Abstract:
An agricultural planter is provided with forwardly folding wing members that allow conversion of the planter from a laterally extending operating position to a compact transport position. To increase stability for the planter, the draw bar telescopes as the wing members are folded forwardly into the transport position. Brace members interconnect a forward portion of the draw bar and the wing members. As the wing members fold forwardly, the brace members are arranged to cause a rearward portion of the draw bar to extend rearwardly from the forward portion and effect the telescopic action in the draw bar. A draw bar hitch lock linkage is provided to keep the draw bar compacted when the wing members are in the operating position. A hitch lock actuator is tied into the hydraulic system for the movement of the wing members into the transport position to permit the telescopic action of the draw bar in concert with the forward folding of the wing members.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims domestic priority of U.S. Provisional Patent Application Ser. No. 60/108,025, filed on Nov. 12, 1998, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to agricultural implements, including ground working apparatus, such as planters, and transversely elongated tool bars for supporting the ground working devices, and, more particularly, to a forwardly folding tool bar convertible between a wide, transversely extending operating configuration and a narrow, compact transport configuration. 
     The need to till and cultivate soil for the planting and growing of crops has been a long established practice in agriculture. More recently developed tillage implements have provided increased size and complexity to accommodate different types of crops and the tractors that tow the tillage implements to cover larger areas of soil. Increasing concerns for conservation of natural resources have also had an impact on the design of modern tillage implements, increasing the complexity of these implements. Planters of substantially equal transverse width have also been developed to work in conjunction with these tillage implements, or independently. More typically, large planting implements are operatively coupled with air carts to provide a substantial source of seed and fertilizer for the large demand accompanying such large planting implements. 
     Larger tillage and planting implements allow an operator to perform the required tillage operations over a larger area for each pass of the implement, permitting fuel conservation for the tractor and resulting in less compaction of the soil. The increasing levels of sophistication in tillage implements enable low-till and no-till planting techniques to be utilized with greater success. Since low-till and no-till planting techniques are preferably accomplished with a single pass of the implement over the field, the soil is disturbed only once, minimizing moisture loss and the amounts of pesticides, herbicides and fertilizer that are required. Such larger and more complex tillage implements introduce problems that have been heretofore unknown in the arts. 
     For example, an agricultural tractor could pull a planting implement. Adding an air cart or a seed/fertilizer supply cart to the planting implement increases the weight of the combined implement and requires the tractor and operator to be able to control all of the functions of the combined implement as the single pass is made over the field to plant seeds, place fertilizer into the ground at the proper location, and apply appropriate amounts of herbicides and/or pesticides. Furthermore, that combined implement must be transported from field to field, usually over public highways, requiring the combined implement to be converted into a transport configuration that is substantially narrower in width than the preferred operating configuration of the combined implement. 
     It would be desirable to provide a tool bar for a tillage or planting implement with the capability of folding from a wide, trasversely extending operating position to a narrow, compact transport configuration, requiring interacting latches and actuating devices to facilitate the conversion of the tillage implement and to keep the implement in the transport configuration while being towed from one field to another. 
     SUMMARY OF THE INVENTION 
     It is an object of the instant invention to provide a tool bar that is convertible between a wide transverse field operating configuration and a transversely narrow transport configuration. 
     It is another object of this invention to provide a tool bar that pivots in a forward direction to re-orient pivot axes and hydraulic actuators to allow the transversely extending wing members to fold forwardly into a transport configuration. 
     It is a feature of this invention that the wing members fold forwardly instead of rearwardly to reach a transport configuration. 
     It is an advantage of this invention that an air cart or other mechanism can be towed behind the tool bar without interfering with the conversion of the tool bar between field operating and transport configurations. 
     It is still another object of this invention to provide a transport lock mechanism for use with a forwardly folding tool bar apparatus. 
     It is another feature of this invention that the transport lock mechanism and a caster wheel lock mechanism are operatively interconnected to assist in converting the tool bar between field operating and transport configurations. 
     It is another advantage of this invention that the actuation of the transport lock simultaneously effects actuation of the caster wheel lock for the ends of the wing members. 
     It is still another feature of this invention that a single spring biases both the transport lock mechanism and the caster lock mechanism. 
     It is still another advantage of this invention that the spring is operable to bias the wing latch hook into a closed position when the implement is moving into the transport position and is operable to bias the caster lock into a locking position when the implement is moving into the field operating position. 
     It is still another feature of this invention that a single hydraulic cylinder is capable of actuating both the transport lock mechanism and the caster lock mechanism. 
     It is yet another object of this invention to improve stability of the implement when in a forwardly folded transport configuration. 
     It is yet another feature of this invention that the draw bar is telescopic to lengthen when in a folded transport configuration, while providing a shorter draw bar during operation to improve the stability of the implement, particularly when towing a cart behind the implement. 
     It is still another advantage of this invention to provide improved maneuverability of the implement around turns during operation. 
     It is yet another feature of this invention that the implement is provided with a brace interconnecting the pivotable wing members and the draw bar to enhance the stability of the implement in the field operating position, which braces effect the telescoping of the draw bar when the wing members are folded forwardly into a transport configuration. 
     It is yet another advantage of this invention that the telescopic draw bar is provided with a hitch latching mechanism that is cooperable with the transport lock mechanism to release the draw bar for telescopic movement when the implement is folded into the transport configuration. 
     It is yet another advantage of this invention that the telescopic draw bar is lengthened automatically when the implement is placed into a transport position. 
     It is a further object of this invention to provide a mechanism to allow the wing members to float vertically to follow ground undulations when in the field operating position. 
     It is a further feature of this invention to provide an unfold finger that is cooperable with the wing fold hydraulic cylinders when the implement is moving into the field operating configuration to allow the wing fold cylinders to fold the wing members outwardly, but retracted when the implement is placed in the field operating position to allow the wing fold cylinders to move with the floating wing members. 
     It is a further advantage of this invention that the unfold finger is pivotally mounted in a support structure that moves the unfold finger into an interfering position with respect to the opposing wing fold hydraulic cylinders when the actuators are retracted for folding the wings forwardly, and operates in conjunction with the actuators when the wings are unfolded rearwardly to a laterally extending field working position, and is retracted into a non-interfering position when the tool bar is rotated downwardly into an operative position. 
     It is still a further object of this invention to provide a lock mechanism for the tool bar to fix the tool bar in a forwardly rotated position. 
     It is still a further feature of this invention that the tool bar lock mechanism is actuated by a cable apparatus that is coupled to the wing members to allow a spring loaded clasp member to be moved into an unlocking position when the wing members are unfolded rearwardly into a field operating configuration. 
     It is yet a further object of this invention to provide a method of converting an agricultural implement between a field operating position and a transport position by first forwardly pivoting the tool bar and then forwardly pivoting laterally extending wing members against the draw bar. 
     It is still a further object of this invention to provide a lift assist mechanism for implements having a large lateral working width so that the tool bar can be rotated into an intermediate transport position before effecting a forward folding of the wing members. 
     It is yet a further feature of this invention that the remote distal ends of the opposing wing members are supported by the lift assist mechanism as the tool bar is rotated toward the intermediate transport position. 
     It is still another advantage of this invention that the weight of the tool bar on the tool bar actuators is lessened to enhance the pivotal movement of the tool bar into an intermediate transport position. 
     It is a further advantage of this invention that the lift assist mechanism supports the distal end of the wing members until the center of gravity is such that the tool bar actuators can effectively pivot the entire tool bar. 
     It is a further feature of this invention that the lift assist mechanism supports the distal end of the wing members until approximately 60 degrees of rotation has been attained by the tool bar. 
     It is still a further advantage of this invention that the lift assist mechanism enables conventional four inch diameter hydraulic actuators to rotate a 60 foot wide tool bar. 
     It is still another advantage of this invention that the lift assist mechanism alleviates stress in the wing folding joints on 60 foot tool bars. 
     It is yet a further object of this invention to provide an interlock between the lift assist mechanism and the transport lock for the tool bar so that the tool bar is not released for rotation until the lift assist mechanism has been oriented into a desired position. 
     It is still a further feature of this invention that a cable interconnects the lift assist mechanism and the tool bar transport lock to effect an unlatching of the tool bar transport lock when the lift assist mechanism is properly oriented. 
     It is still another object of this invention to provide a hydraulic system for effecting the conversion of the implement between a field operating position and a transport position. 
     It is yet a further advantage of this invention that the hydraulic system for converting the implement between field operating and transport positions is powered by conventional tractor hydraulic remotes. 
     It is still another feature of this invention that the hydraulic system incorporates a selector valve to switch the hydraulic circuit between a fold circuit and a planter drive circuit. 
     It is yet another feature of this invention that the hydraulic system includes a second circuit for controlling the operation of the rotation of the tool bar and lift assist mechanism once the first circuit has been switched into a mode for folding and unfolding the implement. 
     These and other objects, features and advantages can be accomplished according to the instant invention by an agricultural planter provided with forwardly folding wing members that allow conversion of the planter from a laterally extending operating position to a compact transport position. To increase stability for the planter, the draw bar telescopes as the wing members are folded forwardly into the transport position. Brace members interconnect a forward portion of the draw bar and the wing members. As the wing members fold forwardly, the brace members are arranged to cause a rearward portion of the draw bar to extend rearwardly from the forward portion and effect the telescopic action in the draw bar. A draw bar hitch lock linkage is provided to keep the draw bar compacted when the wing members are in the operating position. A hitch lock actuator is tied into the hydraulic system for the movement of the wing members into the transport position to permit the telescopic action of the draw bar in concert with the forward folding of the wing members. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages of this invention will be 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 schematic right side perspective view of a 60 foot version of a tool bar for a planting implement incorporating the principles of the instant invention, only the pivotable right wing member of the tool bar being depicted along with the lift assist mechanism being depicted as supported on the wing member; 
     FIG. 2 is a top plan view of the portion of a 40 foot version of the planting implement similar to that depicted in FIG. 1, but without the lift assist mechanism, with a plurality of sub-frames mounted on the tool bar on which tillage and/or planting devices are mounted; 
     FIG. 3 is a partial side elevational view of the 40 foot version of the planting implement of FIG. 2 with the tool bar partially rotated, a representative tillage and/or planting device being depicted; 
     FIG. 4 is a schematic right side perspective view of the 60 foot version of the tool bar shown in FIG. 1 with the tool bar being partially rotated to initiate the conversion of the implement into the transport position; 
     FIG. 5 is a schematic right side perspective view of the 60 foot version of the tool bar similar to that of FIG. 4, but with the tool bar completely rotated into an intermediate transport position; 
     FIG. 6A is a side elevational view of the 60 foot version of the planting implement of FIGS. 4 and 5 in the field operating position, the lift assist mechanism being shown extending rearwardly of the tool bar; 
     FIG. 6B is a side elevational view of the planting implement shown in FIG. 6A with the tool bar partially rotated to initiate the conversion of the implement from the operating configuration to the transport configuration, the lift assist mechanism supporting the lateral extremities of the wing members, the position of the tool bar also corresponds to the headland position for the planting implement; 
     FIG. 6C is a side elevational view of the planting implement shown in FIGS. 6A-B with the tool bar rotated to a position where most of the weight of the tool bar is over the caster and fixed wheels of the tool bar, the lift assist mechanism still supporting the lateral extremities of the wing members; 
     FIG. 6D is a side clevational view of the planting implement shown in FIGS. 6A-C with the tool bar fully rotated, the lift assist mechanism being lifted off the ground from the position depicted in FIG. 6C; 
     FIG. 7 is a side elevational view of the implement shown in FIGS. 6A-D with the tool bar fully rotated into an intermediate transport position; 
     FIG. 8 is a schematic right side perspective view of the 60 foot version of the tool bar similar to that of FIGS. 1-3 with the representative right wing pivoted into the transport position and the wing member locked into the transport position by a locking mechanism mounted on the draw bar; 
     FIG. 9 is an enlarged right side perspective view of the forward end of the draw bar to depict the locking mechanism fixing the representative right wing member in the transport position; 
     FIG. 10 is an enlarged front perspective view of the mechanism at the end of wing members providing a combined transport and caster lock; 
     FIG. 11 is an enlarged right side elevational view of a portion of the draw bar of a planting implement incorporating a telescoping hitch latch mechanism; 
     FIG. 12 is a right side elevational view of a portion of the draw bar similar to that of FIG. 11, but with the hitch latch moved to an open position; 
     FIG. 13 is a partial, upper right perspective view of the hitch latch mechanism shown in FIGS. 11-12; 
     FIG. 14 is a partial, lower left perspective view of the hitch latch mechanism seen in FIG. 13; 
     FIG. 15 is a right side elevational view similar to that of FIG. 12, but with phantom lines depicting the abutment and lost motion in the actuator crank; 
     FIG. 16 is an enlarged right side perspective view of the intersection of the draw bar with the tool bar of the planting implement shown in FIG. 1 with the tool bar being in an operative position; 
     FIG. 17 is a right front perspective view of the intersection of the draw bar with the tool bar, similar to that of FIG. 16; 
     FIG. 18 is a right front perspective view of the intersection of the draw bar with the tool bar as shown in FIG. 17, but with the tool bar rotated to initiate the conversion of the implement from the operating configuration to the transport configuration; 
     FIG. 19 is a schematic right side perspective view of a portion of a planting implement similar to that of FIG. 1, but showing an alternative embodiment with a lift assist mechanism; 
     FIG. 20 is an enlarged right front perspective view of the portion of the implement of FIG. 18 where the draw bar intersects with the tool bar; 
     FIG. 21 is a right front perspective view similar to FIG. 20, but with the tool bar rotated to initiate the conversion of the implement from an operating configuration to a transport configuration; 
     FIG. 22 is a schematic diagram of the hydraulic circuit for the folding of the implement between the operating and transport configurations, as well as actuation of the hitch latch and transport latch actuators; 
     FIG. 23 is a schematic diagram of the hydraulic circuit for controlling the rotation of the tool bar, including actuators for the lift assist mechanism for the 60 foot version of the planting implement; and 
     FIG. 24 is logic flow diagram for the operation of the control system for automating the sequencing of the field markers when the planting implement is turned at the headlands. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1-9, a planting implement incorporating the principles of the instant invention, can best be seen. Left and right references are used as a matter of convenience and are determined by standing at the rear of the implement facing the tractor to which the implement is to be connected and, therefore, the normal direction of travel. One skilled in the art will readily realize that the planting implement incorporates a tool bar of the folding kind that extends laterally to each side of a centerline for distances of 15 to 30 feet or more. This folding planting implement  10  is provided with left and right wing assemblies  20  on which are mounted a plurality of gang sub-frames  18  on which are mounted tillage and/or planting devices  19   a  to work the ground and plant seeds, fertilizer, etc as the implement  10  passes over the ground. For purposes of clarity, only the right wing assembly  20  is depicted in the drawings in schematic form. The left wing assembly would be a mirror image of the right wing assembly  20 . 
     The planting implement  10  includes a draw bar  11  supported by ground engaging wheels  12  mounted on a transverse cross frame member  13 . The draw bar  11  is conventionally mounted to a tractor (not shown) to provide motive power for pulling the implement  10  across the field. The tractor (not shown) also provides a source of hydraulic fluid under pressure to power the operation of the hydraulic devices on the implement  10 , as will be described in greater detail below. The implement  10  further includes a transversely extending tool bar  15  that is pivotally connected to the draw bar  11  to rotate about a transverse pivot axis  14 , best seen in FIGS. 16-18. The tool bar  15  is articulated and includes a center section  16  and left and right wing members  21  pivotally connected to the center section  16  for pivotal movement relative thereto about a wing pivot axis  17 , as will be described in greater detail below. 
     Referring now to FIGS. 1 and 2, the planting implement  10  in the normal field operating configuration is depicted schematically. The draw bar  11  is oriented longitudinally for connection to the tractor (not shown) providing motive power. The tool bar  15  is rolled back into a rearward pivoted position from which the planting mechanisms  19   a  extend rearwardly to trail the tool bar  15 . The left and right wing members  21  are transversely extended in a linear manner to the full operating width. A brace  22  interconnects the draw bar  11  and a bracket  23  projecting forwardly (in the normal operating configuration shown in FIG. 1) of the wing members  21 . A transport lock mechanism  30  is mounted on the end of the wing member  21  and projects upwardly therefrom. The remote ends of the wing members  21  is supported by a caster wheel  25  that will be described in greater detail below. 
     Referring now to FIGS. 3-7, the beginning of the conversion of the planting implement from the normal operating configuration to a narrow transport configuration can best be seen, the 60 foot version of the implement  10  with the lift assist mechanism  18  being schematically depicted being shown in FIGS. 4-7. A hydraulic cylinder  27  (best seen in FIG. 16) interconnecting the draw bar  11  and the center section  16  of the tool bar  15  is actuated to cause the tool bar  15  to pivot forwardly about the pivot axis  14 . All three sections of the tool bar  15 , the center section  16  and the left and right wing members  21 , rotate in unison. The lift assist mechanism helps support the distal ends of the wing members, as will be described in greater detail below. 
     The bracket  23  rotates downwardly toward the ground as the tool bar rotates upwardly and forwardly, effecting a pivotal movement of the connected brace  22 . The bracket  23  includes a generally horizontal joint that is positioned in general alignment with the pivot axis  14  about which the tool bar  15  pivots so that the elevation of the joint remains relatively constant as the bracket  23  is rotated with the tool bar  15 . As a result, the brace  22  remains generally stationary during the transition of the tool bar from the field operating position shown in FIG. 6A to the intermediate transport position of FIG.  6 D. The complete rotation of the tool bar  15  is best seen sequentially in FIGS. 6A-6D. The transport lock mechanism  30  is oriented forwardly for engagement with the draw bar  11 , as will be described in greater detail below. Once the tool bar  15  is completely pivoted forwardly and the wing members  21  are folded forwardly, the lift assist cylinders  28  can be actuated to effect an upward pivotal movement of the lift assist mechanism  18  relative to their respective mounting brackets  19  to lift the support wheel  18   a  off the ground, as shown in FIG.  8 . 
     With particular reference to FIGS. 17 and 18, one skilled in the art can see that the wing fold hydraulic cylinders  29  are positioned on top of the tool bar  15  when in the normal operating configuration, but are positioned in front of the tool bar  15  after the tool bar  15  has been fully pivoted forwardly to the position shown in FIGS. 6D,  7  and  18 . Actuation of wing fold hydraulic cylinders  29 , best seen in FIGS. 8 and 18, will then cause the wing members  21  to fold forwardly. As shown in FIGS. 8 and 9, the transport lock mechanism  30  will ultimately engage a latch retainer bar  36  mounted on the draw bar  11  to fix the wing member  21  in a transport position. The caster wheels  25  are released to pivot as necessary to finally orient parallel to the wing member  21  when in the transport position and remain castering to accommodate the turning of the implement  10  around turns, when in the transport position. 
     With particular reference to FIGS. 9 and 10, one skilled in the art will see that the transport lock mechanism  30  includes a latching hook  31  pivotally mounted on a support bar  32 . A wing latch hydraulic cylinder  33  controls the pivotal movement of the latch hook  31 . A first abutment  34  fixed to the support bar  32  limits the pivotal movement of the latch hook  31  in a closed direction. The latch retainer bar  36  is part of a latch tower  35  mounted in a vertical orientation on the draw bar  11  for proper engagement with the latch hook  31  when the wing member  21  is pivoted into the transport position. Simply, the wing latch actuator (hydraulic cylinder)  33  is pivoted into a closed position against the first abutment  34  to capture the latch retainer bar  36  when the wing member  21  is moved into the transport position. The specific configuration of the latch tower  35  with the generally vertically oriented retainer bars  36  allows the folded wing assemblies  20  to float vertically to move over ground undulations about the now horizontal wing pivot axis  17   b  while remaining latched in the transport position. 
     The wing latch hydraulic cylinder  33  also actuates a caster lock mechanism  40  that controls the castering movement of the caster wheels  25 . When in the normal operating position, the caster wheels  25  need to be locked into a forward direction to keep the left and right wing assemblies  20  in a proper working orientation. The axis which allows the assembly to caster when in the transport position, is horizontal in the field working position and needs to be locked to stabilize the wheel assembly in the field position. When the wing assemblies  20  are in the transport position, the caster wheels  25  are still in a forward direction, but are turned approximately 90 degrees relative to the wing member  21  as compared to the operating position. To make this pivoting movement relative to the wing member  21 , the caster wheels  25  must be unlocked to permit them to caster. 
     The caster lock mechanism  40  includes a crank  42  pivotally mounted on the support bar  32  and connected to the wing latch hydraulic cylinder  33  at one end and to a lost motion link  43  at the other end. A caster lock hook  45  is pivotally mounted on the wing member  21  and has a pin  46  projecting outwardly therefrom for engagement with the slot  44  in the lost motion link  43 . A spring  47  is anchored on the wing member  21  and connected to the pin  46  on the caster lock hook  45  to bias the pivotal movement of the caster lock hook  45  toward engagement with an opening  49  appropriately placed on an otherwise solid disk  48  on the caster wheel  25 . As is described in greater detail below, the spring  47  is also effective to bias the wing latch hook  31  into a closed position when the wing latch actuator  33  is filly retracted to form a solid link between the wing latch hook  31  and the crank  42 . The crank  42  is also engageable with a second abutment  39  that keeps the wing latch hook in an open position when the wing latch actuator  33  is fully extended. 
     In operation, the caster lock mechanism  40  keeps the caster wheel locked in a forward directing orientation when the planting implement  10  is in a normal operating configuration by keeping the caster lock hook  45  engaged with the opening  49  in the caster disk  48 . The biasing spring  47  urges the caster lock hook  45  into the locking engagement with the disk  48 . When the wing latch actuator  33  draws the latch hook  31  back against the first abutment  34 , the wing latch hydraulic cylinder  33  continues its retraction stroke by pulling on the crank  42 , which, in turn, pulls the lost motion link  43  away from the caster lock hook  45  bottoming out the pin  46  in the slot  44 . The continued pulling of the lost motion link  43  overcomes the biasing force exerted by the spring  47  to withdraw the caster lock hook  45  out of the opening  49  in the disk  48 , thereby freeing the caster wheel  25 . 
     Upon the return of the planting implement  10  to the operating  10  configuration, the wing latch actuator  33  extends to rotate the crank  42  and push the lost motion link  43  toward the caster lock hook  45 . The biasing spring  47  pulls the caster lock hook into engagement with the caster disk  48  which will ride on top of the disk  48  until the caster wheel  25  rotates into the proper position for the opening  49  to align with the hook  45 . The pin  46  is free to ride in the slot  44 , while the hook  45  is riding on top of the disk  48 , as the lost motion link  43  is pushed by the actuator  33  to a position corresponding to fill engagement of the hook  45  into the opening  49 . 
     Referring now to FIGS. 11-15, the details of the hitch latching mechanism  50  can best be seen. The draw bar  11  is telescopic to enhance the operating and transport capabilities of the planting implement. With an air cart (not shown) mounted to the rear of the planting implement  10  as is commonly done to provide a supply of seed and fertilizer to the planting devices  19   a , better tracking can be attained for the implement  10  by shortening the draw bar  11  when in the operating configuration, as the implement  10  better follows the tractor, particularly in tight turns, when the hitch is shortened. 
     Accordingly, the draw bar  11  is designed to telescope to a longer length when in the transport configuration to accommodate the forward folding of the wings  21 . The hitch latching mechanism  50  controls the telescopic action of the draw bar  11 . A lower latch member  51  is pivotally supported on the rear portion  11   a  of the draw bar and has a latching tab  52  that is engageable with a transverse bar-like stop member  54  fixed to the forward portion  11   b  of the draw bar. When pivoted into engagement with the stop member  54 , the latching tab  52  prevents the forward portion  11   b  of the draw bar from extending forwardly relative to the rearward portion  11   a.    
     The lower latch member  51  is controlled in operation by a actuation lever  56  pivotally mounted on the right side of the draw bar  11  on the same pivot axis as the lower latch member  51  and connected to a hydraulic actuator  55  pinned to the rearward portion  11   a  of the draw bar. The actuation lever  56  has a crank portion  57  that is engageable with the lower latch member  51  to cause the lower latch member  51  to pivot  10  downwardly away from engagement with the stop member  54 . The crank portion  57  is configured so as to require a predetermined amount of rotation before causing pivotal rotation of the lower latch member  51  for reasons that will become apparent below. The left side of the lower latch member  51  extends upwardly as a spring arm  58  that is connected to a biasing spring  59  anchored on the draw bar  11  rearwardly of the lower latch member  51 . The biasing spring  59  urges the lower latch member  51  into upward pivotal movement that causes engagement with the draw bar  11  and the stop member  54  mounted thereon. Each brace  22  is pivotally connected to the forward portion  11   b  of the draw bar by bracket  24 . 
     The fold sequence includes the appropriate lengthening actuation of the hitch lock actuator  55  to pivot the actuation lever  56  into engagement with the lower latch member  51 , causing the lower latch member  51  to pivot downwardly out of engagement with the stop member  54 . The wing members  21  are then folded forwardly to bring the latch hook  31  of the transport lock mechanism  30  into engagement of the retainer bar  36  on the latch tower  35 . This forward folding movement pushes the brace  22  forwardly against the bracket  24  and, thereby, pushes the forward portion  11   b  of the draw bar forwardly relative to the rearward portion  11   a  and, as a result, lengthening the draw bar  11 . Once the wing assemblies  20  have been latched into a transport position, the hitch actuator  55  can retract to allow the lower latch member  51  to be urged back into engagement with the forward portion  11   b  of the draw bar, so as to be ready to lock the draw bar  11  in the shortened configuration when the wing members  21  are to be unfolded. The latching tab  52  is formed with a cam surface  53  that is positioned in alignment with the stop member  54 . 
     Unfolding the wing assemblies  20  back into their operating position will draw the braces  22  rearward to provide their respective support of the wing assemblies  20 . As the braces move rearwardly, the forward portion  11   b  of the draw bar also retracts rearwardly causing the stop member  54  to engage, ultimately, the cam portion  53  of the lower latch member  51 . The stop member  54  will effectively cause the cam portion  53  of the lower latch member  51  to move downwardly to allow the passage of the stop member  54  rearwardly thereof, after which the lower latch member  51  re-engages the lower stop member  54  fixing the position of the draw bar  51  for the operating configuration. The lost motion feature of the actuation lever  56  allows the lower latch member  51  to deflect downwardly for the passage of the stop member  54 , while the biasing spring  59  urges the upward pivotal movement of the lower latch member  51 . 
     Referring now to FIGS. 16-18, the details of the mechanism for effecting the pivotal rolling of the tool bar  15  can best be seen. The tool bar  15  is pivotally connected to the draw bar  11  by a transverse pivot axis  14 . A pair of hydraulic cylinders  27 , one positioned on either side of the draw bar  11 , control the pivotal movement of the tool bar  15  about the pivot axis  14 . The hydraulic cylinders  27  are connected to the draw bar  11  support structure forming part of the transverse frame  13  and to corresponding fold cranks  26  fixed to the tool bar  15 . When contracted, the hydraulic cylinders  27  pivot the fold cranks  26  and the attached tool bar  15  forwardly about the pivot axis  14 , which is the initiation of the fold sequence. One skilled in the art will recognize that this forward pivoting of the tool bar  15  is also the action taken to raise the planters off the ground at the headlands of the field, which will be described in greater detail below. When extended, the hydraulic cylinders  27  roll the tool bar  15  rearwardly into the operating position. In this operating position, the tool bars  15  need to have the capability to float vertically with changing ground undulations by pivoting about the wing pivot axis  17 . Setting the wing fold cylinders  29  to a float setting would provide float capabilities, but such action requires positive operator input which cannot be relied upon. 
     Each wing fold cylinder  29  is anchored on the corresponding wing member  21  and connected at the opposing end to a wing fold crank assembly  60  including a first crank link  61  pivotally mounted on the wing member  21  and being pivotally connected at the inboard end thereof to a second link member  62  positioned above the center section  16  of the tool bar  15 . Each second link member  62  is pivotally connected to a third link support member  63  which in turn is pivotally mounted on the center section  16 . The third link support member  63  is formed and mounted to be able to rotate through an arc of approximately 45 degrees from a outboard position in which the third link support member  63  is abutted against a first abutment  64  on the center section  16  to an inboard position passing through an opening in a support tower  66 . When the planting implement  10  is in the operating position, the wing member  21  is movable through a range of vertical movement about the wing pivot axis  17  corresponding to the range of pivotal movement of the third link support member  63  which is not effective to stop the floating movement of the wing assemblies  20  until the pivotal movement of the third link support member  63  bottoms out on the first abutment  64  or interferes with the opposing third link support member  63 . 
     During the unfold sequence of operation, the wing fold hydraulic cylinders  29  require a support against which to push in order to effect the movement of the wing member  21  relative to the center section  16 . To accomplish this positive support of the wing fold hydraulic cylinders  29  during the unfold sequence, while permitting a range of floating movement to the wing assemblies  20  when in the operating configuration, an unfold finger  65  was provided. The unfold finger  65  is mounted on the rear draw bar  11   a  to be positionable to fit within the support tower  66  such that the unfold finger  65  can fit between the opposing third link support members  63  during the unfold sequence. The unfold finger  65  is biased toward a rearward most position defined by the lost motion links  65   a  to yield with the forwardly folding tool bar  15  and support tower  66 . The unfold finger  65  provides a removable abutment lodging between the third link support members  63  during the fold and unfold sequences against which both hydraulic wing fold cylinders  29  can push to extend and unfold the wing assemblies  20 . 
     When raising the tool bar  15  forwardly toward the transport position, the unfold finger  65  will become oriented within the support tower  66  as the tool bar  15  approaches the intermediate transport position. The unfold finger  65  can yield within the lost motion links  65   a  against the third link support members  63  until the wing fold hydraulic cylinders  29  are retracted to effect a pivotal folding of the wing members  21 , at which time the third link support members  63  will pivot in an outboard directions until engaging the first abutments  64  to provide a support against which the wing fold cylinders  29  can work. When this event occurs, the float gap within the support tower between the third link support members  63  opens up so that the unfold finger  65  can fall therebetween. To unfold the planting implement  10 , the hydraulic wing fold cylinders are actuated to extend causing the third link support members  63  to pivot in an inboard direction until impacting the unfold finger  65  which is located therebetween. The unfold finger  65  thereby provides support against which the wing fold cylinders  29  can push to extend the wing members toward the operating position. When the tool bar  15  is then pivoted rearwardly by the main hydraulic cylinders  27 , the support tower  66  moves rearwardly away from the unfold finger  65  until the implement  10  is against re-converted into the transport configuration. 
     Referring now to FIGS. 19-21, a tool bar lock mechanism  70  for the tool bar  15  can be seen. The tool bar lock  70  includes a pivoted lock clasp member  71  carried by the central part of the tool bar  15 . The lock clasp member  71  is biased into a locking position by a lock spring  72  anchored on the tool bar  15 . The lock clasp member  71  is movable into a position to engage a lock rod  73  carried by the draw bar  11  when the tool bar  15  is pivotally rotated to the forwardly rolled transport position, as is described in detail above. The pivotal movement of the lock clasp member  71  is controlled by a cable  74  interconnecting the lock clasp member  71  and a wing member  21 . When the wing member  21  is pivoted out into a fully laterally extending position, as depicted in FIG. 19, the cable  74  pulls on the pivoted lock clasp member  71  to force a pivotal movement thereof in opposition to the lock spring  72  to pivotally move the lock clasp member  71  into an unlocked position. The folding of the wing member  21  toward a transport position, as described above, will relax the tension on the cable  74 , allowing the cable  74  to go slack and permitting the biasing lock spring  72  to move the lock clasp member  71  into a locked position in engagement with the lock rod  73 . 
     The cable  74  is either attached to the wing member  21  adjacent to and on the outboard side of the wing pivot axis  17  for standard (40 feet wide) versions, or to a lift assist mechanism (not shown) located on an outboard portion of a larger version (60 feet wide) of the tool bar  15  so that the toolbar lock mechanism  70  will not be disengaged until the lift assist mechanism  18  has been rotated to its downward limit so that the lift assist mechanism  18  will begin supporting the tool bar  15  when the tool bar  15  is rotated back more than about 30 degrees. The lift assist mechanism  18  provides assistance to the main tool bar hydraulic cylinders  27  under conditions where the overall length of the tool bar  15  is too great for the tool bar cylinders  27  to cause the forwardly rolling of the entire tool bar  15 . Preferably, the lift assist mechanism  18  will support the remote distal end of the wing members  21  by a wheel  18   a  engaging the ground to provide support and assist in the raising of the tool bar  15  up to a position of approximately 60 degrees at which point the center of gravity is such that the cylinders  27  can effectively pivot the entire tool bar  15 . The operation of the lift assistance mechanism  18  can be seen in reference to FIGS. 6A-6D, where the lift assist wheel  18   a  remains in contact with the ground until the tool bar  15  has been rotated sufficiently to allow the cylinders  29  to continue the effort unassisted. 
     Referring now to FIG. 22, a diagram of a portion of the hydraulic system  80  for the implement  10  operable as described in detail above can be seen. The implement hydraulic system  80  is connectable to conventional tractor hydraulics (not shown) to provide a source of hydraulic fluid under pressure. The hydraulic system  80  includes a selector valve  81  operable to alternatively direct the hydraulic fluid under pressure to either the hydraulic planter drive circuit  83  or the fold circuit  85  which includes the wing fold cylinders  29 , the wing latch hydraulic cylinders  33 , and the hitch latch hydraulic cylinder  55 , which are operable as described in detail above. The fold circuit  85  is operable to effect the folding and unfolding of the implement  10  in the following manner: 
     Folding Sequence: 
     1. To convert the implement  10  from an operating configuration to a transport configuration, preferably an electronic control system is set from a planting mode to a folding mode. This action actuates a solenoid in the hydraulic circuit  80  to move the selector valve  81  blocking communication to the planter drive circuit  83  and opening communication with the fold circuit  85 . This action also activates solenoids in the second hydraulic circuit  90  (FIG. 23) so that the field markers will be fully folded and to override the headland sensor  91 . Hydraulic pressure is applied through line  92  to retract the tool bar actuators  27  and effect rotation of the tool bar  15  upwardly. Simultaneously, the inner and outer field marker actuators  93 ,  94  will be retracted if not already done so. 
     2. After the tool bar  15  has been rotated upwardly and forwardly, hydraulic pressure is applied to line  86  which simultaneously energizes the extension of the hitch latch actuator  55  and the retraction of the wing latch actuators  33  and the wing fold cylinders  29 . The flow restrictors  89  on the wing fold cylinders  29  slow the speed of operation of the hydraulic circuit  85 . The path of least resistance results in the extension of the hitch latch actuator  55  and the retraction of the wing latch cylinders  33 . As a result, the actuation lever  56  opens the lower latch member  51  to release the telescopic draw bar  11 . 
     3. Simultaneously, the wing latch actuators  33  rotate the respective latch hooks  31  to the locked position against the corresponding first abutments  34  while releasing the caster lock  40  by rotating the crank  42  until the slot  44  in the lost motion link  43  bottoms out and overcomes the spring force exerted by the spring  47  to disengage the caster lock hook  45  from the disk  48  on the caster wheel assembly  25 , allowing the caster wheel  25  to freely rotate about a generally vertical axis. In this configuration, the biasing spring  47  now biases the wing latch hook  31  into the locked position against the first abutment  34 . 
     4. Hydraulic pressure will now retract the wing fold cylinders  29  to pivot the wing members  21  about their now upright wing pivot axis  17  until the wing members  21  have been moved into the transport position shown in FIG.  8 . The engagement of the wing latch hooks  31  with the latch retainer bar  36  allows the wing latch hooks  31  to open slightly against the biasing force exerted by the springs  47  to capture the latch retainer bar  36  and lock the wing members  21  in the transport position. As noted above, the forward folding of the wing members  21  causes the telescopic motion of the draw bar  11  by the braces  22  pushing on the forward draw bar portion  11   b  to force the rearward draw bar portion  11   a  rearwardly. Furthermore, the wing members  21  remain supported on the respective caster wheels  25  instead of being carried directly on the draw bar  11 . 
     Unfold Sequence: 
     1. The planter controls will be set in the folding mode from previously folding the implement to the transport position. In this mode, valve  81  will direct hydraulic fluid under pressure to line  88  to energize the retraction of the hitch latch actuator  55  and the extension of the wing latch cylinders  33  and the wing fold cylinders  29 . As noted above, the path of least resistance of the hydraulic circuit  85  is to the hitch latch actuator  55  and the wing latch cylinders  33 . The hitch actuation lever  56  is pivoted to allow the spring  59  to bias the lower latch member  51  into the closed position; however, the rearward pivoting of the actuation lever  56  allows some freedom of movement of the lower latch member  51  against the spring  59 . 
     2. Simultaneously, the wing latch cylinders  33  extend to pivot the wing latch hook  31  into an open position and to pivot the crank  42  to permit the spring  47  to bias the caster lock hook  45  against the disk  48 . The second abutment  39  engages the crank  42  to allow the wing latch hook  31  to stay in the open position. 
     3. Hydraulic pressure then allows the wing fold cylinders to extend to return the wing members  21  to the transversely extending, field operating position. As the wing members  21  unfold rearwardly, the braces  22  pull the forward and rearward draw bar portions  11   a  and  11   b  together until the stop member engages the cam portion  53  of the latching tab  52  to force a downward motion in the lower latch member  51  against the spring  59  until the hitch latching mechanism  50  is fully engaged. 
     4. By pulling the implement  10  forwardly, the caster wheels  25  will align properly and allow the caster lock hook  45  to slip into the opening  49  on the disk member  48  to lock the caster wheels  25  in the forward direction while in the field operating mode. 
     5. The planter controls are selected from folding mode to planter mode to enable the tool bar  15  to be lowered to the working position. This switches valve  81  to communicate with line  84  and switches valve  101  in valve block  95  to the fully open position so the tool bar actuators  27  can be extended. A work position sensor (not shown), responsive to the position of the tool bar  15 , maintains valves  103  and  104  in the closed position in which check valves do not allow extension of the markers via actuators  93 ,  94  until the tool bar  15  is lowered. Pressure is applied to the second hydraulic circuit  90  through line  99  to extend the tool bar actuators  27  to rotate the tool bar  15  rearwardly and downwardly, as described above, to move the tool bar  15  into a field operating position. 
     6. For the 60 foot version of the implement  10  provided with a lift assist mechanism  18 , the lift assist mechanism  18  is lowered first for support of the tool bar  15  before lowering the tool bar  15 . Pressure is first applied to line  92  to extend the lift assist actuators  28  until they become fully extended and the lift assist mechanism  18  is at its lowest limit, at which point a cable  74  disengages the tool bar lock  70  so that the tool bar can then be lowered. The tool bar lock  70  will prevent the actuators  27  from rotating the tool bar  15  until the lock  70  is released by the cable  74 . Pressure is then applied to line  99  in the hydraulic circuit  90  to extend the tool bar actuators  27  while the tool bar  15  is rotated downwardly. Once the lift assist wheels  18   a  contact the ground, the lift assist actuators  28  will retract as the tool bar  15  continues to be lowered to the working position. A working position stop (not shown) stops the rotation of the tool bar  15  at the appropriate position corresponding to the working position. 
     7. Setting the control system to the planting mode in step 5 above enables the operation of the planter drive circuit  83 . This also allows the headland sensor  91  to control the tool bar actuators  27  in the second hydraulic circuit  90 . The operation  2  of the field markers through the actuators  93 ,  94  can be controlled automatically or manually. 
     The operation of the headland sensor  91  will stop the rotation of the tool bar  15  upwardly, as though moving toward the intermediate transport position described above, at a position corresponding to approximately 30 degrees of rotation to raise the planting units  19   a  out of the ground to facilitate the turning of the implement  10  at the headlands of the field being planted. This limited rotation of the tool bar  15  places the planting units  19   a  in a raised position that can be quickly returned to the lowered planting or working position defined by the working position stop (not shown). As noted above, the operation of the headlands sensor is overridden by the shifting of the circuits  80 , 90  to the fold sequence. 
     Field markers are used on planters to place a mark in the unplanted ground so that the operator will know where to steer the tractor to keep the rows of crop made during each respective pass of the planting mechanism  10  evenly spaced. The structure and general operation of field markers are described in detail in Canadian Patent Application No. 2,252,296, filed Oct. 30, 1998, of Flexi-Coil Ltd., the corresponding U.S. patent application of David R. Hundeby, Ser. No. 09/428,526, being filed on Oct. 28, 1999, and entitled “Field Marker for Agricultural Implement”, the description of which is incorporated herein by reference. Deployment of the field markers generally requires operator input to retract one field marker and extend the opposing field marker as the tractor and implement are making a turn at the headlands of the field. 
     As shown in FIG. 23 and 24, the planting implement  10  includes a control mechanism  100  that is effective during the planting operation upon the raising of the tool bar  15  at the headlands to operate automatically the outer field marker actuators  94  to alternately fold one marker while deploying the other. A manual control (not shown) will allow the deployed marker to be raised to avoid an obstacle. Once the control system  100  is set in an AUTO mode and the valve  102  controlling the flow of hydraulic fluid to the marker actuators  93 ,  94  is moved to the on position, the control system  100  will extend and retract the left and right field markers in an alternating manner automatically when the tool bar  15  is raised to the headlands position depicted in FIG. 6B, and then lower the appropriate field marker for travel in the opposite direction when the tool bar  15  is returned to the working position depicted in FIG.  6 A. Providing this function automatically enables the operator to remain attentive to the timing of the tractor and implement at the headlands and setting the planting implement  10  in the ground at the proper location for planting the crop. 
     Preferably, the control system  100  will include a first switch for enabling the system and a second switch for placing the control system in the AUTO mode. A third switch will control the first hydraulic system  80  between a fold operation and a planting operation, as is described above, and a fourth switch is operable for enabling either the inner marker actuators  93  or the outer marker actuators  94 , or both the inner and outer marker actuators  93 ,  94  together. A work switch  98  is preferably a proximity sensor mounted on the tool bar  15  to provide a signal to the control system  100  to indicate whether the tool bar  15  is moving toward the lowered working position (in-ground) or toward the raised headlands position (out-of-ground). The control system  100  also has a memory capability to recall which of the marker valves  103 ,  104  was last placed in the on or open position, and thereby actuating the corresponding left or right marker actuators. 
     When actuated by the operator, the control system  100  will direct hydraulic fluid under pressure to move the opposing left and right marker actuators appropriately with the movement of the tool bar between worldng and headlands positions. Once the control system  100  is set in the AUTO mode, the control system checks at step  105  and to determine through the proximity sensor  98  whether the tool bar  15  is moving upwardly toward the headlands position or downwardly toward the working position. If the tool bar  15  is moving upwardly toward the headlands position, the left and right solenoids are both moved to the off positions at step  106  to effect the retraction of both field markers, although only one of which would have been deployed. 
     If at query  105 , the tool bar  15  was moving downwardly toward the working position, the system  100  checks at step  107  to recall if the left solenoid, as opposed to the right solenoid, had been the last one actuated. If at step  107  the left solenoid had been the last one actuated, then the system  100  at step  108  activates the right solenoid to deploy the opposite field marker. If at step  107 , the left solenoid had not been the last solenoid actuated, then at step  109 , the left solenoid is actuated to deploy the left field markers, which would be opposite to the previously deployed right field markers. 
     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.