Abstract:
An agricultural sprayer is provided, having a plurality of wheels. By providing six wheels, a narrow overall wheel width may be maintained to allow for use of the sprayer in post-emergent crop spray applications. By providing six wheels, a greater amount of fluid may be provided on the vehicle without increasing soil compaction. By providing low soil compaction and a high fluid capacity, the applicator may be utilized in both pre-emergent and post-emergent situations, and may be utilized on wet or soft ground, where standard applicators may not be utilized.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates in general to an agricultural sprayer and, more particularly, to a high-clearance agricultural sprayer with a high fluid capacity and low ground compaction. 
   2. Description of the Prior Art 
   It is well known in the art to provide methods and apparatuses for applying fluid in agricultural applications. Applicators typically include a frame supporting a large fluid container and driven by large wheels. As refueling the container wastes a considerable amount of valuable time, especially if inclement conditions provide a small window of opportunity to apply fluid to an agricultural field, it is desirable to carry as much fluid on the applicator as possible. 
   Conversely, it is desirable to minimize the impact of the applicator on the soil. Compacted soil is undesirable for many reasons, including the difficulty associated with subsequently working the field and the detrimental impact compaction has on plants and their root systems. Applicators, therefore, are typically provided with very large wheels, having very large footprints to minimize the pressure applied to any single point in the field. Such applicators typically have very wide wheels to distribute the pressure associated with large fluid containers over as wide an area as possible. 
   It is also desirable to apply fluid, such as herbicides and the like, to crops after the crops have emerged. In an effort to maximize the crop yield, crops are typically planted in rows very close to one another. Such close planting often prohibits pre-emergent applicators from being used, as the extremely wide tires are wider than the crop rows. Use of a pre-emergent applicator on growing crops would cause the crops to be compacted and destroyed under the wheels of the applicator. Accordingly, post-emergent applicators are typically provided with wheels sufficiently narrow to ride between the rows of crops to avoid any damage thereto. 
   Unfortunately, narrowing the wheels to avoid crop damage increases the pressure the wheels transfer to the footprint. Accordingly, prior art machines have typically had to reduce the fluid capacity and, therefore, the weight of post-emergent applicators to reduce the impact of the compaction the applicator transmits to the soil during application. This reduction in capacity requires more frequent refills, delaying the application process, and resulting in lost income and productivity. 
   Accordingly, it would be desirable to provide a multi-use applicator which would provide for a very large fluid capacity, while maintaining a minimal compaction of the soil. The difficulties encountered in the prior art discussed hereinabove are substantially eliminated by the present invention. 
   SUMMARY OF THE INVENTION 
   In an advantage provided by this invention, an agricultural fluid applicator having an increased fluid capacity is provided. 
   Advantageously, this invention provides an agricultural fluid applicator with a narrow wheel width for application of fluid to post-emergent crops. 
   Advantageously, this invention provides a six wheel agricultural fluid applicator with an improved steering system. 
   Advantageously, this invention provides a six wheel agricultural fluid applicator with an improved suspension system to reduce stress on the frame. 
   Advantageously, in the preferred example of this invention, an agricultural vehicle is provided with a frame and six wheels. The wheels are mounted to the frame and provided with a diameter at least one and one-half meters, and a width no greater than one meter. The wheels are also preferably provided three on each side of the frame, at least two-hundred fifty centimeters from one another. Preferably, the vehicle is provided with a fluid capacity of at least four thousand liters, and a clearance at least one-hundred centimeters high and two-hundred centimeters wide. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described, by way of example, with reference to the accompanying drawings in which: 
       FIG. 1  illustrates a top perspective view of an agricultural sprayer incorporating the present invention; 
       FIG. 2  illustrates a top plan view of the agricultural sprayer of  FIG. 1 ; and 
       FIG. 3  illustrates a side elevation of the leg boom suspension and steering system of the agricultural sprayer of  FIG. 1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   An agricultural spray system according to the present invention is shown generally as ( 10 ) in  FIG. 1 . The system includes a vehicle ( 12 ) coupled to a spray system ( 14 ). The spray system ( 14 ) includes a large capacity fluid container ( 16 ) which may be of any desired capacity. In the present invention, the capacity is forty-five hundred and forty-two liters, but may be six-thousand fifty-six liters, sixty-eight hundred and four liters, seventy-five hundred and seventy liters, or any desired capacity. The tank is constructed using materials known in the art, such as those used to construct the STS  10  and STS  12  sprayers manufactured by Hagie Manufacturing Company of Clarion, Iowa. The spray system ( 14 ) also includes a hydraulic pump ( 18 ), powered by a diesel engine ( 20 ) in a manner such as that known in the art. ( FIG. 2 ). The spray system ( 14 ) also includes a spray boom ( 22 ), provided with a plurality of spray nozzles ( 24 ). The spray system ( 14 ) is also provided with a plurality of hydraulic lines ( 26 ), coupled from the hydraulic pump ( 18 ) to the spray boom ( 22 ). A plurality of fluid lines ( 28 ) are also provided between the fluid container ( 16 ), spray boom ( 22 ) and spray nozzles ( 24 ). 
   The present spray system ( 10 ) also includes a driver&#39;s cab ( 30 ) provided on a frame ( 32 ), which also supports the fluid container ( 16 ) and diesel engine ( 20 ). As shown in  FIG. 1 , the system ( 10 ) is provided with six wheels ( 34 ), ( 36 ), ( 38 ), ( 40 ), ( 42 ) and ( 44 ). As shown in  FIG. 1 , each wheel ( 34 ), ( 36 ), ( 38 ), ( 40 ), ( 42 ) and ( 44 ) includes a center wheel ( 46 ) and tire ( 48 ). Since the wheels ( 34 ), ( 36 ), ( 38 ), ( 40 ), ( 42 ) and ( 44 ) are of a like construction and similarly assembled, albeit as mirror-imaged pairs, only the wheel ( 36 ) will be described in detail, with like numbers being applied to like parts. 
   The wheel ( 36 ) is coupled to the leg assembly ( 50 ) shown in  FIG. 3 , which is the subject of U.S. Pat. No. 6,371,237, and which is incorporated hereby reference. As shown in  FIG. 3 , the leg assembly ( 50 ) is provided with a hydraulic motor ( 52 ) and an output shaft ( 54 ). The output shaft ( 54 ) is welded or otherwise secured to a transfer disc ( 56 ). The transfer disc ( 56 ) is coupled to the center wheel ( 46 ) by a plurality of lugs ( 58 ). As shown in  FIG. 3 , the top of the leg assembly ( 50 ) is provided with a suspension system ( 60 ) and steering system ( 62 ), similar to that described in U.S. Pat. No. 6,371,237. The width of the wheel ( 36 ) and leg assembly ( 50 ) is preferably less than forty-nine centimeters. The midlines ( 64 ) of the right side wheels ( 36 ), ( 40 ) and ( 44 ) are preferably separated from the midlines ( 66 ) of the left side wheels ( 34 ), ( 38 ) and ( 42 ) by a distance of three-hundred five centimeters. The midlines ( 64 ) and ( 66 ) may alternatively be separated by a distance of three-hundred, ninety-one centimeters, or any desired distance to accommodate the width and separation of crop rows ( 68 ). As described in U.S. Pat. No. 6,371,237, all of the leg assemblies ( 50 ) may be attached to crossbars to allow the midlines ( 64 ) and ( 66 ) to be adjusted to any desired width. 
   By providing the suspension systems ( 60 ) to each of the wheels ( 34 ), ( 36 ), ( 38 ), ( 40 ), ( 42 ) and ( 44 ), all of the wheels ( 34 ), ( 36 ), ( 38 ), ( 40 ), ( 42 ) and ( 44 ) track across the ground ( 76 ), even in situations where the ground ( 76 ) is hilly or undulating. If the suspension systems ( 60 ) were not so provided, and if the vehicle ( 12 ) were to move across very hilly or undulating terrain, or to encounter a large rock or other obstacle (not shown), one or more wheels ( 34 ), ( 36 ), ( 38 ), ( 40 ), ( 42 ) and ( 44 ) may leave the ground, causing a great amount of torsional stress to the frame ( 32 ). Over a period of time, accumulated stress could cause the frame ( 32 ) to fail. By allowing the wheels ( 34 ), ( 36 ), ( 38 ), ( 40 ), ( 42 ) and ( 44 ) to raise and lower independently, the stress to the frame ( 32 ) is greatly reduced. 
   As shown in  FIG. 1 , the steering system ( 62 ) is coupled to the hydraulic pump ( 18 ) and to a steering flow controller ( 70 ) coupled to a steering wheel ( 72 ) located within the cab ( 30 ). The steering flow controller ( 70 ) is also coupled to a central processing unit ( 94 ) controlled by a rocker switch ( 74 ) located within the cab ( 30 ). The rocker switch ( 74 ), via the central processing unit ( 94 ), actuates the steering flow controller ( 70 ) to operate in two different modes: a synchronous mode and an asynchronous mode. In synchronous mode, when the steering wheel ( 72 ) is rotated in a clockwise direction, the central processing unit ( 94 ) causes the steering flow controller ( 70 ) to turn the front wheels ( 34 ) and ( 36 ) and the rear wheels ( 42 ) and ( 44 ) to the right. The steering flow controller ( 70 ) actuates valves which cause fluid pumped by the hydraulic pump ( 18 ) to actuate two hydraulic actuators ( 76 ) and ( 78 ) associated with the front two steering systems ( 80 ) and ( 62 ) to rotate the front two wheels ( 34 ) and ( 36 ) to the right. In synchronous mode, the steering flow controller ( 70 ) also actuates valves which cause fluid pumped by the hydraulic pump ( 18 ) to actuate two hydraulic actuators ( 82 ) and ( 84 ) associated with the rear two steering systems ( 86 ) and ( 88 ) to rotate the rear two wheels ( 42 ) and ( 44 ) to the right. 
   In asynchronous mode, when the steering wheel ( 72 ) is rotated in a clockwise direction, the central processing unit ( 94 ) causes the steering flow controller ( 70 ) to turn the front wheels ( 34 ) and ( 36 ) to the right and the rear wheels ( 42 ) and ( 44 ) to the left. In asynchronous mode, the steering flow controller ( 70 ) still actuates valves which cause fluid pumped by the hydraulic pump ( 18 ) to actuate the two hydraulic actuators ( 76 ) and ( 78 ) associated with the front two steering systems ( 80 ) and ( 62 ) to rotate the front two wheels ( 34 ) and ( 36 ) to the right. In asynchronous mode, however, the steering flow controller ( 70 ) actuates the valves associated with the two rear hydraulic actuators ( 82 ) and ( 84 ) in the reverse direction, thereby rotating the rear two wheels ( 42 ) and ( 44 ) to the left for a tighter turning radius. In both synchronous and asynchronous modes, turning the steering wheel does not actuate the center wheels ( 38 ) and ( 40 ) in either direction. 
   As shown in  FIGS. 2-3 , the front steering systems ( 62 ) and ( 80 ) and rear two steering systems ( 86 ) and ( 88 ) are provided with angle sensors ( 90 ) coupled between the hydraulic actuators ( 76 ), ( 78 ), ( 82 ) and ( 84 ) and the shafts ( 92 ) associated therewith. The angle sensors ( 90 ) are coupled to the central processing unit ( 94 ). When the rocker switch ( 74 ) is actuated, the central processing unit ( 94 ) utilizes the angle sensors ( 90 ) to determine the angle of the rear wheels ( 42 ) and ( 44 ) relative to the front wheels ( 34 ) and ( 36 ). Once this angle has been determined, the central processing unit ( 94 ) causes the steering flow controller ( 70 ) to turn the rear wheels ( 42 ) and ( 44 ) to the proper angle relative to the front wheels ( 34 ) and ( 36 ) associated with the selected mode. 
   If the rocker switch ( 74 ) is being actuated into synchronous mode, the central processing unit ( 94 ) causes the steering flow controller ( 70 ) to turn the rear wheels ( 42 ) and ( 44 ) to the same angle as the front wheels ( 34 ) and ( 36 ). If the rocker switch ( 74 ) is being actuated into asynchronous mode, the central processing unit ( 94 ) causes the steering flow controller ( 70 ) to turn the rear wheels ( 42 ) and ( 44 ) to in the opposite direction as the front wheels ( 34 ) and ( 36 ). 
   If desired, steering of the center wheels ( 38 ) and ( 40 ) may be provided in a similar manner. Also, the central processing unit ( 94 ) may be programmed in response to rotation of the steering wheel ( 72 ), to rotate the rear wheels ( 42 ) and ( 44 ) the same amount as the front wheels ( 34 ) and ( 36 ), or more or less, depending upon the turning performance desired. 
   As shown in  FIG. 2 , the container ( 16 ) is located centrally between the front wheels ( 34 ) and ( 36 ), and rear wheels ( 42 ) and ( 44 ), to more evenly distribute the weight of the fluid ( 96 ) provided within the container ( 16 ). The preferred embodiment of the vehicle ( 12 ) defines a clearance at least one meter high and at least two meters wide, but may, of course, define any desired clearance to accommodate post-emergent crops ( 98 ). The vehicle ( 12 ) is preferably designed to have a spray boom ( 22 ) which collapses so that the overall dimension of the system ( 10 ) is no greater than three-hundred, ninety-seven centimeters high, and three-hundred, sixty-six centimeters wide, to allow the system ( 10 ) to be transported across public roadways. While more than six wheels may be provided, at least six wheels are preferable to distribute the weight of the fluid ( 79 ) across a wider area to allow the system to apply fluid ( 79 ) to crops ( 98 ) on softer soil, and/or wetter ground, and to reduce the detrimental impact of soil compaction on the crops ( 98 ). Preferably, the outer diameter of the wheels ranges from one hundred and eighty three centimeters to two hundred and five centimeters. 
   The foregoing description and drawings merely explain and illustrate the invention. The invention is not limited thereto, except insofar as the claims are so limited, as those skilled in the art who have the disclosure before them will be able to make modifications and variations therein, without departing from the scope of the invention. For example, it is anticipated that the system ( 10 ) may be provided with eight or more wheels, as desired.