Abstract:
A drive system for agricultural implements having at least one floating head and a tongue that may be disposed at various angles relative to a longitudinal angle of the implement. Two swivel gearbox assemblies are used, each comprising a first 90° gearbox rigidly attached to the implement and a second 90° gearbox that is permitted to rotate about an axis passing through one of its shafts and one of the first 90° gearbox&#39;s shaft. Because the tongue angle is variable, the drive shafts for driving the implement must take on a plurality of angles. The swiveling gearbox assemblies allow variable angles at the tongue and at the header.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    U.S. patent application Ser. No. 11/927,866 filed Oct. 30, 2007 (Our Reference 2-5169-110) and U.S. patent application Ser. No. 11/928,010 filed Oct. 30, 2007 (Our Reference 2-5169-111) are hereby incorporated by reference herein in their entirety. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO MICROFICHE APPENDIX 
       [0003]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present invention relates generally to an agricultural implement, including a floating work tool. More particularly, the present invention relates to an improved drive system for agricultural implements having one or more floating work tools. 
         [0006]    2. Background Art 
         [0007]    Some towable agricultural implements require that the implement be towed off to one side of the tractor when in operation—possibly with the ability to be towed on either side—and directly behind the tractor for transport. The towing at these various locations is effected by angling the implement tongue relative to an implement longitudinal axis, while maintaining an orientation of an implement frame with respect to that longitudinal axis. The need for this flexibility presents difficulties in providing shaft power smoothly to the implement regardless of the tongue angle. Universal joints are relatively inexpensive and permit changes of drive direction, but reduce energy transfer efficiency, are unable to accommodate great angles, and produce oscillating power transfer when at and angle. Furthermore, universal joints require regular maintenance and eventual replacement. 
         [0008]    There is, therefore, a need for a method and apparatus for providing shaft power to towed implements having the ability to operate with varying tongue angles. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    An object of the present invention is to provide a drive system for a towed implement, such as an agricultural mower, permitting:
       the implement tongue to be angled through a range of angles relative to a longitudinal axis of the implement;   a header of the implement to be raised and lowered; and   the implement header to be positioned for both transport and operation.       
 
         [0013]    To effect the various aspects of the above object, two pairs of swiveling gearboxes are utilized, wherein the axis of rotation associated with their ability to swivel is vertical. Additionally, the drive shaft connecting a given pair of gearboxes rotates about the same axis of rotation. Each of the gearboxes in each pair alters the drive direction by 90°. 
         [0014]    A tongue gearbox system comprises a swiveling pair of gearboxes wherein the upper gearbox is rigidly affixed to the underside of the implement tongue while the lower gearbox is free to rotate about the vertical axis of rotation. The lower gearbox receives shaft power directly from the tractor Power Takeoff (PTO). The upper gearbox passes the shaft power along the drive shaft running to the implement. Because the lower gearbox can rotate relative to the tongue, the tongue may be angled through a range of angles relative to the longitudinal axis of the mower without inhibiting the shaft power transmission in any way. Hence, the implement may be towed directly behind the tractor or swung to either side of the tractor. 
         [0015]    A sub-frame gearbox system comprises a swiveling pair of gearboxes wherein the lower, sub-frame gearbox is rigidly affixed to the sub-frame while the upper gearbox is free to rotate about the vertical axis of rotation. The implement tongue may be angled through a range of angles relative to the sub-frame and the upper gearbox swivels relative to the sub-frame to accommodate the various drive shaft angles. The sub-frame gearbox provides a 90° drive-angle change to drive the work tool(s). 
         [0016]    Gear ratios may be selected for these swiveling gearbox assemblies as needed for a given application. 
         [0017]    Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1   a  is a side elevation of an agricultural mower in a transport configuration; 
           [0019]      FIG. 1   b  is a side elevation of the agricultural machine in an operating configuration; 
           [0020]      FIG. 2   a  is a top plan view of the agricultural mower with a sub-frame in the transport configuration; 
           [0021]      FIG. 2   b  is a top plan view of the agricultural mower with the sub-frame in the operating configuration and the mower trailing to the right of a tractor; 
           [0022]      FIG. 2   c  is a top plan view of the agricultural mower with the sub-frame in the operating configuration and the mower trailing to the left of the tractor; 
           [0023]      FIG. 3  is a perspective view of the tongue gearboxes, pivotally connected with a vertical axis; 
           [0024]      FIG. 4  is a front elevation view of the cutter bar mounted beneath the header at an outer end; and 
           [0025]      FIG. 5  is a side elevation of an agricultural mower in a transport configuration. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    Referring now to the drawings wherein like reference numerals indicate identical or corresponding parts throughout the several views, the present invention comprises a suspension system for an agricultural mower  1 , shown in its entirety in  FIGS. 1   a - 2   c , and  5 . The present invention relates to a drive system capable of transmitting rotation from a Power Takeoff (PTO) shaft of a towing tractor to the cutters of an agricultural mower having multiple frames able to pivot and rotate as described in U.S. patent application Ser. No. 11/927,866, filed Oct. 30, 2007, which is hereby incorporated in its entirety by reference. The multi-frame mower  1  having the aforementioned motions enables the cutter bars  9  to float on the ground. Float provides the ability to engage the ground surface such that a consistent cut height is achieved. This desirable quality held by such a mower  1  requires the driveshaft configuration of the present invention. 
         [0027]    In one embodiment, a two-point arm structure  3  is used to connect the mower tongue  2  to the two lower links of a 3-point tractor linkage (not shown) properly positioning the mower  1  such that the PTO shaft from the tractor can be connected to the tongue gearbox system  4  via an implement driveline  37  comprising a universal joint. The two-point arm  3 , as particularly illustrated in  FIG. 3 , is connected to the tractor links by cylindrical pins  75  which pass through spherical bearings, or ball joints, in the tractor links to allow for ground slope variations in the direction of travel as well as relative roll angle between the tongue  2  and the tractor. 
         [0028]    For the purposes of this document, including the claims, the usual direction of travel is hereby defined as the direction the agricultural mower  1  is drawn during mowing. For instance, in  FIGS. 1   a ,  1   b , and  5 , said usual direction of travel is to the left. 
         [0029]    An alternative embodiment of the hitch system is shown in  FIG. 5 . In this embodiment, the tongue  2  is attached to a tractor drawbar by a pin-type hitch  67 , thereby properly positioning the mower  1  to permit the tractor PTO shaft to be connected to a tongue jack-shaft (not shown) via an implement driveline  37  comprising a universal joint. The main shaft  5  connects to the jack shaft at the front of the tongue  2 . 
         [0030]    The tongue gearbox system  4  is comprised of an upper gearbox  24  and a lower gearbox  25 , shown in  FIG. 3 , which each alter the axis of rotation of the driveshaft by 90° and also can provide gear reduction. The two gearboxes  24 ,  25  are pivotally connected with a common shaft defining a vertical axis of rotation  70 . This assembly is a swiveling gearbox assembly  4  which allows the upper gearbox  24  to be rigidly mounted to the tongue while allowing the lower gearbox  25  to rotate freely about the vertical axis of rotation  70 . With this configuration, the tractor may be positioned by angling the tongue to various angles relative to the longitudinal axis  52  of the agricultural mower  1 . This allows the mower  1  to be positioned in a wide variety of locations relative to the towing machine, two of which are illustrated in  FIGS. 2   b  and  2   c . The collective change in the orientation of the drive axis of rotation, in the elevational plane, is 0°, as shown in  FIG. 1   b , such that the main shaft  5  exiting the rear of the tongue gearbox system  4  has an axis of rotation in the longitudinal direction. The rear end of this shaft  5  is supported by a strut mounted on the underside of the tongue  2 , and further connects via a universal joint or a Constant Velocity (CV) joint to a secondary shaft  23  (see  FIGS. 2   b  and  2   c ) which transmits drive power rearward to the upper sub-frame gearbox  35  ( FIG. 1   a ). The output shaft of the upper sub-frame gearbox  35  is also the input shaft of the lower sub-frame gearbox  36 , making these two gearboxes  35 ,  36  a swiveling pair, referred to here as the “sub-frame gearbox system”  18 , as described for the tongue gearbox system  4 . In the sub-frame gearbox system  18 , the lower sub-frame gearbox  36  is rigidly mounted to the sub-frame  10  while the upper sub-frame gearbox  35  rotates freely to stay generally aligned with the tongue  2 , via a steering link or steering bar  7 . A benefit of the secondary shaft  23  is that the secondary shaft  23  may be oriented at a variable angle with the tongue  2  such that the sub-frame  10  can be raised or lowered relative to the tongue  2  and main frame  15 . 
         [0031]    The secondary shaft  23  is connected to the sub-frame gearbox system  18  via a universal joint or a constant velocity joint and through a friction clutch  22  which is in-line such that under excessive torque it will disengage the drive system, as is well understood by those of ordinary skill in the art. The swiveling sub-frame gearbox system  18  permits the driveshaft  5 ,  23  to perform its function even when the tongue  2  is not orthogonal to the sub-frame  10 . Clearly, such is allowed by the pivotal mounting of the tongue to the main frame  15 , controlled by a swing cylinder  17 . A steering bar  7  extends between the sub-frame gearbox system  18  and the tongue strut, and is connected such that the sub-frame  10  is allowed to lift and lower. The upper gearbox  35  alters the axis of rotation of the shaft by 90° into the lower gearbox  36  which changes the rotation angle by 90° again and transmits the rotation into shafts extending out to the headers  6  via universal joints. 
         [0032]    The arms  8  are pivotally connected to the sub-frame  10  such that they may rotate about a vertical axis of rotation between a transport position ( FIGS. 1   a ,  2   a , and  5 ) and a mowing position ( FIGS. 1   b ,  2   b , and  2   c ). In the transport position, the arms  8  rotate to a position such that the cutter bars  9  are substantially parallel to the longitudinal axis  52 . In the mowing position, the arms rotate to a position such that the cutter bars  9  are substantially perpendicular to the longitudinal axis  52 , and are slightly offset relative to one another. The ability to fold in the arms  8  for transport enables a wide-cut agricultural mower  1  to be narrowed sufficiently for legal transport on U.S. roadways. Additionally, because the cutter bars  9  fold within a horizontal plane, the center of mass of the agricultural mower  1  remains low, enhancing stability. 
         [0033]    Folding is effected by a folding cylinder  85 . Because the folding of the cutter bars  9  does not entail lifting the cutter bars  9 , folding may alternatively be performed manually. Folding the cutter bars  9  on a vertical pivot axis  69  on which the arms  8  pivot to the transport position, makes the agricultural mower  1  very stable when compared with the alternative of folding on a horizontal pivot axis. Offsetting the arms  8  and slightly overlapping them in the transverse direction allows the cutter bars  9  to rotate independently, while not missing any crop or being in danger of having their blades impact each other. With the cutterbars  9  offset, the mower is better able to follow the ground contour. 
         [0034]    The arm shafts  20  are connected to the lower sub-frame gearbox  36  via universal joints which allow the arms  8  to rotate inward for transport or outward for mowing. In the transport position the universal joints are not intended to allow rotation of the arm shafts  20 . Each arm  8  pivotally supports a header  6  with a cylindrical bearing  38  as shown in  FIG. 4 . This allows rotation of the header  6  with an axis of rotation perpendicular to that header  6 , which in the mowing position allows the cutter bars  9  to follow the terrain. The header  6  supports a cutter bar  9  on its outer end by a vertical support structure  26  which is rigidly connected to the header  6 . The header  6  further includes a 90° gearbox  21  located at the outer end of the header  6 . This entire assembly has a center of gravity approximately located at the pivot point  38 , such that the cutter bar  9  will remain level when the header  6  is suspended by the arm  8 . The 90° gearbox  21  of each header  6  accepts the arm shafts  20  through universal or CV joints to transmit the rotation through vertical shafts  27  leading to the cutter bars  9 . The universal or CV joints allow for the pivoting of the header  6  with respect to the arm  8 . Preferably, the cutter bars  9  themselves are supported from above only at their outer ends by the vertical support structure  26 , such that the cutter bars  9  are cantilevered from that point inward. The drive shaft to the cutter bar  27  is aligned with this vertical support structure  26 , such that the cutter bar supporting structure and drive are in the same space, minimizing disruption to the flow of cut material. 
         [0035]    Located at the outer end of each cutter bar  9 , a first disk  16   a  is mounted atop the cutter bar  9 . This first disk  16   a  is specifically designed for accepting the driveshaft  27  from above via a universal joint. The driveshaft  27  is protected by a drum which throws cut material to the side of the driveshaft and discourages wrapping on the shaft as it extends downward from the header  6 . The first disk  16   a  as well as subsequent disks  16  spaced along the cutter bar  9  self-contain small 90° gearboxes. A hexagonal shaft connects the row of cutter disks  16   a ,  16  and rotates with an axis of rotation substantially parallel to the arm  8 . Blades mounted to the cutter disks  16   a ,  16  are rotated about the vertical axis of each disk  16   a ,  16  to cut the crop. 
         [0036]    The novel drive system herein described may be utilized for any implement making use of a floating work tool. The invention is not intended to be limited to agricultural mowers. 
         [0037]    The above embodiments are the preferred embodiments, but this invention is not limited thereto. It is, therefore, apparent that many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.