Patent Publication Number: US-9894831-B2

Title: Twin-row planter with tandem driven seed meters

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application is a divisional of application Ser. No. 14/589,508 filed Jan. 15, 2015. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to row-crop planters and, in particular, to a twin-row planter with tandem driven seed meters. 
     BACKGROUND OF THE INVENTION 
     Modern farming practices strive to increase yields of agricultural fields. Yields can be increased by increasing plant populations. Efforts have been made to increase plant populations by planting row crops with narrower row spacing, allowing more rows to be planted in a field, which may require harvesting with special equipment configured for harvesting narrow rows, such as narrow row heads for the harvesting implements. Twin-row planters have been developed that plant seeds as a pair of row segments that are closely width-spaced. Each pair of row segments is spaced from adjacent pairs of row segments at conventional row widths, allowing conventional heads to be used on the harvesting implements. This is typically done by mounting a pair of row units with a corresponding pair of seed meters at each row segment, with the seed meters longitudinally staggered in a forward seed meter and rearward seed meter relationship. Seed meters of twin-row planters are typically also made from components are narrower than in non-twin-row planters, with each of the seed meters separately mounted to the toolbars of the twin-row planters. This longitudinal staggering and relatively narrower component configuration of the paired row units provides the mounting space needed for separately mounting the paired row units and their corresponding pair of seed meter drive systems from a toolbar of the twin-row planter. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a twin-row planter with tandem driven seed meters at a pair of row units at each row segment of a twin-row planter. A tandem drive system may drive the seed meters in a tandem manner with a single transmission assembly simultaneously rotating a pair of seed discs in the pair of seed meters at each respective row unit. This allows the tandem drive system to occupy relatively little space on the twin-row planter, providing enough space so that the pair of row units at each row segment may have full-sized seed meters arranged side-by-side adjacent in transverse alignment with each other, without additional weight from a separate drive system for each seed meter. An indexing system is provided that allows for quickly changing an amount of relative rotational or angular indexing of seed disks inside of the pair of seed meters at the pair of row units of each row segment to control longitudinal spacing between delivery locations of seeds from the seed disks. This allows for driving rotation of the seed disks at an identical rate of rotation while providing adjustability of delivery characteristics to accommodate planting different seed types in different planting sessions with seed disks having different seed pocket spacing(s) on the seed disks, to provide consistent plant spacing after emergence. 
     According to another aspect of the invention, the pair of row units at each row segment of the twin-row planter may be supported from a single head bracket supported by a toolbar of the twin-row planter, with the pair of row units spaced close enough to each other to deliver seeds in first and second planted row segments that can be harvested with a single row segment of a standard-width harvester, for example, with the first and second planted row segments being transversely spaced from each other by between about 5 inches and 10 inches, such as between about 7 inches and 8 inches. 
     According to another aspect of the invention, a twin-row planter is provided with a chassis towable behind a tractor through an agricultural field for planting seeds onto the field during a planting session. Multiple row segments are supported by the chassis. Each of the multiple row segments includes a first seed meter supported at the row segment for singulating seeds for individual delivery onto the field. The seeds are delivered out of the first seed meter in a first planted row segment, with the seeds longitudinally aligned and spaced apart from each other. A second seed meter is supported at the row segment for singulating seeds for individual delivery onto the field in a second planted row segment. The seeds are delivered out of the second seed meter in a second planted row segment, with the seeds from the second seed meter longitudinally aligned and spaced apart from each other and longitudinally staggered with respect to the first planted row segment. A tandem drive system with a transmission assembly delivers power to both the first and second seed meters for singulating and delivering seeds on the first and second planted row segments, respectively. 
     According to another aspect of the invention, transmission assembly may include a shaft assembly with a first shaft segment and second shaft segment engaging and rotating in unison with the first shaft segment. The first shaft segment may deliver power to the first seed meter and the second shaft segment may deliver power to the second seed meter. The first seed meter may further include a first seed disk rotated by the first shaft segment of the shaft assembly inside the first meter to convey individual seeds through the first seed meter for individual delivery onto the field in the first planted row segment. The second seed meter may further include a second seed disk rotated by the second shaft segment of the shaft assembly inside the second meter to convey individual seeds through the second seed meter for individual delivery onto the field in the second planted row segment. 
     According to another aspect of the invention, an indexing system is arranged with respect to the shaft assembly to selectively adjust an angular index position of the seed disks of the first and second seed meters with respect to each other. The indexing system may include an indexing disk hub system having a disk hub configured for adjusting an angular index position of the disk hub with respect to the shaft assembly to correspondingly adjust the angular index position of the seed disks of the first and second seed meters with respect to each other. The indexing disk hub system may include a shaft hub mounted to and rotating in unison with the shaft assembly and a disk hub adjustably mounted to the shaft assembly for rotation in unison with the shaft hub. The disk hub may be movable from a first angular position with respect to the shaft hub to a second angular position with respect to the shaft hub. This allows for adjusting relative positions of seed pockets in the first and second seed disks with respect to each other while rotating in unison with each other during the planting session to change spacing characteristics of the seeds in the first planted row segment relative to the seeds in the second planted row segment. The disk hub may engage a first end surface of the shaft hub, and the indexing system may further include a clamping ring engaging a second end surface of the shaft hub. The clamping ring and disk hub may be configured to loosen and tighten for selectively unclamping and clamping the shaft hub therebetween. This respectively unlocks the indexing disk hub system permitting adjustment of the angular index position of the disk hub with respect to the shaft assembly and locks the indexing disk hub system for locking the disk hub and the shaft assembly into rotational unison with each other. The shaft hub may include slots extending through the thickness of the shaft hub. The slots may define perimeters extending longitudinally across portions of the first and second end surfaces of the shaft hub. Fasteners may extend through the slots of the shaft hub, interconnecting the disk carrier and the clamping ring. The fasteners may be movable the length of the slots to slide along the slot for adjusting of the angular index position of the disk hub with respect to the shaft assembly. 
     According to another aspect of the invention, the indexing system may include an indexing shaft hub system having a first shaft hub connected to the first shaft segment of the shaft assembly and a second shaft hub connected to the second shaft segment of the shaft assembly. The indexing shaft hub system may be configured for adjusting an angular index position of the first and second shaft hubs with respect to each other to correspondingly adjust the angular index position of the seed disks of the first and second seed meters with respect to each other. The indexing shaft hub system may further include a coupler assembly selectively locking the first and second shaft hubs into rotational unison with each other for correspondingly locking the first and second shaft segments of the shaft assembly into rotational unison with each other. The coupler assembly of the indexing shaft hub system may include a pin and multiple bores in the first and second shaft hubs. Each of the multiple bores may be configured to receive the pin for establishing a respective predetermined angular index position of the first and second shaft hubs with respect to each other and a corresponding predetermined angular index position of the seed disks of the first and second seed meters with respect to each other. One of the first and second shaft hubs may be axially movable with respect to the other one of the first and second shaft hubs for adjusting an angular index position of the first and second shaft hubs with respect to each other by withdrawing the pin from a first one of the multiple bores and inserting the pin into a second one of the multiple bores. 
     According to another aspect of the invention, the indexing system may include a multiple-index position seed disk system including a shaft hub mounted to and rotating in unison with the shaft assembly. The shaft hub may include a hub body with lugs extending from the hub body. At least one of the first and second seed disks may include a first set of mounting holes and a second set of mounting holes configured to receive the lugs of the shaft hub to arrange at least one of the first and second seed disks in a first angular index position and a second angular index position, respectively. Each of the first and second seed disks may have a first set of mounting holes with each of the mounting holes of the first set of mounting holes having a first perimeter shape and a second set of mounting holes with each of the mounting holes of the second set of mounting holes having a second perimeter shape. The multiple-index position seed disk system may include a first shaft hub mounted to the first shaft segment of the shaft assembly with the first shaft hub including a hub body with lugs extending from the hub body and having a first perimeter shape configured to receive the mounting holes of the first set of mounting holes to mount a first seed disk at a first angular index position relative to the shaft assembly. A second shaft hub is mounted to the second shaft segment of the shaft assembly. The second shaft hub has a hub body with lugs extending from it, with the lugs having a second perimeter shape configured to receive the mounting holes of the second set of mounting holes to mount a second seed disk at a second angular index position relative to the shaft assembly. In this way, the different shapes of the different sets of mounting holes ensure the disc(s) is mounted in the correct angular index position for the particular seed meter(s). 
     According to another aspect of the invention, at each row segment, the seed meters may be mirror images of each other. Each of the first and second seed meters may include a seed chamber and an air pressure chamber. The seed and air pressure chambers of the first and second seed meters are mirrored with respect to each other about a line of reflection extending in a longitudinal direction between the first and second seed meters. 
     According to another aspect of the invention, the tandem drive system includes a transmission assembly delivering power to a single location at a shaft assembly. The shaft assembly may extend transversely between the first and second seed disks along a common axis of rotation of the first and second seed disks and may deliver power from the transmission assembly to simultaneously rotate the first and second seed disks. This may allow the seed meters to be parallel to each other in transversely aligned, side-by-side, relationship within each of the row segments of the twin-row planter. 
     According to another aspect of the invention, the indexing system is configured to selectively disengage the first and second shaft segments of the shaft assembly to permit relative rotation of the first and second shaft segments of the shaft assembly during an indexing adjustment procedure. The selective disengagement by way of the indexing system also facilitates removal of either one of the meters without having to remove the other. The indexing system is further configured to selectively engage and lock the first and second shaft segments of the shaft assembly into rotational unison with each other with the first and second seed disks angularly indexed with respect to each other at times other than during the indexing adjustment procedure. 
     Other aspects, objects, features, and advantages of the invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such modifications. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout. 
         FIG. 1  illustrates a simplified schematic view of a twin-row planter with tandem driven seed meter in accordance with the present invention; 
         FIG. 2  illustrates a variant of the planter of  FIG. 1 ; 
         FIG. 3  illustrates a simplified schematic view of a row unit meter of the planter of  FIG. 1 ; 
         FIG. 4  illustrates a simplified schematic view of a variant of the row unit meter of  FIG. 3 ; 
         FIG. 5  illustrates a simplified schematic view of another variant of the row unit meter of  FIG. 3 ; 
         FIG. 6  illustrates a side elevation view of a seed meter of the row unit of  FIG. 5 ; 
         FIG. 7  illustrates a side elevation view of a seed meter of the row unit of  FIG. 5 ; 
         FIG. 8  illustrates an exploded isometric view of an indexing system of the present invention; 
         FIG. 9  illustrates a side elevation view of another indexing system of the present invention; 
         FIG. 10  illustrates an end view of a shaft hub of the indexing system of  FIG. 9 ; 
         FIG. 11  illustrated a side elevation of a seed disk of another indexing system of the present invention; 
         FIG. 12  illustrated a side elevation of a disk hub of another indexing system of the present invention; and 
         FIG. 13  illustrated a side elevation of a disk hub of another indexing system of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings and specifically to the simplified schematic representations of  FIGS. 1 and 2 , a twin-row planter  5  is shown with a tandem drive system  7  for driving both seed meters  9  in a pair of row units  11 A,  11 B at each row segment  13  of the planter  5  while facilitating angular indexing coordination of components of the seed meter to optimize twin-row seed placement consistency within staggered planted row planted row segments  12 A,  12 B of singulated seeds in a twin-row  12  delivered by the row units  11 A,  11 B at each row segment  13 , as explained in greater detail elsewhere herein. The planter  5  may be or may include components of planters available from Case IH, such as the EARLY RISER® series planters and/or the twin-row planters such as models Twin-Row 4025A39S, 1225AFF, 1625AFF, and 825A3PM, also available from Case IH. The planter  5  is towed behind a tractor  15  and has a chassis  17  with a frame including a toolbar  19  that supports the multiple row segments  13 , which are substantially identical. Each row segment  13  has a twin-row configuration with its respective pair of row units  11 A,  11 B connected to a single head bracket  21  that is attached to the toolbar  19  through a parallel linkage system (not shown) mounting each row segment  11  to the planter chassis  17 . At each row segment  13 , pair of row units  11 A,  11 B and the respective seed meters  9  are parallel to each other in a transversely aligned, side-by-side relationship with each row unit  11 A,  11 B and its seed meter  9  longitudinally spaced from the toolbar  19  by the same distance. Each row unit  11 A,  11 B has ground-engaging tools (not shown) that may include opening and closing mechanisms such as opener disks and closing disks, respectively, or other ground-engaging tools for opening and closing a furrow. The ground-engaging tools may also include a gauge wheel configured for adjusting furrow depth by limiting soil penetration of the furrow-opening mechanism of the ground-engaging tools while creating a furrow and a press wheel may be arranged to roll over the closed furrow to firm the soil over the seed to further close the furrow and promote favorable seed-to-soil contact. 
     Still referring to  FIGS. 1 and 2 , seed is stored in bulk on the planter  5  in a bulk seed storage system  23  that delivers the storage seed to the row units  11 A,  11 B at each row segment  13 . Referring now to  FIG. 1 , the seed storage system is shown as a central bulk storage system, with bulk fill tanks  25 , that holds the seeds in bulk that will be pneumatically delivered from the bulk fill tanks  25  to the row units  11 A,  11 B at each row segment  13 . Referring now to  FIG. 2 , the seed storage system is shown as an on-row bulk storage system, with on-row bulk fill hoppers  27 , that holds the seeds in bulk that will be gravity fed to the row units  11 A,  11 B at each row segment  13 . Regardless of where the seeds are stored on the planter  5  and how the seeds are delivered to the row units  11 A,  11 B at each row segment  13 , the seed meter  9  at each row unit  11 A,  11 B is configured to singulate and deliver individual seeds to the agricultural field to provide the planted row planted row segments  12 A,  12 B of singulated seeds in each twin-row  12 . The seeds delivered from the first row unit  11 A are deposited onto the field so that they are longitudinally aligned and spaced apart from each other within the planted row segment  12 A, with seed placements represented by the dashed-line circles in the planted row segment  12 A. The seeds delivered from the first row unit  11 B are deposited onto the field so that they are longitudinally aligned and spaced apart from each other within the planted row segment  12 B, with seed placements represented by the dashed-line circles in the planted row segment  12 B. The seeds of the first and second planted row segments  12 A,  12 B are transversely spaced close enough to each other to be harvested with a single row segment of a standard-width harvester. The first and second planted row segments  12 A,  12 B may be transversely spaced from each other by between about 5 inches and 10 inches, such as between about 7 inches and 8 inches. The seeds of the first planted row segment  12 A are longitudinally staggered with respect to the seeds of the second planted row segment  12 B. Adjacent twin-rows  12  of adjacent row segments  13 , which may be defined by longitudinally extending center-lines that extend between the first and second planted row segments  12 A,  12 B, are spaced from each other by distances allowing the twin-rows  12  to be harvested with a single row segment of a standard-width harvester, such as about 30 inches, 24 inches, or other standard row spacing. 
     Referring now to  FIGS. 3-5 , each seed meter  9  includes an internal seed disk  29  with seed pockets  31  for picking up and carrying the individual seeds through the seed meter  9 . The tandem drive system  7  simultaneously rotates both seed disks  29  of the seed meter  9  at each row segment  13  through a seed pool inside of the seed meter  9  to expose the seed pockets  31  to the seeds in the seed pool to pick up the seeds in the seed pockets  31 . Although shown as extending axially through or between opposing surfaces of the seed disk  29 , the seed pockets  31  may extend at least partially into an outer circumferential surface of the seed disk  29 . The seed meters  9  can be purely mechanical-type seed meters  9  or can be pneumatic seed meters  9 , as shown. Pneumatic seed meters  9  are operatively connected to an airflow system  33 . The airflow system  33  may include a positive air pressure source and/or a vacuum source for establishing positive and/or vacuum pressures and corresponding air flows for operation of seed meters  9  at the row units  11 A,  11 B, such as within air pressure chambers of the seed meters  9 . The positive air pressure source and vacuum sources can be known pumps, fans, blowers, and/or other known airflow system components. When the seed storage system  23  is configured with a central bulk storage system ( FIG. 1 ), the airflow system  33  includes a seed conveyance airflow system providing an airflow that entrains the seeds to move the seeds from bulk storage in the bulk fill tanks  25  through seed conduits to the row units  11 A,  11 B, such as to mini-hoppers (not shown) that feed the seed meters  9 . When the seed meters  9  are positive pressure pneumatic seed meters  9 , the airflow system  33  is configured to provide a positive airflow and a corresponding positive pressure within the seed meters  9  to push seeds into and hold the seeds in the seed pockets  31  of the seed disks  29  by positive pressure through introducing pressurized air into the seed meters  9 . When the seed meters  9  are vacuum pressure pneumatic seed meters  9 , the airflow system  33  is configured to provide a vacuum airflow and a corresponding negative pressure within the seed meters  9  to pull and hold the seeds in the seed pockets  31  of the seed disks  29  by vacuum pressure introduced into the seed meters  9  by evacuating air out of the seed meters. 
     Referring now to  FIGS. 3-5 , each seed meter  9  has a housing  35  that includes interconnected covers, shown as a seed-side cover  37  and a vacuum-side cover  39  that collectively enclose the interior of the seed meter  9  and cover the seed disk  29 . The seed-side cover  37  is arranged parallel to and spaced from the seed disk  29 . A seed reservoir  41  in which the seed pool collects is defined in the space between the seed-side cover  37  and the seed disk  29 . A seed inlet  43  extends through the seed-side cover  37  to define a passageway as an entry point allowing seeds to enter the seed reservoir  41  from the bulk seed storage system  23  ( FIGS. 1 and 2 ). The vacuum-side cover  39  is arranged parallel to and spaced from the seed disk  29 , on the other side of the seed disk than the seed-side cover  37 . An air pressure chamber shown as vacuum chamber  45  in which the vacuum pressure is created in the housing  35  is defined in the space between the vacuum-side cover  39  and the seed disk  29 . A vacuum inlet  47  extends through the vacuum-side cover  39  to define a passageway through which air can flow out of the housing  35  to establish vacuum pressure inside the seed meter  9 . A seed tube  49  extends from an outlet  51  of the housing  35 . The seed tube  49  receives seeds that are released from the seed disk  29  through the outlet  51  and directs the seed to the soil. 
     Referring now to  FIGS. 3 and 4 , the seed meters  9  are shown as mirror images of each other. The components and segments of the seed meters  9  of the row units  11 A,  11 B including the seed disks  29 , the seed reservoirs  41 , and the vacuum chambers  45  are mirrored with respect to each other about a line of reflection extending in a longitudinal direction between the seed meters  9  of the of the row units  11 A,  11 B. Referring now to  FIG. 3 , the seed reservoirs  41  of the seed meters  9  of the row units  11 A,  11 B are arranged facing each other. A shared seed inlet duct  53  defines a T-shaped or split outlet body with a single duct inlet  55  that is operably connected to components of the bulk seed storage system  23  to direct seeds through the seed inlet duct  53  to the seed reservoirs  41  of both seed meters  9  of the row units  11 A,  11 B at each row segment  13 . Referring now to  FIG. 4 , the vacuum chambers  45  of the seed meters  9  of the row units  11 A,  11 B are arranged facing each other. A shared vacuum inlet duct  57  defines a T-shaped or split outlet body with a single duct inlet  59  that is operably connected to the airflow system  33  to draw air out of and create a vacuum pressure within the vacuum chambers  45  of both seed meters  9  of the row units  11 A.  11 B at each row segment  13 . 
     Referring now to  FIG. 5 , instead of being mirror images of each other, the seed meters  9  are shown arranged with the same general side-to-side layouts. Referring now to  FIGS. 5-7 , the vacuum inlet  47  is arranged at different locations on the vacuum-side cover  39  on the two seed meters  9  of the row units  11 A,  11 B. The vacuum inlet  47  of the seed meter  9  of row unit  11 A is arranged relatively lower on the seed meter  9 , closer to the seed tube  49  ( FIG. 6 ). The vacuum inlet  47  of the seed meter  9  of row unit  11 B is arranged relatively higher on the seed meter  9 , further from the seed tube  49  ( FIG. 7 ). The clocked or misaligned relationship of the row unit  11 A seed meter  9  vacuum inlet  47  and the row unit  11 B seed meter  9  vacuum inlet  47  provides sufficient clearance for a vacuum line or hose (not shown) to extend between the seed meters  9  of the row units  11 A,  11 B. 
     Referring again to  FIGS. 3-5 , the seed disks  29  of each seed meter  9  are driven into rotation by the tandem drive system  7  that includes an indexing system  61  that is configured to facilitate angular indexing coordination of the seed disks  29  to provide a desired predetermined seed delivery pattern of the planted row planted row segments  12 A,  12 B at each twin-row  12 . After the seed disks  29  are indexed with respect to each other during an indexing adjustment procedure, explained in greater detail elsewhere herein, the tandem drive system  7  provides consistent delivery characteristics of the seeds from the seed meters  9  of the row units  11 A,  11 B by simultaneously delivering power to and rotating the seed disks  29  in unison with each other through a common power flow path. 
     Still referring to  FIGS. 3-5 , the tandem drive system  7  includes a transmission assembly  63  selectively delivering power to the seed meters  9  of the row units  11 A,  11 B as controlled by a tractor control system and/or planter control system, which can include an industrial computer or, e.g., a programmable logic controller (PLC), along with corresponding software and suitable memory for storing such software and hardware including interconnecting conductors for power and signal transmission for controlling electronic, electro-mechanical, and hydraulic components of the seed meters  9  and tandem drive system  7  and other components of the planter  5 . The transmission assembly  63  is shown with mechanical chain drives  65  that deliver rotating driving power from a rotating shaft  67 . The shaft  67  is driven to rotate from the ground through movement of the planter  5 , such as by a traction-drive-type drive wheel, ground-engaging drive sprocket, or may be rotated by a motor such as an electric motor, pneumatic motor, or hydraulic motor. Clutches  69  are controlled by the control system to engage and disengage for selectively transmitting rotation of the shaft  67  into movement of chains  71  which rotate sprockets that are attached to and rotate a shaft assembly  73  that drives rotation of a pair of disk hubs  74  mounted to the shaft assembly  73  and that support the seed disks  29  such that rotation of the shaft assembly  73  rotates both seed disks  29 . Clutches  69  may be, for example, air clutches or electromechanical clutches, configured to selectively transmit rotation of or prevent transmission of rotation of the shaft(s)  67  to the shaft assembly  73 , coupling or uncoupling power between the shaft(s)  67  and the shaft assembly  73  and thus to the seed disks  29 . 
     Still referring to  FIGS. 3-5 , the shaft assembly  73  includes a first shaft segment  73 A rotating the seed disk  29  in the seed meter  9  of the first row unit  11 A and a second shaft segment  73 B rotating the seed disk  29  in the seed meter  9  of the second row unit  11 B. During a planting session, the first and second shaft segments  73 A,  73 B are locked into rotation unison with each other. When the first and second shaft segments rotate in unison with each other, the seeds released from the first and second row units  11 A,  11 B are delivered with seed spacing that is intra-row consistent within each of the planted row segment  12 A,  12 B and inter-row consistent between the seeds in the first planted row segment  12 A and the second planted row segment  12 B. The intra-row seed and plant spacing is established primarily by the spacing between seed pockets  31  of the seed disks  29 . The inter-row seed and plant spacing is established primarily and can be adjusted by the indexing system  61 . The indexing system  61  allows for adjusting the longitudinal spacing of the seed positions of the planted row segments  12 A,  12 B to achieve predetermined spacing characteristics by facilitating arranging the seed disks  29  in predetermined angular index positions with respect to each other. The predetermined angular index positions may be discrete positions of components of the indexing system  61  that provide corresponding amounts of angular indexing of the seed disks  29  based on the type of seed being singulated by the seed disks  29  and, for example, spacing of the seed pockets  31  in the seed disks  29  and thus seed placement in the planted row segments  12 A,  12 B of each twin-row  12 . 
     Referring now to  FIG. 8 , the indexing system  61  is shown with an indexing disk hub system  75  that is configured to support the disk hub  74  for adjustable movement relative to the shaft assembly  73  during the indexing adjustment procedure and then re-locks the disk hub  74  into rotational unison with the shaft assembly  73 . The disk hub  74  has a hub body  77  that may be plate-like with a circular outer perimeter shape with opposite first and second end surfaces  79 ,  81  facing respectively toward and away from the seed disk  29 , a central portion of which is shown in  FIG. 3 . The disk hub  74  has lugs  83  extending from the end surface  79  that faces the seed disk  29 . Lugs  83  are configured to support the seed disk  29  by fitting into mounting holes  84  of the seed disk  29 . Each lug  83  is a perimeter shape extending collectively around first and second segments of the lug  83 . The first segment of the lug  83  defines a main segment  85  of the lug  83  through which a bore  87  extends and that is, from an end view, generally circular. A second segment of the lug  83  defines a finger segment  89  that is, from an end view, generally elongate and extends tangentially away from the main segment  85  of the lug  83 . A central bore  91  extends entirely through the hub body  77  at its central axis and is configured to concentrically accommodate shaft assembly  73 , such as the first and/or second shaft segment  73 A,  73 B therein. As shown, the shaft assembly  73  is concentrically housed within the central bore  91  of the disk hub  74  and can rotate relative to the shaft assembly  73 . Relative rotation of the disk hub  74  upon the shaft assembly  73  is restricted by the interaction of disk hub  74  and a shaft hub  93  that is fixed with respect to the shaft assembly  73 . The shaft hub  93  has a hub body  95  that may be plate-like with a circular outer perimeter shape with opposite first and second end surfaces  97 ,  99  facing respectively toward and away from the seed disk  29 . The shaft hub  93  has a central bore  101  that extends entirely through the hub body  95  at its central axis and is configured to concentrically accommodate shaft assembly  73 . Shaft hub fixing bores  103  extend radially through the hub body  95  and are aligned with each other on opposite sides of the hub body  95  and a shaft bore  105  extending radially through the shaft assembly  73 . A pin  107  extends through the shaft hub fixing and shaft bores  103 ,  105  to fix the hub body  95  and the shaft assembly  73  to each other, locking the hub body  95  and shaft assembly  73  into rotational unison with each other. Slots  109  extend through the entire thickness of the hub body  95  of the shaft of  93 . Each slot  109  has first and second ends  111 ,  113  and defines an opening that is elongate and curved, generally parallel to the outer perimeter of the hub body  95  between the first and second ends  111 ,  113 . 
     Still referring to  FIG. 8 , the indexing disk hub system  75  includes a clamping ring  115  with a body  117  that may be ring-shaped or generally annular with opposite first and second end surfaces  119 ,  121  facing respectively toward and away from the seed disk  29 . The clamping ring  115  has a central opening  123  through which the shaft assembly  73  extends and lobes  125  extending radially outward from an outer circumferential surface of the body  117 , spaced from each other about a perimeter of the clamping ring  115 . Each lobe  125  has a bore  127  that aligns with the bores  87  of the disk hub lobes  83 . Fasteners  129  (only one shown) extend through the bores  87  of the disk of the lobes  83 , through the shaft hub slots  109  and into and are secured within the clamping ring lobe bores  127 . This provides a stacked arrangement of the indexing disk hub system  75  with the shaft hub  93  sandwiched between the disk hub  74  and the clamping ring  115 , with respective end surfaces of the disk hub  74 , shaft hub  93 , and clamping ring  115  engaging each other. Tightening and loosening the fasteners  129  allows the components of the indexing disk hub system  75  to be locked as a unit against each other or to permit relative movement of the disk hub  74  and clamping ring  115  relative to the shaft hub  93  for adjusting indexing positions of the seed disk  29  during an indexing adjustment procedure. Indexing adjustment movement of the disk hub  74  and clamping ring  115  relative to the shaft hub  93  is limited to the amount of travel permitted by the fasteners  129  along the length of the shaft hub slots  109 , with first and second stop positions defined when the fasteners  129  engage the first and second ends  111 ,  113  of the slots  109 . 
     Referring now to  FIG. 9 , the indexing system  61  is shown with an indexing shaft hub system  131  that is configured to allow for indexing adjustment procedures by adjusting relative angular index positions of the first and second shaft segments  73 A,  73 B with respect to each other. The indexing shaft hub system  131  is a first shaft hub  133  arranged for rotational unison with the first shaft segment  73 A and a second shaft hub  135  arranged for rotation unison with the second shaft segment  73 B. The first and second shaft hubs  133 ,  135  are configured to selectively engage with each other to translate rotation between the first and second shaft segments  73 A,  73 B. Adjusting the relative rotational or angular index positions of the first and second shaft hubs  133 ,  135  when engaged for locking the first and second shaft segments  73 A,  73 B into rotational unison correspondingly changes the relative angular index positions of the first and second shaft segments  73 A,  73 B and the corresponding seed disks  29  with respect to each other. The first shaft hub  133  has a hub body  137  that may be plate-like with a circular outer perimeter shape with opposite first and second end surfaces  139 ,  141  facing respectively toward and away from the second shaft hub  135 . A pin  143  extends from an intermediate portion of the first surface  139  of the hub body  137  toward the second shaft hub  135  for locking the first and second shaft hubs  133 ,  135  to each other. A stub shaft  145  extends from a central portion of the first surface  139  of the hub body  137  toward the second shaft hub  135  for maintaining alignment of the first and second shaft hubs  133 ,  135  and the first and second shaft segments  73 A,  73 B with respect to each other. A collar  147  extends from the second surface  141  of the hub body  137  to facilitate axial movement of the first shaft  133  with respect to the shaft assembly  73 . Collar  147  has a first end  149  attached to a central portion of the first shaft hub  133  and a second end  151  spaced from the first shaft hub  133 . The collar  147  has a circumferential side wall  155  extending around a bore  157  that concentrically receives the first shaft segment  73 A. A slot  159  extends through the circumferential side wall  155  of the collar  147 . Pins  161  extend from an outer surface of the first shaft segment  73 A, with one pin  161  arranged within the slot  159  to define a restricted travel path of the collar  147  and the first shaft  133  is guided by the slot  159  sliding over the pin  161 . 
     Still referring to  FIG. 9 , a biasing arrangement  163  pushes the first shaft hub  133  toward the second shaft hub  135  in a default or resting state that is overcome temporarily during the indexing adjustment procedure. The biasing arrangement  163  includes a pair of flanges  165  with a biasing member shown as a spring  167  mounted concentrically outside of the first shaft segment  73 A between the flanges  165 , pushing the flanges  165  away from each other. The pin  161  shown toward the left-hand side retains the flange  165  shown toward the left-hand side in place on the first shaft segment  73 A. The flange  165  shown toward the right-hand side is attached to the second end  151  of the collar  147 . The flanges  165  hold the spring  167  in compression, which urges the collar  147  and first shaft hub  133  toward the second shaft hub  135 . The second shaft hub  135  has a hub body  169  that may be plate-like with a circular outer perimeter shape with opposite first and second end surfaces  171 ,  173  facing respectively toward and away from the first shaft hub  133 . 
     Referring now to  FIGS. 9 and 10 , bores  175  extend into an intermediate portion of the first end surface  171  of the hub body  169  with openings facing toward the first shaft hub  133  for receiving the pin  143  of the first shaft hub  133  for locking the first and second shaft hubs  133 ,  135  to each other. Referring now to  FIG. 10 , the bores  175  are spaced from each other about the first end surface  171  of the hub body  169 , shown as represented in different positions  175 A,  175 B, and  175 C. Aligning and inserting the pin  143  into the bores  175  at the different positions  175 A,  175 B,  175 C provides different predetermined angular indexing positions of the first and second shaft segments  73 A,  73 B with respect to each other because the first shaft hub  133  is rotationally fixed with respect to the first shaft segment  73 A, and the second shaft hub  135  is rotationally fixed with respect to the second shaft segment  73 B. A central bore  177  extends into a central portion of the first end surface  171  of the hub body  169 , with an opening facing toward the first shaft hub  133 . The central bore  177  is configured to receive the stub shaft  145  for maintaining alignment of the first and second shaft hubs  133 ,  135  and the first and second shaft segments  73 A,  73 B with respect to each other, even when the stub shaft  145  advances toward and regresses away from a bottom wall  179  of the central bore  177  when the first shaft hub  133  is released toward or pulled away from the second shaft hub  135  during the indexing adjustment procedure. 
     Referring now to  FIGS. 11-13 , the indexing system  61  is shown with a multiple-index position seed disk system  181  that is configured to allow for indexing adjustment procedures by adjusting requiring the seed disks  29  ( FIG. 11 ) to mount to the disk hub  74  ( FIG. 12 ) on the first shaft segment  73 A in only a first angular index position and to the disk hub  74  ( FIG. 13 ) on the second shaft segment  73 B in only a second angular index position, providing a predetermined relative amount of angular index between the seed disks  29  in the seed meters  9  of the first and second row units  11 A,  11 B ( FIGS. 3-5 ). Referring now to  FIG. 11 , the seed disk  29  has first and second sets  183 ,  185  of mounting holes  84 . The mounting holes  84  of the first set  183  have a first perimeter shape  187  and the mounting holes  84  of the second set  185  have a second perimeter shape  189 . 
     Referring now to  FIG. 12 , the lugs  83  of the disk hub  74  arranged on the first shaft segment  73 A have a first perimeter shape  191  that corresponds to the first perimeter shape  187  of the first set  183  of mounting holes  84  ( FIG. 11 ) of the seed disk  29 . This permits mounting the seed disk  29  onto the disk hub  74  in the seed meter  9  of the first row unit  11 A in only a first mounting position, with the first set  183  of the mounting holes  84  fit over the lugs  83  with the first perimeter shape  191  ( FIG. 12 ), providing a predetermined angular index position of the seed disk  29  for the first row unit  11 A ( FIGS. 3-5 ). 
     Referring now to  FIG. 13 , the lugs  83  of the disk hub  74  arranged on the second shaft segment  73 B have a second perimeter shape  193  that corresponds to the second perimeter shape  189  of the second set  185  of mounting holes  84  ( FIG. 11 ) of the seed disk  29 . This permits mounting of the seed disk  29  onto the disk hub  74  in the seed meter  9  of the second row unit  11 B in only a second mounting position, with the second set  185  of the mounting holes  84  fit over the lugs  83  with the second perimeter shape  193  ( FIG. 13 ), providing a predetermined angular index position of the seed disk  29  for the second row unit  11 B ( FIGS. 3-5 ). 
     Regardless, the indexing system  61  allows for quickly and accurately changing inter-row spacing characteristics of the seeds in the first planted row segment  12 A and the second planted row segment  12 B ( FIGS. 1 and 2 ). Indexing system  61  does this by facilitating adjustment of relative amounts of rotational or angular indexing of the seed disks  29  based at least in part on the seed type being planted and the configuration of the seed disks  29  for planting a particular type of seed. A desired spacing characteristic of seed placement for the seeds in the first and second planted row segments  12 A,  12 B may be a function of a disk angle of index between the seed disks  29  of the seed meters  9  of the first and second row units  11 A,  11 B and a function of the spacing of adjacent seed pockets  31  of the particular seed disk(s)  29 . A desired disk angle of index of the seed disks  29  of the seed meters  9  of the first and second row units  11 A,  11 B can be 60 degrees plus one-half of a seed angle of index of each seed disk  29 , provided by an angle defined between imaginary straight lines extending from adjacent seed pockets  31  through and converging at an axis of rotation of the seed disk  29 . For example, if imaginary straight lines extending from adjacent seed pockets  31  through and converging at the axis of rotation of the seed disk  29  defines a seed angle of index of 6-degrees, then the disk angle of index of the pair of seed disks  29  at each row segment  13  should be 63 degrees. 
     Many changes and modifications could be made to the invention without departing from the spirit thereof. The scope of these changes will become apparent from the appended claims.