Abstract:
A disc harrow composed of one or more disc gangs has a subframe coupled to the disc gangs to move the disc gangs in response to variations in farmland terrain to limit the impact of obstructions when encountered during the harrowing process. When the obstruction is cleared, the subframe automatically returns the disc gangs to their pre-obstruction position. In addition to reducing the potentially-damaging impact of obstructions, the subframe also maintains a more consistent reel depth during undulations or changes in the farmland terrain, such as during harrowing of slopes or unleveled fields such as valleys, near waterways, and along fence rows.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to agricultural implements, and in particular, to an implement having a pivoting mechanism to which a disc gang is mounted that changes the elevation of the disc gang is response to variations in terrain contours. 
       BACKGROUND OF THE INVENTION 
       [0002]    Once a crop has been harvested, residual crop materials frequently remain on the farmland surface. Typically, these residual crop materials are incorporated within the soil profile of the farmland in an effort to maintain soil nutrient integrity. For example, management of corn cropped fields commonly includes the incorporation of the residual corn stalks with field soil once the corn, and occasionally a portion of the stalk, has been harvested. Whereas some growers harvest a majority of the kernel, cob, and stalk material, others harvest only the kernel and discharge a majority of the chaff or cob and stalk materials onto the farmland. Regardless of the quantity of stalk material that is harvested, the subsequent preparation of the farmland requires incorporation of the stalk or crop residue with the field soil. It is generally understood that the size of the crop residue particles as well as the surface area of the crop residue exposed to the soil affects crop residue decomposition. Specifically, reduced crop residue particle size and increased surface contact of the crop residue with adjoining soil improves crop residue decomposition. 
         [0003]    Frequently, a crop residue conditioner, such as a stalk chopper, is pulled across the harvested field during autumn. The stalk chopper cuts the remaining stalks into smaller, more easily workable and degradable sized pieces. Thereafter, a disc harrow is used to smooth and level the farmland or seedbed and till a portion of the crop residue with the soil. The disc harrow not only mixes the crop residue with the underlying soil to return nutrients to the soil but also can be used to establish a residue layer over the farmland to protect against erosion and provide moisture control during the winter months before replanting in the spring. 
         [0004]    Disc harrows include one or more disc gangs, each including a series of steel discs or reels with tapered or beveled peripheral edges. The discs, although tending to roll or rotate as they are pulled forward, penetrate into and break up the soil and stalks and other crop residue. The soil and crop residue then ride along and across the concave surfaces so as to be turned or inverted. A portion of the residue is buried with this turning, with the percentage of buried residue increasing with the amount of soil turning. The amount of crop residue that is retained on the seedbed surface may also be controlled by setting the angle of attack or “gang angle”, such as described in U.S. Pat. No. 6,612,381, the disclosure of which is incorporated herein by reference. 
         [0005]    During harrowing of the farmland the disc harrow may encounter various obstructions, such as rocks, stumps, and roots. To reduce the impact of such obstructions and thereby potential damage to the disc harrow, the disc gangs are often resiliently supported on the harrow mainframe so that each gang can independently yield to the obstructions. Conventionally, the reels are mounted to a shaft or axle which is then mounted to the harrow mainframe via U-shaped or C-shaped spring members, also referred to as shanks or cushions. These spring members are designed to absorb the blunt forced placed on the disc gangs when the reels meet with an obstruction. However, these spring members are typically coupled to the mainframe and the gang shaft in a fixed connection, as illustrated in U.S. Pat. Nos. 4,066,132 to Rehn, 4,404,372 to Rozeboom, and 7,131,501 to Svendsen et al. As a result, when an obstruction is encountered during harrowing the springs will deflect to absorb some the impact of the obstruction, but the obstruction remains in the path of the harrow until forcibly cleared by the rotating reels or forcibly pulled over the obstruction by the tractor or other towing means. Moreover, once the spring has fully deflected, it cannot absorb any additional force placed on the disc gangs. As such, while such cushions have reduced wear to the disc gangs, their effectiveness is limited when larger farmland obstructions are encountered. 
         [0006]    Thus, there remains a need for a farm implement having a shock absorbing assembly that not only absorbs the impact of an obstruction during the harrowing process, but also places less stress on the farm implement during clearing of the obstruction. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a disc harrow having a subframe resiliently mounted to one or more disc gangs and the disc harrow mainframe. The subframe is designed to allow the disc gangs to respond to variations in the farmland terrain to limit the impact of obstructions when encountered during the harrowing process. Specifically, the subframe automatically rises relative to the disc harrow mainframe when an obstruction is encountered thereby lifting the disc gangs over the obstruction. When the obstruction is cleared, the subframe automatically lowers to its previous position and thus also lowers the disc gangs. In addition to reducing the potentially-damaging impact of obstructions on the disc harrow and its components, the subframe also maintains a more consistent reel depth during undulations or changes in the farmland terrain, such as during harrowing of slopes or unleveled fields such as valleys, near waterways, and along fence rows. The disc harrow therefore provides more consistent and uniform soil clod sizes, cutting depth, and soil/residue mixing despite changes in farmland contour. 
         [0008]    Therefore, in accordance with one aspect, the present invention is directed to a disc harrow having a mainframe and a subframe coupled to the main frame. The disc harrow further has a disc gang assembly coupled to the subframe and composed of a plurality of crop residue and soil tilling reels. A pivoting mechanism is coupled to the subframe and the mainframe, and is configured to move the disc gang assembly relative to the mainframe when an obstruction is encountered during harrowing of a farmland. 
         [0009]    According to another aspect, the present invention includes a farm implement for tilling a farmland. The farm implement has a mainframe defined by a pair of rails and a subframe carrying a harrow and centrally positioned between the pair of rails. The farm implement further has a pivoting mechanism resiliently coupling the subframe to the mainframe. The pivoting mechanism automatically elevates the harrow relative to the mainframe when an obstruction is encountered. 
         [0010]    In accordance with another aspect of the present invention, an apparatus for tilling crop residue and soil is presented. The apparatus has a disc harrow including a first disc gang and a second disc gang connected to the first disc gang by a floating frame. A mainframe is defined by a pair of rails and a plurality of transverse supports, and carries the disc harrow and is coupled to the floating frame by at least one cushion. The floating frame is centered relative to the pair of rails. The at least one cushion is adapted to maintain the disc harrow at a defined depth during normal working operation and automatically elevate the disc harrow relative to the mainframe when an obstruction is encountered during harrowing of a field. 
         [0011]    Other objects, features, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout. 
           [0013]    In the drawings: 
           [0014]      FIG. 1  is an isometric view of a disc harrow according to one aspect of the invention; 
           [0015]      FIG. 2  is an isometric view of a portion of the disc harrow shown in  FIG. 1 ; 
           [0016]      FIG. 3  is a section view taken along line  3 - 3  of  FIG. 2 ; 
           [0017]      FIG. 4  is a section view similar to  FIG. 3  showing movement of a disc gang from a normal working position to a clear-an-obstruction position; 
           [0018]      FIG. 5  is a section view similar to  FIG. 4  showing movement of the disc gang back to the normal working position once an obstruction has been cleared; 
           [0019]      FIG. 6  is a section view taken along line  6 - 6  of  FIG. 2 ; and 
           [0020]      FIG. 7  is a section view similar to  FIG. 6  showing oscillation of a disc gang according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Referring now to  FIG. 1 , a disc harrow  10  has a mainframe  12  defined by a pair of rails  14  connected to one another by a series of transverse supports  16  spaced from one another along the length of the rails  14 . The disc harrow  10  is designed to be towed by a tractor or other powered device. In this regard, the disc harrow  10  includes a hitch  18  for connecting the mainframe  12  to the tractor. In the illustrated embodiment, the disc harrow  10  includes a pair of disc gangs  20 ,  21  mounted to the mainframe  12  using a subframe  22 , which will be described in greater detail below. The pair of disc gangs includes a forward disc gang, designated by numeral  20 , and a rearward disc gang, designated by numeral  21 . 
         [0022]    The disc gangs  20 ,  21  are connected to one another by an I-beam  24  and a pair of gang braces  26 , only one of which is visible in the figure. Each disc gang  20 ,  21  has a series of reels or discs  28  each of which is mounted to a disc support beam  30 ,  31 , respectively, by a clamping device  32 . In the illustrated example, each disc support beam  30 ,  31  has a pair of support arms  30   a ,  30   b  and  31   a ,  31   b , respectively. The support arms are angled relative to one another in such a manner that disc support beam  30  is generally V-shaped whereas disc support beam  31  has a generally inverted V shape. Collectively, the pair of disc support beams  30 ,  31  when connected together by I-beam  24  have a generally H-shape. Each clamping device  32  includes a clamp  34  fastened to a clamp plate  36  having a downwardly extending arm  38  that connects to the hub  40  of each reel  28 . 
         [0023]    With additional reference to  FIG. 2 , the subframe  22  has a forward pipe  42  and a rearward pipe  43  spaced from one another and coupled to respective transverse supports  16  using suitable connectors. The rearward pipe  43  is coupled to a cross brace  44  secured to the disc support beam  31  of the rearward disc gang  21 . Cross brace  44 , using a suitable connection, is coupled to each support arm  31   a ,  31   b . Pipe  43  and cross brace  44  are coupled to one another with a bracket and hinge arrangement  46  that allows the height of the rearward disc support beam  31 , and thus the rearward disc gang  21 , to be adjusted. More particularly, rearward pipe  43  mechanically communicates with forward pipe  42  via piston  48  that is coupled to forward pipe  42 . A bracket and hinge arrangement  50  is used to couple the forward pipe  42  to I-beam  24 . The piston  48  is also connected to an actuator  52  via a lever  54  that is rotatable about forward pipe  42 . In this regard, the actuator  52  may be energized to pull lever  54  forward to lower the forward disc gang  20  and the rearward disc gang  21  or push lever  54  rearward to raise the forward disc gang  20  and the rearward disc gang  21 . When lowering the disc gangs  20 ,  21 , the actuator  52  is activated so that lever  54  pushes piston  48  rearward, which causes lever  56  coupled to rearward pipe  43  to rotate downward, thereby resulting in the rearward disc gang  21  being lowered in concert with the forward disc gang  20 . When raising the disc gangs  20 ,  21 , the actuator  52  is activated so that lever  54  pulls piston  48  forward, which causes lever  56  coupled to rearward pipe  43  to rotate upward, thereby resulting in the rearward disc gang  21  being raised in concert with the forward disc gang  20 . This construction allows the disc gangs  20 ,  21  to be positioned at an infinite number of heights defined between the rotational limits of levers  54 ,  56 . 
         [0024]    The subframe  22  also includes a pair of lateral supports  58 , one of which is bracketed to pipe  42  and the other of which is coupled to a pivoting mechanism  60 . As further illustrated in  FIG. 3 , pivoting mechanism  60  includes a cushion  62 , having a curved shape, coupled to a respective lateral support  58 . The cushion  62  is coupled to a pipe, which in the illustrated example is forward pipe  42 , by a bracket  64 . Bracket  64  includes a pin  66  about which cushion  62  is secured by a clamp  68 . This coupling allows the cushion  62  to rotate or otherwise pivot relative to bracket  64  when the disc gang  20  encounters an obstruction. 
         [0025]    The cushion  62  presents a spring load on lateral support  58  which is coupled to the disc gangs  20 ,  21  by brace  26 . During unobstructed passage of the disc gangs  20 ,  21 , the spring load maintains the depth of the disc gangs  20 ,  21  at a relatively constant level. When an obstruction is encountered, cushion  62  will deflect thereby absorbing the force imparted by the obstruction. When the force of impact exceeds the bias of the cushion  62 , the cushion  62  will rotate about pin  66  thereby drawing the disc gangs  20 ,  21  upward relative to the mainframe  12 , as shown in  FIG. 4 . In this regard, cushion  62  is designed to provide a two-stage response to impact with a larger obstruction. In the first stage, the cushion  62  deflects. In the second stage, the cushion  62  will draw the disc gangs  20 ,  21  upward relative to the mainframe  12  thereby drawings the disc gangs  20 ,  21  over and thereby clearing the obstruction. When the bias of the obstruction removed, i.e., the obstruction has been cleared, the spring bias of the cushion  62  is restored, the cushion rotates downwardly relative to pin  66 , as shown in  FIG. 5 , and returns the disc gangs  20 ,  21  to their normal working depth. 
         [0026]    It is recognized that the disc harrow  10  may have one or more pivoting mechanisms to assist with obstruction clearing. For example, a pivoting mechanism could be coupled to each of the support beam arms. In another example, when at least two pivoting mechanisms  60  are used, mounted on opposite sides of the subframe  22 , the subframe  22  and thus the disc gangs  20 ,  21  may be caused to oscillate when an obstruction is encountered. More particularly,  FIG. 6  shows a front elevation view of a portion of the disc harrow  10  during normal working operation. When an obstruction is encountered of sufficient size to overcome the bias of the cushion of either pivoting mechanism, the disc gangs  20 ,  21  will oscillate. Thus, the disc gangs will be allowed to move side to side and front to rear when an obstruction of sufficient size is encountered, as illustrated in  FIG. 7 . 
         [0027]    The present invention has been described with respect to a disc harrow, but is understood that the present invention is equivalently applicable with other soil tilling implements. Moreover, the invention may be applicable for a stand-alone disc harrow or a farm implement carrying multiple types of soil tillage tools. For example, cultivating tines may be coupled to the transverse supports  16 . Additionally, it is contemplated that the reels  28  of the disc gangs  20 ,  21  may be of similar size or of dissimilar size. For example, the forward disc gang  20  may have large reels for primary tillage whereas the rearward disc gang  21  may have smaller reels for secondary tillage. 
         [0028]    Many changes and will modifications could be made to the invention without departing from the spirit thereof. The scope of these changes will become apparent from the appended claims.