Abstract:
A steerable axle assembly for a grain cart or manure tank unit designed to be pulled in a forward direction over and agricultural field by a farm tractor is disclosed. The invention involves a steering axle assembly that is easily guided to improve the maneuverability and safety of the unit and reduce field compaction. The steering system design features angled kingpins that transfers some of the unit weight to assist in turns. Thus, the steering system reduces the resistance of the unit steering system to turning and minimizes ground compaction during turns. The steering system is particularly designed for rear-steering grain carts and manure tank units and larger versions of such units with multiple alternating steering and non-steering axles.

Description:
CROSS-REFERENCED TO RELATED APPLICATIONS 
       [0001]    Not applicable 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable 
       BACKGROUND OF THE INVENTION 
       [0003]    I. Field of the Invention 
         [0004]    The present invention relates generally to grain carts and manure tanks that are not self-propelled and that are designed to be pulled behind a farm tractor. More particularly, the invention relates to a steering axle assembly designed for grain carts and manure tank trailers that facilitates turning and maneuverability while minimizing soil loading and compaction. 
         [0005]    II. Related Art 
         [0006]    Non-motorized trailer-mounted agriculture utility vehicles in the form of grain carts and manure tanks that are designed to be pulled behind motorized vehicles, specifically farm tractors, have been used for a long period of time. Grain carts are typically used in combination with various types of combines in grain-harvesting operations in which the grain is separated from stalks in threshing and separation steps and is first collected in a grain tank in the combine from which it is discharged through a grain tank unload tube into a grain cart pulled alongside the combine. Large capacity and easy maneuverability are desirable attributes for such grain carts inasmuch as this increases the efficiency of the grain harvesting operation. While increased capacity for grain carts is desirable, it is also desirable that the implements minimize the degree to which the soil in the field is compacted by the cart, particularly when the cart is fully loaded. An example of such a cart is shown in U.S. Pat. No. 6,488,114 B1 to McMahon et al. 
         [0007]    Manure tanks have also long been used to distribute manure-containing mixtures over large field areas. The tanks, at times, are heavily laden and also must be highly maneuverable and need to have a minimum impact in terms of soil compaction when pulled through a field while applying the tank contents. 
         [0008]    One important aspect of pulled grain carts and manure tanks is the ability of such vehicles to maneuver in the field while maintaining a minimum impact on the soil over which they travel. This is directly affected by the design and operation of steerable axles on such vehicles. These vehicles typically include rear-steering axles and fixed front axles in the case of two-axle vehicles and may alternate steering and fixed axles on vehicles which have three or more axles. In addition, these vehicles must have the ability to be easily pulled down roads. 
         [0009]    A rear-steering axle assembly which utilizes an offset kingpin arrangement is shown in U.S. Pat. No. 6,267,198 B1. That axle is particularly suited for rear steering on a grain harvesting combine. 
         [0010]    While progress has been made, there remains a need for steering axles that improve the steering function for better maneuverability and safer operation and which also reduce field compaction and allow for higher capacity loads by enabling the use of larger tires. 
       SUMMARY OF THE INVENTION 
       [0011]    By means of the present invention, there is provided a steerable axle assembly designed for utility agriculture vehicle units in the form of grain carts and manure tanks designed to be pulled in a forward direction over an agricultural field by a motorized farm tractor. The invention involves an axle assembly that is easily guided to improve the maneuverability and safety of the unit and reduce field compaction. The steering system design reduces the amount of weight of the unit concentrated on kingpins and transmitted through the wheels to the ground during turns. Thus, the steering system reduces the resistance of the unit steering system to turning and minimizes ground disturbance and compaction during turns. The steering system improves the performance of rear-steering grain carts and manure tank units having two axles and larger versions of such units with multiple alternating steering and non-steering axles. 
         [0012]    One embodiment of the steerable axle assembly of the invention includes a pair of spaced kingpin receiver arrangements supported by a common central axle member, a spindle receiver carried by each kingpin receiver and a spindle mounted in each spindle receiver, each such spindle being adapted to carry a wheel. A kingpin is mounted in each kingpin receiver and each kingpin receiver is disposed in the structure such that a kingpin mounted in the kingpin receiver is positioned at a compound acute angle with the common central axle member, the angle being both directed inward toward the central axle member and rearward of the central axle member. Each of the spindle receivers is mounted to pivot about a kingpin. An arrangement is provided for connecting the kingpin spindle receivers together so that they operate in unison. This may be a hydraulic connection or a tie rod arrangement. In a turn, the kingpin angle causes the outward spindle in the turn to travel in an arc that pivots upward and forward to thereby facilitate the turning of the steering axle. 
         [0013]    A damping device such as a hydraulic cylinder may be provided to bias the self-steering axle toward a neutral position in which the wheel alignment is returned to a straight ahead direction as the axle assembly comes out of a turn situation. 
         [0014]    The self-steering axle assembly of the invention may be paired with a non-steering axle assembly to support a frame for supporting a grain cart or manure tank with the self-steering axle being the rear axle in the assembly. Larger vehicles may be provided with more than one self-steering axle. These include vehicles with three axles in which the front and rear axles are steering axles and the intermediate axle is non-steering and even larger units, for example, ones having four axles wherein the front, second and fourth axles are self-steering and the third axle is non-steering, etc. 
         [0015]    In an alternate embodiment, the steering system of at least one steering axle in the grain cart or manure tank unit can incorporate mechanically controlled steering arrangement using a drive line shaft attached to the drawbar of a conveying vehicle such as a tractor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    In the drawings: 
           [0017]      FIG. 1  is a perspective view of a grain cart support frame with a tandem axle assembly in accordance with the present invention; 
           [0018]      FIG. 2  is a perspective view of a grain cart support frame having three independent axles in accordance with the present invention; 
           [0019]      FIG. 3  is an exploded view of a steering kingpin system constructed in accordance with the invention; 
           [0020]      FIG. 4  is a view of the steering kingpin system of  FIG. 3  assembled attached to a fragment of a vehicle frame; 
           [0021]      FIG. 5  is a rear elevational view of an assembled steering axle system with a tie rod connector; 
           [0022]      FIG. 6  is a top view of an assembled steering axle system similar to that of  FIG. 5  with parts removed for clarity; 
           [0023]      FIG. 7  is a rear elevational view of an alternative embodiment of an assembled steering axle system in accordance with the invention; 
           [0024]      FIG. 8  is a top view of a tandem assembly showing hydraulic connections and additional non-steering wheels; 
           [0025]      FIGS. 9A-9F  show top views ( 9 A,  9 C,  9 E) and rear views ( 9 B,  9 D,  9 F) of a steering kingpin system illustrating a right turn ( 9 A and  9 B), a straight or neutral position ( 9 C and  9 D) and a left turn ( 9 E and  9 F) with respect to a pulled vehicle illustrating the action of the kingpin steering axle system of the invention; 
           [0026]      FIG. 10  represents a bottom perspective view of an alternative embodiment of a steerable axle system with mechanically controlled steering; 
           [0027]      FIG. 11  is a perspective view of a grain cart having two independent axles; 
           [0028]      FIG. 12  is a perspective view of a grain cart similar to that of  FIG. 3  having three independent axles; 
           [0029]      FIG. 13  is a perspective view of a grain cart with four independent axles; 
           [0030]      FIG. 14  is a perspective view of a manure tank utilizing two independent axles; and 
           [0031]      FIG. 15  is a perspective view of a manure tank including a fifth wheel setup having a tandem front axle set and three independent rear axles. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    In accordance with the following detailed description, there is presented one or more embodiments associated with the present inventive concepts. These embodiments are intended as examples of such concepts, but are not intended to limit the scope of the present invention in any manner as variations within the confines of the inventive concepts may occur to those skilled in the art. 
         [0033]    As used herein, the term “axle assembly” refers to a set of opposed spaced assemblies for carrying wheels aligned on opposite sides of a vehicle frame, whether or not they are connected by a common member. Thus, the spaced assemblies may enjoy a common axle tube or other possibly unconnected mounting arrangement. The axle assemblies may be steering in which the wheels can pivot about kingpins or non-steering in which the wheels assume a fixed position. Steering axle assemblies include a connecting member or other arrangement to coordinate the turning of both wheels in unison. 
         [0034]      FIGS. 1 and 2  depict non-motorized grain cart support frames mounted on two ( FIG. 1 ) and three ( FIG. 2 ) independent axle assemblies as shown generally at  30  and  32 , respectively. In  FIG. 1 , the grain cart  30  includes a frame  34  with an associated conventional fixed-position hitching tongue  36  secured to the frame. Non-steering wheel assemblies are partially shown at  36  and  38  with mounted tires  40 . The vehicle frame further includes spaced parallel longitudinal frame members or frame rails  42  and  44  and a series of cross braces as at  46 . Spaced heavy symmetrical wheel support assemblies, one of which is shown at  48 , are attached to the frame and connected by common cross member  50 . One of two spaced kingpin steering assemblies in accordance with the invention, and discussed in greater detail below, is shown at  52 . This assembly makes up part of a steering rear axle system. The steering system embodiment of  FIG. 1  includes kingpin assemblies coordinated by symmetrically opposed self-centering hydraulic cylinders, as will be explained. Support pads for carrying a bin container for a cart, a tank or the like are mounted on the frame at  54 . 
         [0035]      FIG. 2  depicts a non-motorized cart frame of an alternate, slightly different construction. It includes a frame  60  and fixed attached hitching tongue  62 . The frame includes spaced parallel frame rails  64  and  66  spanned by a plurality of cross members as at  68 . This vehicle includes three spaced axle systems in which the front and rear axle assemblies are steering assemblies and the intermediate assembly is non-steering. In this embodiment, the wheel-carrying assemblies are connected by heavy common cross members or axle tubes as at  70 . Shock-absorbing cylinders associated with a suspension system for the axle tubes are shown at  72 . 
         [0036]      FIG. 3  depicts an exploded view of a typical kingpin steering system, generally at  100 , which represents one of a pair of opposed symmetrically constructed assemblies that make up a steering axle assembly in accordance with the invention. The kingpin steering system further includes a kingpin receiver assembly  102  and a spindle receiver  104 . A spindle and wheel assembly is shown at  106 , including a spindle  108  and a wheel  110  mounted on the spindle. The kingpin receiver assembly further includes spaced, generally parallel, kingpin receiving members  112  and  114 , which hold and position an angled kingpin  116  and also accommodate the spindle receiver  104 . They also provide bearing surfaces for the assembly to operate. A lip seal member is shown at  118  on the lower bearing surface and a nut  120  secures the kingpin in place. It should also be noted that the nut clamps the upper plate  112  to the lower plate  114  causing the load of the weight of the unit to be carried more evenly. 
         [0037]    The spindle receiver  104  includes an integral hollow spindle tube  122  for receiving a corresponding spindle member  108 . The assembly further includes a series of thrust washers  124  that carry the vertical load of the vehicle and an o-ring  126  that is mounted beneath the thrust washers to seal the upper bearing surface from the environment. An attachment plate  128  cooperates with members  130  using fasteners (not shown) to attach the assemblies  104  and  106  together. 
         [0038]    In this embodiment, the kingpin receiver assemblies are attached by intermediate structural members to a common central axle member or axle tube  132  and a fluid-operated, preferably hydraulic, steering cylinder  134  is provided having the rod end  136  mounted to the spindle receiver  104  using tab  138 . The other end of the cylinder is connected to a member  140  fixed to the axle tube  132 , as shown in  FIG. 4 . 
         [0039]    The hydraulic cylinder  134  is actually a damping cylinder which performs two functions. First, it controls the speed at which the steering system turns and, second, the hydraulic cylinder has three hydraulic connections at  142 ,  144  and  146  and is pressurized to center the steering system, that is, it urges the system to assume a neutral or aligned straight forward position to allow the unit to back up or to be transported down a road easily, for example, with the spindles in what amounts to a locked position. 
         [0040]    This embodiment also includes a tie rod  148  connected between the spindle receivers  104 , one connector of which is shown at  150 . The tie rod forces the spindle receivers to operate (pivot) in unison by mechanical connection. 
         [0041]    The system of  FIG. 3  is shown assembled in  FIG. 4  and attached to a fragment of a vehicle frame at  152 . 
         [0042]      FIGS. 5 and 6  show rear elevational and top views of steering axle assemblies in accordance with the embodiment of  FIGS. 3 and 4 . As can be seen from the figures, a key feature of the kingpin steering system of the invention lies in the mounting disposition of the kingpins. The kingpins are disposed at a compound acute angle with the common axle tube or other support member such that the kingpins are disposed to extend in a rearward and inward manner rather than being mounted in a conventional vertical plane. An important aspect of the invention is the mounting of the kingpins at a compound angle that allows the spindles to travel in an arc that wants to pivot up and forward with the weight of the unit resting on the bearing surfaces. The tie rod  148  that connects the left kingpin steering system, including the left spindle assembly, shown at  160  in  FIGS. 5 and 6 , with the right kingpin steering system  162  using respective connectors  164  and  166 , as shown in  FIG. 6  causes the spindles to operate in unison. This is further illustrated in the turning, straightening and opposite direction turning sequences depicted in  FIGS. 9A-9F . Easy turning and relief of stress on the kingpins is accomplished as the spindle receivers, and so the spindles rotate in a plane perpendicular to the disposition of the kingpins, rather than in a flat trajectory accommodated by the normal vertical disposition of kingpins. 
         [0043]    In addition, this configuration reduces ground traveling in turns and further enables the vehicle to accommodate larger tires, typically up to two meters in diameter or greater, thereby reducing ground loading even more. 
         [0044]      FIG. 7  is a top view of an alternative embodiment of an assembled single steering axle system in accordance with the invention. The steering axle is shown generally at  170  and includes spaced symmetrically opposed and otherwise identical kingpin steering assemblies for steering as at  172  and  174  that include compound angled kingpins  176  and  178  respectively. The kingpins are attached to the frame and coordinated by two separate hydraulic cylinders  180  and  182  supplied from a common hydraulic fluid line  184  and common connector  186 . The common hydraulic connection enables the cylinders  182  and  182  to act in the manner of a tie rod to coordinate the turning of assemblies  172  and  174  as was the case with the damping cylinder of  FIGS. 3-5 , the cylinders  182  and  182  act to return the assemblies to a forward directed position. Fragments of frame members are shown at  188  and  190  with cross brace  192  and shock absorbing suspension devices are shown at  194  and  196 . 
         [0045]      FIG. 8  is a top view of a tandem axle assembly also showing similar hydraulic connections. The steering axle assembly is shown generally at  200  and includes steering spaced, opposed symmetrically constructed kingpin assemblies at  202  and  204 . These assemblies are attached to structural members  206  and  208 , respectively, which, in turn, attach to a common structural member  210 . This system also features a pair of hydraulic steering cylinders  212  and  214 . Cylinder  212  connects a corresponding pivoting spindle receiver  216 , a structural member  206  using a plate member  218 . Likewise, cylinder  214  connects pivoting spindle receiver  220  with member  208  using a member  222 . The cylinders  212  and  214  are provided with hydraulic fluid from a common source  224  in a manner that coordinates both cylinders to operate together and also pressurizes the cylinders to center to stabilize the steering system so that it favors locking the spindles in a forward position. 
         [0046]    In this embodiment, note that the kingpins  226  and  228  are disposed at the same angle as those enumerated with respect to the previously described embodiments. Additional non-steering or fixed position assemblies are shown at  230  and  232 , which are also structurally attached to the forward portion of common member  210  through an intermediate structure. As can be seen from the drawing, the assemblies  230  and  232  are fixed in a neutral or straightforward position. 
         [0047]      FIG. 10  represents a bottom perspective view of an alternative embodiment of a steerable axle system that employs mechanically controlled steering. The system, shown generally at  300 , includes angled kingpin steering systems at  302  and  304  with common tie rod  306 . The kingpin steering system  304  includes a spindle receiver  308  connected at  310  to a second tie rod  312  which, in turn, is attached at  314  to an eccentric steering arm  316  instead of to a hydraulic cylinder, as shown in the embodiment of  FIGS. 3-6 , for example. The steering arm  316  is attached to a steering shaft  318  that rotates and operates the eccentric steering arm  316 . The shaft  318  is held by bearings as at  320  and extends to be connected by a universal joint  322  to a drive line shaft  324 . The drive line locks and controls the amount of steering available in the axle system and is, in turn, connected via a second universal joint  326  to the draw bar of a tractor or other motorized pulling vehicle. In this manner, the act of the tractor turning transfers the necessary torque to the steering axle to rotate the system in the correct amount in the direction. Both kingpin assemblies are coordinated via the connection with common tie rod  306  and the kingpins are set at an angle as per previous embodiments. 
         [0048]    The remaining drawing figures depict various non-motorized agriculture implement grain cart and manure tank units suitable for use with the steering systems and combination axle systems of the present invention. Thus,  FIG. 11  is a perspective view of a grain cart having two tandem independent axles.  FIG. 12  is a perspective view of a grain cart similar to that depicted in  FIG. 11 , but provided with three independent axles. In this arrangement, normally the front and rear axles would be steering axles and the intermediate axle fixed.  FIG. 13  depicts a grain cart similar to those shown in  FIGS. 11 and 12  provided with a four-axle arrangement in which the second and fourth or first, second and fourth axles may be steering axles.  FIG. 14  is a perspective view of a manure tank with two independent axle systems, the rear axle system of which is a steering axle. Finally,  FIG. 15  is a perspective view of a manure tank having a fifth wheel setup utilizing a tandem front axle set in conjunction with three rear axle sets, the initial and final ones of which typically are steering axles, with the intermediate axle being fixed. 
         [0049]    It will be appreciated that the steering axle arrangement of the present invention lends itself for use with any combination of steering and non-steering axles in grain carts and manure tanks designed to be pulled in a forward direction by a motorized conveyance. 
         [0050]    This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.