Abstract:
A scraper bowl for attachment to the frame of an earth scraper is disclosed. The scraper bowl includes a pair of spaced apart side walls, with each of the side walls being adapted for pivotable attachment to the scraper frame, a back wall, and a floor. The floor includes a fixed section and a moveable section, with the moveable section including a forward edge defining a cutting blade. Accordingly, the sidewalls, the back wall and the floor cooperate to contain material scraped from a support surface as the scraper bowl proceeds along a path.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the priority benefit of U.S. Provisional Application No. 60/239,625 filed Oct. 10, 2000, the entire disclosure of which is incorporated herein by reference. 
     
    
     
       FIELD OF INVENTION  
         [0002]    The present invention relates generally to earth scrapers incorporating scraper bowls, and more particularly to a scraper bowl having a moveable cutting blade.  
         BACKGROUND OF THE INVENTION  
         [0003]    Earth scrapers are devices for the cutting, loading, transporting, discharging, and spreading of earth. An earth scraper is typically a tractor drawn apparatus having a scraper bowl which scrapes earth material from the ground and temporarily stores it for transport and later discharge. The scraper bowl is typically a box or bowl shaped structure having an open top, and includes a floor having a cutting blade at its front edge.  
           [0004]    Typically, the scraper bowl is pivotally mounted to a frame, such as the frame of the towing tractor, so that, as the bowl pivots about the frame, the cutting blade can be brought into position to penetrate the ground. The cutting blade scrapes earth material from the ground as the device is drawn along, thus loading the scraped earth material into the bowl.  
           [0005]    Earth scrapers may be constructed as stand-alone units having a towing tongue such that the scraper is towable behind a tractor. Alternatively, scrapers may be constructed as part of motorized, self-driven vehicles that have been designed especially for scraping operations. For such motorized scrapers, the scraper bowl is pivotally attached to the frame of the vehicle between the front and rear axles of the vehicle. On stand-alone scrapers, the scraper is pivotally mounted to a draft frame having a wheeled axle, with the draft frame being attachable to a tractor.  
           [0006]    To cut and load earth material into the scraper bowl, the scraper bowl is rotated or pivoted so that the cutting edge forms an angle with the ground. The angle will depend on the desired depth of the cut. As the scraper bowl is moved forward over the ground, the cutting blade penetrates the earth, thus cutting the ground such that the forward movement of the device loads the cut earth material into the bowl. An apron at the front edge of the bowl is partially closed so as to provide a gap between a bottom edge of the apron and the cutting blade to allow the cut earth material to enter the bowl, and to retain the material that has accumulated in the scraper bowl.  
           [0007]    When the bowl must be unloaded, the apron opens and an ejector plate moves forward, thus pushing the earth material out of the scraper bowl. By controlling the rates at which the ejector plate and the scraper vehicle move forward, an operator can control the spreading of the earth material as it discharges from the scraper bowl.  
           [0008]    The draft force required to move the cutting edge through the ground increases as material accumulates into the bowl. A standing wave or surcharge of disturbed earth material builds up in front of the cutting edge, and the required draft force increases further as new material enters the bowl. If the draft force exceeds that available to the scraper bowl, the cutting edge must be raised to reduce the depth of cut. Also, the cutting forces have vertical components that act downward until some fifty to sixty percent of the material payload is loaded into the bowl. The vertical components act ahead of the pivot and provide a moment at the rear axle, therefore limiting the useful traction of the rear wheels.  
           [0009]    Accordingly, an improved scraper bowl would be desirable. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a side elevational view of a self-driven earth scraper incorporating a scraper bowl;  
         [0011]    [0011]FIG. 2 is a front isometric view of a scraper bowl assembled in accordance with the teachings of the present invention and which is adapted for use with the earth scraper of FIG. 1;  
         [0012]    [0012]FIG. 3 is a rear isometric view of the scraper bowl illustrated in FIG. 2;  
         [0013]    [0013]FIG. 4 is a side elevational view of the scraper bowl illustrated in FIGS. 2 and 3; and  
         [0014]    [0014]FIG. 5 is a side elevational view similar to FIG. 4 but illustrating a section of the floor in a rearward position. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    The example described herein is not intended to be exhaustive or to limit the scope of the invention to the precise form or forms disclosed. Rather, the following exemplary embodiment has been chosen and described in order to best explain the principles of the invention and to enable others skilled in the art to follow the teachings thereof.  
         [0016]    Referring now to the drawings, an earth scraper of the type commonly employed in the art is shown in FIG. 1 and is generally referred to by the reference numeral  10 . The earth scraper  10  may be a self-driven motorized scraping apparatus that is used for scraping earth material from the ground for storage and later discharge. It will be understood that the teachings of the present invention are equally applicable to stand-alone scraping units that are drawn by a towing vehicle, such as a tractor. However, for the sake of simplicity, only the self-driven earth scraper  10  will be discussed herein. The earth scraper  10  includes front wheels  12  and rear wheels  14  attached to a frame  16 . The earth scraper  10  also includes an engine (not shown) and a drive system (not shown), both of which may be conventional, and which enable the earth scraper  10  to proceed along a path over the ground  18 .  
         [0017]    Referring to FIGS.  2 - 4 , a scraper bowl assembled in accordance with the teachings of the present invention is generally referred to by the reference numeral  20 . The scraper bowl  20  includes a pair of side walls  22   a  and  22   b . Each of the side walls  22   a ,  22   b  is attachable to the scraper frame  16  in a manner well known to those skilled in the art, such that the scraper bowl  20  is pivotable with respect to the scraper frame  16 . Conventional actuators (not shown) and controls (not shown) may be employed for controlling the pivoting action of the scraper bowl  20  relative to the frame  16 .  
         [0018]    The scraper bowl  20  also includes a back wall  24  and a floor  26 . The floor  26  includes a fixed section  28  and a moveable section  30 , with the moveable section  30  including a forward edge  31  having a cutting blade  32 . The pair of side walls  22   a ,  22   b , the back wall  24 , and the floor  26  cooperate to hold the material that is scraped as the scraper moves along a path.  
         [0019]    As shown in FIG. 4, the moveable section  30  includes a plurality of rollers  34 , with the rollers  34  engaging one or more tracks  36  defined in the sidewalls  22   a ,  22   b , so that the moveable section  30  is moveable between a rearward position and a forward position. The rollers  34  and the tracks  36  may be supplied by any one of a suitable manufacturers of heavy equipment components. An example of suitable components may be obtained from Pacific Bearing Company and sold under the HEVI RAIL® name.  
         [0020]    One or more conventional actuators  38  (shown schematically in FIGS. 4 and 5) engages the moveable section  30 , thus enabling the moveable section  30  to move back and forth along the tracks  36  supported by the rollers  34 . The actuator  38  may be a hydraulic actuator of the type commonly employed in the art. Alternatively, the actuator  38  may comprise a rack and pinion type system (not shown) or other gear-based system (not shown). It will be understood that the moveable section  30  may be moved to any position between the rearward position (FIG. 5) and the forward position (FIG. 4). As the moveable section  30  moves toward the forward position, the moveable section  30  moves substantially out from under the fixed section  28 , thus extending or closing the floor  26 . As outlined above, the moveable section  30  defines a section of the floor  26 , and thus when the moveable section  30  is in the rearward position, the floor  26  is partially open, with at least a portion of the moveable section  30  being disposed generally under the fixed section  28 .  
         [0021]    The scraper bowl  20  may include an ejector plate  40 . If provided, the ejector plate  40  is preferably disposed at the rear section of the scraper bowl  20 . The ejector plate  40  may be moveable between an initial position (disposed generally rearward) and a discharge position (disposed generally forward and indicated in phantom in FIG. 5).  
         [0022]    The ejector plate  40  is operatively mounted to pair of upper ejector tracks  42   a  and  42   b , which are generally disposed along the sidewalls  22   a  and  22   b , respectively (shown in FIGS. 2 and 4). The ejector plate  40  further is mounted to a pair of lower ejector tracks  44   a ,  44   b , which are generally disposed along the sidewalls  22   a  and  22   b , respectively (shown in FIG. 4). The tracks  42   a ,  42   b ,  44   a , and  44   b  guide the ejector plate  40  between the initial position (rearward) and the discharge (forward) position. Preferably, the ejector plate  40  engages the upper ejector tracks  42   a ,  42   b  and the lower ejector tracks  44   a ,  44   b  with a plurality of rollers, which include a lower set of rollers  46  (shown in FIG. 4) and an upper set of rollers  48  (shown in FIG. 4). The rollers  46 ,  48  and their associated tracks  42   a ,  42   b ,  44   a ,  44   b , may be constructed of readily available heavy equipment components of the type commonly employed in the art. An ejector actuator  50  engages the ejector plate  40  to move the ejector plate  40  between the initial position (rearward) position and the discharge (forward) position. The actuator  50  may be a hydraulic actuator, or, alternatively, a rack and pinion or other gear-based actuating system.  
         [0023]    The scraper bowl  20  further includes an apron  52  mounted adjacent the front portion of each of the side walls  22   a ,  22   b . The apron  52 , which may be conventional, spans the distance between the side walls  22   a ,  22   b  and is moveable between a first position and a second position. A gap defined between the apron  52  and the floor  26  changes as the apron  52  moves between the first position and the second position. The scraper bowl  20  also includes side cutting blades  54 , which are positioned at the front edge of the side walls  22   a ,  22   b.    
         [0024]    In operation, as will be explained in greater detail below, the scraper bowl  20  is rotated about a draft frame pivot  56  to bring the cutting blade  32  to an angled position relative to the ground. As is known, the angle of this position is adjustable using conventional controls and actuators. As the scraper  10  proceeds along a desired path, the cutting blade  32  engages the ground below the surface of the ground, thus cutting the earth material in the path of the scraper  10 . As the scraper  10  proceeds along the path, the material is forced into the scraper bowl  20 . As the scraper  10  continues, freshly cut material forces the previously cut material up the cutting blade  32  and into the scraper bowl  20 .  
         [0025]    As outlined above, the scraper bowl  20  is pivotable relative to the frame  16  of the scraper  10 . Thus, the scraper bowl may be rotated back (e.g., the scraper bowl may be rotated counter-clockwise when viewing FIG. 4 or  5 ) about the draft frame pivot  56  when either the scraper bowl  20  is filled with material, or when the desired amount of material is scraped from the path. This rotation thus lifts the cutting blade  32  upwardly and out of the ground. The material in the scraper bowl  20  then may be transported to a discharge location (not shown) and discharged from the scraper bowl  20 .  
         [0026]    In accordance with the disclosed example, the moveable section  30  is initially positioned under the floor  26  and behind the draft frame pivot  56 . At its initial position as illustrated in FIG. 5, the cutting blade  32  is either aligned with or positioned forward of a forward edge  29  of the fixed section  28 . As shown in FIGS.  2 - 5 , the fixed section  28  includes an inclined surface  58  at its forward edge  29  that acts as a ramp to load earth material onto the fixed section  28 . The front of the scraper bowl  20  is then lowered by rotating the scraper bowl  20  about the draft frame pivot  56  (in a clockwise direction when viewing FIGS. 4 and 5), such that when the scraper  10  moves along the path, the cutting blade  42  penetrates the surface of the ground at a desired cutting depth. Once the position and angle of the cutting blade  32  are set, the scraper  10  proceeds forward along the path, thus engaging and cutting into the earth as outlined above such as the earth material is cut and loaded into the scraper bowl  20 .  
         [0027]    In at least one possible mode of operation, the operator of the scraper bowl  20  controls the speed of the scraper  10 , the angle of rotation of the scraper bowl  20  (i.e., the depth of cut), and the position of the cutting blade  32 . The operator can also control the rate of advance or withdrawal of the cutting blade  32  and the rate of rotation of the scraper bowl  20 . The operator selects the depth of cut, which can vary depending on soil and ground conditions. The operator typically sets the depth of cut based on experience, knowing that depending on soil and ground conditions, a cut that is too deep will slow down the scraper  10  and may even cause a total stoppage as wheel traction falls below the force necessary to move the scraper  10  forward to cut the ground (i.e., wheel spin may result). If wheel spin occurs, the operator can raise the scraper bowl  20  or withdraw the cutting blade  32 , or both.  
         [0028]    As the scraper  10  moves forward, the freshly cut material pushes the previously cut material up onto the moveable section  32 , and further onto the fixed floor  26  by pushing the previously cut material up the inclined surface  58 . Initially, as the rear wheels of the scraper move forward onto the freshly cut surface (i.e. the rear wheels will be positioned lower than the front wheels). The operator may have to adjust the depth of cut by stopping the scraper  10 , and, for example, move the moveable section  32  rearward, adjust the angle of rotation of the scraper bowl  20 , and then resume moving the scraper  10  forward to resume cutting.  
         [0029]    Because the moveable section  30  is initially under the fixed section  28 , the earth material tends to accumulate first on the fixed section  28 . Stated another way, with the moveable section  30  disposed in or toward the rearward position of FIG. 5, the earth material tends to accumulate more readily toward the back of the scraper bowl rather than toward the front of the scraper bowl.  
         [0030]    As the scraper  10  continues to move forward and more material is loaded into the scraper bowl  20 , the moveable section  30  may gradually be moved forwardly toward the forward position. The moveable section  30  may also be moved forwardly toward the forward position in stages as the scraper bowl  20  fills from the rear to the front. For example, the operator can fill the section of the scraper bowl  20  that is above the fixed section  28  first, and then move the moveable section  30  forward either gradually or in stages to fill the forward section of the scraper bowl  20 . Should the scraper  10  continue to proceed along the path, eventually the moveable section will reach the forward extent of its allowable travel. When the scraper bowl  20  is filled or the scraping stops for some other reason, the scraper bowl  20  may be rotated about the draft frame pivot  56  toward its pre-scraping position. The material may then be transported to a discharge location.  
         [0031]    The actual loading rate would depend on a number of variables, including, for example, the actual physical dimensions of the scraper bowl, the type, density and/or moisture content of the earth material, the speed of the scraper  10 , the angle of the scraper bowl  20  relative to the frame  16 , and the position of the apron. A skilled and experienced operator of conventional scrapers would readily be able to attain and control a desired loading rate, and would readily be able to determine the best position of the moveable section  30  as well as the best angle for the scraper bowl  20 .  
         [0032]    Typically, the material in the scraper bowl  20  is either unloaded at a certain location, or controllably spread over a desired area. To unload the material, the moveable section  30  may be moved rearwardly, such that the moveable section  30  is gradually moved under the fixed section  28 . As this happens, a gap or opening is gradually formed in the floor  26  as the moveable section  30  and its attached cutting blade  32  move rearwardly away from the forward extent of the scraper bowl  20 . Material in the scraper bowl  20  is free to fall through the gap, thus unloading the forward portion of the scraper bowl  20 .  
         [0033]    To unload the material that is held in the rear section of the scraper bowl  20 , the ejector plate  40  may be moved forwardly to push material toward the forward section of the scraper bowl  20 . The scraper bowl  20  may further be unloaded by simultaneous backward movement of the moveable section  30  and forward movement of the ejector plate  40 .  
         [0034]    The rate by which material is unloaded from the scraper bowl  20  or spread in a certain area can be controlled by the rates of forward movement of the ejector plate  40 , backward movement of the moveable section  30 , and forward (or rearward) travel of the scraper  10 . For example, to unload the material without any controlled spreading, the moveable section  30  may be moved to its most rearward position, while simultaneously moving the ejector plate  40  to its most forward position.  
         [0035]    Alternatively, in order to spread the loaded material in a desired area in a more controlled manner, the moveable section  30  may be moved back to a predetermined position that yields a desired material unloading rate through the gap opened between the cutting blade  32  and the forward extent of the scraper bowl  20 . With controlled gradual forward movement of the ejector plate  40 , loaded material falls through the gap at a desired rate. The speed of the scraper  10  as it travels in a desired spreading area during controlled unloading, controls the rate by which material is spread in that area. The material can also be unloaded by moving the apron  52  to open the front section of the scraper bowl, while simultaneously moving the ejector plate  40  forward to push the material out from the front of the scraper bowl  20 .  
         [0036]    The material can further be unloaded by simultaneously moving the apron  52  to open the front section of the scraper bowl, and moving the moveable section  30  backward to open a very large gap between the cutting blade  32  and the apron  52 . This unloading method of using rearward movement of the moveable section  30  combined with movement of the apron  52  may be used when uncontrolled or relatively rapid dumping of the material in a certain location is desired. The actual unloading rate would depend on a number of variables, including, for example, the actual physical dimensions of the scraper bowl, the type, density and/or moisture content of the earth material, the speed of the scraper  10 , the angle of the scraper bowl  20  relative to the frame  16 , and the position of the apron  52 . Again, a skilled and experienced operator of conventional scrapers would readily be able to attain and control a desired unloading rate and would readily be able to determine the best position of the moveable section  30  and the best position of the apron  52 .  
         [0037]    In the disclosed example, it will be appreciated that the scraper bowl  10  may reduce the forces required to cut and load earth material into the scraper bowl  20 , and will give more control over such forces to the operator of the scraper  10 . As the scraper bowl  20  is rotated so as to lower the cutting blade  32 , the cutting blade  32  moves under the ground surface, loading disturbed earth material into the scraper bowl  20 . To avoid the buildup of a surcharge of disturbed earth material in front of the cutting blade  32 , the moveable section  30  may be moved progressively forward, which according to the disclosed example may offer certain operational advantages. These advantages may include, by way of example rather than limitation, may be explained as follows. The progressive forward movement of the cutting blade  32  as the scraper bowl  20  is loaded may substantially reduce the downward force on the cutting blade  32 , because a buildup of earth material in front of or on top of the cutting blade  32  is lessened or eliminated. Second, the material loaded into the scraper bowl is initially loaded into the rearward portion of the scraper bowl  20 . The rear loading of the scraper bowl  20  of the present invention reduces the downward forces on the cutting blade  32  because of a reduction in build-up of collected earth material behind the cutting blade  32 . The rear loading of the scraper bowl  20  does not create a clockwise moment about the draft frame pivot  56  (when viewing FIG. 4), and thus the traction of the rear tires  14  of the scraper  10  is not reduced. Instead, the rear loading of the scraper bowl  20  creates a downward force behind the draft frame pivot  56 , thus creating a moment (counter-clockwise in FIG. 4) about the draft frame pivot  56 , which increases traction of the rear tires  14  of the scraper  10 . Third, the material inside the scraper bowl  20  can be unloaded without opening the apron  52 . After the scraper bowl  20  is loaded, the backward movement of the moveable section  30  opens a gap between the cutting blade  32  and the front edge of the scraper bowl  20 . The collected material in the scraper bowl falls through the gap as the ejector plate  40  moves forward to push more material onto the gap, thus eliminating the need, in certain circumstances, for opening the apron  52 .  
         [0038]    Those skilled in the art will appreciate that, although the teachings of the invention have been illustrated in connection with certain embodiments, there is no intent to limit the invention to the disclosed example. Instead, the intention of this application is to cover all modifications and embodiments fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents.