, and in other examples from about 2.5° to about 7.5°; and/or   (g) an axial side wall taper (i.e., side walls diverging away from one another in a front-to-rear direction) over at least a portion of their overall lengths, which in some examples are inclined within a range of 0° to about 3°, in other examples in a range of about 1° to about 3°, in other examples less than 2°, and in other examples less than 1°.       
 
         [0018]    Truck bodies having one or more of these features can exhibit improved dumping and/or reduced carryback characteristics, particularly for hauled materials having a high moisture and/or high clay content but also for hauled materials of other kinds. 
         [0019]    Other aspects, advantages, and features of the invention will be described in more detail below and will be recognizable from the following detailed description of example structures in accordance with this invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The present invention is illustrated by way of example and is not limited in the accompanying figures, in which like reference numerals indicate the same or similar elements throughout. 
           [0021]      FIG. 1  illustrates an example truck including a truck body in accordance with some examples of this invention. 
           [0022]      FIG. 2A  is a perspective view of an inventive truck body. 
           [0023]      FIG. 2B  is a top view of an inventive truck body. 
           [0024]      FIG. 2C  is a top view of an inventive truck body. 
           [0025]      FIG. 2D  is a side view of an inventive truck body. 
           [0026]      FIG. 2E  is a side cross section view of an inventive truck body. 
           [0027]      FIG. 2F  is a side schematic view of an inventive truck body. 
           [0028]      FIG. 2G  is a rear end view of an inventive truck body. 
           [0029]      FIG. 3  illustrates a cross sectional view of transition surface structures between adjacent surfaces in accordance with some examples of this invention. 
           [0030]      FIG. 4  illustrates a cross sectional view of a transition surface extending between adjacent surfaces in a space defined by the adjacent surfaces and an equiangular diagonal extending between the adjacent surfaces. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0031]      FIG. 1  illustrates a dump truck  100  including a truck body  200  in accordance with some examples of this invention. As shown in the figures, the dump truck  100  includes a truck or tractor  102  and a truck body  200  (also called a truck tray) pivotally engaged with it. The front portion  202  of the truck body  200  is pivoted upward about an axis  204  as shown in  FIG. 1  (e.g., using hydraulics or other lifting or rotating mechanisms as are known and used in the art) to dump the payload out of the rear end  206  of the truck body  200 . While other designs are possible, truck bodies  200  of this type typically have an open top side (providing access to the truck payload bed  212  from the top) and an open rear end. Alternatively, if desired, covers or a tailgate could be provided to at least partially cover one or more of the top or rear end  206 . The front portion  202  of this example truck body  200  includes a forward extending canopy portion  208  that extends over and protects the roof of the truck cabin  104  and the truck  100 , e.g., during loading of the truck body  200 . The truck body  200  may be made from multiple parts, e.g., from steel or other high strength and durable materials as are conventionally known and used in the art. 
         [0032]    The truck body is shown in detail in  FIGS. 2A-2G . The truck body  200  is shown with a “whalebone” or ribbed type construction, including a plurality of structural ribs  210  that extend around and beneath the payload bed  212  of the truck body  200 , from one side to the other. While seven individual ribs  210  are shown in this example structure  200 , other numbers of ribs and/or other structures may be used without departing from this invention. Additionally, one or more longitudinally (front-to-back) oriented ribs or spines may be included to provide additional strength and stiffness. The exterior structure of the truck body  200  may be similar to or have at least some features in common with the truck body structure shown in Australian Patent Application No. 2007221920 entitled “An Improved Truck Body,” published Apr. 3, 2008, which is entirely incorporated herein by reference. This “whalebone” type construction provides a strong yet relatively lightweight truck body construction, which helps reduce fuel consumption and increase payload. Truck bodies in accordance with examples of this invention may have any of the desired structural features of the truck body described in Australian Patent Application No. 2007221920. 
         [0033]    The payload bed  212  of this example truck body  200  is defined by a headboard or front wall  220 , a left side wall  222  (when facing the front), a right side wall  224  and a floor or bottom surface  226 . The interior structure of the payload bed  212  of this example truck body structure  200  includes transition surfaces at various corners of these walls. More specifically, as shown in  FIGS. 2A through 2G : (a) a curved transition surface  230  extends between the floor  226  and the front wall  220 ; (b) a curved transition surface  232  extends between the front wall  220  and each of the side walls  222  and  224 ; and (c) a curved transition surface  234  extends between the floor  226  and each of the side walls  222  and  224 . While the various features and characteristics of the transition surfaces  232  and  234  on the right and left sides of the truck body  200  may be the same or different (and may change over their overall lengths), in this illustrated example, the transition surfaces  232  and  234  on one side of the truck body  200  mirror the corresponding surfaces  232  and  234  on the other side of the truck body  200 . Additional features and potential features of these transition surfaces  230 ,  232 , and  234  will be described in more detail below. 
         [0034]    As mentioned above, a curved transition surface  230  extends between the front wall  220  and the floor  226  of the truck body as a front transition surface. See, for example,  FIGS. 2A-2C ,  2 E, and  2 F. While this transition surface  230  may have a wide range of curvatures in various different shapes, in some example structures in accordance with this invention, this transition surface  230  will have a radius (also called “RFront to Bottom” herein) of at least 500 mm, and in some examples, at least 600 mm. As still additional examples, this transition surface  230  may have an RFront to Bottom within a range of about 500 mm to about 1500 mm, and in some examples from about 600 mm to about 1200 mm. In this illustrated example truck body structure  200 , transition surface  230  has an RFront to Bottom of about 900 mm. 
         [0035]    In the illustrated example, the transition surface  230  between the front wall  220  and the floor  226  is curved and maintains a constant curvature over its entire length (i.e., from one interior side of the truck body  200  to the other interior side, excluding the extreme corner regions  236  described in more detail below). This is not a requirement. Rather, if desired, the curvature of the transition surface  230  may change one or more times over its length. That is, the RFront to Bottom values may vary over the length of the transition surface  230  and/or a more square corner area may be provided (e.g., in the middle area). In some example structures according to this invention, the transition surface  230  will be curved (e.g., in the manners described above) over at least 50% of its overall length, and in some examples, over at least 75% or over at least 90% of its overall length. 
         [0036]    Another transition surface  232  extends from the side wall  222  to the front wall  220  and a corresponding curved front corner transition surface  232  extends from the side wall  224  to the front wall  220 , each forming a corner transition surface. See, for example,  FIGS. 2A-2C ,  2 E, and  2 G. These front corner transition surfaces  232  may have the same or different curvature specifications without departing from this invention (and in this illustrated example, they have the same curvature specifications), and they may have a wide range of curvatures. In some example structures according to this invention, each front corner transition surface  232  will have a radius of curvature (“RFront Corner”) of at least 300 mm, and in some examples, at least 600 mm. As some more specific examples, RFront Corner may be from about 550 mm to about 1500 mm or even from about 600 mm to about 1000 mm. In this illustrated example truck body  200 , each front corner transition surface  232  has an RFront Corner of about 600 mm. 
         [0037]    In the illustrated example, the front corner transition surfaces  232  between the front wall  220  and the side walls  222  and  224  are curved and maintain constant curvatures over their entire heights (i.e., from the top of the truck body  200  to the bottom of the truck body  200 , excluding the extreme corner regions  236  described in more detail below). This is not a requirement. Rather, if desired, the curvatures of the transition surfaces  232  may change one or more times over their overall heights and/or one or more square corner areas may be provided. In some example structures according to this invention, the transition surfaces  232  will be curved over at least 50% of their overall heights, and in some examples, over at least 75% or over at least 90% of their overall heights. If a more “square corner” area is provided at the junction between the front wall  220  and the side walls  222  and/or  224 , preferably this area is located closer to the top rail  250  of the truck body  200  than toward the floor  226 . 
         [0038]    A curved transition surface  234  extends from the side wall  222  to the floor  226 , and a corresponding curved transition surface  234  extends from the side wall  224  to the floor  226 , each as a side transition surface. See, for example,  FIGS. 2A-2C  and  2 E. These bottom corner transition surfaces  234  may have the same or different curvature specifications without departing from this invention (and in this illustrated example, they have the same curvature specifications), and they may have a wide range of curvatures. In some example structures according to this invention, each bottom corner transition surface  234  will have a radius of curvature (“RBottom Corner”) of at least 300 mm, and in some examples, at least 600 mm. As some more specific examples, RBottom Corner may be from about 550 mm to about 1500 mm or even from about 600 mm to about 1000 mm. In this illustrated example truck body  200 , each bottom corner transition surface  234  has an RBottom Corner of about 600 mm. 
         [0039]    In the illustrated example, the bottom corner transition surfaces  234  between the floor  226  and the side walls  222  and  224  are curved and maintain constant curvatures over their entire lengths (i.e., from the front of the truck body  200  to the rear of the truck body  200 , excluding the extreme corner regions  236  described in more detail below). This is not a requirement. Rather, if desired, the curvatures of the transition surfaces  234  may change one or more times over their overall lengths (e.g., having different RBottom Corner values at different areas) and/or one or more square corner areas may be provided. In some example structures according to this invention, the transition surfaces  234  will be curved in the manners described above over at least 50% of their overall lengths, and in some examples, over at least 75% or over at least 90% of their overall lengths. If a more “square corner” area is provided at the junction between the floor  226  and the side walls  222  and/or  224 , preferably this area is located closer to the rear of the truck body  200  than toward the front of the truck body. 
         [0040]    The various transition surfaces  230 ,  232 , and  234  may be provided in the overall truck body structure  200  in any desired manner without departing from this invention. In some examples, the truck body walls  220 ,  222 ,  224 , and  226  will be fit together in a square or relatively square manner (e.g., with square or relatively square corners), and separate, curved transition surfaces  230 ,  232 , and/or  234  will be separately fit to the walls  220 ,  222 ,  224 , and  226  (e.g., by welding, by mechanical fasteners, etc.). The weld seams (or other seams or joints) may be ground smooth and/or polished to reduce the roughness of the interior surface of the bed  212  (and thereby reduce the likelihood of the seam or joint forming an origination site for developing carryback). When produced in this manner, spaces  240  left between the transition surface(s)  230 ,  232 , and/or  234  and the various walls  220 ,  222 ,  224 , and/or  226  with which they are engaged may provide a channel through which diesel exhaust may be routed, if desired (e.g., for heating areas of the bed  212 ). Additionally or alternatively, if desired, diesel exhaust may be routed through hollow areas provided in one or more of the ribs  210 . Liners with beneficial surface properties can also be added to further reduce the roughness of the interior surface of the bed  212 . 
         [0041]    As another alternative, if desired, one or more of the transition surfaces  230 ,  232 , and/or  234  may be provided as a unitary, one-piece construction with one or more of the truck body walls  220 ,  222 ,  224 , and/or  226 . As yet another example, the transition surfaces  230 ,  232 , and/or  234  may constitute structural members that join the separate wall members  220 ,  222 ,  224 , and/or  226  without the adjacent surfaces meeting. 
         [0042]    As shown in  FIGS. 2A and 2B , the bottom front corner region  236  of the truck body  200  constitutes an area where the three transition surfaces  230 ,  232 , and  234  meet in this illustrated example. If desired, this bottom front corner region  236  could be shaped to correspond to (and act as a continuation of) any one of the transition surfaces  230 ,  232 , and/or  234 . Alternatively, this bottom front corner region  236  may be shaped as a composite shape of two or more of the transition surfaces  230 ,  232 , and  234 . As yet additional examples, the bottom front corner region  236  may be shaped to substantially correspond to the interior surface of a spherical shell or a portion of a toroid. Advantageously, this bottom front corner region  236  may be shaped to avoid sharp corners (e.g., to provide corners having smooth surfaces and corners without right or acute angles) and to provide a smooth transition between the joined walls. This bottom front corner region  236  may be made from one or multiple parts without departing from this invention. 
         [0043]    If desired, the bottom front corner region  236  may be one or more separate parts engaged with one or more of the various transition surfaces  230 ,  232 , and/or  234  as the truck body interior is being constructed. Alternatively, if desired, the bottom front corner region  236  (or a portion thereof) may be integrally formed with one or more of the various transition surfaces  230 ,  232 , and/or  234  as a unitary, one-piece construction. Advantageously, the exposed surface of the bottom front corner region  236 , as well as any junction areas with other transition surfaces  230 ,  232 , and/or  234 , may be ground or polished or covered with a suitable liner to provide a smooth, exposed surface to reduce or eliminate origination sites for developing carryback. 
         [0044]    Other advantageous geometric features of the truck body payload bed  212  surface may be provided in some example structures according to this invention. For example, if desired (and as best shown in  FIGS. 2A ,  2 E, and  2 F), the front or headboard wall  220  can be curved over at least a portion of its height and/or across at least a portion of the width of the front wall. The curvature is concave within the cavity of the truck body, and can be about one axis or two or more parallel axes. This curved front wall  220  can help limit carryback as it achieves a more vertical and eventually overhanging face on the upper portion of the front wall  220  as the dumping angle increases, thereby generating cleaner and faster material release from the front wall during dumping. Additionally, the curvature can help improve the overall stiffness and strength of the truck body  200 , limiting or reducing impact damage, which is advantageous when material is loaded into the payload bed  212 . The curved front wall  220  also increases the overall payload volume of the truck bed  212  (as compared to a vertical front wall  220 ) without substantially affecting the truck body  200  weight. 
         [0045]    While a range of curvatures may be used, in some truck body structures  200  according to this invention, the front wall  220  may have a radius of curvature (“RFront Wall”) of at least about 2500 mm about a horizontal axis rearward of the front wall, but in some examples having a radius of curvature within a range of about 2500 mm to about 5000 mm or even within a range of about 3000 mm to about 4500 mm. In a preferred embodiment, the front wall  220  has an RFront Wall of about 3500 mm or about 3950 mm. 
         [0046]    As noted above, as another option or alternative, this front wall  220  may be sloped (e.g., flat or substantially flat and leaning outward with respect to the bed  212  interior). When sloped and leaning outward, the front wall  220  (when in a hauling position) may lean toward the truck front end by less than about 15° (with respect to a vertical line), and in some examples, by an angle of from about 1° to 15° or from about 2° to 10°. 
         [0047]    In the illustrated example, the front wall  220  is curved (with a constant curvature) over its entire height (above the transition surface  230 ) about a horizontal axis. This is not a requirement. Rather, if desired, the front wall curvature may change one or more times over its overall height (e.g., having different RFront Wall values at different areas) and/or one or more straight or flat wall portions may be provided. In some example structures according to this invention, at least 50% of the front wall  220  will be curved, and in some examples, at least 75% or over at least 90% of the front wall will be curved. Where only a portion of the front wall is curved preferably the lower portion of the front wall is curved. 
         [0048]      FIGS. 2A ,  2 E and  2 F illustrate another feature that may be provided in truck bodies  200  in accordance with at least some examples of this invention. The bottom floor  226  of this illustrated example truck body structure  200  includes a forward flat bed area  226   b  which is substantially linear in its rearward extension. The rear portion  226   a  of the floor  226  extends upward above the front portion  226   b . This ramped area  226   a  provides or contributes to various advantageous features of this example truck body  200  construction. First, because the rear portion  226   a  provides a more pronounced upward slant at the rear of the truck body  200  when the truck body  200  is in the downward position, the payload bed  212  of the truck body  200  has a somewhat increased capacity (as compared to a flat tail), i.e., the truck body  200  is able to retain a greater heaped load. Depending on the inclination of the rear portion  226   a , the capacity of the payload bed  212  can be increased, for example, by at least 3%, and in some examples, by at least 5% or by at least 10% (as compared to a continuous flat floor). The rear portion of floor  226   a  can be curved, flat or a combination of shapes. 
         [0049]    The curved or ramped area  226   a  also tends to hold the bulk of the material from discharging initially when the front of the truck body is raised. This initial holding of the bulk of the material causes the bed  212  to rise to a greater vertical angle before the dump begins. While this may, in many cases, result in slightly delayed initial portions of the dump sequence, the material is overall discharged from the truck body in a more laminar fashion at a higher velocity and momentum. This more laminar, faster, and more forceful movement of the discharging material (as compared to a truck bed without ramped area  226   a  or other features) helps sweep more of the material out of the bed  212 , helps loosen stuck on material, and limits material flow dead spots, resulting in a cleaner dump, reduced material dribble, and reduced carryback. This modified discharge movement of the dumping material during the dump helps loosen and “sweep” the surfaces, especially floor  226  and front wall  220 , to better clean out material and reduce carryback. In addition, the overall dump time is often reduced as compared to a conventional truck body. 
         [0050]    The curved or ramped area  226   a  also tends to eject the material rearward and further away from the rear end of the truck body  200 , which helps keep the dumped material away from the tires and/or mechanical structures underneath the truck body  220  (e.g., the hydraulics, braking systems, axles, differentials, and the like) and helps eject the material over berms or rills with added vertical clearance between the tail and the berms or rills in the fully dumped position. The curved or ramped area  226   a  also tends to increase stiffness and strength of the rear portion of the truck body  200  without adding any substantial weight to the truck body  200 . 
         [0051]    Truck bodies  200  can use any of a range of tail configurations and/or angular structures to provide inclined rear portion  226   a  and to produce or enhance the above advantageous effects without departing from this invention. In  FIG. 2F , a floor line  240  (also called a front floor reference line) corresponds to a rearward continuation of the flat front floor surface  226   b . A ramp line  242  (also called a rear floor reference line) extends upward and rearward from forward floor line  240 . The rear floor portion  226   a  extends along or above ramp line  242 . 
         [0052]    The payload bed  212  has a length L from the front end  244  of the front wall  220  to the rear end  206  as shown in  FIG. 2F . The ramp line  242  in some examples rearwardly diverges from the floor line  240  at a ramp point  243  that is located at least 6/10 of the length L of the payload bed from front end  244  and preferably more than 8/10 the length and more preferably more than 9/10 of the length L of the payload bed. The ramp line  242  can diverge from the floor line in some examples at an angle α within a range of about 1° to about 20°, in some examples more than 10°, and in some examples from about 10° to about 17.5°. In a preferred example, the ramp line has an upward angle of about 15°. 
         [0053]    In the illustrated example, the rear portion  226   a  is curved or slanted upward over the entire width of the truck body  200  (e.g., from side  222  to side  224 ). This is not a requirement. Rather, if desired, the area  226   a  may change curvature or slant angle one or more times over the overall width of the truck body  200  and/or one or more straight or flat surface portions may be provided over the overall width. In some example structures according to this invention, at least 50% of the width of area  226   a  will be curved or slanted upward (e.g., in the manners described above), and in some examples, at least 75% or over at feast 90% of the width of area  226   a  will be curved or slanted. 
         [0054]    The shape of the bottom surface or floor  226  within the curved or ramped area  226   a  may vary widely without departing from this invention. If desired, as shown in  FIG. 2F , this area  226   a  may be curved somewhat, optionally with a surface thereof lying on an arc of a circle. Other curved shapes are possible without departing from the invention. As another example, if desired, the rear floor portion  226   a  could be flat and angled upward with respect to the flat area  226   b.    
         [0055]    This illustrated example truck body  200  includes additional geometric features on its interior surface. For example, the side walls  222  and  224  in this example truck body structure  200  taper outward with respect to a vertical angle (when the truck body  200  is oriented in a downward, load receiving condition). This angle is also called a “vertical side wall taper angle” herein. Stated another way, in this illustrated example, as best shown in  FIG. 2G , the side walls  222  and  224  extend away from one another in a bottom-to-top direction (i.e., dimension WBottom&lt;dimension WTop in  FIG. 2G ). While variations are possible, in some truck body structures  200  in accordance with this invention, each side wall  222 ,  224  will have a vertical side wall taper angle (with respect to a vertical direction with the truck body  200  in a fully downward position) within a range of 0° to about 10°, and in some examples from about 2.5° to about 7.5°. 
         [0056]    As another potential feature, truck bodies  200  in accordance with at least some examples of this invention may include a front to back taper (e.g., the interior surfaces of the side walls  222  and  224  become spaced further apart at the truck body bottom  226  as one moves from the front of the payload bed  212  to the rear of the payload bed  212 ). Stated another way, and as best shown in  FIG. 2B , in this illustrated example, the dimension WFront&lt;WRear. This “front to back taper angle,” with respect to a longitudinal centerline direction C/L (see  FIG. 28 ), may be within a range of from about 0° to about 3° (for each wall  222  and  224 ), and in some examples, from 0° to about 2° (for each wall  222  and  224 ) or from about 0° to about 1° (for each wall  222  and  224 ). 
         [0057]    In the illustrated example, the side walls  222  and  224  taper outward continuously with respect to a vertical reference line over their entire lengths (e.g., the walls  222  and  224  slant outward over their entire length from front to back). These are not requirements. Rather, if desired, the vertical side wall taper angle may change over some portions of the side wall structures  222 ,  224 , e.g., from top to bottom and/or from front to back. Advantageously, at least the bottom and front portions of the side walls will have the vertical side wall taper features described above (e.g., at least the bottom 50% and/or at least the front 50%, and in some examples, at least the bottom 75% and/or at least the front 75% or even at least the bottom 90% and/or at least the front 90%). 
         [0058]    In the illustrated example, the side walls  222  and  224  taper outward continuously with respect to a longitudinal axis or center line C/L over their entire heights (e.g., the walls  222  and  224  slant outward toward the sides over their entire height from front to back). These are not requirements. Rather, if desired, the front to back taper angle may change over some portions of the side wall structures  222 ,  224 , e.g., from top to bottom and/or from front to back. Also, the side walls can be parallel in a bottom-to-top direction and/or a front-to-back direction. 
         [0059]      FIGS. 2D through 2F  further illustrate that the top rail  250  (i.e., the top edge) of each side wall  222  and  224  curves generally downward from a highest point at or near the front of the payload bed  212  to a lowest point at or near the rear of the payload bed  212  (with the bed  212  in its downward position). The top rail  250  curved in this manner helps prevent contact (and any resultant damage) between the loading machinery and the side walls  222  and  224  of the truck body  200 . Additionally, this feature improves loading efficiency (as the material need not be lifted as high for loading), reduces lifting requirements, and decreases loading cycle times. This top rail  250  may be curved or straight and slanted over at least a portion of its front-to-back length, e.g., in manners that are conventionally known and used in the truck body art. 
         [0060]    In one preferred example, a truck body  200  includes a tail  226   a  that is along or above a ramp line  242  with an inclination of about 15°, parallel side walls, a curved side transition surface  234  between the floor and each side wall having a RBottom Corner of about 600 mm, a curved front or headboard wall  220  having an RFront Wall of about 3500 mm, a curved front transition surface  230  between the floor and the front wall having a RFront Bottom of about 900 mm, and a curved corner transition surface between the front wall and each side wall  232  having a RFront Corner of about 600 mm. A truck body having these features exhibits improved dumping and/or reduced carryback characteristics for at least some materials and/or applications. 
         [0061]    In another preferred example, as shown in  FIG. 3 , the transition surfaces  230 ,  232 , and/or  234  may be flat transition surfaces that extend at oblique angles θ with respect to the surfaces or walls  220 ,  222 ,  224 , and/or  226  that they interconnect. More specifically, in some example structures according to this invention, a main, substantially flat portion of a transition surface  230 ,  232 , and/or  234  the transition surface may form an oblique angle θ with a main, substantially flat portion of a wall  220 ,  222 ,  224 , and/or  226 . In the example shown in  FIG. 3 , θ 1  is equal to θ 2 , and each is greater than 90°. If desired, however, θ 1  may be different from θ 2  (while both are still over 90°). Advantageously, if desired, θ 1  and θ 2  will each be equal to or greater than 120°, and in some examples, greater than 130°. In this illustrated example, θ 1  and θ 2  are about 135°. 
         [0062]    In another preferred example, the transition surface  230  within the truck body will be at least 500 mm and transition surfaces  232  and  234  will be at least 300 mm. Alternatively, the transition surfaces are at least 500 mm or even at least 600 mm. If the transition surface becomes too small, a relatively tight corner may be exposed to the material to be transported, and this tight corner may support origination of carryback. 
         [0063]    The transition surfaces join two adjacent surfaces such as a wall and the floor. Preferably, the transition surface is curved with a radius of curvature. Alternatively, the transition surface can comprise one flat surface as illustrated in  FIG. 3  or may include two or more flat surfaces each at an obtuse angle to the next adjacent flat surface. Alternatively, the transition surface may be a combination of curved surfaces and flat surfaces. Curves other than arcs of a circle (i.e., radii) may be used. For example, the curved surfaces may be shaped as portions of an ellipse, oval, parabola, hyperbola, or other geometric shape. Other curved surfaces without a constant radius of curvature also are possible. Advantageously, the exposed surfaces of the transition surfaces will be smooth and/or will not include sharp corners having an acute angle exposed to the material being transported. 
         [0064]    In non-circular and non-linear transition surfaces (such as in curved transition surfaces with a changing radius of curvature) the transition is still preferably sufficiently broad to lessen the risk of carryback. For example, the transition surface extends along or outside of a diagonal reference line K between the two adjacent surfaces as shown in  FIG. 4 . Diagonal line K extends between the adjacent surfaces such that the angles λ are equal. The planes of the surfaces meet at corner C and the midpoint of the diagonal line K is a distance M from the corner. In one preferred embodiment, the distance M is 120 millimeters. 
         [0065]    According to these examples, the transition surface can be a wide variety of shapes that remains along or outside of the diagonal reference line K. A transition surface so defined can advantageously dump a load with minimal binding of the load in the corners. The adjacent surfaces of  FIG. 4  are shown as perpendicular, but the adjacent surfaces can be at an obtuse or acute angle to each other. Where one or both of the adjacent surfaces are curved, the plane of the surfaces defining the corner C can be defined by a tangent to the curved surface at the terminating edge or preferably at the contact point of the transition surface on the one or both adjacent surfaces. 
         [0066]    The present invention is described above and in the accompanying drawings with reference to a variety of example structures, features, elements, and combinations of structures, features, and elements. The purpose served by the disclosure, however, is to provide examples of the various features and concepts related to the invention, not to limit the scope of the invention. One skilled in the relevant art will recognize that numerous variations and modifications may be made to the example structures described above without departing from the scope of the present invention. For example, the features discussed above for improving dumping of the load from the truck body can be provided on their own or in combination with one or more of the other features as desired.