Abstract:
An adjustable and foldable V-shaped hay rake is an agricultural tool used for raking hay on fields, in which, for each arm of the hay rake, all the mechanisms for moving the arm are centered on a single adjustable master support plate.

Description:
FIELD OF THE INVENTION 
     The present invention concerns an agricultural tool used for gathering hay. More particularly, it relates to a towable adjustable and foldable V-shaped hay rake. 
     BACKGROUND INFORMATION 
     Towable hay rakes having two adjustable rake arms provided with hay raking wheels, in which the rake arms are movable, usually by the action of one or more hydraulic cylinders, from a folded transport position to a working “V” position for gathering hay in the field are known. Such towable hay rakes include, for example, those described in U.S. Pat. Nos. 4,183,198, 4,214,428, 4,753,063, 4,974,407, 4,977,734, 6,405,517 and 7,318,312. 
     None of the hay rakes available so far, however, is entirely satisfactory from all points of view. While they all may be successful with respect to accomplishing the hay gathering task for which they were designed, they also may be more complex and expensive than is desirable given the great need for these important agricultural tools. 
     SUMMARY 
     These problems and inconveniences may be addressed by the hay rake described herein, which, because of its innovative design, not only is highly effective in its hay gathering capacity, but is also more robust, simpler, and thus less expensive to build and easier to operate. 
     According to an example embodiment of the present invention, a hay rake includes: a central frame; at least two wheels attached to the central frame; a tow bar attached to the central frame and extending in a frontward direction from the central frame; and a wing assembly including an arm coupled to the central frame by a pivot joint defining a pivot axis about which the wing assembly is rotatable with respect to the central frame, a wing coupled in a fixed position to an end of the arm opposite the pivot joint such that the only degree of freedom between the wing and the central frame is rotation about the pivot axis, the wing arranged for mounting a plurality of hay rake wheels along a length of the wing, and an arm actuator mount fixedly coupled to the arm. The rake includes a wing actuator having a first end coupled to the arm actuator mount and a second end coupled to the central frame, the actuator being arranged to actuate the wing assembly between an outward position and an upward position. Preferably, the wing is horizontal and angled outwardly in the frontward direction when the wing assembly is in the outward position, and the pivot axis is skewed such that the wing is horizontal and parallel to the forward direction when the wing assembly is in the upward position. 
     The arm may be arranged such that any adjustments to the wing orientation may be effected at the arm without the need for additional components such as, e.g., support members that attach to the wing and to the arm and/or central frame to set the wing angle. For example, according to some examples of the present invention, the angle of the wing with respect to the arm and/or central frame and the distance of the wing from the central frame may be altered solely by making adjustments on the arm, such as, e.g., moving a pin between different holes in the arm. In this manner, the distance of the wing from the central frame may be altered by telescoping the arm and setting the arm length with a pin that is inserted through holes in each of the telescoping sections of the arm, and the angle of the wing may be adjusted by rotating the wing and fixing the rotational position by inserting a single pin through both a hole in the arm and a hole in the wing. Further, as the rotation of the wing assembly between the upward position and the outward position may occur at a single joint at the end of the arm opposite the wing, all movement and adjustments of the wing with respect to the central frame may occur via a single arm, thus providing a highly flexible system with a relatively small number of parts. This relatively low level of complexity may allow for lower manufacturing costs and less potential points of failure from a reliability standpoint. 
     The hay rake may also include a spring structure arranged to engage the wing assembly when the wing assembly is in the outward position so as to apply a spring force against downward rotation of the wing assembly about the arm pivot axis. The spring structure may include a spring and an engagement element, the spring coupled to the central frame and the engagement element, wherein the wing assembly further includes a spring hook arranged to engage the engagement element when the wing assembly is moved from the upward position to the outward position. The engagement of the engagement element by the spring hook may pull the engagement element in a direction away from the spring. The spring hook and the arm actuator mount may be integrally formed as a single piece. The engagement element may be an eye bolt. The spring hook and the arm actuator mount may be formed as a plate. The plate may be flat. The pivot axis may pass through the plate. The pivot joint may pass through an aperture in the plate. 
     The hay rake may include two wing assemblies, one of which is mounted to be extendable from a left side of the central frame and the other of which is mounted to be extendable from a right side of the central frame, where the wings of the two wing assemblies may form a V-shaped arrangement when each of the wing assemblies is in the outward position. 
     The angle of the wing may be adjustable, where the fixed position of the wing may be selected from a range of positions. The wing may be fixed in the fixed position by inserting a fastener through a fastening hole in an extension of the wing and through a fastening hole in the arm. 
     The hay rake may include a plurality of rake wheel attachment arms rotatably coupled to the wing. The arms may be arranged to couple the plurality of hay rake wheels to the wing. The hay rake may also include a plurality of springs, where each of the plurality of springs couples a respective one of the plurality of rake wheel attachment arms to the wing to provide individual spring support to each of the plurality of hay rake wheels. 
     The hay rake may include a posterior support arm that is vertically rotatably attached to the central support frame, where the posterior support arm is arranged to support a posterior rake wheel. The hay rake may also include a rear actuator arranged to lower and raise the posterior support arm. The hay rake may include a spring arranged to support the posterior support arm. 
     The hay rake may include a connecting rod rotatably mounted at a first end to the central frame, where the connecting rod in a first position is configured to attach at a second end to a pin extending from the wing assembly to secure the wing assembly in the upward position and in a second position is configured to attach at the second end to a pin extending from the central frame. 
     According to another example embodiment of the present invention, a hay rake includes: a central frame; at least two wheels attached to the central frame; a tow bar attached to the central frame and extending in a frontward direction from the central frame; and a wing assembly including an arm coupled to the central frame by a double axis hinge defining two pivot axes about which the wing assembly is rotatable with respect to the central frame, a wing coupled in a fixed position to an end of the arm opposite the pivot joint such that the only degree of freedom between the wing and the central frame is rotation about the pivot axes, the wing being arranged for mounting a plurality of hay rake wheels along a length of the wing, and an arm actuator mount fixedly coupled to the arm, the arm actuator being a linear actuator. The hay rake includes a wing actuator having a first end coupled to the arm actuator mount and a second end coupled to the central frame, the actuator arranged to actuate the wing assembly between an outward position and an upward position. The wing is horizontal and angled outwardly in the frontward direction when the wing assembly is in the outward position, and the joint is arranged such that the wing is moved into a position horizontal and parallel to the forward direction by the linear actuation of the arm actuator. 
     According to yet another example embodiment of the present invention, a hay rake includes: a central frame; at least two wheels attached to the central frame; a tow bar attached to the central frame and extending in a frontward direction from the central frame; and a wing assembly including an arm coupled to the central frame at a pivot joint which allows the wing assembly to rotate with respect to the central frame, and a wing coupled to an end of the arm opposite the pivot joint, the wing being arranged for mounting a plurality of hay rake wheels along a length of the wing. The wing assembly also includes an actuator mount coupled to the arm, the actuator mount being configured to couple to an actuator arranged to cause rotation of the wing assembly about the pivot joint between an outward position and an upward position, and a spring hook coupled to the arm. The hay rake further includes a spring structure coupled to the central frame and including a spring and an engagement element, where the spring applies resistance when the engagement element is moved with respect to the central frame. The spring hook may be arranged to engage the engagement element when the wing assembly is moved from the upward position to the outward position so as to provide a spring force against downward rotation of the wing assembly. The engagement of the of the engagement element by the spring hook may cause the engagement element to extend away from the spring. The spring hook and the actuator mount may be integrally formed as a single piece. 
     According to another example embodiment of the present invention a hay rake includes: a central frame; at least two wheels attached to the central frame; a tow bar attached to the central frame and extending in a frontward direction from the central frame and a wing assembly. The wing assembly includes an arm coupled to the central frame by a pivot joint defining a pivot axis about which the wing assembly is rotatable with respect to the central frame, a wing coupled to an end of the arm opposite the pivot joint, the wing being adjustable among multiple positions by rotating the wing with respect to the arm about a wing adjustment axis wherein the wing is arranged for mounting a plurality of hay rake wheels along a length of the wing, and a wing adjustment actuator arranged to rotate the wing about the wing adjustment axis. The hay rake also includes a wing assembly actuator arranged to actuate the wing assembly between an outward position and an upward position. The wing adjustment actuator may include a hydraulic cylinder disposed between a joint on the wing and a joint on the arm. The wing adjustment axis may be vertical when the wing assembly is in the outward position. The pivot axis may skewed so as to be angled outwardly and downwardly in the frontward direction. 
     Further features and aspects of example embodiments of the present invention are described in more detail below with reference to the appended Figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described in greater detail with reference to the accompanying drawings, a brief description of which follows: 
         FIG. 1  is a top plan view of one embodiment of the hay rake of the present invention with rake arms in the open working position. 
         FIG. 2  is a perspective view of the hay rake of  FIG. 1 . 
         FIG. 3  is a perspective view of the hay rake of  FIG. 1  with rake arms in the raised and closed transport position. 
         FIG. 4  is another more detailed perspective view of the hay rake of  FIG. 1  (without hay rake wheels). 
         FIG. 5   a  is another more detailed perspective view of the hay rake of  FIG. 2  with rake arms in the raised and closed transport position (without hay rake wheels). 
         FIG. 5   b  is a breakout view of section A of the hay rake illustrated in  FIG. 5   a.    
         FIG. 5   c  is a breakout view of section B of the hay rake illustrated in  FIG. 5   a.    
         FIG. 6  is a perspective view showing another embodiment of the hay rake of the present invention. 
         FIG. 7  is a perspective view showing the details of yet another embodiment of the hay rake of the present invention. 
         FIGS. 8 and 9  are perspective views of another embodiment of the hay rake of the present invention. 
         FIGS. 10 to 12  are perspective views of another embodiment of the hay rake of the present invention. 
         FIG. 13  is a top view schematically illustrating the hay rake of the present invention. 
         FIG. 14  is a right side view schematically illustrating the hay rake of the present invention. 
         FIG. 15  is a right side view of the hay rake illustrated in  FIG. 3 . 
         FIG. 16  is a perspective view of a portion of the right side of the hay rake illustrated in  FIG. 1 . 
         FIG. 17  is an exploded view of a portion of the right side of the hay rake illustrated in  FIG. 1 . 
         FIG. 18  is a perspective view of a portion of the right side of the hay rake illustrated in  FIG. 3 . 
         FIG. 19  is a lower perspective view of a portion of the right side of the hay rake illustrated in  FIG. 3 . 
         FIG. 20  is a perspective view of a portion of the hay rake illustrated in  FIG. 3 . 
         FIG. 21  is a top view of another embodiment of a hay rake of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     For ease of reference the same reference numbers are used to designate the same or corresponding elements throughout the Figures. Referring to  FIGS. 1 to 5   c,  one exemplary embodiment of the rake of the invention includes a central frame  910 , which includes a transverse member  911 , equipped with a tow bar  920  that extends in a frontward direction and roller wheels  907  and  908 . 
     A “T”-shaped adjustable hay rake arm or wing assembly  101 ,  102  is rotatably connected to either end of the transverse member  911 . The “T”-shaped adjustable rake arms  101 ,  102  are composed of extendible arm sections  103  and  104  and mobile wings or wing sections  105  and  106 . Each of the extendible sections  103  and  104  of the respective rake  20  arms  101  and  102 , is composed of a first longitudinal section  107 ,  108  and a second longitudinal section  109 ,  110 . The first and second longitudinal sections are configured so that they slide telescopically with respect to one another. Each of the first longitudinal sections  107  and  108  is equipped with a principal fastening hole  451 ,  452 , and each of the second longitudinal sections  109  and  110  is equipped with a plurality of fastening holes  453 ,  454  so that a fastening key  455 ,  456  may be inserted simultaneously through both the principal fastening hole  451 ,  452  and one of the plurality of fastening holes  453 ,  454  in order to secure the length of the rake arm. Each of the mobile wing sections  105  and  106  is connected in a crosswise manner to its respective second longitudinal sections  109  and  110 , so that each pivots around its respective shaft or linchpin  111 ,  112 . Each of the second longitudinal sections,  109  and  110 , is equipped with a principal fastening hole  461 ,  462 . Each of the mobile wing sections are equipped with a plurality of fastening holes  457 ,  458 , so that fastening key  463 ,  464 , may be inserted simultaneously through both the principal fastening hole  461 ,  462  and one of the plurality of fastening holes,  457 ,  458  in order to secure the desired angle of the mobile wing with respect to the extendible section of the rake arm, thereby providing the wing  105 ,  106  with a fixed position with respect to the extendible section of the rake arm. One or more hay raking wheels  901  are mounted along the length of each mobile wing section  105 ,  106 . 
     In one arrangement, a master support plate  301 ,  302  which pivots around a shaft or linchpin  303 ,  304  is provided for each rake arms  103 ,  104 . The first part  107 ,  108  of the extendible arm section  103 ,  104  is fixedly attached to the support plate  301 ,  302  such that the arm section  103 ,  104  rotates together with the support plate  301 ,  302  about the shaft. Preferably, the linchpin  303 ,  304  is set at an angle that allows the rake arm to rotate downwards, backwards, and outwards to attain the working position or upwards, inwards, and forwards to attain the transport position. Referring to  FIGS. 13 and 14 , this orientation of the linchpin  303 ,  304  provides an axis of rotation  1303 ,  1304  that is angled when viewed from above, as illustrated in  FIG. 13 , and from the side, as illustrated in  FIG. 14 . When viewed from above, the axis of rotation  1303 ,  1304  forms an angle a with a centerline  1100  of the central frame  910 , the centerline  1100  being oriented along the frontward direction  1101  of the rake. The frontward direction is the direction in which the hay rake is pulled via the tow bar  920  when the hay rake is pulled in a straight line. The centerline  1100  is parallel to reference line  1105 ,  1106  that runs through the joint formed by shaft or linchpin  303 ,  304 . The axis of rotation  1303 ,  1304 , when viewed from above, is angled in an outward direction as it progresses in the frontward direction  1101  away from the linchpin  303 ,  304 . In this manner, the axis of rotation  1303 ,  1304  forms the angle α as shown in  FIG. 13 . 
     Referring to  FIG. 14 , the axis of rotation  1303 ,  1304  is also angled downwardly at an angle β as the axis progress in the frontward direction  1101  of the rake. The angle β is formed between the axis of rotation  1303 ,  1304  and the ground or surface  1110  on which the hay rake is towed. The angle β is also formed between the axis of rotation  1303 ,  1304  and the frontward direction  1101 , which is parallel to the ground  1110 . 
     As a result of the angles α and β formed by the axis of rotation  1303 ,  1304 , the axis of rotation  1303 ,  1304  intersects the vertical plane containing the centerline  1100  at a point that is rearward and above the joint formed by the linchpin  303 ,  304 . It is this skewed orientation that allows the wing section  105 ,  106  to be transferred from (a) an outward position where the wing section  105 ,  106  is angled outwardly in the forward or frontward direction  1101  while being simultaneously parallel to the ground  1110 ; to (b) an upward position where the wing section  105 ,  106  is parallel to the centerline  1100  while being simultaneously parallel to the ground  1110 . This may be accomplished despite the only degree of freedom between the wing section  105 ,  106  and the central frame  910  being the single axis of rotation  1303 ,  1304  provided by the joint formed by the linchpins  303 ,  304 . 
     The angle α is selected from the range of 14 to 24 degrees, more preferably 16 to 22 degrees, and most preferably 18 to 20 degrees, e.g., 19 degrees. The angle β is selected from the range of 10 to 20 degrees, more preferably 12 to 18 degrees, and most preferably 14 to 16, e.g., 15 degrees. Although the angles α and β as illustrated are fixed, it should be appreciated that, according to other examples, the angles α and β may be adjustable. The angles 19 degrees and 15 degrees for α and β, respectively, may be well-suited where the wing is at a 30 degree angle from the forward direction (i.e., where the wings form a “V” shape of 60 degrees) when the wing is in the outward position. 
     The central frame  910  includes oblong holes  349 . An actuator  341 , e.g., a linear actuator such as a hydraulic or pneumatic cylinder, with connecting shaft or linchpin  347  is connected to the central frame  910  by inserting the connecting linchpin  347  through apertures in a first clevis of the actuator  341  and through the oblong hole  349  which is positioned in the first clevis. The actuator  341  is connected at its opposite end to an arm actuator mount  321  that is formed as an arm or extension of the support plate  301 . This connection is provided by connecting a second shaft or linchpin  345  through apertures in a second clevis of the actuator  341  and through a hole in the actuator mount  321  to thereby form a joint that is at a radial distance from the axis of rotation of the wing assembly  101  about the shaft  303 . This distance provides a lever arm such that the actuator  341  may provide a torque to the plate  301  and thereby actuate the wing assembly  101  between an outward position, shown, e.g., in  FIG. 2 , and an upward position, shown, e.g., in  FIG. 3 . The central frame  910  also includes oblong hole  350 . An actuator  342 , e.g., a hydraulic or pneumatic cylinder, with connecting shaft or linchpin  348  is connected to the oblong hole  350  of central frame with linchpin  348  and to an actuator mount  322  of support plate  302  with a connecting shaft or linchpin  346 . In this regard the actuation of the wing assembly  102  is the same or a mirror-image of that described above with respect to wing assembly  101 . 
     Spring  905  has a first end  951  coupled to the central frame  910  and a second end  953  coupled to an engagement element  955 , e.g., an eye bolt or a hook, by rod  957  that passes through spring  905 . Spring  906  has a first end  952  coupled to the central frame  910  and a second end  954  coupled to an engagement element  956  by rod  958  that passes through spring  906 . A spring hook  401  is attached to support plate  301  and engages eye bolt  955 , and a spring hook  402  is attached to support plate  302  and engages eye bolt  956 . Although the engagement elements  955  and  956  are eye bolts, it should be appreciated that the engagement elements may be any appropriate structure, e.g., a hook, for engaging the spring hooks  401  and  402 . Although the springs  905  and  906  are coil springs, any appropriate type of spring may be provided, including, e.g., a spring arm, that is engaged by the spring hook  401 . 
     Referring to  FIG. 6 , which for reasons of clarity depicts only half of another exemplary embodiment of the rake of this invention, rake wheel pivoting or attachment arms  806  are pivotally attached to mobile wing section  106 . Preferably, springs  804  are attached to mobile wing section  106  and arms  806 . Hayraking wheels  902  are mounted on hay rake wheel pivoting arms  806  and springs  804  together provide individual spring support for each of hay making wheels  902  individually. 
       FIG. 7  shows another exemplary embodiment of the hay rake of the present invention in which protective housings  903  and  904  cover springs  905  and  906 . The hydraulic power, drive, and command lines of hydraulic cylinder  341  and hydraulic cylinder  342  are not depicted. However, those of ordinary skill in the art would recognize that such lines often present in machines of this type and would be well aware of many suitable types that could be used. 
     When hydraulic cylinders  341  and  342  are elongated the support plates  301  and  302  pivot downwards around linchpins  303  and  304 , bringing the adjustable hay rake arms  101  and  102  to a lowered or outward position for work. Simultaneously hooks  401  and  402  engage eye bolts  955  and  956 , subjecting the movement of master support plates  301  and  302  and, therefore, wing assemblies  101  and  102  to the effect of springs  905  and  906 . In this position the presence of oblong holes  349  and  350  allows support plates  301  and  302  and wing assemblies  101  and  102  to make small rotational movements so that the wing assemblies  101  and  102  adapt better to irregularities of the soil without disturbing the actuators  341  and  342 , e.g., hydraulic cylinders. The presence of springs  905  and  906  counters the weight of wing assemblies  101  and  102  and thus reduces their weight on the ground. When actuators  341  and  342  are contracted, support plates  301  and  302  pivot upwards around linchpins  303  and  304 , bringing the adjustable hay rake arms  101  and  102  to a raised position for transport and storage. 
     The length and angle of the adjustable hay rake arms in the working position can be adjusted as needed by adjusting the lengths of extendible sections  103  and  104 , and by adjusting the angles of the mobile wing sections  105  and  106 . Once the appropriate position is determined, the rake arms are set at the desired length using fastening keys  455  and  456 . Fastening key  455  is inserted through both fastening hole  451  and the appropriate fastening hole of the plurality of fastening holes  453 , and fastening key  456  is inserted through both fastening hole  452  and the appropriate hole of the plurality of fastening holes  454  depending on the desired length. The angles of the wing sections  105  and  106  are adjusted by rotating the wing around shafts or linchpins  109  and  110 , respectively, to the desired angle. The desired angle is then set by inserting the fastening key  463  through both fastening hole  461  and the appropriate fastening hole of the plurality of fastening holes  457 , and inserting fastening key  464  through both fastening hole  462  and the appropriate fastening hole of the plurality of fastening holes  458 , depending on the desired angle, thereby securing each of the wing sections  105  and  106  in a fixed position. 
     Although the fixed position may be adjusted, the range of adjustment may be such that any of the fixed positions results in the wing sections  105  and  106  being substantially horizontal and substantially parallel to the forward direction, i.e., the direction in which the rake is towed, when in the upward position. 
     It is also possible to have springs  804  provide individual spring support for each of the haymaking wheels  902 , as well as including protective housings  903  and  904  to cover springs  905  and  906 . 
     Referring to  FIGS. 8 and 9 , another example hay rake has an applications plate  504  applied to the middle portion of the central frame  910 , the movable rear arm, posterior rake wheel support arm  502  is vertically rotatably connected to the applications plate  504 . A central posterior rake wheel  501  is applied to the rear movable arm. A spring  503  is connected to the movable rear arm  502  and the applications plate  504 . An oblong hole  505  is provided in the applications plate  504  together with piston and hydraulic cylinder  506 , which connects pin  507  threaded in oblong hole  505  and joint  508  on the movable rear arm. 
     This additional hay rake wheel in the center rear position may further rake the hay already raked by the rake wheels attached to the two wing assemblies  101  and  102 . The center rear rake wheel  501  can be lowered into the working position as shown in  FIG. 8  or raised into the transport position as shown in  FIG. 9  by extension or contraction of the rear actuator  506 , e.g., a piston and hydraulic cylinder assembly. Spring  503  counters the weight of the central rear hay rake wheel  501  and thus reduces its weight on the ground. Furthermore, in the working position, the presence of oblong hole  505  allows the movable rear arm  502  to make small rotational movements thus better adapting the position of the movable rear rake arm and the central rear hay rake wheel  501  to the irregularities of the ground without affecting the piston and hydraulic cylinder assembly  506 . 
     Referring to  FIGS. 10 to 12 , which relate to another example of the invention, protruding pins  601  and  603  are provided on the central frame member  910  and protruding pin  605  is provided on the first longitudinal section of the extendible arm section  103 . Protruding pins  602  and  604  are provided on the central frame member  910  and protruding pin  606  is provided on the first longitudinal section of the extendible arm section  104 . A connecting rod  607  having at its two extremities holes  609  and  611  adapted to engage pins  601 ,  603  and  605 , and a connecting rod  608  having at its two extremities holes  610  and  612  adapted to engage pins  602 ,  604  and  606  are provided. All the protruding pins are provided with safety plugs designed to hold the connecting rods  607  and  608  in place. 
     The connecting rods  607  and  608  operate as follows. When the rake arms  103  and  104  are raised in the transport position as shown in  FIG. 11 , connecting rod  607  is positioned so that protruding pin  601  is in hole  609  and the protruding pin  605  is in hole  611  and connecting rod  608  is positioned so that protruding pin  604  is in hole  612  and the protruding pin  606  is in hole  610 . In this way whatever movement, even accidental, of the rake arms  103  and  104  is prevented due to the connecting arms  607  and  608 . When the rake arms are lowered in the working position, however, as shown in  FIG. 10 , the connecting rod  607  is positioned so that protruding pin  601  is in hole  609  and protruding pin  603  is in hole  611  and connecting rod  608  is positioned so that protruding pin  602  is in hole  6010  and protruding pin  604  is in hole  612 . In this way the connecting rods  607  and  608  do not interfere with the movement of the rake arms  103  and  104 . Alternatively, when one connecting rod is fixed in one position and the other is fixed in the other position, then one rake arm is blocked in the operating position while the other is free to move. This allows for a very simple and safe way to lower and use only one rake arm while the other is secure in the transport position. 
       FIGS. 15 to 20  provide various views of the hay rake illustrated, e.g., in  FIGS. 1 to 3 . Referring to the exploded view of  FIG. 17 , a supplemental support plate or flange  1302  is provided on the first longitudinal section  108  opposite and parallel to the master support plate  302 . In this regard, the first longitudinal section  108  is coupled to the central frame  910  such that respective apertures in the supplemental support plate  1302  and the master support plate  302  align with opposite ends of a rotation support sleeve  1344  of the central frame  910 . After this alignment, the rotation shaft or linchpin  304  is inserted through the supplemental support plate  1302 , the sleeve  1344 , and the master support plate  302 . The shaft or linchpin  304  is then secured in its axial position by inserting a pin (not shown) through transverse holes  1346  of a flange  1348  and a transverse hole  1350  of the shaft  304 . Although the flange  1348  illustrated in  FIG. 17  is fixed to the master support plate  302 , e.g., by welding, it should be appreciated that the flange  1348  may be separate from the master support plate  302 . Further, although the shaft  304  is arranged so as to rotate with the first longitudinal section  108  about the sleeve  1344 , it should be appreciated that the shaft  304  may be arranged to be rotationally stationary with respect to the sleeve  1344  such that the first longitudinal section  108  rotates with respect to the shaft  304  about the axis of the shaft  304 . Rotation of the longitudinal section  108  may occur via a bushing, bearing, or any other appropriate mechanism. 
     When the components are assembled, the first end  952  of the spring  906  is coupled to the central frame  910  and the second end  954  of the spring  906  is coupled to the engagement element  956  by rod or shaft  958  that passes through the spring  906 . The first end  952  couples to a lower surface of a spring support plate or flange  1900  of the central frame  910 . The spring support plate has an aperture through which the rod or shaft  958  passes, while an engagement structure (in this case a loop) extends above the spring support plate or flange  1900 . To maintain the orientation of the engagement structure, the rod or shaft  958  is keyed within the spring support plate or flange  1900 . In this example, the rod or shaft  958  has a rectangular cross section in an upper region  1956  that passes through a rectangular aperture in the spring support plate or flange  1900 . Thus, the engagement element  956  is maintained at a proper angle to be engaged by the spring hook  402  of the master support plate  302 . The spring  906  is secured at its lower end  954  by an end cap  1958  that includes a flange arranged to axially constrain the spring  906 . A lower portion  1954  of the rod or shaft  958  extends through the end cap  1958 . A nut  1960  is applied to a threaded end of the lower portion  1954  to axially secure the end cap  1958  on the lower portion  1954 . Because the lower portion  1954  has a different cross section (in this example, circular) than the upper portion  1956 , the upper section  1956  serves as a positive stop when attaching the end cap  1958 , thus eliminating any uncertainty with respect to the axial position of the end cap  1958  when tightening the nut  1960 . In this regard, the upper portion  1954 , with its rectangular cross section, performs a dual function in that it rotationally keys the engagement element  956  with respect to the spring support plate or flange  1900 , while also providing a positive stop against which the end cap  1958  may be tightened via the nut  1960 . 
     When the spring hook  402  engages the loop of the engagement element  956 , the engagement element  956  is pulled upwardly, which causes the rod or shaft  958  to translate upwardly, along with the end cap  1958 , with respect to the spring support plate or flange  1900 . This upward translation causes the spring  906  to be compressed between the flange of the end cap  1958  and the lower surface of the spring support plate or flange  1900 . The range of travel may be limited when the spring is compressed by a spacer  1962 , which forms a positive or hard stop between an upper surface of the end cap  1958  and the bottom surface of the spring support plate or flange  1900 . Alternatively, the spacer may be omitted such that the top surface of the end cap  1958  may contact the lower surface of the spring support plate  1900  to form a positive or hard stop. The fully extended position of the spring  906  is controlled by a positive or hard stop between the engagement element  956  and an upper surface of the spring support plate or flange  1900 . In this manner, the range of travel of engagement element  956  with respect to the spring support plate  1900  may be provided. The spring may be preloaded or at a rest state when in the fully extended position. 
       FIG. 21  illustrates another embodiment of the hay rake according to the present invention. The hay rake shares many features with the embodiments described above and illustrated in  FIGS. 1 to 20 . The hay rake of  FIG. 21  differs, however, in that it includes wing actuators  3001  and  3002  mounted to the wings  105  and  106 . A pivot  3003  about which the wing section  105  rotates with respect to the second longitudinal section  109  of the extendible arm section  103  is illustrated. Also illustrated is a pivot  3004  about which the wing section  106  rotates with respect to the second longitudinal section  110  of the extendible arm section  104 . The actuator  3001 , e.g., a hydraulic cylinder/piston assembly, connects the joint  3005  on the wing section  105  to the joint  3007  on the second longitudinal section  109  of the extendible arm  103 . The wing actuator  3002 , e.g., a hydraulic cylinder/piston assembly, connects the joint  3006  on the wing section  106  to the joint  3007  on the second longitudinal section  110  of the extendible arm  104 . The operation of the embodiment represented in this figure is as follows: when hydraulic cylinder/piston assembly  3001  is elongated or retracted, wing  105  rotates one way or another around the hinge  3003  with respect to the second longitudinal section  109  of the extendible arm  103  and when hydraulic cylinder/piston assembly  3001  remains fixed, second longitudinal section  109  of the extendible arm also remains fixed. The same happens with wing section  106  under the action of hydraulic cylinder/piston assembly  3002 . In this way the working position of wing sections  105  and  106  is regulated by the actions of the hydraulic cylinder/piston assemblies  3001  and  3002 . This may be particularly advantageous because adjustment of the operating angle of wings  105  and  106  can be carried out by the simple action of the actuator commands, e.g., hydraulic commands, quickly and at a safe distance, directly by the operator of the machine without the operator having to get out of the vehicle, e.g., tractor. This mechanism even allows adjustment of the wings  105  and  106  while the hay rake is in operation. 
     It should be appreciated that although the actuators, e.g., cylinder/piston assemblies, illustrated in  FIG. 21  are disposed rearward of the pivots  3003  and  3004 , the actuators may be disposed forward of the hinges or pivots  3003  and  3004 . It should be further appreciated that although the hinges  3003  and  3004  provide rotation axes that are vertical when the wing assemblies are in the outward position, the rotation axes may be non-vertical. 
     The actuators  3001  and  3002  allow the wings  105  and  106  to be easily adjusted to a horizontal position when in an upward position. In this regard, it is possible to dispense with the skewed rotation of axes of the wing assemblies  101  and  102  where, e.g., parallel, horizontal rotation axes are provided. However, it may be advantageous to maintain the skewed axes in order to limit the necessary stroke of the actuators  3001  and  3002 , as the actuators  3001  and  3002  could then be used for the minor adjustments while the rotation about the skewed axes accounts for the wings  105  and  106  being in a substantially parallel and horizontal upward position. 
     Although the examples shown in the Figures utilize a joint with a single axis of rotation, it should be appreciated that other types of joints may be provided. For example, the double axis hinge described, e.g., at col. 8, lines 25 to 52 of U.S. Pat. No. 6,000,207, which is expressly incorporated herein in its entirety by reference thereto, may be provided. In this manner, the joint may have two axes of rotation. The hinge or joint allows the wing to be moved into a position horizontal and parallel to the forward direction by a single linear actuator. 
     Compared to prior art hay rakes, the hay rake of the present invention may be advantageous in that it is both very effective and easily adjusted. It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and the methodology of the present invention, without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. Moreover, the features described herein may be used in any combination.