Abstract:
A tine harrow has a plurality of harrow tines mounted on and downwardly depending from a harrow frame. The tines are configured to be moveable between a lowered position and a raised position, and at least one tine lowerable or raiseable to a different relative position in relation to a surface of a field than others of the tines. The ability to lower and raise individual tines or rows of tines to different positions in relation to a surface of a field provides more effective response of the tine harrow to changing land conditions. The positions to which individual tines or rows of tines are lowered or raised may be selectively set to further enhance effectiveness of the response of the tine harrow to changing land conditions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of United States Provisional Patent Application Ser. No. 62/114,242 filed Feb. 10, 2015, the entire contents of which is herein incorporated by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to an apparatus, system and method for tilling a field. In particular, the present invention relates to control of a tine harrow, especially as part of an apparatus, system and method for a conservation tillage strategy. 
       BACKGROUND OF THE INVENTION 
       [0003]    Apparatuses, systems and methods for tilling agricultural fields are very well known in the art. Apparatuses typically comprise a cultivator frame having multiple and various tilling attachments attached thereto, laid out on the frame in a variety of patterns to maximize the desired tilling effect. The apparatus is dragged behind a vehicle during the tilling operation. 
         [0004]    In particular, conservation tillage, or vertical tillage as it is sometimes called, has recently become a tilling strategy of choice in many instances. Conservation tillage minimally disturbs the soil prior to planting in order to allow air to penetrate the mat of crop residue left in the field from the previous harvest. Apparatuses, systems and methods for conservation tillage are known in the art, for example United States patents U.S. Pat. No. 7,762,345 issued Jul. 27, 2010, U.S. Pat. No. 8,113,295 issued Feb. 14, 2012, U.S. Pat. No. 8,196,672 issue Jun. 12, 2012, U.S. Pat. No. 8,307,908 issued Nov. 13, 2012 and U.S. Pat. No. 8,307,909 issued Nov. 13, 2012, the entire contents of all of which are herein incorporated by reference. 
         [0005]    In addition to coulter wheels, chisel plows, V-shaped shovels, sub-soiling teeth and other field working tools, a tillage apparatus may comprise leveling attachments at the rear of the cultivator frame. The leveling attachments may be mounted to a rear transverse cross-member of the frame. Leveling attachments may comprise, for example, spike or tine harrows, leveling bars, rotary harrows, etc., which are dragged behind the cultivator frame to level the field after the field is worked by the field working tools. 
         [0006]    A conservation tillage apparatus may be drawn at faster speeds than conventional tillage apparatuses. Although there is no theoretical upper limit on speed, conservation tillage apparatuses may be operated at speeds of from 8-18 miles per hour. Operating at such faster speeds causes the crop residue to be cut more finely and reduces the likelihood of becoming stuck in wet soil conditions. However, operating at faster speeds, especially above 12 miles per hour, can create significant problems with leveling attachments being dragged behind the cultivator frame. 
         [0007]    Harrows are implements (leveling attachments) comprising sets of teeth, tines or ridges that when dragged over ploughed land break up clods, remove weeds, and cover seed. A tine harrow is a harrow having a plurality of narrow profile tines or spikes downwardly depending from a harrow frame. The tines may be spaced apart transversely on the harrow frame to form a row, and a plurality of rows may be spaced apart longitudinally on the harrow frame to form an array of tines on the harrow frame. Two or more harrow frames may be mounted at the rear of the cultivator frame, usually forming a transverse row of tine harrows. Adjusting the angle of the harrow tines changes how aggressively the tines interact with the land by raising and lowering the ends of the tines with respect to the land. The desired aggressiveness of the harrow tines depends on land conditions, which may change from day-to-day, or even from place-to-place on the land. Angle adjustment of the tines is generally done collectively so that the angles of all of the tines on a given harrow frame, and indeed all of the tines on all the harrow frames mounted on the cultivator frame, are changed at the same time. A number of ways to accomplish such angle changes are known in the art, for example as described in U.S. Pat. No. 8,657,026 issued Feb. 25, 2014. 
         [0008]    However, prior art apparatuses do not permit independent control of each tine or at least a single row of tines, which limits the effectiveness of the tine harrow in changing land conditions. There remains a need for ways of adjusting the position of individual tines or individual tine rows in one or more tine harrows in relation to a surface of the land. 
       SUMMARY OF THE INVENTION 
       [0009]    According to the present invention, there is provided a tine harrow comprising a plurality of harrow tines mounted on and downwardly depending from a harrow frame, the tines configured to be moveable between a lowered position and a raised position, at least one tine lowerable or raiseable to a different relative position in relation to a surface of a field than others of the tines. 
         [0010]    The ability to lower and raise individual tines or rows of tines to different positions in relation to a surface of a field provides more effective response of the tine harrow to changing land conditions. Depending on the positions to which the tines may be set, the tines may interact with the field less or more aggressively. In some embodiments, the tines may interact with the field when in either of the lowered or raised positions, and the positions to which the tines may be set may change how aggressively the tines interact with the field when the tines are in both the lowered and raised positions. In other embodiments, the tines may interact with the field when in the lowered position but not when in the raised position, and the positions to which the tines may be set may change how aggressively the tines interact with the field when the tines are in the lowered position. 
         [0011]    Further, rather than the at least one tine having just one position to which the tine may be lowered or raised, the position to which the at least one tine may be lowered or raised may be set selectively to one of a plurality of different positions to further enhance effectiveness of the response of the tine harrow to changing land conditions. Selectively setting the position of the at least one tine comprises the ability to select tine position from a plurality of different possible positions. Thus, those tines or rows of tines whose positions can be selectively set may have a plurality of different possible lowered or raised positions in relation to the field, which may be selected depending on land conditions, operator desires or any other factor. Being able to independently control the position in relation to the field of individual tines or tines in individual rows of tines, for example by independently controlling the angle or pitch of the tines, also permits control over down-pressure of the tines, which permits control over whether residue is let through the harrow or not. 
         [0012]    The harrow frame may be mounted on a cultivator frame as part of a tillage apparatus. The cultivator frame has a longitudinal axis in the direction of motion of the tillage apparatus as it is being dragged across the land. The longitudinal axis runs from front to rear (or rear to front) of the cultivator frame. The cultivator frame has a transverse axis that is perpendicular to the longitudinal axis and runs left to right (or right to left) of the cultivator frame. The front end of the cultivator frame is mounted to the transportation (e.g. vehicle) that drags the apparatus. The cultivator frame may have a plurality of longitudinally spaced apart transverse frame-members and a plurality of transversely spaced apart longitudinal frame-members. 
         [0013]    The harrow frame is preferably mounted at a rear of the cultivator frame. Directionality in relation to the harrow frame may be expressed in the same manner as directionality in relation to the cultivator frame. The harrow frame may comprise longitudinally spaced apart transverse harrow frame-members and a plurality of transversely spaced apart longitudinal harrow frame-members. The tines may be mounted on any of the harrow frame-members. Preferably, the tines are mounted in a plurality of transverse rows on rotatable transverse harrow frame-members. 
         [0014]    The harrow frame may comprise at least one section of tines. In some embodiments, the tines may be arranged in a plurality of transverse rows in the section. In some embodiments, the tines in at least one transverse row in at least one of the at least one sections are lowerable or raiseable to the different relative position in relation to the surface of the field than others of the tines. In some embodiments, the tines that are lowerable or raiseable to the different relative position may be selectively lowerable or raiseable to at least two different relative positions. 
         [0015]    In some embodiments, the tines may be lowered and raised by rotation of the tines about respective transverse axes. The transverse axes may be defined by longitudinally spaced-apart rotatable transverse axles mounted on the harrow frame. The transverse axles may have the tines mounted thereon. The tines may be configured on the transverse axles so that rotation of the transverse axles rotates the tines through an angle, which lowers or raises ends of the tines. 
         [0016]    Any suitable mechanism may be employed for lowering and raising the tines. For example, actuating mechanisms (actuators) may be configured to move one or more tines between the lowered and raised positions. Some examples of actuators include hydraulic cylinders (e.g. rephasing hydraulic cylinders), electrical actuators (e.g. linear actuators), mechanical actuators, pneumatic actuators (e.g. inflatable bags) and motors (e.g. hydraulic and electric motors). A given actuator may be configured to move individual tines or groups of tines. Groups of tines may be all of the tines on the harrow, sections of tines or rows of tines. In one embodiment, each tine may be connected to a dedicated actuator so that the raising and lowering of each tine may be independently controlled. In another embodiment, only the tines for which a different relative position is desired may be connected to dedicated actuators while others of the tines are lowered and raised together by an actuator. Preferably, one actuator is responsible for lowering and raising one section of tines, and the tines within that section for which a different relative position is desired are connected to the actuator by a mechanism for effecting the different relative position. 
         [0017]    Configuring the actuators to move the tines may be accomplished in any manner suitable for the type of actuator being used. Actuators may be connected to the tines through any one or more of mechanical linkages, wheels (e.g. pulleys, sprockets, pinions, gears, etc.), pressure lines and the like. For example, a linkage arm may be connected to transverse axles and translation of the linkage arm, for example longitudinal translation, rotates the transverse axles about a transverse axes thereby rotating the tines thereby lowering or raising the tines. In another embodiment, wheels mounted on longitudinally spaced apart transverse axles may be interconnected by a common drive structure configured to rotate the wheels thereby rotating the transverse axles about the transverse axes thereby rotating the tines thereby lowering or raising the tines. 
         [0018]    To effect a different relative position for certain tines or rows of tines, the connections between the actuators and the tines may be suitably adapted. In one embodiment, connecting arms may connect longitudinally spaced apart transverse axles to a linkage arm where at least one of the connecting arms is connected to the linkage arm at a different relative location in relation to their transverse axles than the other connecting arms in relation to their transverse axles. The angles at which the tines depend from the respective transverse axles are therefore different, resulting in a different relative position of the tines in relation to the field. Such an arrangement may be made selective by permitting selective connection of at least one of the connecting arms to the linkage arm at least two different longitudinally spaced-apart locations on the linkage arm and/or at least two different spaced-apart locations on the connecting arm. In selective connection, the locations are configured so that connection of the at least one of the connecting arms at a first location selects a first relative position in relation to the surface of the field to which the tines may be lowered or raised, and connection of the at least one of the connecting arms at a second location selects a second relative position in relation to the surface of the field to which the tines may be lowered or raised. Connecting arms may be connectable to the linkage arm in any suitable manner that permits rotation of the transverse axles by translation of the linkage arm. Such connections may permit rotational motion at the connection, and may in some embodiments be accomplished by a pin through aperture arrangement, ball and socket arrangement, or the like. 
         [0019]    In another embodiment, with wheels mounted on longitudinally spaced apart transverse axles and a common drive structure configured to rotate the wheels together, the common drive structure may comprise a driven endless loop (e.g. a chain, belt or the like) around the wheels or a translatable toothed rack mounted on the harrow frame where the wheels are sprockets, pinions, gears or the like having teeth that mesh with the teeth of the rack. In this embodiment, at least one of the wheels may be configured differently to rotate by a different amount than others of the wheels thereby rotating the transverse axle of the differently configured wheel by a different amount thereby lowering or raising the tines on the transverse axle of the differently configured wheel by a different amount than others of the tines. The differently configured wheel may comprise a different diameter, a different number of teeth, differently spaced teeth or combinations thereof. The wheels may be replaceable with other wheels of different configurations (e.g. different diameters, number of teeth or teeth spacing) to permit selection of the amount by which the desired tines are lowerable or raiseable. 
         [0020]    The tillage apparatus is preferably a conservation tillage apparatus. The tillage apparatus may have one or more other leveling attachments mounted thereon, for example other spike harrows, leveling bars, rotary harrows, etc. The tillage apparatus may have one or more field working tools mounted thereon, for example coulter wheels, chisel plows, V-shaped shovels, sub-soiling teeth, etc. Leveling attachments are generally mounted on the cultivator frame rearward of the field working tools. 
         [0021]    Further features of the invention will be described or will become apparent in the course of the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    In order that the invention may be more clearly understood, embodiments thereof will now be described in detail by way of example, with reference to the accompanying drawings, in which: 
           [0023]      FIG. 1A  is a side view of a section of a tine harrow having three transverse rows of harrow tines illustrating how the tines may be lowered and raised by a rephasing hydraulic cylinder. 
           [0024]      FIG. 1B  is a side view of a section of a tine harrow having three transverse rows of harrow tines illustrating another arrangement of how the tines may be lowered and raised by a rephasing hydraulic cylinder. 
           [0025]      FIG. 1C  is a schematic diagram of a hydraulic circuit for use with rephasing hydraulic cylinders for lowering and raising tines of sections of a tine harrow, the hydraulic circuit being shown in context with a cultivator frame to a rear of which the sections of the tine harrow are attached. 
           [0026]      FIG. 2  is a side view of a section of a tine harrow having three transverse rows of harrow tines illustrating how the tines may be lowered and raised by an electrical actuator. 
           [0027]      FIG. 3  is a side view of a section of a tine harrow having three transverse rows of harrow tines illustrating how the tines may be lowered and raised by a combination of an inflatable air bag and a tension spring. 
           [0028]      FIG. 4  is a side view of a section of a tine harrow having three transverse rows of harrow tines illustrating how the tines may be lowered and raised by a motor. 
           [0029]      FIG. 5A ,  FIG. 5B  and  FIG. 5C  are side views of a section of a tine harrow having three transverse rows of harrow tines illustrating how connection of rows of tines at different locations on a translatable linkage arm selectively controls relative positions of the tines in the rows in relation to a surface of a field. 
           [0030]      FIG. 6  is a side view of a section of a tine harrow having three transverse rows of harrow tines illustrating how a rack and pinion mechanism selectively controls relative positions of the tines in the rows in relation to a surface of a field. 
           [0031]      FIG. 7  is a side view of a section of a tine harrow having three transverse rows of harrow tines illustrating how a chain and pinion mechanism selectively controls relative positions of the tines in the rows in relation to a surface of a field. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0032]      FIG. 1A ,  FIG. 1C ,  FIG. 2 ,  FIG. 3  and  FIG. 4  illustrate aspects of various preferred embodiments of actuating mechanisms by which tines or rows of tines of a tine harrow may be lowered and raised. The actuating mechanisms permit “on-the-fly” lowering and raising of tine harrow sections between the lowered and raised positions of the tines. In one embodiment, a lowermost position of the tines is a field-engaging position, while an uppermost position of the tines is a field-disengaging position. In another embodiment, both the lowermost and uppermost positions may be field-engaging.  FIG. 10 ,  FIG. 5A ,  FIG. 5B ,  FIG. 5C ,  FIG. 6  and  FIG. 7  illustrate various aspects of preferred embodiments of arrangements for selectively controlling relative positions of the tines in relation to the surface of the field. With appropriate design, any of the actuating mechanisms for lowering and raising the tines or rows of tines may be combined with any one or more of the arrangements for selectively controlling relative positions of the tines in relation to the surface of the field. 
         [0033]      FIG. 1A  depicts the use of a hydraulic cylinder  11 , for example a rephasing hydraulic cylinder, configured to lower and raise a harrow section  10  having three transverse rows  12   a ,  12   b ,  12   c  of harrow tines  13   a ,  13   b ,  13   c . Because  FIG. 1A  is a side view, other tines in each of the rows  12   a ,  12   b ,  12   c  are not seen. The tines  13   a ,  13   b ,  13   c  in each row  12   a ,  12   b ,  12   c  are mounted on respective transverse rotatable axles  14   a ,  14   b ,  14   c . The axles  14   a ,  14   b ,  14   c  are connected to an elongated longitudinally-oriented and translatable linkage bar  15  through respective connecting bars  16   a ,  16   b ,  16   c . The connecting bars  16   a ,  16   b ,  16   c  are rigidly connected to the axles  14   a ,  14   b ,  14   c , and are pivotally connected to the linkage bar  15  by pins  17   a  (not visible),  17   b ,  17   c  through apertures in the linkage bar  15 . One of the connecting bars  16   b  is also pivotally connected at first cylinder pivot point  18  to one end of the hydraulic cylinder  11 . The other end of the hydraulic cylinder  11  is pivotally connected at second cylinder pivot point  19  to a mounting arm  20  rigidly mounted through a mounting tube  21  on a longitudinal frame-member  22  of the harrow section  10 . The hydraulic cylinder  11  comprises a barrel  23  and an extendible rod  24 , and the barrel  23  is shown connected at pivot point  18  while the rod  24  is shown connected at pivot point  19 . However, the hydraulic cylinder  11  may be reversed so that the barrel  23  is connected at pivot point  19  while the rod  24  is connected at pivot point  18 . In operation, extension or retraction of the rod  24  causes translation of the connecting bar  16   b  in an arcuate path, which in turn causes longitudinal translation of the linkage bar  15 . Because the connecting bars  16   a ,  16   b ,  16   c  are pivotally connected to the linkage bar  15 , translation of the linkage bar  15  causes translation of the connecting bars  16   a ,  16   c  along an arcuate path in a manner similar to connecting bar  16   b . The arcuate translation of the connecting bars  16   a ,  16   b ,  16   c  causes rotation of the axles  14   a ,  14   b ,  14   c , which causes the  13   a ,  13   b ,  13   c  to rotate thereby lowering or raising distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c . In  FIG. 1A , the tines  13   a ,  13   b ,  13   c , the connecting bars  16   a ,  16   b ,  16   c , the linkage bar  15  and the hydraulic cylinder  11  are shown in solid lines when the tines  13   a ,  13   b ,  13   c  are in a lowered position and in dashed lines when the tines  13   a ,  13   b ,  13   c  are in a raised position. In  FIG. 1A , extension of the rod  24  raises the tines  13   a ,  13   b ,  13   c  into the raised position; however, the hydraulic cylinder  11  may instead be configured to raise the tines  13   a ,  13   b ,  13   c  into the raised position when the rod  24  retracts. 
         [0034]      FIG. 1B  depicts an arrangement similar to  FIG. 1A  except that the connecting bars  16   a ,  16   b  each have two possible points of pivoting connection  17   a ,  17   d  and  17   b ,  17   e , respectively, to the linkage bar  15 . As in the embodiment depicted in  FIG. 1A , the harrow section  10  has three transverse rows  12   a ,  12   b ,  12   c  of harrow tines  13   a ,  13   b ,  13   c . Because  FIG. 1B  is a side view, other tines in each of the rows  12   a ,  12   b ,  12   c  are not seen. The tines  13   a ,  13   b ,  13   c  in each row  12   a ,  12   b ,  12   c  are mounted on respective transverse rotatable axles  14   a ,  14   b ,  14   c . The axles  14   a ,  14   b ,  14   c  are connected to the elongated longitudinally-oriented and translatable linkage bar  15  through respective connecting bars  16   a ,  16   b ,  16   c . The connecting bars  16   a ,  16   b ,  16   c  are rigidly connected to the axles  14   a ,  14   b ,  14   c , and are pivotally connected to the linkage bar  15  by pins  17   d ,  17   e ,  17   c  through apertures in the linkage bar  15 . The connecting bar  16   a  has a possible second point of pivoting connection  17   a  to the linkage bar  15 , and the connecting bar  16   b  also has a possible second point of pivoting connection  17   b  to the linkage bar  15 . The extra possible points of connection on the connecting bars permit selective control of the relative positions of the tines in relation to a surface of a field, because connecting the linkage bar  15  to a different point on one or both of connecting bars  16   a ,  16   b  will change the angle through which the tines rotate for the same translational distance of the linkage bar  15 . Other features illustrated in  FIG. 1B  function similarly to the corresponding features in  FIG. 1A . 
         [0035]    Referring to  FIG. 1C , a hydraulic circuit  30  is depicted for use with rephasing hydraulic cylinders  31   a - f  for lowering and raising tines of sections of a tine harrow. The hydraulic circuit  30  is shown in context with a cultivator frame  1  to a rear of which the sections of the tine harrow (not shown) are attached. The rear of the cultivator frame is toward the bottom of  FIG. 1C . 
         [0036]    Rephasing hydraulic cylinders are two or more hydraulic cylinders plumbed in series or parallel, with the bores and rods sized such that all rods extend and/or retract equally when hydraulic fluid flow is directed to the first, or last, cylinder within the hydraulic circuit. Preferably, the rephasing hydraulic cylinders are plumbed in series. In series applications, the bore and rod sizes are typically different. This hydraulic synchronization of rod positions eliminates the need for a flow divider in the hydraulic system, or any type of mechanical connection between the cylinder rods to achieve synchronization. The rephasing hydraulic cylinders on the tine harrow may all point in one direction such that extension of the rods is all toward the front or to the rear, or directions in which the cylinder point may have some cylinder rods extending toward the front while the rods of other cylinders extend toward the rear. The best arrangement for a given application may depend on the combination that permits the most efficient hydraulic circuitry. For the present tine harrow application, having all of the rods extend in the same direction is preferred. 
         [0037]    As seen in  FIG. 1C , the hydraulic circuit  30  comprises a plurality of hydraulic lines containing hydraulic fluid for transmitting hydraulic pressure to the rephasing hydraulic cylinders  31   a - f . Each cylinder  31   a ,  31   b ,  31   c ,  31   d ,  31   e ,  31   f  controls the lowering and raising of one tine harrow section. Two cylinders may be used to control one section, for example cylinders  31   c - d  together control a main central section of tines. Cylinders  31   a - c  are connected in series with respect to each other and cylinders  31   d - e  are connected in series with respect to each other, but cylinders  31   a - c  are in parallel to cylinders  31   d - e . Further, neighboring cylinders  31   a - c  on one side of the harrow and neighboring cylinder  31   d - e  on the other side of the harrow alternate in whether extension or retraction of the cylinder lowers the respective harrow sections. Thus, the three cylinders within each of cylinders  31   a - c  and cylinders  31   d - e  are plumbed sequentially from rear-to-rear-to-front. That is, the first cylinders  31   c ,  31   d  of each group closest to the hydraulic supply receive fluid at the front and deliver fluid from the rear, the second cylinders  31   b ,  31   e  of each group receive fluid at the rear and deliver fluid from the front, and the third cylinders  31   a ,  31   f  of each group receive fluid at the front and deliver fluid from the rear. Front is a direction toward the front of the cultivator frame  1  and rear is a direction rearward of the cultivator frame  1 .  FIG. 1C  shows the cylinders  31   a - f  when the harrow sections are lowered. Thus, extension of cylinders  31   a ,  31   c ,  31   d ,  31   f  and retraction of cylinders  31   b ,  31   e  lowers the respective harrow sections. 
         [0038]    Under normal operation to lower the harrow sections, hydraulic fluid pressure is transmitted to the circuit from a hydraulic supply and a hydraulic pump on a tractor through a feed line coupled with coupling  32  to hydraulic line  33 . Fluid flow is split left and right at line junction  34 . Fluid flowing right passes through cylinders  31   c ,  31   b ,  31   a  before returning to line junction  35  and then back via hydraulic line  36  to coupling  37  connected to a return line for returning hydraulic fluid to the hydraulic supply. Likewise, fluid flowing left passes through cylinders  31   d ,  31   e ,  31   f  before returning to line junction  35  and then back via hydraulic line  36  to coupling  37  connected to a return line for returning hydraulic fluid to the hydraulic supply. Raising the harrow sections may be accomplished by reversing the fluid low in the hydraulic circuit. Cylinders  31   c  and  31   d  are preferably tied together so that hydraulic fluid arriving at line junction  34  from line  33  (or line junction  35  from line  36 ) is distributed evenly between the two sides of the hydraulic circuit  30  even if there may be a difference in load on the two sides of the harrow. The cylinders  31   c  and  31   d  may be tied hydraulically, mechanically or by any other suitable means. 
         [0039]      FIG. 2  depicts an arrangement similar to  FIG. 1A  except that an electrical actuator  41  (e.g. a linear actuator) is used instead of a hydraulic cylinder to lower and raise the harrow section  10 . As in the embodiment depicted in  FIG. 1A , the harrow section  10  has three transverse rows  12   a ,  12   b ,  12   c  of harrow tines  13   a ,  13   b ,  13   c . Because  FIG. 2  is a side view, other tines in each of the rows  12   a ,  12   b ,  12   c  are not seen. The tines  13   a ,  13   b ,  13   c  in each row  12   a ,  12   b ,  12   c  are mounted on respective transverse rotatable axles  14   a ,  14   b ,  14   c . The axles  14   a ,  14   b ,  14   c  are connected to the elongated longitudinally-oriented and translatable linkage bar  15  through respective connecting bars  16   a ,  16   b ,  16   c . The connecting bars  16   a ,  16   b ,  16   c  are rigidly connected to the axles  14   a ,  14   b ,  14   c , and are pivotally connected to the linkage bar  15  by pins  17   a  (not visible),  17   b ,  17   c  through apertures in the linkage bar  15 . One of the connecting bars  16   a  is also pivotally connected at first actuator pivot point  48  to one end of the actuator  41 . The other end of the actuator  41  is pivotally connected at second cylinder pivot point  49  to a mounting arm  50  rigidly mounted through a mounting tube  51  on the longitudinal frame-member  22  of the harrow section  10 . The actuator  41  comprises a barrel  43  and an extendible rod  44 , and the barrel  43  is shown connected at pivot point  49  while the rod  44  is shown connected at pivot point  48 . However, the actuator  41  may be reversed so that the barrel  43  is connected at pivot point  48  while the rod  44  is connected at pivot point  49 . In operation, extension or retraction of the rod  44  causes translation of the connecting bar  16   a  in an arcuate path, which in turn causes longitudinal translation of the linkage bar  15 . Because the connecting bars  16   a ,  16   b ,  16   c  are pivotally connected to the linkage bar  15 , translation of the linkage bar  15  causes translation of the connecting bars  16   b ,  16   c  along an arcuate path in a manner similar to connecting bar  16   a . The arcuate translation of the connecting bars  16   a ,  16   b ,  16   c  causes rotation of the axles  14   a ,  14   b ,  14   c , which causes the  13   a ,  13   b ,  13   c  to rotate thereby lowering or raising distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c . In  FIG. 2 , the tines  13   a ,  13   b ,  13   c , the connecting bars  16   a ,  16   b ,  16   c , the linkage bar  15  and the actuator  41  are shown in solid lines when the tines  13   a ,  13   b ,  13   c  are in a lowered position and in dashed lines when the tines  13   a ,  13   b ,  13   c  are in a raised position. In  FIG. 2 , retraction of the rod  44  raises the tines  13   a ,  13   b ,  13   c  into the raised position; however, the actuator  41  may instead be configured to raise the tines  13   a ,  13   b ,  13   c  into the raised position when the rod  44  extends. Electrical actuators have an advantage related to the ability to sense the position of the rod  44 , which permits more accurate positioning of the tines  13   a ,  13   b ,  13   c  in a position in relation to the field that is intermediate between the fully lowered position and the fully raised position. 
         [0040]      FIG. 3  depicts an arrangement similar to  FIG. 2  except that an inflatable air bag  61  and a tension spring  62  are used instead of an electrical actuator to lower and raise the harrow section  10 . As in the embodiment depicted in  FIG. 2 , the harrow section  10  has three transverse rows  12   a ,  12   b ,  12   c  of harrow tines  13   a ,  13   b ,  13   c . Because  FIG. 3  is a side view, other tines in each of the rows  12   a ,  12   b ,  12   c  are not seen. The tines  13   a ,  13   b ,  13   c  in each row  12   a ,  12   b ,  12   c  are mounted on respective transverse rotatable axles  14   a ,  14   b ,  14   c . The axles  14   a ,  14   b ,  14   c  are connected to the elongated longitudinally-oriented and translatable linkage bar  15  through respective connecting bars  16   a ,  16   b ,  16   c . The connecting bars  16   a ,  16   b ,  16   c  are rigidly connected to the axles  14   a ,  14   b ,  14   c , and are pivotally connected to the linkage bar  15  by pins  17   a ,  17   b  (not visible),  17   c  through apertures in the linkage bar  15 . One of the connecting bars  16   a , is also pivotally connected at first air bag pivot point  68  to one end of the air bag  61 . The other end of the air bag  61  is pivotally connected at second air bag pivot point  69  to the mounting arm  50  rigidly mounted through the mounting tube  51  on the longitudinal frame-member  22  of the harrow section  10 . The tension spring  62  is connected at a first end  63  to the pin  17   a  and at a second end  64  to a pin  17   d  to immovably connect the second end  64  of the spring  62  to the mounting arm  50 . The first end  63  of the spring  62  is moveable in conjunction with the arcuate movement of the connecting bar  16   a . However, the mounting of the air bag  61  and the spring  62  may be configured so that the air bag  61  and the spring  62  are immovably mounted at the opposite ends. In operation, inflation of the air bag  61  from a compressed air source, for example a compressor mounted on the vehicle, causes translation of the connecting bar  16   a  in an arcuate path, which in turn causes longitudinal translation of the linkage bar  15 . Because the connecting bars  16   a ,  16   b ,  16   c  are pivotally connected to the linkage bar  15 , translation of the linkage bar  15  causes translation of the connecting bars  16   b ,  16   c  along an arcuate path in a manner similar to connecting bar  16   a . The arcuate translation of the connecting bars  16   a ,  16   b ,  16   c  causes rotation of the axles  14   a ,  14   b ,  14   c , which causes the  13   a ,  13   b ,  13   c  to rotate thereby lowering distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c . In addition, arcuate movement of the connecting bar  16   a  caused by inflation of the air bag  61  stretches the tension spring  62 . Reducing air pressure in the air bag  61  permits the spring  62  to compress under the force of the tension acquired when the spring  62  was stretched, thereby causing reverse arcuate translation of the connecting bars  16   a ,  16   b ,  16   c  causing reverse rotation of the axles  14   a ,  14   b ,  14   c , which causes the  13   a ,  13   b ,  13   c  to rotate thereby raising distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c . In  FIG. 3 , the tines  13   a ,  13   b ,  13   c , the connecting bars  16   a ,  16   b ,  16   c , the linkage bar  15 , the air bag  61  and the spring  62  are shown in solid lines when the tines  13   a ,  13   b ,  13   c  are in a lowered position and in dashed lines when the tines  13   a ,  13   b ,  13   c  are in a raised position. In  FIG. 3 , inflation of the air bag  61  lowers the tines  13   a ,  13   b ,  13   c  into the lowered position; however, the air bag  61  may instead be configured to raise the tines  13   a ,  13   b ,  13   c  into the raised position when the air bag  61  is inflated. 
         [0041]      FIG. 4  depicts an arrangement similar to  FIG. 1A  except that a motor  81  (e.g. an electric or hydraulic motor) is used instead of a hydraulic cylinder to lower and raise the harrow section  10 . As in the embodiment depicted in  FIG. 1A , the harrow section  10  has three transverse rows  12   a ,  12   b ,  12   c  of harrow tines  13   a ,  13   b ,  13   c . Because  FIG. 4  is a side view, other tines in each of the rows  12   a ,  12   b ,  12   c  are not seen. The tines  13   a ,  13   b ,  13   c  in each row  12   a ,  12   b ,  12   c  are mounted on respective transverse rotatable axles  14   a ,  14   b ,  14   c . The axles  14   a ,  14   b ,  14   c  are connected to the elongated longitudinally-oriented and translatable linkage bar  15  through respective connecting bars  16   a ,  16   b ,  16   c . The connecting bars  16   a ,  16   b ,  16   c  are rigidly connected to the axles  14   a ,  14   b ,  14   c , and are pivotally connected to the linkage bar  15  by pins  17   a ,  17   b ,  17   c  through apertures in the linkage bar  15 . One of the connecting bars  16   b  is rigidly connected to a pinion gear  85  having teeth configured to engage teeth of a drive gear  84  mounted on a drive shaft  83  of the motor  81 . The motor  81  is rigidly mounted through mounting tubes  21 ,  51  on the longitudinal frame-member  22  of the harrow section  10 . In operation, rotation of the drive shaft  83  causes rotation of the drive gear  84 , which causes rotation of the pinion gear  85  by virtue of the meshed teeth of drive gear  84  and the pinion gear  85 . Rotation of the pinion gear  85  causes translation of the connecting bar  16   b  in an arcuate path, which in turn causes longitudinal translation of the linkage bar  15 . Because the connecting bars  16   a ,  16   b ,  16   c  are pivotally connected to the linkage bar  15 , translation of the linkage bar  15  causes translation of the connecting bars  16   a ,  16   c  along an arcuate path in a manner similar to connecting bar  16   b . The arcuate translation of the connecting bars  16   a ,  16   b ,  16   c  causes rotation of the axles  14   a ,  14   b ,  14   c , which causes the  13   a ,  13   b ,  13   c  to rotate thereby lowering or raising distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c . In  FIG. 4 , the tines  13   a ,  13   b ,  13   c , the connecting bars  16   a ,  16   b ,  16   c  and the linkage bar  15  are shown in solid lines when the tines  13   a ,  13   b ,  13   c  are in a lowered position and in dashed lines when the tines  13   a ,  13   b ,  13   c  are in a raised position. In  FIG. 4 , lowering of the tines  13   a ,  13   b ,  13   c  is effected by the motor  81  being driven in one direction, while raising of the tines  13   a ,  13   b ,  13   c  is effected by the motor  81  being driven in the reverse direction. 
         [0042]      FIG. 5A ,  FIG. 5B  and  FIG. 5C  illustrate one embodiment of how relative positions of tines of a tine harrow in relation to a surface of a field may be selectively controlled. In  FIG. 5A ,  FIG. 5B  and  FIG. 5C , the harrow section  10  has three transverse rows  12   a ,  12   b ,  12   c  of harrow tines  13   a ,  13   b ,  13   c  as described in connection with  FIG. 1A . The tines  13   a ,  13   b ,  13   c  are lowered and raised by the hydraulic cylinder  11  as described in connection with  FIG. 1A . An elongated longitudinally-oriented and translatable linkage bar  95  in  FIG. 5A ,  FIG. 5B  and  FIG. 5C  differs from the linkage bar illustrated in  FIG. 1A  by having more apertures  98   a ,  98   b ,  98   c ,  98   d ,  98   e ,  98   f  at which the connecting bars  16   a ,  16   b ,  16   c  may be connected. In  FIG. 5A ,  FIG. 5B  and  FIG. 5C , the tines  13   a ,  13   b ,  13   c , the connecting bars  16   a ,  16   b ,  16   c , the linkage bar  95  and the hydraulic cylinder  11  are shown in solid lines when the tines  13   a ,  13   b ,  13   c  are in a lowered position and in dashed lines when the tines  13   a ,  13   b ,  13   c  are in a raised position. Furthermore, in  FIG. 5C , a neighboring cylinder  211  on a separate harrow section is shown for context. 
         [0043]    In  FIG. 5A ,  FIG. 5B  and  FIG. 5C , the connecting bar  16   a  may be pivotally connected to the linkage bar  95  by the pin  97   a  through only one possible aperture  98   a . The connecting bar  16   b  may be pivotally connected to the linkage bar  95  by the pin  97   b  through two possible apertures  98   b  (as seen in  FIG. 5A  and  FIG. 5B ), and  98   d  (as seen in  FIG. 5C ). The connecting bar  16   c  may be pivotally connected to the linkage bar  95  by the pin  97   c  through two possible apertures  98   c  (as seen in  FIG. 5A ), and  98   e  (as seen in  FIG. 5B  and  FIG. 5C ). By comparing the relative positions at the lowermost positions of the distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c  in  FIG. 5A ,  FIG. 5B  and  FIG. 5C , it is apparent that the relative positions in relation to the field of the distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c , and therefore the aggressiveness of the interaction of the tines  13   a ,  13   b ,  13   c  with the field, may be selectively controlled by selecting the apertures at which the connecting bars  16   a ,  16   b  are connected to the linkage bar  95 . The apertures  98   a ,  98   b ,  98   c ,  98   d ,  98   e ,  98   f  are spaced-apart longitudinally on the linkage bar  95 , therefore the same longitudinal translation of the linkage bar  95  will result in a different amount of rotation of the transverse rotatable axles  14   a ,  14   b ,  14   c  depending on the apertures at which the connecting bars  16   a ,  16   b  are connected. The differing amount of rotation of the transverse rotatable axles  14   a ,  14   b ,  14   c  results in differences in the relative positions of the tines  13   a ,  13   b ,  13   c  in relation to the field. Additionally or alternatively, the relative positions of the tines  13   a ,  13   b ,  13   c  in relation to the field may be controlled by differing the lengths of one or more of the connecting bars  16   a ,  16   b ,  16   c.    
         [0044]      FIG. 6  illustrates a second embodiment of how relative positions of tines of a tine harrow in relation to a surface of a field may be selectively controlled. In  FIG. 6 , the harrow section  10  has three transverse rows  12   a ,  12   b ,  12   c  of harrow tines  13   a ,  13   b ,  13   c  rigidly mounted on respective transverse rotatable axles  14   a ,  14   b ,  14   c  as described in connection with  FIG. 1A . Mounted concentrically on the transverse axles  14   a ,  14   b ,  14   c  are toothed pinions  106   a ,  106   b ,  106   c , respectively, which rotate with the transverse axles  14   a ,  14   b ,  14   c . A longitudinally-oriented elongated translatable toothed rack  105  is configured so that the teeth of the rack  105  mesh with the teeth of the pinions  106   a ,  106   b ,  106   c . The teeth of the toothed rack  105  also mesh with teeth of a drive gear  184  mounted on a drive shaft  183  of a motor  181 . Rotation of the drive shaft  183  by the motor  181  causes rotation of the drive gear  184 , which causes the toothed track  105  to translate longitudinally. Longitudinal translation of the toothed track  105  causes the pinions  106   a ,  106   b ,  106   c  to rotate, thereby causing rotation of the transverse axles  14   a ,  14   b ,  14   c , which causes the tines  13   a ,  13   b ,  13   c  to rotate thereby lowering or raising the distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c . Whether the tines  13   a ,  13   b ,  13   c  are lowered or raised is controlled by the direction that the motor  181  drives the drive shaft  183 . Because the  106   a ,  106   b ,  106   c  have different diameters, the pinions  106   a ,  106   b ,  106   c  will each rotate through a different angle of arc, resulting in the tines  13   a ,  13   b ,  13   c  rotating through a different angle of arc, resulting in the distal ends  25   a ,  25   b ,  25   c  of the tines  13   a ,  13   b ,  13   c  of each row  12   a ,  12   b ,  12   c  achieving different positions in relation to the field. By selecting pinions of appropriate diameter, the relative positions of the tines in each row may be selected. One or more of the pinions  106   a ,  106   b ,  106   c  may be changed out for a differently sized pinion or a pinion with a different number of teeth when desired, provided the rack  105  is configurable to mesh with all of the pinions if desired. 
         [0045]      FIG. 7  illustrates a third embodiment of how relative positions of tines of a tine harrow in relation to a surface of a field may be selectively controlled. The embodiment depicted in  FIG. 7  is similar to the one in  FIG. 6  except that the toothed rack is replaced with an endless loop drive chain  185 . The drive chain  185  meshes with the teeth of the pinions  106   a ,  106   b ,  106   c  and with the teeth of the drive gear  184 . The chain  185  may be driven in either direction to lower and raise the tines  13   a ,  13   b ,  13   c . Operation of the embodiment in  FIG. 7  is essentially the same as the one described in connection with  FIG. 6 . 
         [0046]    The novel features of the present invention will become apparent to those of skill in the art upon examination of the detailed description of the invention. It should be understood, however, that the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the specification as a whole.