Abstract:
A tillage tool includes a relatively narrow shank that slices through the soil while a ripper point at its lower end fractures and lifts the subsoil. Minimum surface disturbance adjacent the opposite sides of the shank is assured through the provision of a pair of independently mounted down-pressure wheels on opposite sides of the shank that engage and apply constant downward pressure against soil tending to erupt at the top surface. Each down pressure wheel is mounted to the shank assembly by its own leaf spring so that the two wheels react to ground changes independently of one another and without adversely affecting each other. A guide plate associated with each leaf spring prevents twisting of the spring as it flexes and provides stops for limiting the opposite extremes of up and down flexing of the spring.

Description:
TECHNICAL FIELD 
   This invention relates to the field of tillage equipment and, more particularly, to a deep ripper tillage tool that minimizes surface disturbance through the use of independent, spring-mounted down pressure wheels on opposite sides of each shank assembly of the tool. 
   BACKGROUND AND SUMMARY 
   In many deep ripping situations, it is desirable to leave the ground surface as undisturbed as possible to avoid the need for extensive surface preparation prior to other subsequent operations, such as seed planting. Many deep ripper points have a tendency, however, to cause surface eruptions on opposite sides of the tillage shank due to the lifting and fracturing action of wings and other inclined surfaces on the ripper point. Thus, it is known in the art to provide downwardly spring-biased ground wheels on opposite sides of the shank assembly to resist soil eruption at those locations and to press down and firm the ridges or berms created on opposite sides of the shank assembly. See for example U.S. Pat. Nos. 6,502,644 and 6,012,534. 
   However, in both of those prior patents, the two wheels associated with each shank assembly are pivotally mounted to the shank assembly on a common carrier that causes both wheels to rise and fall together as terrain changes are encountered by either one of the wheels. Because surface variations are often different on opposite sides of the shank assembly, rises encountered by one wheel will cause both wheels to lift even though the other wheel may not be experiencing the same condition. Consequently, the unnecessarily lifted wheel may fail to perform its downward pressing function in the most desired manner. 
   The present invention overcomes deficiencies in the prior art by providing a pair of firming wheels for each shank assembly that are separately and independently mounted to the shank assembly so that each wheel rises and falls independently of the other. Each wheel therefore reacts to soil conditions on its own side of the shank assembly without being affected by conditions encountered by the other wheel, to the end that a better overall firming action is obtained for the field. 
   Furthermore, in the present invention the down pressure wheels are mounted to the shank assembly in a simplified manner, i.e., by a spring for each wheel that serves the dual roles of a mounting means for the wheel and a source of down pressure or bias for the wheel. Preferably, the spring comprises a leaf spring. Instead of pivoting about a relatively short radius during up and down movement, each wheel simply moves up and down in a straight line path of travel as the leaf spring flexes during build up and release of its stored energy. 
   In one preferred embodiment, each leaf spring is generally J-shaped and is disposed in a horizontal attitude with its long leg extending fore-and-aft and the wheel attached to the rear end of the leg. The short leg of the spring is spaced below the long leg and is integrally attached thereto adjacent the front of the leaf spring by an arcuate bight portion of the spring. The short leg is attached to the shank assembly in a secure fashion so that primarily only the upper leg flexes as the wheel applies down pressure during field operations. The bight of the leaf spring is looped around an upright guide plate having an upper edge that forms a seat for the upper leg of the leaf spring and limits its downward flexing movement. Anti-twist structure comprising a pair of depending members on the leaf spring embrace the upright guide plate to prevent twisting of the upper leaf spring leg during the flexing action, while other interacting structure between the rear edge of the guide plate and the depending members keep the upper leaf spring leg moving in a rectilinear path of travel during its flexing motion. The short leaf spring leg is attached to the bottom edge of the guide plate, and provision is made to adjust the home position of each wheel by angularly adjusting the vertical position of the guide plate. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a right front isometric view of a tillage tool constructed in accordance with the principles of the present invention, such tool incorporating independent, spring-mounted down pressure wheels in accordance with the present invention; 
       FIG. 2  is a left side elevational view thereof illustrating in cross section a tubular tool bar to which the shank assembly of the tool is mounted; 
       FIG. 3  is a fragmentary, top plan view of the tool with parts broken away to reveal details of construction; 
       FIG. 4  is a fragmentary rear elevational view illustrating the independent action of the two down pressure wheels of each shank assembly during operation, parts being broken away to reveal details; 
       FIG. 5  is an exploded isometric view of the tool; 
       FIG. 6  is an enlarged, fragmentary isometric view of the tool illustrating in particular the guide plate thereof with the leaf spring seated on the top edge of the guide plate in its at rest or home position; and 
       FIG. 7  is an enlarged isometric view of the guide plate and associated structures similar to  FIG. 6  but showing the leaf spring flexed up to its upper limit of travel. 
   

   DETAILED DESCRIPTION 
   The present invention is susceptible of embodiment in many different forms. While the drawings illustrate and the specification describes certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments. 
   The drawings illustrate a single row unit of a tillage tool in accordance with the present invention. It will be appreciated, however, that, typically, a plurality of such row units are mounted on a common tool bar that may be three-point mounted to a tractor (not shown). Thus, in  FIG. 2 , a tubular tool bar  10  is illustrated, and a shank assembly broadly denoted by the numeral  12  is shown attached to tool bar  10 . Each shank assembly  12  includes as its primary parts a mounting bracket  14 , a slender, generally upright shank  16 , and a ripper point  18  attached to the bottom end of shank  16 . 
   Mounting bracket  14  includes a pair of downwardly and rearwardly extending plates  20  and  22  that are spaced apart laterally and are maintained in such condition by one-half  24  of a clamp  26  for securing bracket  14  to tool bar  10 . Plates  20 ,  22  are also maintained in their spaced apart condition by a top plate  28  and a bottom plate  30  spanning the distance between the two upright plates  20 ,  22 . The other half  32  of clamp  26  matingly engages the opposite side of tool bar  10 , and clamp halves  24 ,  32  are secured together by bolts  34 . 
   Shank  16  is a slender, plate-like shank that is substantially wider in a fore-and-aft direction than in a transverse direction. The upper end of shank is received between plates  20 ,  22  of bracket  12  and is securely held in such position by a pair of bolts  36  and  38 . Shank  16  extends generally downwardly and slightly forwardly from the lower rear end of bracket  14  and may include an inclined, sharpened shin  40  along its leading edge to serve as a hardened cutting surface for opening a slit in the ground during advancement of the tool. The ripper point  18  at the bottom of shank  16  may take a variety of different forms as well understood by those skilled in this art and generally includes a plurality of upwardly and rearwardly inclined lifting and fracturing surfaces such as those appearing on wings  42  of ripper point  18 . 
   Each of the mounting bracket plates  20 ,  22  has a smaller adaptor plate  42  attached to the exterior surface thereof by the bolts  36  and  38  used to secure shank  16  to bracket  14 . Adaptor plate  42  has a pair of cylindrical spacers  44  and  46  that are welded thereto and project laterally outwardly therefrom for supporting a generally upright, irregularly shaped guide plate  48 . Spacers  44  and  46  are internally threaded so as to threadably receive a pair of corresponding screws  50  and  52  that secure guide plate  48  to spacers  44 ,  46 . 
   Screw  50  is received within an elongated hole  54  in the nose of guide plate  48  ( FIGS. 5 ,  6  and  7 ), while screw  52  is received within any selected one of a series of notches  56  disposed on an arc having its center at the elongated hole  54 . Notches  56  open rearwardly to a correspondingly arcuate slot  58  that extends in opposite directions slightly beyond the endmost notches  56  in the series. Thus, when screws  50  and  52  are loosened, guide plate  48  may be pushed forwardly to the extent permitted by the back end of elongated hole  54  and arcuate slot  58 , whereupon guide plate  48  may be pivoted about screw  50  to adjust the angular position of guide plate  48  relative to shank assembly  12 . When rear screw  52  is aligned with the selected notch  56 , guide plate  48  may be shifted rearwardly to engage screw  52  within such notch, whereupon screws  50  and  52  are retightened to maintain guide plate  48  in its selected position of angular adjustment. 
   As perhaps seen most clearly in  FIGS. 6 and 7 , each guide plate  48  includes a top edge  60 , a bottom edge  62 , a notched front edge  64 , and a generally upright rear edge  66 . Bottom edge  62  has a transverse mounting plate  67  affixed thereto and extending laterally outwardly therefrom in opposite directions. Opposite ends of mounting plate  67  are provided with bolt holes  68  ( FIG. 7 ) for receiving leaf spring mounting bolts  70 . Top edge  60  is provided with a generally centrally disposed notch  72 , and rear edge  66  has a shoulder  74  that projects rearwardly therefrom at the intersection of rear edge  66  with top edge  60 . 
   The two guide plates  48  carry respective springs  76  and  78  that serve as the means by which a pair of corresponding down pressure or firming wheels  80  and  82  are mounted to the shank assembly  12 . Preferably, springs  76  and  78  comprise leaf springs, but other types of springs may also be satisfactory such as, for example, torsion springs. The two leaf springs  76  and  78  are generally J-shaped and horizontally disposed with their long leg  84  spaced above the lower, short leg  86  thereof. An arcuate bight  88  is located at the front ends of legs  84  and  86  and integrally interconnects such legs. The free end of short leg  86  is secured to mounting plate  67  using the bolts  70 , while the free end of the upper long leg  84  has a generally trapezoidal shaped mounting plate  90  secured thereto by a plurality of bolts  92 . Each mounting plate  90 , in turn, has an inverted, generally L-shaped wheel arm  94  secured thereto by a plurality of bolts  96 . Each wheel arm  94  rotatably supports a corresponding wheel  80  or  82  at its lower end. Mounting bolts  96  are received within a transverse adjustment slot  98  in mounting plate  90  so that the lateral positions of wheels  80  and  82  may be somewhat adjusted relative to leaf springs  76 ,  78  and shank assembly  12 . 
   The upper leg  84  of each leaf spring  76 ,  78  is seated on top edge  60  of the corresponding guide plate  48 , unless the leaf spring has been flexed upwardly because its wheel  80  or  82  has been lifted by rises in the terrain. Thus, top edge  60  serves as a stop for limiting downward movement of top leg  84  of leaf spring  76  or  78 . Each top leg  84  is also provided with a follower for guide plate  48  in the form of a pair of laterally spaced, depending plate members  100  and  102  that are disposed on opposite inboard and outboard sides of the corresponding guide plate. Plate members  100 ,  102  have outturned flanges  104  and  106  respectively at their upper ends that receive a pair of U-bolts  108  and  110  securing members  100 ,  102  to upper leg  84 . 
   As illustrated in  FIG. 6 , each pair of plate members  100 ,  102  has a cross pin  112  adjacent the upper forward corners thereof that spans the plates and is received within notch  72  when top leg  84  is seated down against top edge  60  of guide plate  48  in its at rest position. In addition, the plate members  100 ,  102  have a cross bar  114  across their lower, rear extremities that is affixed to the plates and abuts shoulder  74  when leaf spring leg  84  is flexed upwardly to a certain predetermined extent as illustrated in FIG.  7 . Thus, shoulder  74  serves as a stop to limit the extent of upward travel of leaf spring leg  84 . Bar  114  moves along straight rear edge  66  during up and down flexing of leaf spring leg  84  so as to limit up and down movement of wheels  80 ,  82  to a generally straight line path of travel. 
   Operation 
   It should be apparent from the foregoing that as the tool moves across a field with its shanks  16  cutting through the soil, ripper points  18  fracture and lift the subsoil. Although the points  18  are designed to minimize disturbance on the surface of the ground, a certain amount of upheaval or eruption tends to occur on opposite sides of each shank  16 . However, by adjusting each guide plate  48  to the appropriate angular position depending upon the running depth of the points  18 , wheels  80  and  82  for each shank  16  ride on top of such upheavals and press them downwardly as they attempt to form, thereby preventing them from becoming excessive. As leaf springs  76  and  78  are flexed upwardly, they store energy that produces a downwardly directed restoring force pressing wheels  80  and  82  against the ground. The amount of down pressure exerted by wheels  80 ,  82  is adjusted by adjusting the angular position of the guide plates  48 , taking into account the planned running depth of the shanks  16 . 
   It will be noted as illustrated in  FIG. 4  that the leaf springs  76 ,  78  of each pair can flex up and down independently of one another. Thus, each leaf spring  76 ,  78  reacts to its own particular ground surface conditions experienced by its pressure wheel  80  or  82  as the case may be. Consequently, both pressure wheels  80 ,  82  are assured of being constantly engaged with the ground surface and exerting an appropriate amount of down pressure. If both wheels  80 ,  82  were mounted on the same common carrier, as found in prior art devices, a ground rise on one side of the shank experienced by one of the wheels could result in lifting the other wheel out of its proper pressing relationship. Thus, in the present invention, each pressure wheel  80 ,  82  reacts only to the conditions which it alone confronts and experiences, to the end that the field is left in better condition for subsequent operations such as seed planting. 
   It will be noted also that depending plate members  100 ,  102  of each leaf spring cooperate with the corresponding upright guide plate  48  to retain the spring against twisting during up and down flexing thereof. They also keep top leg  84  of each leaf spring properly aligned with the upper edge  60  of the guide plate  48  so as to keep top leg  84  in proper position for reseating against edge  60  when shanks  16  are lifted out of the soil. Each cross bar  114  also keeps the top leaf spring leg  84  from flexing upwardly too far so that the lower ends of plate members  100 ,  102  are never allowed to lift completely off guide plate  48 . And, cross bar  114  also guides top leaf spring leg  84  in a generally straight line, up and down path of travel as it flexes. However, if the uneven terrain or a ground-lying obstacle should happen to exert a sudden rearward force on one or both of the wheels, the cross bar of the affected wheel can be pulled back away from guide edge  66  to the extent necessary to accommodate such occurrence. 
   The inventor(s) hereby state(s) his/their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of his/their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.