Abstract:
An agricultural tillage implement with a hydraulic system having a left wing hydraulic subsystem with an outer left wing hydraulic circuit supplying hydraulic pressure and flow to an actuator for actuating an actuator of an outer left wing folding implement section, and a right wing hydraulic subsystem having an outer right wing hydraulic circuit for actuating the actuator of an outer right wing implement section; the hydraulic system additionally having a hydraulic flow divider dividing hydraulic flow and pressure between the outer left wing hydraulic circuit and the outer right wing hydraulic circuit, the hydraulic flow divider being configured to coordinate the motion of the outer left wing section and the outer right wing section.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation-in-part application based upon U.S. non-provisional patent application Ser. No. 14/532,563, entitled “AGRICULTURAL TILLAGE IMPLEMENT WHEEL CONTROL”, filed Nov. 4, 2014, which is a non-provisional of U.S. Provisional Application Ser. No. 61/903,492, entitled “AGRICULTURAL TILLAGE IMPLEMENT WHEEL CONTROL”, filed Nov. 13, 2013 which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to agricultural implements, and, more particularly, to agricultural tillage implements. 
         [0004]    2. Description of the Related Art 
         [0005]    Farmers utilize a wide variety of tillage implements to prepare soil for planting. Some such implements include two or more sections coupled together to perform multiple functions as they are pulled through fields by a tractor. For example, a field cultivator is capable of simultaneously tilling soil and leveling the tilled soil in preparation for planting. A field cultivator has a frame that carries a number of cultivator shanks with shovels at their lower ends for tilling the soil. The field cultivator converts compacted soil into a level seedbed with a consistent depth for providing excellent conditions for planting of a crop. Grass or residual crop material disposed on top of the soil is also worked into the seedbed so that it does not interfere with a seeding implement subsequently passing through the seedbed. 
         [0006]    Tillage equipment prepares the soil by way of mechanical agitation of various types, such as digging, stirring, and overturning. Examples of which include ploughing (overturning with moldboards or chiseling with chisel shanks), rototilling, rolling with cultipackers or other rollers, harrowing, and cultivating with cultivator shanks. 
         [0007]    Tillage is often classified into two types, primary and secondary. There is no strict definition of these two types, perhaps a loose distinction between the two is that tillage that is deeper and more thorough is thought of as primary, and tillage that is shallower is thought of as secondary. Primary tillage such as plowing produces a larger subsurface difference and tends to produce a rough surface finish, whereas secondary tillage tends to produce a smoother surface finish, such as that required to make a good seedbed for many crops. Harrowing and rototilling often combine primary and secondary tillage into one operation. 
         [0008]    Wheels are often integral with tillage implements and are used for both transportation of the implement, and for depth control of the tillage elements. The prior art includes control systems that raise and lower the wheel assemblies as an entire unit, which can result in interference with components of foldable wing sections as the wing sections are folded. 
         [0009]    What is needed in the art is an easy to use system that orchestrates the folding of the implement sections. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention provides a tillage implement that has several tilling sections with the ability to coordinate the various sections as the sections are being folded. 
         [0011]    The invention in one form is directed to an agricultural tillage implement with a hydraulic system having a left wing hydraulic subsystem with an outer left wing hydraulic circuit supplying hydraulic pressure and flow to an actuator for actuating an actuator of an outer left wing folding implement section, and a right wing hydraulic subsystem having an outer right wing hydraulic circuit for actuating the actuator of an outer right wing implement section; the hydraulic system additionally having a hydraulic flow divider dividing hydraulic flow and pressure between the outer left wing hydraulic circuit and the outer right wing hydraulic circuit, the hydraulic flow divider being configured to coordinate the motion of the outer left wing section and the outer right wing section. 
         [0012]    An advantage of the present invention is that the implement has a decreased profile in the transport mode. 
         [0013]    Another advantage of the present invention is that the control system choreographs the movement of the wing sections to keep the implement balanced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0015]      FIG. 1  is a top perspective view of an embodiment of an agricultural tillage implement of the present invention, in the form of a field cultivator, in an unfolded position; 
           [0016]      FIG. 2  is a front view of the field cultivator shown in  FIG. 1 ; 
           [0017]      FIG. 3  is a top perspective view of the field cultivator shown in  FIGS. 1-2 , with the outer wing sections folded to a transport position; 
           [0018]      FIG. 4  is a front view of the field cultivator shown in  FIG. 3 , with the outer wing sections folded to the transport position; 
           [0019]      FIG. 5  is a top perspective view of the field cultivator shown in  FIGS. 1-4 , with the middle wing sections folded to a transport position; 
           [0020]      FIG. 6  is a front view of the field cultivator shown in  FIG. 5 , with the middle wing sections folded to the transport position; 
           [0021]      FIG. 7  is a top perspective view of the field cultivator shown in  FIGS. 1-6 , with the inner wing sections folded to a transport position; 
           [0022]      FIG. 8  is a front view of the field cultivator shown in  FIG. 7 , with the inner wing sections folded to the transport position; 
           [0023]      FIG. 9  is a perspective view of part of the main frame section of the field cultivator of  FIGS. 1-8 ; 
           [0024]      FIG. 10  is a side view of the field cultivator of  FIGS. 1-9 , with a primary focus on a wing section; 
           [0025]      FIG. 11  is a schematic representation of part of an embodiment of a hydraulic control system of the present invention of the field cultivator of  FIGS. 1-10 ; 
           [0026]      FIG. 12  is a schematic representation of part of another embodiment of a hydraulic control system of the present invention of the field cultivator of  FIGS. 1-10 ; 
           [0027]      FIG. 13  is a schematic representation of part of yet another embodiment of a hydraulic control system of the present invention of the field cultivator of  FIGS. 1-10 ; 
           [0028]      FIG. 14  illustrates a tillage implement including a support of disk blades being pulled by a tractor shown in schematic fashion; 
           [0029]      FIG. 15  is a plan view of a hydraulic system shown in the prior art for the tillage implement of  FIG. 14 ; 
           [0030]      FIG. 16  is a plan view of a hydraulic system for the tillage implement of  FIG. 14 ; 
           [0031]      FIG. 17  is a plan view of a preferred hydraulic system for the tillage implement of  FIG. 14  in a first state; and, 
           [0032]      FIGS. 18-22  show the hydraulic system of  FIG. 17  in different states. 
       
    
    
       [0033]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0034]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown an embodiment of a tillage implement of the present invention. In the illustrated embodiment, the tillage implement is in the form of a field cultivator  10  for tilling and finishing soil prior to seeding. 
         [0035]    Field cultivator  10  is configured as a multi-section field cultivator, and includes a center frame section  12 , also referred herein as a main section  12 , and a plurality of wing sections  14 ,  16  and  18 . In the illustrated embodiment, field cultivator  10  has a triple-fold configuration with three left wings sections designated  14 A,  16 A and  18 A, and three right wing sections designated  14 B,  16 B and  18 B. Wing sections  14 A and  14 B are each inner wing sections, wing sections  16 A and  16 B are each middle wing sections, and wing sections  18 A and  18 B are each outer wing sections. 
         [0036]    Center frame section  12  is the center section that is directly towed by a traction unit, such as an agricultural tractor (not shown). Center frame section  12  generally functions to carry a shank frame  20  for tilling the soil, and a rear auxiliary implement  22  for finishing the soil. A pull hitch  24  extends forward from shank frame  20 , and is coupled with the traction unit in known manner. 
         [0037]    Rear auxiliary implement  22  includes a spring tooth drag  26  and a rolling (aka, crumbler) basket  28  which coact with each other to finish the soil. However, rear auxiliary implement  22  can be differently configured, such as a spike tooth drag, cultivator shanks, etc. 
         [0038]    Shank frame  20  generally functions to carry cultivator shanks  30  with shovels  32  at their lower ends for tilling the soil. Rear lift wheels  34  are used for raising and lowering the shank frame  20  with a hydraulic lift cylinder (not specifically visible in  FIGS. 1 and 2 ), and a pair of front gauge wheels  36  are used to level the shank frame  20  during a field operation. 
         [0039]    Similarly, each inner wing section  14 A and  14 B, middle wing section  16 A and  16 B, and outer wing section  18 A and  18 B includes a shank frame  20  for tilling the soil, a rear auxiliary implement  22  for finishing the soil, rear lift wheels  34  and front gauge wheels  36 . These components are slightly different from but still similar to the like-named components described above with regard to center frame section  12 , and are not described in further detail herein. 
         [0040]    During use, it is periodically necessary to move the field cultivator  10  from an unfolded (operating) position to a folded (transport) position. First, each outer wing section  18 A and  18 B is folded laterally inward and over a respective middle wing section  16 A and  16 B ( FIGS. 3 and 4 ). With the outer wing sections  18 A and  18 B in the folded state, each middle wing section  16 A and  16 B is then folded laterally inward and over a respective inner wing section  14 A and  14 B ( FIGS. 5 and 6 ). With the middle wing sections  16 A and  16 B in the folded state, each middle wing section  16 A and  16 B is then folded laterally inward and over the center frame section  12  ( FIGS. 7 and 8 ). To unfold the field cultivator  10  and transform back to the field or operating position shown in  FIGS. 1 and 2 , the folding sequence described above is simply reversed. 
         [0041]    The outer wing sections  18 , middle wing sections  16  and inner wing sections  14  are stacked together in a vertically arranged stack over the center frame section  12  when in the folded state. To allow this type of nested stacking configuration, each of the wing sections  14 ,  16  and  18  have a pivot axis  38 ,  40  and  42 , respectively, which is vertically offset to allow the wing sections to lie flat against the laterally inward shank frame  20 /frame section  12  when in the folded state. The middle wing sections  16  have a pivot axis  40  that is vertically higher than pivot axes  38  and  42  of adjacent wing sections  14  and  18 , when in the unfolded state. 
         [0042]    Different countries and states have different regulatory highway requirements concerning oversized vehicles on the road. In the US, some states exempt agricultural equipment from such regulations, while others require that any type of vehicle on a road must comply with the oversized vehicle regulations. In Europe, the regulations may be stricter concerning the height and width of vehicles which may travel on a road without being accompanied by an escort vehicle. With the triple-fold field cultivator  10  of the present invention, the overall frontal profile dimensions when in the folded state fit within regulatory requirements for both the US and Europe. More particularly, with all of the wing sections  14 ,  16  and  18  in the folded state, the field cultivator  10  is then in a transport position with an overall frontal profile having dimensions with a maximum width “W” of no greater than approximately 20 feet, preferably approximately 18 feet wide, and a height “H” of no greater than approximately 14 feet, preferably approximately 13 feet, 6 inches high ( FIG. 8 ). 
         [0043]    These maximum frontal profile dimensions include all of the shank frames  20 , shanks  30 , rear lift wheels  34  and front gauge wheels  36 , when in the folded state. The rear auxiliary implements  22  are considered to be add-ons to the main field cultivator  10 , and may be outside these overall frontal profile dimensions, at least if not folded upwardly for the transport position. However, it is the intention that all of field cultivator  10 , including the rear auxiliary implements  22 , be within these maximum frontal profile dimensions when in the transport position. 
         [0044]    Now, additionally referring to  FIGS. 9 and 10  there is shown further details of implement  10 . Main section  12  is shown in  FIG. 9  with wheel assemblies  50  having actuators  54 , which provide depth level control for main section  12  when implement  10  is in field mode and support for the folded implement  10  while in transport mode. 
         [0045]    A typical wheel assembly  52  is shown for one of the wing sections  14 ,  16  and  18  in  FIG. 10 . Wheel assemblies  52  include actuators  56 , a linkage system  60  and an adjustable link  62 . A controller  58  (shown abstractly in the figures) orchestrates the movement of wheel assemblies  50  and  52  in field and transport modes and during the transition to/from the field and transport modes. 
         [0046]    Wheel assemblies  50  are shown having actuator  54  coupled more directly to the rear wheels and a linkage system is used to move the wheels that are to the fore of the rear wheels. Wheel assemblies  52  have actuator  56  positioned between the rear and fore wheels with linkage system  60  coupling both the rear and fore wheels for coordinated movement. Adjustable link  62  allows for an independent manual fore/aft leveling adjustment of each section. 
         [0047]    Actuators  54  and  56 , are under the independent and individual control of controller  58  so that sections  12 - 18  can each be individually adjusted for depth control of shovels  32  (which are tillage elements) of each section in a manner substantially independent of the other sections while in the field mode of operation. As implement  10  is transitioned from the field mode to the transport mode and the sections are being folded together, controller  58  causes wheel assemblies  52  to go from the fully extended position, as shown in  FIG. 10  with actuator  56  fully extended, to being partially retracted (or even fully retracted) as seen in the folded wing sections of  FIG. 6 . This effectively lowers the profile of each wing section  14 - 18  as the particular wing section is folded. While controller  58  may be a set of valves manually controlled by an operator, it is contemplated that controller  58  would be an electronic control system that controls the sequence of lowering the profile of each wing section, as it is being folded by the actuators used for the purpose of folding wing sections  14 - 18 . 
         [0048]    Controller  58  is programmed to prevent the wheels of the folded sections from being extended by the use of manual controls (not shown), which would cause interference with adjacent sections. This preclusion of the use of manual controls prevents damage that could otherwise occur. To the extent that interference or damage can occur by the improper positioning of the wheel assemblies during the folding process, before the section is fully folded, controller  58  likewise prevents the manual controls from overriding the process undertaken by controller  58 . 
         [0049]    The present invention advantageously orchestrates the lowering of the profile of each folding wing section in order to lower the overall profile of implement  10  when implement  10  is in the transport mode. The present invention uses a control system to choreograph the transition from the field (or operational) mode to the transport mode, as the height profile of each section of wing sections  14 - 18  is controlled, as the sections are folded for transport and when the process is reversed as implement  10  transitions from the transport mode to the field mode. 
         [0050]    Now, additionally referring to  FIG. 11 , there is shown a hydraulic system  200  having a left wing hydraulic subsystem  202  and a right wing hydraulic subsystem  204 , which is a mirror image of left wing hydraulic subsystem  202 . Hydraulic subsystems  202  and  204  each have an outer wing hydraulic circuit  206 , at least one intermediate wing hydraulic circuit  208 , and an inner wing hydraulic circuit  210 . 
         [0051]    Outer wing hydraulic circuit  206  includes an actuator  212 , an electrically controlled valve  218  and flow controls  226  and  228 . In a like manner intermediate wing hydraulic circuit  208  includes actuators  214 , an electrically controlled valve  220  and flow controls  226  and  228 . In a similar manner inner wing hydraulic circuit  210  includes actuators  216 , an electrically controlled valve  222 , flow controls  226  and  228 , and a valve  224 . A check valve  230  is coupled between circuits  208  and  210 . A proportional flow control valve  232  is coupled to both left wing hydraulic subsystem  202  and right wing hydraulic subsystem  204 , so that flow is controlled to each selected wing section on each side for a coordinated balanced action of like wing sections as implement  10  transitions between an operational mode and a transport mode or vice versa. 
         [0052]    Flow controls  226  and  228  allow unrestricted flow into their assigned cylinder yet restrict the outgoing flow. This allows each implement section, as it reaches an over-center condition, where gravity functions to encourage the movement of the section, to be cushioned, slowed or moved in a controlled manner as that section is pivoting. 
         [0053]    Check valve  230  is a flow circuit between intermediate wing hydraulic circuit  208  and inner wing hydraulic circuit  210  and allows for pressure to be exerted on the rod side of cylinders  216  when flow to the piston side of cylinders  214  is taking place. This forces inner wing sections  14 A and  14 B to remain down and not rotating as intermediate wing sections  16 A and  16 B are being pivoted. This advantageously effectively causes the construct to behave as a truss reducing the stress on wing hinge joints. 
         [0054]    Valve  224  is operated in coordination with valve  222  to control the movement of inner wing sections  14 A and  14 B in the sequential movement of the wing sections as they transition from the transport mode to the operational mode and vice versa. 
         [0055]    Now, additionally referring to  FIG. 12  there is illustrated another embodiment of a hydraulic system  200 , here designated as  200 A with similar elements using similar reference numbers as the previously discussed embodiment. Here there are two check valve circuits  236  and  238  that, similar to valve  230  in the previous embodiment, cause each wing section, as it is being pivoted to cause the next inner section to receive pressure to the rod side of the respective hydraulic cylinders. In this embodiment hydraulic circuit  208  has a valve  220 A, and a valve  234 , which makes hydraulic circuit  208  function similar to hydraulic circuit  210  of the previous and the present embodiments. 
         [0056]    Now, additionally referring to  FIG. 13  there is illustrated yet another embodiment of a hydraulic system  200 , here designated as  200 B with similar elements using similar reference numbers as the previously discussed embodiments. In this embodiment three position valves  220 B and  222 B are used that control the flow, counter flow and isolation/blocking of flow positions. 
         [0057]    The sequence of operations for any of the embodiments will now be discussed. As the sequence of transitioning from the field mode to the transport mode begins under the control of controller  58 , wheel assemblies  52  are extended by way of actuators  54  and  56 , as illustrated by arrows  100  in  FIG. 2 . Next, outer wing sections  18 A and  18 B are lifted using outer wing hydraulic circuits  206 , with wheel assemblies  52  associated with outer wing sections  18 A and  18 B being moved in direction  102  either as out wing sections  18 A and  18 B are moved in direction  104 , or these particular wheel assemblies may be moved in direction  102  after sections  18 A and  18 B are folded, all as illustrated in  FIG. 4 . 
         [0058]    Next wing sections  16 A and  16 B are folded in by pivoting in direction  106  (see  FIG. 6 ), by way of the activation of hydraulic circuits  208 . This movement places sections  18 A and  18 B respectively between sections  14 A and  16 B; and  14 B and  16 B. Then wheel assemblies  52  associated with wing sections  16 A and  16 B are moved in direction  108 , hence retracting these wheel assemblies to lower the profile associated therewith. Next wing sections  14 A and  14 B are moved in direction  110  (see  FIG. 8 ) by hydraulic circuits  210  thereby placing all of the wing sections above main section  12 . Then the wheel assemblies associated with inner wing sections  14 A and  14 B are retracted in direction  112 . These coordinated actions give implement  10  a profile of height H and width W. 
         [0059]    To transition implement  10  from the transport mode shown in  FIG. 8  to the operational or field mode as shown in  FIG. 2  the forgoing steps are reversed. The operational control of wheel assemblies  52  is undertaken in concert with the folding/unfolding operation and takes advantage of the individual depth control system, for the movement of the wheels, which allows the tilling elements to be controlled in each wing section on an individual basis. 
         [0060]    Now, additionally referring to  FIG. 14 , there is shown a tillage apparatus  310  which generally includes a tractor  312  shown schematically and an agricultural tillage implement  314  for tilling the soil prior to seeding. It should be noted that many different tools may be employed with the tillage implement  314  beyond the embodiment shown. This embodiment illustrates the use of wheel positioning to control the implement and the wheel positioning aspect is used in the transition of implement  10  to/from the transport mode and field mode. 
         [0061]    Agricultural tillage implement  314  is configured as a multi-section field disk ripper  314 , and includes a carriage frame assembly  316 . Carriage frame assembly  316  is the section that is directly towed by a traction unit, such as agricultural tractor  312 . Carriage frame assembly  316  includes a pull hitch  318  generally extending in a travel direction  320 , and forward and aft oriented carrier frame members  322  which are coupled with and extend from pull hitch  318 . Reinforcing gusset plates  324  may be used to strengthen the connection between pull hitch  318  and carrier frame members  322 . 
         [0062]    The tillage implement  314  has a center section  326 , an inner right wing section  330  and an outer right wing section  334  as viewed in  FIG. 14 . A left inner wing section  328  connects with a left outer wing section  332 . The center section  326  is pivotally connected to the inner wings  328  and  330  by pivotal interconnections at  336 . The right inner wing section  330  and right outer wing section  334  are pivotally interconnected at  340 . The left inner wing section  328  and outer left wing section  332  are interconnected at pivotal joints  338 . The details of the pivotal joints are omitted to enable a clearer understanding of the present invention. However, it should be understood that the pivotal connections allow articulation of the various sections between a field position in which each of the sections are substantially in a common plane and a transport position in which the outer wing sections  332  and  334  are folded, as well as the inner wing sections  328  and  330 , to enable sufficient road clearance. 
         [0063]    Actuator assemblies  342  are connected between the center section  326  and inner wing sections  328  and  330  to enable pivoting between the field and transport position. Actuator assemblies  344  are interconnected between right inner wing section  330  and outer right wing section  334  as well as inner left wing section  328  and outer wing section  332  to enable the pivoting movement. 
         [0064]    The center section  326  has a forward frame member  346  extending across carrier frames  322  and secured thereto. Center section  326  additionally has an aft frame member  348  structurally interconnected with carrier frames  322  at their aft end. As is noted, the frame elements  346  and  348  extend generally laterally with respect to the direction of movement  320  of the agricultural implement. Frame members  346  and  348 , however, extend at an angle as is known in the tillage art to produce appropriate working of the soil. The frame members  346  and  348  provide support beneath them for gangs of disc blades  350 . The gangs of disc blades  350  are resiliently connected to the frame elements in appropriate fashion to provide smooth working of the soil. 
         [0065]    The inner wing sections  328  and  330  each have a forward frame member  352  and an aft frame member  354 . These frame members are interconnected by forward and aft oriented inner frame members  356  and outer frame members  358 . The forward and aft frame members  352  and  354  form an extension of forward and aft frame members  346  and  348 . The forward and aft frame members  352  and  354  each also support gangs of disc blades  350 . 
         [0066]    The outer wing sections  332  and  334  each have forward and aft frame members  360  and  362  which each support gangs of disk blades  350 . Frame members  360  and  362  are interconnected by inner frame members  364  and outer frame members  366 . 
         [0067]    The various sections  326 ,  328 ,  330 ,  332  and  334  of the tillage implement  314  are positioned at variable positions relative to the soil and thus set the position of the gangs of disk harrows  350  above the soil and the depth they cut into the soil. As illustrated, the variable support elements are shown as wheel sets but it should be understood that other forms of variable support may be employed. As illustrated, wheel sets  368  are pivotally interconnected with carrier frames  322  so that they provide support to the forward and aft frame members  346  and  348  relative to the soil. Wheel sets  370  are interconnected with frame element  358  to support and variably position inner wing sections  328  and  330  relative to the soil. In addition, wheel sets  372  are pivotally mounted on frame members  366  to support and variably position outer wing sections  332  and  334  at a variable distance relative to the soil. Hydraulic actuators  374  and  376  manipulate wheel sets  368  to establish the distance of center section  326  relative to the soil. Actuators  378  and  380  support and variably position sections  328  and  332  relative to the soil. Finally, actuator assemblies  382  and  384  support and variably position sections  330  and  334  relative to the soil. 
         [0068]    In addition, castor wheel assemblies  386  on section  332  and  388  on section  334  orient the fore and aft angle of the tillage implement  314  relative to the soil. Actuators  390  and  392  are employed for this purpose. 
         [0069]    The actuators described above are shown as hydraulic and for this purpose a hydraulic control unit  394  is mounted in the tractor  312  and has a pump  400  for pressurizing hydraulic fluid to control the actuators. The hydraulic control unit  394  receives inputs from an electronic control unit (ECU)  396  which receives various inputs set out below, in addition to an operator input through control unit  398 . 
         [0070]    The hydraulic interconnection established by a typical prior art system for elevating the various sections of the tillage implement  314  is shown in  FIG. 15 . In this arrangement, each of a set of actuators  402   a,    404   a,    406   a  and  408   a  is connected to a hydraulic control pressure by supply conduits  410   a  and  412   a.  As is illustrated in  FIG. 15  the actuators  402   a - 408   a  are connected in parallel so that the pressure uniformly applies to each actuator in the set. As described above however, the actuators may become out of sync due to linkage past a piston thus requiring additional steps in the field to ensure synchronization of the actuators. 
         [0071]    In accordance with the present invention, a control system and method set forth in  FIG. 16  overcomes these difficulties.  FIG. 16  shows actuators  374 ,  376 ,  378  and  380 . The operation of the additional actuators is similar and is omitted to enable a better understanding of the present invention. Each of the actuators  374 ,  376 ,  378  and  380  has an output shaft  375 ,  377 ,  379  and  381 , respectively extending from the actuator body. Each actuator has a piston displaceable within a chamber in the actuator body and connected to the respective output shaft. 
         [0072]    The piston end of the actuator  374  is connected to the hydraulic control unit  394  by a hydraulic line  402 . The output shaft end of actuator  374  is connected to the hydraulic control unit  394  by a return line  404 . In similar fashion, the piston end of actuator  376  is connected by line  406  and a return line  408  is provided to control unit  394 . The piston end of actuator  378  is connected to hydraulic control unit  394  by line  410  and the return line is designated as  412 . Finally, the piston end of actuator  380  is connected to hydraulic control unit  394  via hydraulic line  414  and a return line  416  is provided. The independent connection of the actuators to the hydraulic control unit  394  will enable independent establishment of the height of the units relative to the soil. 
         [0073]    The relative physical position of the hydraulic control unit  394  may be different than the one shown in  FIG. 16 , depending up on the application for the unit. It may be a single module or may be provided in individual control sections. However, the hydraulic control unit  394  is positioned relative to the actuators, it permits independent manipulation of the actuator output shafts as will be described below. 
         [0074]    For this purpose, a displacement detecting device is provided to provide a signal proportional to the displacement of each output shaft relative to the body of the respective actuator. In addition to the displacement signal, a signal reflecting the rate of change of displacement or Δ D/Δ T is provided. The displacement indicating devices are identified as  418  for actuators  374 ,  420  for actuators  376 ,  422  for actuator  378  and  424  for actuator  380 . The displacement indicating devices  418 ,  420 ,  422  and  424  provide signal inputs to the ECU via lines  426 ,  428 ,  430  and  432 , respectively. The displacement indicating devices are devices that provide appropriate control signals that are proportional to the displacement of the output shaft relative to the various actuators and preferably the rate of change of displacement. The interconnections with the output shafts and actuators are not included to enable a better focus on the basic principle of the invention. Any one of a number of sensors may be employed for this purpose. 
         [0075]    As shown, the displacement sensors and Δ D/Δ T sensors are incorporated into a single unit. However, the Δ D/Δ T signal may be provided in a separate unit  419  shown in dashed lines for actuator  374 . Unit  419  may be connected to ECU  396  by a line  427 , also shown as a dashed line. Similar units would be provided for actuators  376 ,  378 , and  380  if it is desired to use separate units for displacement and Δ D/Δ T signals. 
         [0076]    The invention is applied to the tillage implement of  FIG. 14  by initially setting the implement on a level surface for calibration. The implement  314  is raised to the maximum extent where each individual actuator has its output shaft at its maximum length. At this point, a bypass port in the piston provides a bypass for return flow back to the actuator control unit  394 . This ensures that any air entrained in the system due to assembly or other reason is passed to the hydraulic system. The implement  314  is then lowered so that the tools, in this case the gangs of disk blades  350 , just touch the level surface. Preferably this surface would be a level concrete surface. Once the actuators are adjusted to reach this point, individual readings of the displacement between the actuator rod and the actuator body are taken with full hydraulic fluid in the chambers. The displacement signals of the individual actuators are stored in the ECU  396 . The resultant individual actuator displacement signals are considered the synchronized set point for the signals. It should be apparent to those skilled in the art that the use of placing the tools at the plane of the soil is but one of a number of reference points that define a unitary plane used in defining the reference plane. 
         [0077]    The tillage implement is then in a position to have each of the actuators raise and lower the individual frame elements in unison to provide a uniform height above the ground and a uniform depth when the gangs of disk blades  350  are positioned in the soil. Periodically during the operation of the tillage implement, the readings of the individual actuators are determined and, if they deviate from the set point initially established, the hydraulic control system provides appropriate hydraulic fluid to achieve the same set point. This is done independently of the other actuators so that correction is applied individually to each actuator unit. The tillage implement  314  is then able to provide accurate depth of penetration among the gangs of disk harrows  350 . 
         [0078]    The implement may be adjusted additionally in the field. In this procedure, the operator prepares a test run into the soil in a field and then measures the depth of the penetration of the disk blades. To the extent that it is necessary to make a minor adjustment, the individual cylinder that is out of sync with the remaining cylinders is adjusted and a new set point is established as the level uniform plane. This ensures that field conditions such as wheel loading and other factors have a minimal and easily correctable impact on the tillage operation. 
         [0079]    In addition, the actuators are corrected for the differential rate of displacement change by the Δ D/Δ T so that the entry of the gangs of disk blades  350  is uniform at the beginning of the field and the withdrawal is uniform at the end of the field. The process of recalibration may be made automatic so that it does not interfere with the immediate operator directed tillage over a field and preparing the soil. 
         [0080]    The hydraulic system illustrated in  FIGS. 17-22  illustrates a preferred hydraulic system for the tillage implement of  FIG. 14 . The system shown in  FIGS. 17-22  is described by specifically referring to  FIG. 17 . The system will be explained by using actuators  374 ,  376  and  378 . The additional actuator or actuators are omitted from the description to enable a clearer understating of the invention. The pump for pressurizing the hydraulic fluid is designated as  400  and the hydraulic control unit  394  schematically shown in  FIG. 16  is connected to the actuators as will be explained below. A dashed line designated as  394  is used to indicate the valves and lines below are also part of the hydraulic control unit. In this system there is a hydraulic line  480  connected to the hydraulic control unit  394  and a second hydraulic line  482  for hydraulic fluid between the actuators and the hydraulic control unit  394 . In this system the line  480  connects to a first three-way valve  484  and line  486  which is connected to the piston end  488  of actuator  374 . The output shaft end  490  of actuator  374  has a line  492  leading to an additional three-way valve  494 . From there a line  496  extends to the piston end  498  of actuator  376 . The output shaft end  500  of actuator  376  has a line  502  extending to a third three-way valve  504 . Finally, a line  506  extends to the piston end  508  of actuator  378 . A line  510  at the output shaft end of actuator  378  connects with line  482  leading to the hydraulic control unit  394 . Bypass line  512  leads from three-way valve  484  and has a connecting line  514  to valve  594  and a connecting line  516  to three way valve  504 . 
         [0081]    The three-way valves are each set up so that when they are de-energized there is flow from the adjacent hydraulic line to the respective piston end of the associated actuator. In other words, when valves  484 ,  594  and  504  are de-energized, the flow is from line  480  to  486 ,  492  to  496 , and  502  to  506 , respectively. When each solenoid valve or three-way valve is energized there is flow between the adjacent hydraulic line and the bypass line. In other words, when valve  484  is energized, flow to  486  is blocked and flow is directed from line  480  to line  512 . Correspondingly, when valve  494  is energized, the flow is from line  492  to line  514  with the flow to  496  blocked. Finally, when valve  504  is energized, the flow is from line  502  to line  516  with the line  506  blocked. 
         [0082]    The sensors  418 ,  420  and  422  are employed to measure the actual displacement of output shaft  375 ,  377  and  379  but are not shown in these figures to aid in the understanding of the invention. There are signal inputs from the ECU  396  to the valves and these are made through line  520  for valve  484 , line  522  for valve  594  and line  524  for valve  504 . 
         [0083]    The arrangement set forth above enables a traditional series connection between the actuators but with the possibility to minimize the number of hydraulic lines deployed on the carrier frame and still retain the ability to provide individual adjustment.  FIG. 17  shows the state where actuator  374  is to be adjusted. In this case, the valves  484 ,  594  and  504  are all de-energized so that the flow to the piston end  488  of actuator  374  causes the output shaft to be adjusted in accordance with the signals of the corresponding sensor. Since actuators  376  and  378  are also in series, they move also. The view of  FIG. 17  shows a movement of the output shaft  375  toward extension and the view in  FIG. 18  shows the shaft  375  retracting. In this case, the output shafts  377  and  379  retract also. 
         [0084]    Once the cylinder  374  is adjusted, the system moves to actuator  376 . In this condition, shown in  FIG. 19 , valve  484  is energized so that flow to the piston end  488  of actuator  374  is blocked and the flow passes through line  412 . In this case, the solenoid  494  is energized so that flow occurs between line  514  and  496  to the piston end  498  of actuator  376 . This causes the hydraulic flow from the actuator to be applied to the output shaft to move the output shaft  377  towards extension. At the same time the output shaft  379  of actuator  378  moves with it. The view in  FIG. 20  shows the condition when the actuator is moving in a position to retract output shaft  377 . In this case, the flow is back through line  512  and to the hydraulic control unit  394  through line  480 . 
         [0085]    Once this is done, the actuator  378  is to be adjusted and in this case the actuator  374  and  376  are locked so that the flow is by line  512  to through valve  504  to the piston end  508  of actuator  378 .  FIG. 21  shows the output shaft  379  in an extension mode and  FIG. 22  shows the output shaft  379  in a retracting mode. Once the actuator  378  is adjusted the valves  484 ,  494  and  504  are de-energized so that the actuators  374 ,  376  and  378  may act in unison as in a series connection. For additional actuators, the procedure for adjustment follows the same steps until all actuators are adjusted. The above system and method enables individual adjustment of the actuators, but with the traditional series connection between the actuators and resultant minimization of the hydraulic lines on the tillage implement. 
         [0086]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.