Abstract:
A self-propelled chopper cane harvester is equipped with a front frame section including opposite sides which are each mounted for pivoting about a respective upright pivot axis. Respectively mounted to the opposite sides of the front frame section are front wheels and row dividers. A steering cylinder is mounted for pivoting the frames to opposite sides of a straight ahead position to thereby effect steering of the front wheels. A topper mechanism is mounted so as to pivot or turn in response to the steering of the harvester.

Description:
FIELD OF THE INVENTION 
     The present invention relates to sugar cane harvesters and more particularly relates to steering arrangements for such harvesters. 
     BACKGROUND OF THE INVENTION 
     The steering arrangement on a typical front wheel steered, rubber tired sugar cane chopper harvester includes steerable wheels mounted to axles supported for pivoting about respective upright pivot structures located outboard of transversely spaced, fore-and-aft extending main frame members. A pair of crop dividers are respectively mounted to the main frame ahead of the pair of steerable wheels. In order to avoid interference with the frame members during steering operation, a large space is provided between each pivot axis and the adjacent frame member. 
     A first disadvantage of the known steering geometry is that, in order to reposition the harvester on the field headland for entering a new row of cane to be harvested after exiting a row just harvested, an operator must not only turn the steerable wheels but also must do a series of machine reversals in order to enter the new row without damaging the cane. This same sequence may also be repeated at the end of the field when exiting the row and turning onto the headland. In this case, the rear of the machine may be backed into the uncut field, knocking cane down and damaging the crop. With short rows and narrow headlands, the time spent maneuvering existing machines can be longer than the time spent harvesting. 
     A second disadvantage of the known steering geometry is that of restricting the width of the machine throat for accepting crop for being separated from the ground by a pair of counter rotating base cutters located between the main frame members. This restricted feed throat causes a problem referred to as glut/starve feeding when cutting heavily lodged, green cane. The problem begins when stalks of cane bridge the throat and momentarily starve the flow of cane into the machine. When enough cane accumulates to either bend or break the bridged stalks, a glut of cane is fed into the machine. If the cane processing elements located past the throat have enough capacity, the glut of cane will go through the machine, although the quality of the cane exiting the machine will be reduced. If the glut is too large, a choke will occur which will result in machine stoppage to clear it. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided an improved steering arrangement for a rubber tired chopper cane harvester. 
     An object of the invention is to provide a steering arrangement which results in a geometry defining an increased throat width for receiving crop. 
     A more specific object of the invention is to provide a steering arrangement whereby the steerable wheels are mounted for movement together with respective frame sections that are mounted for pivoting about upright axes, whereby the wheels may be mounted close to the frame sections without any possibility of interference, thereby permitting the frame sections to be spaced from each other so as to increase the throat width for receiving crop. 
     Another specific object is to provide a steering arrangement, as defined in the immediately preceding object, wherein in addition to the steerable wheels, the crop dividers are also respectively coupled for pivoting with the frame sections. 
     Still another object of the invention is to provide a steering arrangement wherein the topper mechanism is steered in response to steering the vehicle. 
    
    
     These and other objects will become apparent from a reading of the ensuing description together with the appended drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a right side elevational view of a sugar cane chopper harvester embodying the present invention. 
     FIG. 2 is a fragmentary right side elevational view showing the respective articulated connections between the harvester main frame and the right wheel and topper mechanism. 
     FIG. 3 is a schematic top view showing the power steering cylinder and linkage for effecting steering of the front wheels together with the crop dividers and topper mechanism. 
     FIGS. 4 and 5 are schematic top views respectively of a cane chopper harvester embodying the invention and a prior art cane chopper harvester, with both harvesters being shown in a condition for traveling straight ahead. 
     FIGS. 4A-4D are schematic top views respectively showing the chopper cane harvester of the present invention in a sequence of positions while turning on a sugar cane field headland so as to enter a new row of cane to be harvested. 
     FIGS. 5A-5D are schematic top views showing the prior art chopper cane harvester in a sequence of positions while turning on a sugar cane field headland, this sequence of positions being respectively provided for comparison with those illustrated in FIGS.  4 A- 4 D. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIGS. 1-3, there is shown a sugar cane chopper harvester  10 , here depicted as a rubber tired, chopper harvester. The harvester  10  includes a main frame  12  supported on a pair of rear drive wheels  14  and a pair of steerable front wheels  16  and  18 , respectively. An operator cab  20  is located at a central, forward location of the frame  12 , and located behind the cab  20  is an engine, (not visible), which provides the power for driving the wheels  14  and other driven components of the harvester  10 . 
     The cab  20  gives a seated or standing operator a vantage point for viewing the operation of front-mounted equipment including a topper mechanism  22  mounted to the frame  12  between right- and left-hand crop divider assemblies  24  and  26 , respectively. Located just behind and inwardly of the front wheels  16  and  18  of the harvester  10 , so as to be at opposite sides of a longitudinal centerline of the harvester, are right- and left-hand base cutter units  28  and  30 , respectively, having cutting blades located so as to overlap at the middle of the harvester. 
     Thus, during operation, the crop divider assemblies  24  and  26  straddle a row of cane stalks which pass beneath the frame  12  and are severed from the ground by the base cutter units  28  and  30 . The base cutter units  28  and  30  deliver the stalks to the rear to a feed roller assembly (not shown) that transports the cane stalks to a chopper assembly  32  located between and at a height above the rear wheels  14 . The chopper assembly  32  cuts the cane stalks into lengths called billets which are fed into a primary extractor assembly  34  that operates to clean unwanted material such as leaves and other crop pieces from the billets. The billets then pass into a loading elevator assembly  36  to a secondary extractor assembly  38  which acts to extract further trash from the billets as they are conveyed to a wagon, or the like, that is pulled alongside the harvester  10 . 
     The topper mechanism  22  includes a gathering and cutting head  40  that is kept in a level attitude by being mounted to the frame  12  by a boom including upper and lower parallel arms  42  and  44 , respectively. The rear ends of the arms  42  and  44  are respectively pivotally coupled to a swing frame  46  including a tubular member  48  mounted for swinging about a vertical axis defined by a cylindrical support post  50  that is fixed to a central location of the main frame  12  just below a lower region of the cab  20 . An extensible and retractable boom actuator  51  is coupled between the swing frame  46  and the lower arm  44  and is operable for controlling the operating height of the cutting head  40 . Fixed to a lower end of the support post  50  is a steering arm  52 . 
     The main frame  12  includes right- and left-hand side members  54  and  56 , respectively, to the forward ends of which right- and left-hand forward frame sections  58  and  60  are respectively coupled by right- and left-hand pivot assemblies  62  and  64 , of which only the details of the right-hand pivot assembly  62  are shown, it being understood that the left-hand pivot assembly  64  is similar. The right- and left-hand pivot assemblies  62  and  64  include respective vertical cylindrical, tubular receptacles  66  and  68  forming forward ends of the side members  54  and  56 , and respective pivot pins or posts (not shown) respectively received for oscillating within the receptacles  66  and  68  and fixed to rear ends of top and bottom, horizontal frame members  70  and  72 , respectively, of the right- and left-hand front frame sections  58  and  60 . The front wheels  16  and  18  are mounted to respective axles carried by the forward frame sections  58  and  60  of the main frame  12 . Also mounted.to the front frame section  58  and  60  are the right- and left-front crop divider assemblies  24  and  26 , respectively. Fixed to the top of the right pivot post is an L-shaped right wheel steering arm  74 . A left wheel steering arm  76  is fixed to the top of the left pivot post carried in the receptacle  68  at the front of the left front frame side member  56 . 
     Provided for simultaneously steering the wheels  16  and  18  and the associated divider assemblies  24  and  24  together with the topping assembly  22 , is a steering arrangement  78  including an extensible and retractable steering cylinder  80  coupled between the main frame  12  and the right steering arm  74 . Coupled between the right and left steering arms  74  and  76  is a tie rod  82 , and coupled between the right steering arm  74  and the steering arm  52  of the topper mechanism  22  is a drag link  84 . It is, of course, evident to those skilled in the art, that the steering cylinder  80  could be mounted between main frame  12  and the swing frame  46  or it could be mounted between the main frame  12  and the left wheel steering arm  72 . 
     Referring now to FIG. 4, it can be seen that the main frame  12  is widened in the vicinity of the base cutter assemblies  28  and  30 . In one practical example, the width dimension of the frame  12 , from its rear to a location adjacent the base cutter assemblies  28  and  30 , is about 36 inches, which is a typical width for the entire frame of a prior art harvester. The opposite sides of the frame  12  flare outwardly, in the vicinity of the base cutter assemblies  28  and  30 , to a width dimension of about 50 inches for a total increase in width of about 14 inches. Thus, the front frame sections  62  and  64  are separated by about 50 inches, and since the crop divider assemblies  24  and  26  are joined to the front frame sections  62  and  64 , the throat of the harvester for receiving crop, i.e., the distance between the crop divider assemblies  24  and  26 , is also about 50 inches. 
     Referring now also to FIG. 5, there is shown a prior art cane harvester  90  including a main frame  92  supported on rear drive wheels  94  and steerable front wheels  96  and  98 . The main frame  92  includes right- and left-hand side members  100  and  102  that extend parallel to each other and have crop divider assemblies  106  and  108  respectively mounted to forward ends thereof. The steerable wheels  96  and  98  are carried by axles mounted for pivoting about upright pivot axes  110  respectively defined by supports fixed to the frame side members  100  and  102 . Further, a topper mechanism  108  is mounted centrally between the side members  100  and  102  for operation along the longitudinal center line of the harvester  90 . 
     Referring now to FIGS. 4A and 5A, the cane chopper harvesters  10  and  90  are shown in similar locations in the headland of a sugar cane field, wherein their respective sets of rear drive wheels  14  and  94  are aligned with a path of travel that extends perpendicular to, and is equidistant from ends of, a plurality of sugar cane rows a-f. A typical distance between the rows is 60″ and a typical headland would be approximately equal to four rows in width or about 20′. 
     Referring to FIG. 5A, it can be seen that the turning radius R of the prior art harvester  90  is limited by the inside steerable wheel  98  coming into contact with the frame  92 . With one practical example, the turning radius R is approximately 15′, this being the distance between the center of the inside wheel during a turn and the turning center C′, which is at the intersection of a first line drawn through the centers of the rear wheels  94  and a line drawn perpendicular to the path of travel of, and through the center of, the inside steerable wheel  98 . 
     Referring to FIG. 4A, the same turning radius R of the cane harvester  10  is achieved by turning the front frame sections  58  and  60  of the proposed cane harvester  10 , as required, by operation of the steering cylinder  80 . 
     Referring to FIGS. 4B and 5B, it can be seen that, after the proposed harvester  10  turns through an angle of 20°, the topper mechanism of the harvester  10  will just begin to enter the same row d that is intended to be harvested next. In contrast, the prior art harvester  90 , after turning through an angle of 30°, will begin to enter row f, which is two rows from the row d. which the harvester  92  will eventually enter. 
     Referring now to FIGS. 4C and 5C, it can be seen that after pivoting through an angle of 30°, the topper mechanism  22  of the proposed harvester  10  continues to be aligned with the row d intended to be harvested next and the left row divider  106  is entering the area between the rows c and d as desired for harvesting the row d. In comparison, the prior art harvester  90 , after pivoting through an angle of 45°, the topper mechanism is still two rows beyond the row d intended to be harvested next and the left row divider  106  is beginning to knock down plants located in the row d. 
     Referring next to FIGS. 4D and 5D, it can be seen that, after turning through an angle of 40°, the proposed harvester  10  is almost perfectly aligned with the cane row d, as desired. This is in comparison to the prior vehicle  90 , which after rotating through an angle of 60°, is positioned such that the wheels  96  and  98  are properly aligned for harvesting the row d. However, the left row divider  106  will have knocked over more of the crop in the row d and the right row divider will have knocked down crop in the neighboring row e. Thus, it will be apparent that the topper mechanism  108  will not be positioned properly for beginning the topping of the row d. 
     In normal operations, the operator of the prior art harvester  90  will, at a time prior to reaching the position shown in FIG. 4B, raise the cutting head of the topper mechanism  108  to a level above the height of the cane by extending the boom actuator (not shown). The operator, instead of turning in one continuous motion, as described above with reference to FIGS. 4B-4D, will then proceed to do a series of machine reversals until the crop dividers  104  and  106  can enter the field correctly. At this point, the cutting head of the topper mechanism  108  is lowered to the correct operating height by retracting the boom actuator. Unless the headland is sufficiently wide to accommodate the reversing movement of the harvester  90 , the first stalks in the row of cane to be harvested will not be topped. 
     However, in the case of the proposed harvester  10 , the cutting head  40  of the topper mechanism  22  can be left at the same topping height during the whole turning sequence. With a 21′ wide headland as illustrated, no machine reversals are required to position the harvester  10  correctly with the row of cane to be harvested. 
     Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.