Abstract:
The present invention provides an operator-controllable system that allows the operator to make initial (and preferably optimal) field operation settings for the towed working tool (“implement”) quickly and easily when hitching the working tool to the towing vehicle, e.g., tractor. Once an initial setup is completed, in operation, the invention, which in one form is a leveling arrangement for the working tool, automatically maintains the optimal operation settings throughout the vertical operational range of the working tool. For example, if the optimal operation settings is a level implement throughout its operating range, the leveling arrangement will maintain the implement level as the implement is raised and lowered.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to industrial equipment, e.g., farm and construction equipment, and more particularly, to a method and apparatus for maintaining a working tool level throughout a vertical range of motion. 
         [0002]    One of the keys to optimum performance of tillage equipment is the proper initial setting for field operation, which begins with leveling the implement (“working tool”) longitudinally (along the direction of travel) and laterally (across the implement width). To complicate matters in achieving this initial setting longitudinally, different tractor manufacturers utilize different draw bar heights to optimize their pull point for specific models. Different diameter tires used to meet specific farmer needs cause additional variances in draw bar height. No tillage implement manufacturer has a clear and simple means to accomplish machine leveling, which usually means a tractor driver and field observer are necessary to achieve proper setting. 
         [0003]    Traditionally, to level a tillage implement laterally, one would use mechanical depth collars to restrict lift cylinder movement in the operating position. Although a positive means of controlling depth, depth collars are time consuming, as they require the operator to vacate the operator cab of the tractor and place the same size stop on all lift cylinder locations. 
         [0004]    Another traditional method of accommodating various tractor draw bar heights on many machines is to provide multiple holes in which a hitch may be bolted. While this offers an economical method, it is time consuming and requires substantial effort to fine tune, requiring jacking up the implement, unhitching the tractor, removing and repositioning the hitch, then reconnecting the hitch. Also, the machine can only be properly set for a single depth and therefore precludes running the machine at varying depths without adjustment. This design also results in the front components of the machine to have less vertical clearance during transport situations. 
         [0005]    Moreover, modern self-leveling mechanisms are intended to maintain implement levelness throughout a limited working range of the implement and typically make use of linkages to tie the rear lifting components to a front pivoting pull frame. While these designs adequately keep the frame level throughout its working range, they are still often difficult to adjust thereby requiring a tractor operator and a field observer. It is not uncommon for substantial time and effort to be expended to find the optimal setting. 
         [0006]    Other attempts at frame leveling include using hydraulic means for control, but such systems are independent of machine depth. As a result, they require additional hydraulic control circuits and operator skill and attentiveness in properly adjusting the mechanism. Further, such systems are not automatic and require independent adjustment. 
         [0007]    More recently, hydraulic depth valves have become widely used on implements to control depth. Typical systems use a mechanically actuated valve that limits downward travel to a preset depth. These systems typically still use a mechanical self-leveling mechanism, which still requires two people for making adjustments. Indicators are common among tillage machines but have typically only been used to indicate implement depth. While depth indicators are important to efficient operation of the implement, depth indicators do not indicate implement levelness. 
         [0008]    Therefore, there remains a need for a self-leveling depth setting system that in addition to setting the depth of the tillage implement also maintains implement levelness throughout its vertical range of motion. 
       SUMMARY OF THE INVENTION 
       [0009]    The present invention provides an operator-controllable system that allows the operator to make initial (and preferably optimal) field operation settings for the towed working tool (“implement”) quickly and easily when hitching the working tool to the towing vehicle, e.g., tractor. Once an initial setup is completed, in operation, the invention, which in one form is a leveling arrangement for the working tool, automatically maintains the optimal operation settings throughout the vertical operational range of the working tool. For example, if the optimal operation settings is a level implement throughout its operating range, the leveling arrangement will maintain the implement level as the implement is raised and lowered. 
         [0010]    Therefore, in accordance with one aspect of the invention, a farm implement that is towed by a towing vehicle and that is movable vertically from a working raised position and a working lowered position with the range there-between defining a working operating range for the farm implement includes a main frame to which a plurality of ground engaging tools are mounted. The implement further has a hitch frame that connects the main frame to the towing vehicle and a leveling arrangement connected to the main frame and the hitch frame that continuously maintains the main frame in a substantially level position throughout the working operating range. 
         [0011]    In accordance with another aspect of the invention, an improvement for a farm implement having a main frame movable through a vertical range of positions and a hitch frame is provided. The improvement interfaces with a leveling arrangement for maintaining a constant level of the main frame throughout its vertical range of positions. The improvement includes a first hydraulic actuator operative to raise and lower the main frame and a second hydraulic actuator operative to rotate the hitch frame against a hitch of the towing vehicle simultaneously with operation of the first hydraulic actuator to maintain the main frame level throughout the vertical range of positions. 
         [0012]    According to a further aspect of the invention, a farming system includes a tractor having a hitch, an implement that is towed by the tractor and that is movable vertically from a raised position and a lowered position with the range there-between defining a working operating range for the implement. The implement has a main frame to which a plurality of ground engaging tools are mounted and a hitch frame that connects to the hitch of the tractor. The implement further has a leveling arrangement connected to the main frame and the hitch frame that continuously maintains the main frame in a substantially level position throughout the working operating range. 
         [0013]    Various other features and advantages will be made apparent from the following detailed description and the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0014]      FIG. 1  is a pictorial view of a farming system having a farming implement according to the present invention; 
           [0015]      FIG. 2  is a simplified isometric view of the farming implement of the farming system of  FIG. 1 ; 
           [0016]      FIG. 3  is a side elevation view of the farming implement of  FIG. 2 ; 
           [0017]      FIG. 4A  is an enlarged side elevation view of a front portion of the farming implement of  FIG. 2 ; 
           [0018]      FIG. 4B  is an enlarged side elevation view of a rear portion of the farming implement of  FIG. 2   
           [0019]      FIG. 5  is a schematic of a hydraulic system for the farming implement of  FIG. 2  according to one embodiment of the invention; and 
           [0020]      FIG. 6  is a schematic of a hydraulic system for the farming implement of  FIG. 2  according to an alternate embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Turning now to the figures, a farming system  10  is generally comprised of a farm implement  12  that is hitched to a towing vehicle  14 , such as a tractor. In the illustrated embodiment, the farm implement  12  is a tillage machine but the invention is not so limited. The farm implement  12  is generally comprised of a hitch frame  16  and a main frame  18  to which a plurality of ground engaging tools  20  are conventionally attached. The ground engaging tools  20  in the illustrated embodiment include a combination of shanks  22  and coulters  24  but it is understood that other types or other combinations of tools could be used. The hitch frame  16  couples the main frame  18  to the hitch  26  of the towing vehicle  14  in a conventional manner. 
         [0022]      FIG. 2  provides a simplified isometric view of the farm implement  12 . In the view of  FIG. 2 , for purposes of simplification, the ground engaging tools  20  have been removed. From  FIG. 2  it will be appreciated that the main frame  18  consists a pair of outer rails  28  extending parallel to one another in a longitudinal direction between a header bar  30  and a footer bar  32 . To provide additional stability, the main frame  18  includes an intermediate crossbar  34 . In addition to outer rails  28 , the main frame  18  also has a pair of inner rails  36  that extend parallel to one another in a longitudinal direction between the header bar  30  and a trailing bar  38  that is spaced rearward (in the fore-aft direction) of the footer bar  32 . Working tools, such as harrows (as shown in  FIG. 1 ), may be mounted to the trailing bar  38 . The inner rails  36  are positioned inboard of the outer rails  28 . The rails and bars are interconnected in a known manner using brackets, weldments, and the like. It will also be appreciated that wing frame sections (not shown) may be mounted to the main frame  18  to provide additional width or coverage of the implement. Preferably, such wing sections are pivotally mounted or otherwise associated with the main frame  18  to allow the implement to fold for transport and storage. 
         [0023]    Viewing from the towing vehicle  14  rearward, there is extending transverse to the rails and slightly forward of the footer bar  32  a rod  40  having a first end (not numbered) connected to a first (right) wheel assembly  42  and a second end (not numbered) connected to a second (left) wheel assembly  44 . Wheel assembly  42  includes inboard and outboard tires  46 ,  48 , respectively, mounted in a conventional manner to inboard and outboard axles  50 ,  52 , respectively. The axles  50 ,  52  are both connected to a tire mount  54  that is pivotally connected to a mounting bracket  56  that is connected to the footer bar  32 . The tire mount  54  is caused to pivot relative to the mounting bracket  56  by an actuator  58 , which in a preferred embodiment, is a hydraulic actuator having barrel  60  connected to the footer bar  32  by flange  62  and an extendible rod  64  connected to the tire mount  54  in a conventional manner. When the rod  64  is extended, the wheel assembly  42  is rotated underneath the main frame  18  to raise the main frame  18 . Conversely, when the rod is retracted, the wheel assembly is pivoted away from the footer bar which causes the frame to be lowered. 
         [0024]    Wheel assembly  44  also includes inboard and outboard tires  66 ,  68 , respectively, mounted in a conventional manner to inboard and outboard axles  70 ,  72 , respectively. The axles  70 ,  72  are both connected to tire mount  74  that is pivotally connected to a mounting bracket  76  that is in turn connected to the footer bar  32 . The tire mount  74  is caused to pivot relative to the mounting bracket  76  by an actuator  78 , which in a preferred embodiment, is a hydraulic actuator having a barrel  80  connected to the footer bar  32  by a flange  82  and an extendible rod  84  connected to the tire mount  74  in a conventional manner. When the rod  84  is extended, the wheel assembly  44  is rotated underneath the main frame  18  to raise the main frame  18 . Conversely, when the rod is retracted, the wheel assembly is pivoted away from the footer bar which causes the frame to be lowered. 
         [0025]    With additional reference to  FIGS. 3 ,  4 A, and  4 B, the hitch frame  16  consists of an A-frame  86  with a coupler  88  at the point-end of the A-frame  86  for attaching to the hitch  26  (or tow bar) of the towing vehicle  14 . The legs  86   a,    86   b  of the A-frame  86  are connected to a shortened cross member  90  that is pivotably connected to the header bar  30  by a pair of pivots  92 ,  94 . A cylinder mount  96  is mounted to the legs  86   a,    86   b  generally above the transverse leg  98  of the A-frame  86 . Interconnected between the cylinder mount  96  and the coupler  88  is a turnbuckle  100 . 
         [0026]    A pair of hydraulic cylinders  102 ,  104  is interconnected between the cylinder mount  96  and an inverted V-frame  106 . The legs  106   a,  V-frame  106   b  of the V-frame  106  are attached to the inner rails  36  by brackets  108 ,  110 , respectively. The hydraulic cylinders  102 ,  104  are pivotally coupled to a bracket  112 , which extends from the forward end of the V-frame  106 . This pivoting connection allows the cylinders  102 ,  104  to rotate relative to the V-frame  106 , which, as will be described more fully below, allows the outer rails  28  and the inner rails  36  to be kept relatively level as the vertical position of the tractor hitch  26  changes. 
         [0027]    The turnbuckle  100  is used for setting the height of the coupler  88  to match the height of the hitch  26  for the towing vehicle  14  pulling the farm implement  12 . That is, the towing vehicle  14  and the farm implement  12  are placed in a fore-aft arrangement and on substantially level ground. The turnbuckle  100  is tuned so that the A-frame  86  is pivoted either upward or downward to match the position of the tractor hitch  26 . It is contemplated that the turnbuckle  100  may include markings or other indicators to guide an operator in setting the tension in the turnbuckle  100 , and thus pivoting the A-frame  86 , based on an expected range of tractor hitch positions, e.g., a height range of 15-22″. Once this adjustment has been made for the specific tractor, the turnbuckle  100  does not need to be reset. And, as will be described more fully below, the actuators  58 ,  78  and hydraulic cylinders  102 ,  104  will cooperate to maintain the main frame  18  level through a normal operating range. It is contemplated that tuning devices other than the aforedescribed turnbuckle could be used to adjust the height of the coupler  88 . 
         [0028]    Turning now to  FIG. 5 , the present invention provides a hydraulic system  114  for use with farm implement  12  or other similar type of farming implement. Farm implement  12  has been described as having a main frame  18  supported by a pair of wheel assemblies  42 ,  44 . As noted above however, it is contemplated that the farm implement  12  may be equipped with left and right wing sections (not shown) that are each supported by one or more wheel assemblies (not shown). The hydraulic system  114  will be described with respect to a farm implement having a main frame and a pair of wing sections, and more particularly, a farm implement having hydraulic cylinders  58 ,  78  for raising and lowering the main frame  18  and hydraulic cylinders  116 ,  118  for raising and lowering left and right wing sections, respectively. The hydraulic system  114  further includes hydraulic cylinders  102 ,  104  which are used to pivot the hitch frame  16  against the tractor hitch  26  to keep the main frame  18  level as the main frame  18  is raised and lowered. 
         [0029]    The hydraulic system  114  has a supply line  120  that couples in a conventional manner to the supply port  122  of the towing vehicle  14  and a return line  124  that couples in a conventional manner to the return port  126  of the towing vehicle  14 . The supply line  120  supplies hydraulic fluid to cylinders  58 ,  78  through a diverter  128 . Cylinders  58  and  116  are connected in series such that hydraulic fluid flows from the supply line  120  first through cylinder  58  and then to cylinder  116  through connecting line  130 . In a similar manner, cylinders  78  and  118  are connected in series such that hydraulic fluid from the supply line  120  first through cylinder  78  and then to cylinder  118  through connecting line  132 . 
         [0030]    In the illustrated embodiment, the hydraulic fluid from cylinder  116  dumps directly into the return line  124  whereas hydraulic fluid from cylinder  118  flows through a diverter  134  to supply hydraulic fluid to cylinders  102  and  104 . Hydraulic fluid from both cylinders  102 ,  104  dumps into the return line  124 . It will thus be appreciated that cylinders  58 ,  78 ,  102 ,  104 ,  116 , and  118  are plumbed together. The volumes of the cylinders are specifically coordinated such that the extension rates of the cylinder rods will cause the implement frame (main frame and wing sections) to raise (or lower) equally thereby keeping the frames level as they are raised (or lowered). 
         [0031]    The hydraulic system  114  further has a depth control limit switch  136  plumbed between the supply line  120  and wheel assemblies&#39; cylinders, e.g., cylinders  58  and  78 . The depth control limit switch  136  is utilized to top frame movement at any point in the operational range, thereby allowing an operator to set the depth of tillage. That is, the depth control limit switch  136  stops movement of the frames in the downward direction such that the maximum implement depth desired may be set prior to tillage with the implement fully adjustable above this depth. 
         [0032]    Turning now to  FIG. 6 , a hydraulic system  138  according to another embodiment of the invention is shown. In this embodiment, a flow divider  140  is used to provide the correct ratio of hydraulic flow to the cylinders. Also, in this embodiment, cylinder  118  dumps into the return line  124  rather than cylinders  102 ,  104 . It will further be seen that in this embodiment, a single, rather than two, hydraulic cylinders are used to pivot the hitch frame  16  relative to the tractor hitch  26 . The invention is not so limited however. From  FIG. 6 , it will be appreciated the hydraulic fluid flows to both “sets” of cylinders, e.g., lift cylinders  58 ,  78 ,  116 ,  118  and hitch frame cylinder  102 , through the flow divider  140  rather than between the sets of cylinders. 
         [0033]    From the foregoing, it will be appreciated that the crop residue and soil-conditioning machine of the present invention simplifies initial machine field operation settings. First, the mechanical turnbuckle provides quick and easy adjustment with an indicator showing the positions for draw bar heights from 15-22″. Once this adjustment has been made for the specific tractor used for towing, the turnbuckle need never be changed and the combination of the transport design and hydraulic circuit self levels the implement. 
         [0034]    To set the main depth of the implement, there is a single point depth control (not shown) located conveniently on the leveling frame for easy operator access, e.g., connected to V-frame  106  and rod  40  with a crank handle (not shown) mounted adjacent bracket  112 , on the same side of the tractor as the cab door to minimize distance. By setting this prior to heading to the field, the operator can choose to focus on other operational concerns, while being able to hydraulically raise the machine from the cab. As any of these hydraulic adjustments are made, the self-leveling hydraulic circuit compensates to maintain levelness. 
         [0035]    The hydraulic self-leveling system enables the operator to make “on the go” fine tuning adjustment to the depth of each component on the machine. In an alternate embodiment of the invention, two hydraulic switches—one at the front of the machine attached to the self-leveling component and the other controlling hydraulic fluid flow to the lift cylinders—could be used rather than a flow divider. 
         [0036]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.