Abstract:
A tillage implement includes a hitch adapted for connection to a prime mover. A cultivator section is attached to the hitch. The cultivator section includes a plurality of transversely spaced cultivator members. A tine harrow assembly is connected to the cultivator section in a trailing relationship thereto. The tine harrow assembly includes at least two transversely oriented rows of transversely spaced tines. A first row of tines are adjacent to the cultivator section having the tines arranged such that one of the tines is positioned along a line of travel offset laterally from a line of travel of each the cultivator members to engage soil positioned in a mound to opposing sides of the cultivator members.

Description:
This appl. claims benefit of 60/281,638, filed Apr. 5, 2001. 

   FIELD OF INVENTION 
   The invention relates to soil working implements and, more particularly, relates to a soil working implement having a cultivator and one or more tine harrows sections articulated to the cultivator in a trailing relationship relative thereto. The invention additionally relates to a soil working implement of the above-identified type having tines indexed to sweeps of the cultivator. 
   BACKGROUND OF THE INVENTION 
   A wide variety of tillage implements are used to prepare soil for planting. Some such implements include two or more sections articulated to one another so as to perform multiple functions as they are pulled through fields by a single tractor or other prime mover. One such implement is a cultivator/harrow, which is capable of simultaneously tilling soil and leveling the tilled soil in preparation for planting. This implement includes a cultivator that is towed by a tractor or other prime mover, and a unitary or sectional tine harrow that is towed by the cultivator. 
   The cultivator includes a plurality of cultivator members or “sweeps” (sometimes known as shanks or chisel plows) that are suspended from a frame and that rip into the soil as the machine is pulled across the ground to till the soil. The sweeps are arranged in transversely extending rows. The sweeps of each row are transversely staggered relative to the sweeps of the adjacent rows. In use, each successive row of sweeps tills part of a strip of soil left untilled by the preceding row. The last row of sweeps tills the last untilled strip of the swath, leaving ridges between the sweeps that are flanked by valleys directly behind the sweeps. 
   The harrow is designed to level the tilled soil sufficiently to produce a seedbed that is as level as possible and that is relatively clod free. A clod free, level seedbed formed from soil of relatively small particle size is desirable because it facilitates planting to a uniform depth and, accordingly, promotes uniform germination and uniform emergence. The typical harrow includes a plurality of grounded-engaging tines that penetrate the soil tilled by the cultivator. Multiple harrow sections are often provided, each of which spans a proportionate part of the transverse width of the swath tilled by cultivator. The tines are typically arranged in longitudinally extending, transversely spaced rows. They are intended to redirect soil from ridges or windrows left by the cultivator sweeps into the adjacent valleys, hence leveling the tilled surface. The tines, and/or related equipment such as rotating baskets, also firm the soil and break up clods. 
   Many harrows and harrow sections are designed for use strictly as an attachment to a cultivator. The tines in adjacent rows typically are indexed relative to one another to provide nearly complete coverage of the swath tilled by the cultivator. However, the tines are not indexed with respect to the cultivator sweeps. As a result, some of the tines of the typical harrow are not properly positioned to engage the ridges left by the cultivator sweeps in an optimal sequence. Harrows of this type, therefore, do not level the ridges left by the cultivator sweeps as well as may be desired. In fact, some of the harrow tines may be positioned so as to direct soil towards the ridges left by the cultivator sweeps rather than away from them, hence defeating the purpose of the harrow. 
   These problems are compounded by modern agricultural machinery, which operates at travel speeds of up to 9 mph. A cultivator operating at these speeds leaves deeper ridges than earlier cultivators operated at lower speeds. Known tine placement configurations, even if properly indexed relative to one another produce uniform ridges, still produce ridges that are too large to permit planting as the next operation. 
   Some of the problems mentioned above can be alleviated by replacing the last row(s) of tines with rotary wheels or crumbler wheels that are designed to roll behind the rows of tines and flatten the ridges left by the tines. However, current wheels are not sufficiently even or level relative to the seedbed left by the tines to adequately perform these functions, nor do they reduce soil clod size sufficiently. 
   The need therefore has arisen to provide a tine harrow that is configured to be towed by a cultivator and that has tines that are properly indexed, both relative to one another and to the cultivator sweeps, to maximize the leveling capability of the harrow. 
   SUMMARY OF THE INVENTION 
   It is an object of the invention to avoid the disadvantages of the prior art by providing tines that are properly indexed, both relative to one another and to the cultivator sweeps, to maximize the leveling capability of the harrow. 
   In accordance with the first embodiment of this invention, there is provided a tillage implement including a hitch adapted for connection to a prime mover, a cultivator section attached to the hitch, and a tine harrow assembly attached to the cultivator section. The cultivator section includes a plurality of transversely spaced cultivator members. The tine harrow assembly is attached to the cultivator section in a trailing relationship thereto. The tine harrow assembly includes at least two transversely oriented rows of transversely spaced tines. The first row of tines is adjacent to the cultivator section having the tines arranged such that one of the tines is positioned along a line of travel offset laterally from a line of travel of each of the cultivator members to engage soil positioned in a mound to opposing sides of the cultivator member. 
   The tillage implement may include a second row of tines trailing the first row of tines mounted thereon at positions that are offset laterally from the tines of the first row of tines. 
   The first row of tines may have only two tines positioned along a line of travel between adjacent lines of travel of the cultivators. 
   The tine harrow assembly may include four transversely oriented rows of tines. The third row of tines may include tines mounted thereon at positions laterally offset from the tines of the second row of tines. 
   The tines mounted on the third row may be offset laterally from the tines of both the first and second rows of tines. 
   The fourth row of tines may be offset laterally from the tines of the third row of tines. 
   The tillage implement may include a rotary reel positioned rearwardly from the tine harrow assembly in a trailing relationship thereto. 
   In accordance with a second embodiment of the invention, a method of tilling soil with a tillage implement which includes a cultivator section and a trailing tine harrow assembly; the cultivator section includes a plurality of laterally spaced cultivator members, tine harrow assembly includes a plurality of tines arranged in at least two transversely extending rows of tines, where the method includes the steps of passing the cultivator members through the soil to create a mound of soil positioned laterally to each lateral side of each the cultivator member and engaging the mound of soil created by the cultivator member with a single tine in a first transverse row of the tines oriented along a line of travel offset laterally of a line of travel corresponding to the respective cultivator member. 
   These and other 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 
     The advantages of this invention will become apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a top plan view of a soil working implement constructed in accordance with a first preferred embodiment of the invention; 
       FIG. 2  is a side elevation view of the implement of  FIG. 1 ; 
       FIG. 3  is a side elevation view of a harrow of the implement of  FIG. 1 ; 
       FIG. 4  is a top plan view of a section of the harrow of  FIG. 3 ; 
       FIG. 5  is a perspective view of the harrow section of  FIG. 4 , viewed from above the harrow section; 
       FIG. 6  is a side elevation view of a portion of the harrow section of  FIGS. 4 and 5 , including a tine bar, a hinge, a portion of one of the tines, a portion of a tine slide, and a portion of one of the support arms; 
       FIG. 7  is a perspective view of the hinge of  FIG. 6 ; 
       FIGS. 8-10  schematically illustrate the progressive leveling effect achieved during operation of the harrow of  FIGS. 1-3 ; 
       FIG. 11  is a top plan view of a soil working implement constructed in accordance with a second preferred embodiment of the invention; 
       FIG. 12  is a side elevation view of the soil working implement of  FIG. 11 ; 
       FIG. 13  is a side elevation view of the harrow section of  FIGS. 4-6 , illustrating a floating hitch mechanism and a rake angle adjust mechanism of the harrow section in first operational positions thereof; 
       FIG. 14  is a side elevation view of a portion of the harrow section of  FIGS. 4-6 , illustrating the floating hitch mechanism and the tine rake angle adjust mechanism in second operational positions thereof; 
       FIG. 15  is a side elevation view of the harrow section of  FIGS. 4-6 , illustrating the floating hitch mechanism and the tine rake angle adjust mechanism in third operational positions thereof; and 
       FIG. 16  is an exploded perspective view of the rake angle adjust mechanism. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring now to the drawings and initially to  FIGS. 1 and 2  in particular, a ground working implement  20  constructed in accordance with a first preferred embodiment of the present invention includes a cultivator  22  and a harrow  24  articulated to one another in an end-to-end fashion. The cultivator  22  is configured to be towed by a tractor or other prime mover so as to till the soil over which the implement  20  travels. The harrow  24  is towed by the cultivator  22  and is configured to level windrows or ridges left by the cultivator  22 . The harrow  24  preferably takes the form of a plurality (3 in the illustrated embodiment) of harrow sections  26 ,  28 ,  30  independently articulated to the back of the cultivator  22 . The center harrow section  28  of the illustrated embodiment is wider than the two flanking end sections  26  and  30 . However, different numbers of harrow sections of different relative widths, or even a single harrow section spanning the width of the swath tilled by the cultivator  22 , could be provided if desired. 
   The cultivator  22  is conventional. It includes a frame formed from longitudinal tubular beams  32  and transverse tubular beams  34 , a hitch  36  that couples the frame to a prime mover, and a plurality of cultivator members in the form of shank assembly  38  or plows that extend downwardly from the transverse beams  34  to the ground. As best seen in  FIGS. 2 and 3 , each shank assembly  38  includes a curved arm  40  mounted on the associated transverse beam  34  and a sweep  42  mounted on the bottom end of the arm  40 . The arms  40  are pivotally mounted on the transverse beams  34  and are biased to the rearward-most positions thereof by springs  44 . A plurality of wheels  46  are mounted on arms  48  that are pivotable with respect to the frame. The arms  48  are coupled to a hydraulic cylinder  50  by a suitable linkage  52  that raises and lowers the arms  48  upon cylinder extension and retraction. The wheels  46  therefore can be raised from their illustrated, lowermost position to either  1 ) a partially raised position to reduce the penetration depth of the shank assembly  38  or  2 ) a fully raised position for transport. 
   The shank assembly  38  of successive rows of the illustrated cultivator  22  are indexed relative to the lines of travel of the sweeps of the remaining rows to effect a so-called “split the middle” sweep pattern, which allows for uniform ridges to be formed. The shank assembly  38  ahead of the rear two rows of sweeps take a full cut and leave alternating strips of untilled soil. The shank assembly  38  of the two rear rows till the untilled strips left by the forward sweeps. Specifically, the sweeps in the next to last row till one half of the width of the remaining untilled strips and take out the middle of the ridges left by the sweeps in the row directly in front of that row. The shank assembly  38  of the rear row till the other half of the untilled strips and fill the grooves left by the next to last row of sweeps and take out the middle of the ridge left by the sweeps of the third row, resulting in a groove behind each of the shank assembly  38  of the rear row and a ridge adjacent each groove. 
   Except for being of different widths, the harrow sections  26 ,  28 ,  30  are identical to one another. The following description of harrow section  30  therefore applies equally to sections  26  and  28 . 
   Referring to  FIGS. 3-5 , harrow section  30  includes at least a plurality of tines  60  and a frame that supports the tines  60 . The frame preferably comprises 1) a plurality (4 in the illustrated embodiment) of tine bars  62  that support the tines  60  in longitudinally spaced, transversely extending rows, and 2) a pair of longitudinally extending support arms  64 . The frame is coupled to the cultivator by a pair of floating hitch assemblies (discussed in Section 2) below. 
   Still referring to  FIGS. 3-5 , each of the support arms  64  extends the full length of the harrow section  30 . Each support arm  64  is generally n-shaped when viewed in transverse cross section so as to form a hollow interior that receives a rake angle adjuster slide plate  122  as detailed in Section  3  below. 
   Referring to  FIGS. 6-7 , each tine bar  62  is suspended from the associated support arm  64  by a respective hinge  70 . The hinge  70  allows for automatic movement of individual rows of tines by permitting the tine bars  62  to pivot forwardly. Each hinge  70  is pivotally suspended from the associated support arm  64  by a hinge pin  72  that extends through opposed holes  74  in the support arm  64  and through a bore  76  in the upper portion of the hinge  70 . 
   The tine bar  62  is generally Z-shaped, having an upper, generally vertical leg  80 , a center, generally horizontal leg  82 , and a lower, generally vertical leg  84 . The upper leg  80  is bolted to mounting holes  78  in the hinges  70  via bolts  86 . The lower leg  84  has a plurality of spaced holes for receiving the tines  60 . These holes are spaced symmetrically from one another to provide the tine indexing described below. The rear surface of the upper leg  80  normally rests against stops  88  on slide plates  122  (detailed in Section  3  below) to determine the rake angle of the row of tines mounted on the tine bar  62 . However, the tine bars  62  are free to pivot forwardly away from the stops  88  to permit forward pivoting movement of each of the tine bars  62  independently of the others upon, e.g., reverse movement of the implement, thereby preventing damage to the tines  60 . 
   Referring now to  FIGS. 5 and 6 , the tines  60  may comprise any wire or peg-like structures that level the soil as the harrow  24  passes over it. In the illustrated embodiment, the tines  60  are provided as tine assemblies, each of which is formed from a single piece of spring wire. Each tine assembly includes a pair of transversely-spaced, vertically extending tines  60 , two coils  150  located at the upper ends of the tines  60 , and a transverse portion  152  that connects the coils  150  to one another. The transverse portion  152  also serves as a mount point for mounting each tine assembly on the associated tine bar  62 . Specifically, the transverse portion  152  is held in place by a pair of bolts  154  that extend 1) through a bracket  156  located behind the transverse portion  152 , 2) beneath the transverse portion  152 , and 3) through the indexed and aligned holes in the lower leg  84  of the associated tine bar  62 . This arrangement biases the individual tines  60  against the stops  88 , but allow the individual tines  60  to resiliently deflect away from the stops  88  upon encountering an obstruction. 
   The tines  60  are indexed relative to one another and to the line of travel of the last row of shank assembly  38  on the cultivator  22  so as to maximize the leveling capability of the harrow  24 . Specifically, the front row of tines  60  is positioned such that they split the middle of the ridges or windrows made by the last row of shank assemblies  38 . The second row of tines  60  is indexed to the first row so that each tine  60  of the second row splits the middle of ridges or windrows formed between two adjacent tines of the first row. The tines  60  of the third and fourth rows are also offset relative to the tines of the first and second rows and to each other. In the illustrated embodiment, shank assembly  38  leave a substantial ridge between each pair of grooves on 24″ centers. The tines  60  of the first row are indexed relative to the line of travel of the last row of shank assembly  38  to split the middle of these ridges. Only two tines are positioned in each line of travel between lines of travel of the shank assembly  38 . The first row leaves smaller uniform ridges on 8″ centers. The tines  60  of the second row are offset 4″ relative to the tines of the first row and are located on 8″ centers so as to split the middle of the ridges left by the first row. The tines  60  of the third row are offset 2″ from the tines of the second row and are located on the 4″ centers to cut a new path. The fourth row is offset 4″ from the third row and is arranged to split the ridges left by the third row. 
   The leveling effect achieved by the tine  60  is illustrated in  FIGS. 8-10 , which schematically illustrate the idealized profile of a strip of soil having a ridge left between two adjacent shank assemblies  38  on the last row of the cultivator  22 .  FIG. 8  illustrates that the ridge R left by the shank assembly  38  is relatively large and deep and is flanked at both ends by similarly shaped valleys V 1  and V 2 .  FIG. 9  illustrates that the first and second rows of tines  60 , in combination, break the ridge R of  FIG. 8  into three much shallower, narrower ridges R′ flanked by smaller, narrower valleys V′.  FIG. 10  illustrates that the depths and widths of both the ridges R″ and valleys V″ are reduced still further after passage of the third and fourth rows of tines  60 . A comparison of FIG.  8  and  FIG. 9  illustrates that the primary leveling is performed by the first two rows of tines. The tines  60  of the third and fourth rows function primarily to break up clods and to firm the soil. 
   A rotating basket or “rotary firming wheel” could perform the firming and clod reduction functions of the last two rows of tines. Referring now to  FIGS. 11 and 12 , a harrow  224  is illustrated that is identical to the harrow  24  of the first embodiment except for the fact that the last two rows of tines are replaced with a rotary firming wheel  400  configured to perform the clod reduction and soil firming function. Elements of the harrow  224  corresponding to elements of the harrow  24  are designated by the same reference numerals, incremented by  200 . Harrow  224  therefore includes three harrow sections  226 ,  228 , and  230 , each of which comprises a plurality of rows of tines  260  mounted on tine bars  262 . The tine bars  262  are supported on support arms  264  coupled to the cultivator  22  by a hitch  266 . 
   Still referring to  FIGS. 11 and 12 , a preferred rotary firming wheel assembly  400  includes a rotating basket  402  mounted on spaced brackets  404 ,  406 . Each basket  402  may be formed from any structure or combination of structures that engage the ground so as to break up clods and firm the soil without unnecessarily compacting the soil. 
   The basket  402  of each rotary firming wheel assembly  400  is mounted to the associated harrow section  226 ,  228 ,  230  via a pair of transversely spaced, longitudinally extending mounting arms  410  and a corresponding pair of coil spring flex systems  412 . The lower ends of both mounting arms  410  are connected to a common transverse link  414  that is connected at its ends to the mounting brackets  404 ,  406 . The upper end of each mounting arm  410  is pivotably connected to one end of a plate  416  of the coil spring flex system  412 . The plate  416  is generally triangular, being pivotably mounted on an associated tow arm  300  at a central position thereof and having front and rear ends. The upper end of each mounting arm  410  is connected to the rear end of the associated plate  416 . A spring  418 , connected to the front end of the plate  416  and to a spring support bracket  420  on a tow arm  300 , biases the plate  416  and the mounting arm  410  to a position maintaining a firm contact between the crumbler wheel assembly  400  and the ground. 
   As discussed briefly above, each harrow section is configured to be hitched to the cultivator  22  by a floating hitch arrangement. The floating hitch arrangement permits substantial float of the harrow assembly of that section relative to the cultivator in order to accommodate changes in ground topography. It also maintains a parallel relationship between the harrow assembly and the portion of the harrow that is towed by the cultivator or other towing implement or prime mover. (The harrow assembly of a particular harrow section of the first preferred embodiment comprises the tines  60 , the tine bars  62 , the support arms  64 , and any other structures that move with these structures as a unit). The floating hitch arrangement also is configured to permit each harrow section to pivot relative to the cultivator  22  or other towing implement. The same floating hitch arrangement can be used for both the harrow  24  of the first embodiment and the harrow  24  of the second embodiment. It will therefore be described in conjunction with the first embodiment, it being understood that the discussion applies equally to the second embodiment, and that the hitch arrangement is usable with other types of harrows as well. 
   While the desired effects could be obtained via a variety of structures, they preferably are obtained via a combination of a floating hitch and a four-bar linkage assembly, preferably a parallelogram linkage assembly  90 . Two floating hitches and the associated parallelogram linkage assemblies  90  are preferably provided for each harrow section  26 ,  28 ,  30 . 
   Each floating hitch assembly includes a longitudinally extending tow arm  100  and the hitch  66 . The hitch  66  takes the form of a bracket rigidly affixed to the cultivator  22 . The tow arm is mounted on the bracket so as to be pivotable about a transversely extending, generally horizontal pivot axis. Referring to  FIGS. 5 ,  13 , and  14 , each bracket of the preferred embodiment includes a pair of side plates  92  that are connected to one another by pins  94  so as to form a channel there between for receiving the end of the associated tow arm  100 . The plates  92  are notched at their front ends to form an opening for receiving the drawbar of the cultivator  22 . A clamp arrangement, including a clamp plate  96  and a clamp bolt  98 , is movable into position after the opening engages the drawbar to rigidly clamp the hitch  66  to the drawbar. 
   Referring to  FIG. 15 , the tow arm  100  is pivotably connected to the hitch  66  by a pivot pin  102  extending through the side plates  92  and through the front end of the tow arm. Tow arm pivoting is limited by a channel member  104  that is welded or otherwise affixed to the top of the plates  92  so as to form a stop for the upper surface of the tow arm  100 . The degree of tow arm pivoting movement or “float” permitted by the hitch  66  can be determined by, e.g., setting a desired inclination of the upper surface of the channel member  102  relative to the horizontal. 
   The parallelogram linkage assembly  90  couples the tow arm  100  to an underlying support arm  64  of the harrow section  30  so as to permit relative vertical movement between the support arm  64  and the tow arm  100  while retaining a parallel relationship therebetween. Preferably, the tow arm  100  and support arm  64  each form parts of the parallelogram linkage assembly  90 , hence requiring only the use of two additional links  106  and  108  to complete the parallelogram linkage assembly. Two such links are provided, one at the front end of the support arm  64 , and one at an approximate midpoint of the support arm. Referring to  FIG. 5 , each link  106  and  108  is generally C-shaped in transverse cross-section, with the center leg of the “C” being cut-out at its upper and lower ends so as permit unobstructed pivoting movement of the links  106 ,  108 , tow arm  100 , and support arm  64  relative to one another. The upper cut-outs form clevis mounts for pivotably coupling the upper ends of the links  106 ,  108  to the tow arm  100  via upper pivot pins  110 . The lower cut-outs form clevis mounts for pivotably coupling the lower ends of the links  106 ,  108  to the support arms  64  via lower pivot pins  111 . The pins  111  may double as hinge pins  72  if the holes in the links  106  and  108  properly align with the hinges  70 . 
   Still referring to  FIGS. 13-15 , each harrow section  26 ,  28 ,  30  is biased downwardly against the ground by a pair of tensioner assemblies  114 , one of which cooperates with each hitch  66 . The tensioner assembly  114  includes a spring  116  that generates the biasing force and a chain  118  that transmits the biasing force of the spring  116  to an associated support arm  64  of the harrow section. The spring  116  is hooked to the chain  118  at its rear end and to a clevis pin  120  at its front end. The chain  118  is hooked to the spring  116  at its front end and to a pin  121  on a slide plate  122  of the rake angle adjust mechanism at its rear end. 
   The hitch  66  and parallelogram linkage  90 , in combination, permit the harrow  24  to follow undulations in ground topography independently of the cultivator  22 . In addition, if the harrow section (e.g., section  30 ) encounters obstructions such as logs or boulders as the implement  20  is traversing the field, the tow arms  100  of that section pivot relative to the hitch  66  to allow the harrow section  30  to move independently of the cultivator  22  while maintaining a parallel relationship between the harrow assembly and the tow arms  90 . Variations in tow arm to ground spacing are accommodated by swinging of the tow arms  100  about the links  106  and  108  of the parallelogram linkage assembly  90  (compare  FIG. 13  to FIG.  15 ), thereby maintaining a desired tine penetration depth and negating the need to adjust rake angle or some other aspect of harrow operation every time the operator changes cultivator height. This ability to float also maintains the tine penetration depth despite changes in cultivator penetration depth. 
   The automatic adjustment provided by the parallelogram linkage assembly  90  permits the tines  60  to continue to penetrate the ground even if the sweep  42  of the shank assembly  38  are raised just above the surface of the ground, as commonly occurs when the operator makes a turn at the end of a row. The harrow  24  therefore levels the tire tracks during a turning operation. 
   As discussed briefly above, the rake angle of the tines  60  is determined by the engagement of the tine bars  62  with stops  88 . This angle can be adjusted in a simple and convenient manner simply by moving the stops  88  longitudinally of the harrow section, hence varying the distance between the stops  88  and vertical planes containing the hinge pins  72 . Conveniently, the rake angles for all rows can be adjusted simultaneously and uniformly through the actuation of a single tine slide on each of the support arms  64 . As best seen in  FIGS. 6 and 16 , each tine slide comprises a unitary steel slide plate  122  extending through the channel formed by the associated n-shaped support arm  64 . An access point is provided on the rear end portion of the slide plate  122  to facilitate power or manual actuation of the slide plate  122 . In the illustrated embodiment, the access point comprises a handle  123  formed from an opening in a rear end portion of the slide plate  122 . The handle  123  protrudes sufficiently beyond the rear end of the support arm  64  to provide manual access to the handle  123 , even when the slide plate  122  is in its forward most position. The stops  88  are formed integrally with and extend downwardly from the remainder of the slide plate  122 . The slide plate  122  is retained in the support arm  64  by the hinge pins  72  and by a clevis pin  124  located at the rear of the support arm  64 . The hinge pins  72  extend through elongated slots  126  in the slide plate  122  so as to prevent vertical movement of the slide plate  122  relative to the support arm  64  while permitting relative longitudinally sliding movement therebetween. The clevis pin  124  extends through a rear hole  128  in the slide plate  122  and a selected one of a plurality (3 in the illustrated embodiment) of corresponding holes  130 ,  132 , and  134  in the support arm  64 . Hence, the rake angle of all of the tines  60  on a given harrow section can be adjusted simply by removing the clevis pins of both slide plates  122 , grasping the handles  123 , and moving each slide plate  122  from a first position in which the hole  128  in the slide plate  122  is aligned with one of the holes  130 ,  132 , or  134  in the support arm  64  to a second position in which the hole is aligned with another hole  130 ,  132 , or  134  in the support arm  64 . The clevis pin  124  is then reinserted through the aligned holes to lock the slide plate  122  in its adjusted position. 
   The connection point of the spring tensioner assembly  114  to at least one of the hitch  66  and the slide plate  122  preferably is adjustable to maintain a constant tension on the harrow assembly despite movement of the slide  122  relative to the hitch  66  during a rake angle adjustment operation. In the illustrated embodiment, this adjustment is made possible by providing several mounting holes  140 ,  142 ,  144  on the hitch plates  92  receiving the clevis pin  120  for the spring  116 . The number of holes in the hitch plates  92  preferably equals the number of holes in the support arm  64  for receiving the clevis pin  124 . In the illustrated embodiment, the clevis pin  120  is placed in the upwardmost hole  140  in the hitch plates  92  when the slide plate  122  is in its forwardmost position as seen in  FIG. 13 , in the intermediate hole  142  when the slide plate  122  is placed in its central position as seen in  FIG. 14 , and is in the lowermost hole  144  when the slide plate  122  is in its rearward most position as seen in FIG.  15 . 
   It is understood that the various preferred embodiments are shown and described above to illustrate different possible features of the invention and the varying ways in which these features may be combined. Apart from combining the different features of the above embodiments in varying ways, other modifications are also considered to be within the scope of the invention. 
   The invention is not intended to be limited to the preferred embodiments described above, but rather is intended to be limited only by the claims set out below. Thus, the invention encompasses all alternate embodiments that fall literally or equivalently within the scope of these claims. 
   It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.