Abstract:
An apparatus for maintaining a tillage implement such as a plow at a consistent working depth utilizes a spring biased quadrilateral linkage to maintain the tillage implement in a position having to float forwardly and upwardly from the working depth thereby preventing unwanted flotation of the tillage implement from the working depth until the tillage implement encounters a substantially vertical load.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to an agricultural tillage device and more particularly to a dual acting ground penetrating device and in ever greater particularity to the linkage which maintains such a device at a constant working depth. 
       BACKGROUND 
       [0002]    Damage of earth working tools such as plows by abnormal draft forces caused by striking obstruction, such as roots, stones, etc., has been an age old problem. The problem is aptly described in U.S. Pat. No. 5,560,433 to Grimm which attempted to solve the problem. Many types of devices have been incorporated in agricultural equipment to compensate for shock loads on the implement caused by abnormal draft forces on the earth working tools. Prior ground working devices utilize both floating and tripping movements, allowing them to vertically float out of the ground or to alternately fully trip rearwardly and upwardly out of the ground. These prior device linkage designs, including U.S. Pat. No. 5,560,433 do not utilize the draft load caused by their in ground movement to resist vertical flotation or to help return the earth working tool to its original working depth after a full trip cycle of said linkage is reached. That is to say, with prior designs, the in ground movement of the tillage device is in direct competition with the ground penetrating devices main ground-load applicator (i.e. a down pressure spring). Thus, the ground movement urges the tillage device to float upwardly and rearwardly in a manner that opposes the downward pressure from the spring. On these prior designs, precautions have to be taken to deal with the negative effects of the in ground movement on their contrary linkage configurations. A need exists for a linkage system that will utilize the draft load from the in ground movement, thereby adding to the load from the main ground-load applicator instead of competing with it, making the device hold itself in the ground flotationally, at the desired working depth, until the pre-designed full tripping load is reached. 
       SUMMARY OF THE INVENTION 
       [0003]    A general object of the invention is to avoid unwanted floatation of the tillage tool above its desired tilling level while allowing the tool to trip should excessive force be encountered to avoid damage to the tool or linkage. Another object of the invention is to use the movement through the ground of the tillage implement to augment the downward force applied by the down pressure spring. 
         [0004]    In one embodiment of the linkage configuration of the ground penetrating device, the linkage uses a “float-forward” movement design, which requires the ground attacking tillage device to move forward as the tillage device floats up vertically about the linkage&#39;s pivotal connections with the toolbar frame. The result of this design is a ground penetrating device which utilizes ground motion to resist vertical floatation while the tool is in operation at working depth, thus allowing the full down pressure from the associated spring to be applied. 
         [0005]    In this embodiment, the design also utilizes the ground motion to help return the ground penetrating tool to its original working depth after a full trip that rotates the device up and out of the ground about its main pivotal connection responsive to excessive force. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Referring to the drawings which are appended hereto and which form a portion of this disclosure, it may be seen that: 
           [0007]      FIG. 1  is side elevational view of an embodiment of the invention with the implement in the normal working position; 
           [0008]      FIG. 2  is a side elevational view of the embodiment of  FIG. 1  displaced at a vertically floated position; and, 
           [0009]      FIG. 3A  is a side elevational view showing the interaction of the links in a float movement cycle of the dual acting ground penetrating device. 
           [0010]      FIG. 3B  is a side elevational view showing the interaction of the links in a trip movement cycle of the dual acting ground penetrating device. 
           [0011]      FIG. 4  is a side elevational view of the invention onto a side elevational view of a prior art design. 
           [0012]      FIG. 5  is a side elevational view of one embodiment of the invention with joint connections labeled. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    One or more of the above objects can be achieved, at least in part, by providing a dual acting linkage which creates an upward and forward float path of the tillage device from its full tillage depth when the tillage device encounters a substantially vertical load. More specifically, the linkage is designed to keep the tillage implement from floating vertically upward and forwardly in the presence of a normal draft load. This tendency to move upwardly and forwardly is counter to the forces imparted to the tillage implement by the movement of a prime mover or tractor pulling the implement across a field, thus the components of the draft load resist such upward and forward movement and tend to force the tillage implement to stay at its optimum tillage depth. 
         [0014]    Referring to the drawings for a clearer understanding of the invention it may be seen that the tillage implement  11  or plow unit is connected to a tool bar  12  which is conventionally mounted to a prime mover or tractor, not shown. The tool bar  12  supports a bracket  14  which is secured thereto by a set “V” bolts  15  with complementary nuts and provides a pair of pivot points for the linkage  16  connecting the tool bar to the implement  11 . Main pivot pin  18  provides a connection joint M between bracket  14  and the forward end of a main arm  20 . The rear end of main arm  20  is connected to shank weldment  22  at joint Z by a pivot pin  24 . Shank weldment  22  has tillage implement  11  affixed to its lower end. The upper end of shank weldment  22  is connected to a rear trip link arm  28  at joint X by yet another pivot pin  29 . Rear trip link arm  28  is connected at joint Y to top front link trip arm  30  by pin  32 . Top front link arm  30  is connected to bracket  14  at joint N by pivot pin  34 . Down pressure spring  36  is mounted at joint Y and connected to the main arm  14  at P. It should be noted that the linkage configuration is such that the vertical separation between joint Z and X is always less than the fixed vertical separation between joints M and N at the bracket  14  throughout the entire range of motion of the tillage tool. 
         [0015]    In the embodiments shown, when a rock or other immovable object is encountered, two different device reactions are possible. The first possible reaction, when a force (F) greater than the normal draft load is applied to the tillage implement  11  all joints rotate with exception to joint Y, which is the joint between the top front trip link arm  30  and the top rear tip link arm  28 . It is this reaction that causes the “riding up” floatation problem of the prior art designs. The second possible reaction, when a force (F), greater than the normal draft load, is applied to the tillage implement  11  is all joints rotate except joint Z, which is the joint between the main arm  20  and the shank weldment  22 . It is this reaction that has been purposely designed to occur first when the ground penetrating device encounters the force (F) at the devices working depth. This eliminates the “riding up” problem experienced in the prior art. That is to say, in this linkage configuration of the ground penetrating device, the linkage members have been situated geometrically such that when the dual acting ground penetrating device is at working depth, any force greater than normal draft load will be substantial enough at the main pivotal connection to rotate joint Y and fully trip and rotate the ground penetrating device up and out of the ground. This is because the normal float line for this embodiment is upward and forward, however movement along that float line is resisted by the soil and forward movement of the prime mover, accordingly joint Y “breaks” and the tillage implement rotates. 
         [0016]    The difference in the float lines of the present invention and the prior art are shown in  FIG. 4 . As may be seen the dotted line from the point of the plow upward and rearward is the float path for the tool point in the prior art, thus the normal draft load will tend to cause the tillage implement to rise along this float path in opposition to the downward pressure of spring  36  and the soil will be tilled at an inconsistent depth. In contrast, the float path of the present invention is forward and upward and is resisted by the rearward and downward components of the draft load, thereby maintaining the plow at its desired depth and providing a more uniform tillage. 
         [0017]    In one embodiment of the invention, the distance between connections N and X is approximately 73.5% of the length between pivot connections M and Z when in the normal tillage position. Additionally the length between pivot connections Z and X is approximately 50% of the length between pivot connections M and Z. Additionally the length between pivot connections M and N is approximately 48% of the length between pivot connections M and Z. Also, the rearward horizontal distance of connection N to connection M is approximately 16.5% of the length between pivot connections M and N. The working depth of the tillage device is reached when the vertical distance of connection X to connection Z is approximately 91% of the length between pivot connections Z and X. At this point, the vertical distance produced from connection X to connection Z is approximately 96.5% of the vertical distance of connection N to connection M. While the forgoing relationships yield a forward and upward float path for the tillage implement of this embodiment it is important to note that the relationships may be varied to accommodate other forward and upward float paths that do not lead to a rearward movement of the tillage implement point during normal draft loads. Note that the term length refers to the measure along the component whereas distance refers to the actual linear separation between designated points. 
         [0018]    Referring to  FIG. 1  thru  3   a  for a clearer understanding of the invention, note that in  FIG. 1  the implement is depicted at its full draft position. In  FIG. 2  the implement is depicted at ground level.  FIG. 3   a  is a combined image of the tillage implement at full draft and at an untripped float position just above ground level. It may be noted that the tip of implement  11  above ground level is slightly forward of the tip of the implement  11  at full draft. 
         [0019]    As seen in  FIG. 3B , when force in excess of a predetermined amount is encountered, the linkage retracts along a rearward and upward path T until it reaches its full trip position at which point the reset operation begins. This tripping action occurs before the tillage implement will float thus, the stored energy member or spring  36  serves to cushion the tillage implement during operation but it does not allow the tillage implement to rise above its set tillage depth. 
         [0020]    While in the foregoing specification this invention has been described in relation to certain embodiments thereof, and many details have been put forth for the purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.