Abstract:
A harvester which uses a rotary style cutter bed has a series of rotary cutters extending across the path of travel of the machine and rotatable about individual upright axes. Part of the cutter bed is a flat gear case containing a train of intermeshed spur gears that serve to distribute power between the cutters above the gear train. Each end of the gear case has a hollow, gearless extension welded thereto which supports at least one additional outboard cutter that receives its driving power exteriorally of the gear case. One embodiment uses a mechanical drive to bring power to the upright shaft of the cutter having the first spur gear so that the cutters with gears receive all their power from the driven cutter. The outboard cutters not having gears are driven by exterior, over-the-top drive mechanism coupled with the shafts of the first and last geared cutters, such drive mechanism alternatively taking the form of timing belts with timing sheaves, chains and sprockets, gear box and universal joint couplings or a spur gear train. As an alternative to a mechanical drive, the cutter bar may utilize a pair of hydraulic motors coupled with the shafts of the first and last cutters having gears. All of the gears in the gear case remain positively enmeshed with one another in the gear train, so that the two hydraulic motors share the total load of driving the cutter bed and such loading is balanced between the two hydraulic motors, prolonging the useful life of the gears and other drive components. The added on, outboard cutters are driven over the top using timing belts, timing sheaves, universal couplings or a spur gear train.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to co-pending application Ser. No. 08/234,225 filed Apr. 28, 1994, titled Rotary Cutter Bed Harvester with Non-Auger Conveying Means for Outboard Cutters in the names of Raymond F. Schmitt, et al. and to co-pending application Ser. No. 08/237,033 filed May 3, 1994, titled Harvester with Hydraulically Driven, Flow-Compensated Rotary Cutter Bed in the names of Michael L. O&#39;Halloran, et al. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the field of crop harvesters and, more particularly, to harvesters of the type which utilize a cutter bed having a series of relatively high speed, rotary cutters that sever the standing crop from the ground as the machine advances through the field. 
     BACKGROUND 
     One example of a harvester with rotary cutters is disclosed in U.S. Pat. No. 5,272,859 titled MECHANICAL DRIVE CENTER PIVOT MOWER CONDITIONER, which patent is owned by the assignee of the present invention. The harvesting machine disclosed in the &#39;859 Patent is a pull-type harvester which requires the use of a separate tractor for towing the harvester through the field during use. The operating components of that harvester are mechanically driven through a drive line that is coupled with the power takeoff shaft of the towing tractor. 
     The harvester disclosed in the &#39;859 Patent is also a conditioner, which means that the severed crop materials are passed between a pair of superimposed conditioning rolls before being discharged onto the ground. However, as a practical matter there is a limit to the length which such rolls can have and still function in an optimal manner. Thus, while the width of cut taken by a mower-conditioner using roll type conditioning mechanism can be made significantly wider than the length of the conditioning rolls, the crop that is severed by the machine must somehow be gathered inwardly after severance before being directed through the shorter conditioning rolls. Augers and other consolidating devices can be used behind the cutter bed for this purpose, but this adds an additional expense and subjects the crop materials to extra mechanical handling, which may be undesirable in many cases. The wider the cut, the more difficult the problem of conveying the severed outboard materials toward the center without using some kind of extra conveyor apparatus behind the cutters. 
     Furthermore, in making a longer cutter bed than disclosed in the &#39;859 Patent wherein the endmost cutters are located at the opposite edges of a discharge opening to the conditioner rolls, additional engineering and expense is involved if the extra, added-on cutters are to be driven with their own extra spur gears within the gear case beneath the cutters. Thus, it would be of considerable benefit if additional cutters could be added onto the cutter bed without the need for adding additional internal gearing to the existing gear case. In that way, a standard, uniform size gear case could be used for both the standard length cutter bed and the extended length cutter bed having additional cutters. 
     Commercial hay producers typically use self-propelled machines and usually prefer a wider cutting width than that found on many pull-type units. Along with the extra width, however, comes increased loading on the power distribution drive in the gear case. Moreover, if a standard length gear case is to be utilized, some means must again be provided for extending driving power to additional cutters that are added on to extend the effective length of the cutter bed. Since in many instances the self-propelled tractors available for use with harvesters of this type are conventionally provided with engines capable of supplying pressurized hydraulic fluid for the operating components of a harvesting header, and since hydraulically powered machines are preferred in many instances by commercial operators, it would be desirable and beneficial to provide a hydraulic-driven cuter bed that would meet the needs and desires of commercial operators. 
     SUMMARY OF THE PRESENT INVENTION 
     Accordingly, one important object of the present invention is to provide a way of making a longer cutter bed out of a certain length gear case so that additional cutters can be added to opposite ends of the gear case without necessitating redesign of the internal gear train of the gear case. Stated otherwise, an important object of this invention is to provide a way of using the cutter bed gear case of a shorter width machine, such as a twelve foot cutting width, on a wider cut machine, such as a fifteen foot machine, without designing a whole new gear case, complete with additional gears, bearings and other components appropriate for the wider effective cutting width. 
     Another important object of the present invention is to provide a rotary style machine in which the cut width can be substantially wider than the opening to the conditioner mechanism without requiring the addition of center gathering augers or other consolidating mechanism behind the cutter bed to consolidate the wide volume of cut material before it is presented to the conditioning mechanism. 
     A further important object of the invention is to provide a hydraulically powered, wide cut rotary style harvester that is particularly well-suited for commercial hay operations in which self-propelled tractors are typically favored and achieving high levels of productivity through harvesting speed and maximum cut width is a high priority. In this connection, one important object is to provide a hydraulic drive arrangement which dramatically increases cutter bed life through decreased loading on the individual gears, bearings and other components of the cutter bed, without sacrificing cutting power, blade speed or ground speed of the harvester. 
     Additionally, an important object of the invention is to provide a hydraulic drive for the rotary style cutter bed of a harvester in which the cutter bed speed remains substantially constant even if the engine speed of the mechanism driving a hydraulic pump for the bed lugs down such as when heavy crop conditions are encountered. 
     In carrying out the foregoing and other important objects, the present invention contemplates, in one preferred embodiment, increasing the effective length of a standard-length cutter bed by adding a pair of extensions or supports to opposite ends of the original gear case. Additional rotary cutters are journalled by the extended supports for rotation about upright axes. Instead of increasing the length of the gear train through the gear case, driving power to the added cutters is supplied by overhead drive mechanism that connects upright shafts of the added cutters with upright shafts associated with the opposite end cutters of the original gear case. Such over-the-top mechanism may take the form, for example, of timing belts and pulleys, chain and sprockets, gear boxes and universal joint couplings, or a spur gear train. In the event that the cutter bed is mechanically driven, one of the shafts associated with the original gear case serves as the driving input shaft from which all of the gears in the gear case receive their driving power. On the other hand, if the drive is a hydraulic drive, the present invention contemplates coupling at least one hydraulic motor with the cutter bed. Preferably, a separate hydraulic motor is coupled with each shaft of the two end gears in the gear case and such motors are connected in a parallel fluid flow relationship so that the work of driving the gears in the gear case and their respective cutters, as well as the added-on-cutters, is shared uniformly by both of the hydraulic motors. Such load sharing comes by virtue of the uninterrupted mechanical drive train through the gear in the cutter bed and the parallel fluid connection between the motors. As a result, the loading on individual gears, bearings and other components is dramatically reduced from which it would otherwise be. 
     The hydraulic motors are mounted on the header frame above a horizontal partition or wall that separates the overhead motors from the cutting and consolidating region below the partition. A special flow volume compensating circuit in the hydraulic drive system responds to engine slow-down caused by increased loading in the hydraulic operating circuit so as to allow essentially the same flow volume rate of oil to move to the motors notwithstanding the change in engine speed that would normally cause reduced volume. The cutter speed thus remains substantially unchanged. 
     Alternative consolidating or conveying means associated with the cutters laterally outside of the discharge opening of the header are provided to achieve inward consolidation of cut crop from the outer cutters. Such conveying means may take alternative forms such as an upright platform or conveyor belts a rotary, suspended drum between each pair of outer cutters, or a suspended rotary cage-type impeller between impeller cages of the outer cutters. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top plan view of a pull type harvester having a rotary cutter bed constructed in accordance with the principles of the present invention; 
         FIG. 2  is a top plan view of the cutter bed itself illustrating the rotary cutters; 
         FIG. 3  is an enlarged, fragmentary, front elevational view of the header portion of the machine; 
         FIG. 4  is a further enlarged, fragmentary front elevational view of the left end of the cutter bed (as viewed from the rear of the machine) showing details of construction with parts broken away and illustrated in cross section for clarity; 
         FIG. 5  is a vertical cross sectional view through the outer cutter and its associated mechanism at the left end of the header taken substantially along line  5 - 5  of  FIG. 4 ; 
         FIG. 6  is a similar vertical cross sectional view through the next inboard cutter taken substantially along line  6 - 6  of  FIG. 4 ; 
         FIG. 7  is a fragmentary, front elevational view of the header showing an alternative over-the-top drive arrangement for the two outermost cutters of the cutter bed utilizing gearboxes and universal joints; 
         FIG. 8  is a similar fragmentary, front elevational view of the header illustrating another embodiment of over-the-top drive for the outer cutters utilizing a chain and sprocket mechanism; 
         FIG. 9  is another fragmentary, front elevational view of the header showing an alternative embodiment employing a pair of hydraulic motors for the cutter bed; 
         FIG. 10  is a schematic diagram of the hydraulic circuit for the hydraulic cutter bed driven of  FIG. 9 , including an engine speed, load compensating circuit; 
         FIG. 11  is a fragmentary, front elevational view of the left end of the header illustrating one form of conveying means for directing crop severed by the outboard cutters toward the central discharge opening; 
         FIG. 12  is a horizontal cross sectional view thereof taken substantially along line  12 - 12  of  FIG. 11 ; 
         FIG. 13  is a fragmentary, front elevation view of the left end of the header illustrating a second form of conveying means for the outboard cutters utilizing a rotary drum between the impeller cages of two outermost cutters; 
         FIG. 14  is a generally horizontal cross sectional view thereof taken generally along line  14 - 14  of  FIG. 13 ; 
         FIG. 15  is another horizontal cross sectional view thereof taken substantially along line  15 - 15  of  FIG. 13 ; 
         FIG. 16  is a front elevational view of the left end of the header showing another form of conveying means for the outboard cutters, including an impeller cages located between the impeller cages of the two outermost cutters; 
         FIG. 17  is a horizontal cross sectional view thereof taken substantially along line  17 - 17  of  FIG. 16 ; and 
         FIG. 18  is a top plan view of the spur gear drive arrangement utilized for the cage type conveyor construction of  FIG. 16  (and for outer cutters without an intermediate conveyor cage if desired), with portions of the housing for the spur gear drive being broken away to reveal details of construction. 
     
    
    
     DETAILED DESCRIPTION 
     Extended Cutter Bed Construction 
     The harvester  10  in  FIG. 1  is a pull type harvester having a wheeled frame  12  that supports a forwardly disposed harvesting header  14 . A center pivot tongue  16  is attached at its rear end to the frame  12  via an upright pivot  18  and is adapted to be hitched at its forward end (not shown) to a towing tractor (also not shown). A hydraulic cylinder  20  interconnecting the rear of the tongue  16  and the frame  12  is adapted to be operated from the tractor seat so as to adjust the angular position of the tongue  16  relative to the frame  12  on-the-go, causing the harvester  10  to be adjustably shifted laterally in its trailing relationship with the tractor. A mechanical drive line  22  beneath the tongue  16  connects at its forward end to the power takeoff shaft (not shown) of the towing tractor, while the rear end of the drive line  22  connects to a gearbox  24  ( FIG. 3 ) supported on the header  14  forwardly of the tongue pivot  18 . The gearbox  24  can swivel about an upright axis defined by the journal  26  and is steered in such swiveling movement by a link  28  connected to the underside of the tongue  16  and the gearbox  24 . Such features are fully disclosed in the above mentioned U.S. Pat. No. 5,277,859 which is hereby incorporated by reference into the present specification as need be for a full and complete understanding of the present invention. 
     The header  14  includes a cutter bed  30  as illustrated in  FIGS. 2 ,  3  and  4 . The cutter bed  30  serves as a means by which standing crop is severed from the ground as the machine  10  is advanced. In the particular embodiment illustrated, the cutter bed  30  includes a series of ten rotary cutters  32  extending across the path of travel of the machine and each rotatable about its own upright axis. For the sake of convenience, the ten cutters  32  in  FIG. 2  will be denoted by the letters  32 a- 32 j, beginning with the left most cutter  32  in the series as viewed from the rear of the machine. The group of intermediate cutters  32 b- 32 i are rotatably supported on an elongated, flat gear case  34  that extends underneath the cutters  32 b- 32 i for the full length of the group. The gear case  34  is hollow as shown in FIG.  4  and contains a train of flat spur gears  35  that are operably engaged with one another and thus serve to distribute driving power between one another. Although other forms of power distribution means can be utilized within the case  34 , such as shafts and bevel gears or belts and pulleys, the flat spur gears  35  are preferred. Each of the cutters  32  includes a generally elliptical, formed metal knife carrier  36 , such as illustrated by the cutter  32 a, and a pair of free swinging knives  38  at opposite ends of the carrier  36  as well understood by those skilled in the art. As noted in  FIG. 2 , all of the cutters  32 a- 32 j are ninety degrees out of phase with one another inasmuch as the circular paths of travel of the knives of adjacent cutters overlap one another and must be appropriately out of phase in order to avoid striking each other. Due to the positive mechanical drive connection between the group of intermediate cutters  32 b- 32 i through the spur gears  35 , such cutters always remain properly in phase with one another, the outer cutters  32 a and  32 j remaining in proper phase by means yet-to-be-described. 
     As shown in  FIGS. 2 and 6 , the gear case  34  is carried by a shelf-like cradle  39  that juts forwardly from the lower, front edge of the header  14  and extends along the length thereof. The upper face of the cradle  39  is provided with a long recess or socket across the front of the machine that matingly receives the gear case  34 . As shown in  FIG. 6 , an overhanging peripheral flange on the gear case  34  receives a series of bolt assemblies  41  which secure the gear case  34  to the cradle  39 . Front notches  43  in the leading edge of the cradle  39  ( FIG. 2 ) are positioned between the counterrotating cutters  32 b- 32 i to improve the severing action against those portions of standing crop materials aligned with the zones generally between adjacent cutters instead of directly in front of them. 
     As illustrated particularly in  FIGS. 2-6 , the cradle  39  has a pair of forwardly projecting support bars  39 a at its opposite ends. Each of the support bars  39 a, in turn, has a hollow support extensions  40  welded thereto and projecting laterally outwardly therefrom for rotatably supporting the two outer cutters  32 a and  32 j. Although the extensions  40  are hollow, they contain no spur gears or other power distribution mechanism. Instead, as illustrated by the cutter  32 a in  FIGS. 4 and 5 , each of the outer cutters  32 a,  32 j merely has a bearing assembly  42  secured to the top wall  40 a of extension support  40  for rotatably supporting an upright shaft assembly  44  that projects upwardly from the cutter  32 a or  32 j and defines the axis of rotation thereof. In both of the outer cutters  32 a and  32 j, the carriers  36  are secured to the corresponding shaft assembly  44  for rotation therewith. 
     The shaft assembly  44  of the outer cutter  32 a is centered within an impeller cage  46  of the same construction as the impeller cages in the incorporated &#39;859 patent. Additionally, the shaft assembly  44  includes a lower universal joint  48  housed within the impeller cage  46  in the same manner as the &#39;859 Patent. The cutter  32 a also carries a kidney-shaped impeller plate  49  as in the &#39;859 Patent. The universal joint  48  is connected at its upper end to a shaft  50  that passes through a surrounding sleeve  52  held in a fixed, vertical orientation by a horizontal partition or wall  54  extending above the cutters  32 a and  32 b. As shown in  FIGS. 5 and 6 , the overhead wall  54  merges at its rear extremity with a downwardly and rearwardly sloping back wall  56  to define a region  58  forwardly of the back wall  56  and below the overhead wall  54  within which the cutters  32 a,  32 b and  32 i,  32 j are located. The sleeve  52  projects down beyond the overhead wall  54  a sufficient distance as to extend into the top of the impeller cage  46  without providing support for the shaft assembly  44 , and, at the outer extreme, projects a short distance upwardly above the overhead wall  54 . 
     The shaft  50  projects into a right angle gearbox  60  carried by an upright front wall  62  ( FIG. 5 ) of the header. Inside the gearbox  60 , the shaft  50  operably connects with a horizontal output shaft  64  that ultimately drives a pair of conditioning rolls  66  ( FIG. 2 ) via a belt and pulley drive  68  and a transmission box  70 . 
     The shafts  50  and  64  are operably coupled interiorly of the gearbox  60  with a vertical shaft  72  projecting from the top of the gearbox  60 . Shaft  72  carries a sheave  74  which is entrained by an endless, flexible drive belt  76  extending horizontally inboard of the header where it entrains another sheave  78 . The drive belt  76  is a timing belt of the type provided with a multitude of transverse, evenly spaced ribs along its working surface for meshing engagement with mating, upright groves in the working peripheries of the sheaves  74  and  78 . This eliminates slippage between the timing belt  76  and the sheaves  74 ,  78  during operation, which maintains proper out-of-phase relationship between the outer cutter  32 a and the next adjacent cutter  32 b. The sheave  78  is fixed to an upright shaft  80  which receives driving input power from a large sheave  82  entrained by a flat drive belt  84  leading toward the center of the header. The opposite, lower end of the shaft  80  is coupled with the cutter  32 b for driving the same. Thus, it will be seen that the universal coupling  48  of the cutter  38 a, the shaft  50 , the gearbox  60  and the shaft  72  broadly comprise driven shaft means for the cutter  32 a, while the sheave  74 , the timing belt  76  and the sheave  78  broadly comprises mechanism  83  operably coupling the driven shaft means with the drive shaft  80  for the second cutter  32 b. 
     The belt  84  extends back to the center of the machine and at that location entrains a large sheave  86  that receives driving power from a downwardly projecting output shaft (not clearly shown in the drawings) of the gearbox  24 . 
     The drive shaft  80  of the cutter  32 b is journalled by a pair of upper and lower bearing assemblies  88  and  90  which are in turn supported within a generally C-shaped bracket  92  ( FIGS. 4 and 6 ) fastened to the front wall  62  inboard of the attachment point for the gearbox  60  of cutter  32 a. Shaft  80  projects downwardly from the bearing  90  through a sleeve  94 , similar to the sleeve  52 , which is fixed to the horizontal wall  54  and projects downwardly beyond the same. At a point near the lower end of the sleeve  94  the shaft  80  connects with a universal coupling  96  that is in turn fixed to a short upright shaft (not shown) having the spur gear  35  fixed thereto at its lower end. The short upright shaft of the cutter  32 b is contained within the bearing assembly  42  thereof and such shaft is operably connected to the carrier  36  of the cutter  32 b. A generally kidney shaped impeller plate  98  of the type disclosed in the &#39;859 Patent is secured to the carrier  36  of the cutter  32 b for rotation therewith. Additionally, an impeller cage  100  of the same construction as the cage  46  of cutter  32 a is disposed above the impeller plate  98  encircling the universal coupling  96 . 
     As illustrated in the figures, the cutter  32 b and its drive shaft means comprising the upper shaft  80 , the universal coupling  96  and the lower stub shaft within the bearing  42  are located adjacently outboard of a crop discharge opening  102  in the back wall  56  of the header  14 . As shown in  FIG. 2 , the conditioning rolls  66  are located immediately behind the opening  102 , which in turn is positioned directly behind the cutters  32 c- 32 h. Like the cutter  32 b, the cutter  32 i is located adjacent one end of the opening  102 , and preferably has its upright axis of rotation disposed slightly outboard of such opening. 
     As earlier mentioned, the group of intermediate cutters  32 b- 32 i are drivingly interconnected and distribute power to one another through the train of spur gears  35  contained within the gear case  34  of the cutter bed  32 . There is an unbroken chain of power distribution through the gear case  34  from the cutter  32 b through and including the cutter  32 i. On the other hand, like the cutter  32 a, the cutter  32 j is not driven by a spur gear directly beneath it. Instead, the hollow extension support  40  for the cutter  32 j is empty like the support  40  for the cutter  32 a. 
     The cutter  32 j is driven in a similar manner to the cutter  32 a through an over-the-top mechanism. Like the cutter  32 a, the cutter  32 j includes a universal coupling  104 , a shaft  106  leading upwardly from the coupling  104 , and a sleeve  108  encircling the shaft  106  at the point where shaft  106  is connected to the universal coupling  104 . The sleeve  108  is supported within a top wall  110  which corresponds to the top wall  54  at the opposite end of the header. An impeller cage  112  encircles the universal coupling  104  and has an impeller plate  114 . Instead of passing into a gearbox such as the gearbox  60  associated with cutter  32 a, the upright shaft  106  of cutter  32 j is supported by bearings and a C-shaped bracket  116  like the bearings  88 ,  90  and bracket  92  associated with the cutter  32 b. Thus, the coupling  104  and the shaft  106  constitute driven shaft means for the cutter  32 j. 
     The upper end of the shaft  106  is provided with a ribbed timing sheave  118  which is entrained by an endless timing belt  120 . At its opposite end, the timing belt  120  is entrained around a second timing sheave  122  fixed to the upper end of a shaft  124  associated with the cutter  32 i. The shaft  124  is supported by a C-shaped bracket  126  that is secured to a front wall corresponding to the front wall  62  on the left end of the header. Shaft  124  passes downwardly through a sleeve  128  supported by top wall  110 . A universal coupling  130  joins with the shaft  124  within the sleeve  128  and connects at its bottom end with a short, upright stub shaft (not shown) beneath the carrier  36  of the cutter  32 i, which is in turn secured to an aligned one of the spur gears  35  within the gear case  34 . An impeller cage  132  surrounds the universal coupling  130  and is secured to the carrier  36  of cutter  32 i. As can be seen, the sheave  118 , the belt  120  and the sheave  122  effectively comprise mechanism denoted by the numeral  134  operably coupling the shaft  124  of the cutter  32 i with the shaft  106  of the cutter  32 j externally of the support  40  for driving the cutter  32 j. An impeller plate  133  overlies and is secured to the carrier  36  of cutter  32 i and is ninety degrees out of phase with the impeller plate  114  of the cutter  32 j. 
     As illustrated in  FIG. 2 , the cutters  32 b- 32 i in the intermediate group are arranged in cooperating pair so that the two cutters of each pair rotate in opposite directions. In other words, the cutters  32 b and  32 c rotate toward one another across the front of the cutter bed as do the cutters  32 d,  32 e, the cutters  32 f and  32 g, and the cutters  32 k and  32 i. Consequently, the converging leading edges of the counter rotating cutters tend to direct the severed crop material rearwardly between such cutters at their point of convergence. 
     On the other hand, it will be noted that the two outermost cutters  32 a and  32 j rotate in the same direction across the front of the cutter bed as their next inboard cutters  32 b and  32 i. Accordingly, crop materials severed by the outermost cutters  32 a and  32 j are moved inwardly along the front of the cutters  32 a,  32 b and  32 j,  32 i until reaching the next converging nip point of the cutters in front of the discharge opening  102 . 
     It is to be noted that because the outermost cutters  32 a and  32 j rotate inwardly in the same direction as their next adjacent cutters  32 b and  32 i, the cutters of those particular pairs must be spaced somewhat further from one another than the cutters of the oppositely rotating pairs in order to avoid striking one another. This is observable in  FIG. 2 , for example. Consequently, unless appropriate compensatory measures are taken, there is likely to be a slight decrease in the cutting quality in the zones directly between cutters  32 a,  32 b and  32 i,  32 j. Accordingly, it will be noted that the notches  135  between cutters  32 a,  32 b and  32 i,  32 j are somewhat deeper and wider than the notches  43  along the front edge of the cradle  39 . This allows the standing crop material aligned with notches  135  to enter more deeply into the profile of the cutter bed  30  before the bed passes over the material, thus providing a greater opportunity for the arcuately moving cutter blade  38  to engage and sever the material before it is passed over by the bed  30 . While the spur gears  35  within the gear case  34  preclude the notches  43  from being deeper than illustrated in  FIG. 2 , no such restriction exists with the support extensions  40  due to the fact they are hollow and devoid of mechanism. 
       FIG. 7  illustrates the harvester  10  with a modified form of mechanism that transferers power from the cutter  32 b to the cutter  32 a, and from the cutter  32 i to the cutter  32 j. Thus, in  FIG. 7  the mechanism  136  between the cutters  32 a and  32 b includes a first right angle gearbox  138 , a horizontal output shaft  140  projecting from the gearbox  138  toward the cutter  32 a, a universal joint coupling  142  at the end of shaft  140 , an input shaft  144  at the end of coupling  142 , and a second right angle gearbox  146 . The shaft  50  for the cutter  32 a leads downwardly out of the gearbox  146 . Similarly, the shaft  80  for cutter  32 b extends downwardly out of the gearbox  138 , as well as upwardly to the large sheave  82 . 
     The same type of change is made at the right end of the header in which the power transferring mechanism  148  supplies driving power from the cutter  32 i to the cutter  32 j. The operating components of the mechanism  148  are substantially identical to those of the mechanism  136 , and thus will not be described. 
       FIG. 8  shows another embodiment of the mechanism which transfers power from the cutter  32 b to the cutter  32 a, and from the cutter  32 i to the cutter  32 j. In this arrangement the mechanism  150  between cutter  32 a and cutter  32 b most closely resembles the mechanism  83  of the first embodiment, with the exception that instead of a timing belt and timing sheaves, a chain  152  and sprockets  154 ,  156  are utilized. Similarly, in the mechanism  158  between the cutters  32 i and  32 j, a chain  160 , sprocket  162  and sprocket  164  are used. 
       FIG. 9  illustrates a hydraulic drive arrangement for the cutter bed  30 . In lieu of the mechanical drive arrangement of  FIGS. 1-8 , a pair of rotary hydraulic motors  166  and  168  are utilized to drive the cutters  32 a- 32 j. In the case of the motor  166 , a C-shaped bracket  179  is secured to the upright front wall  62  of the header and carries an elevated platform  172  and struts  173  for motor  166  so that motor  166  is disposed high above the top wall  54  of the crop handling region  58 . An upright shaft  174  projects downwardly from the motor  166  and carries a timing sheave  176  before passing on down to the cutter  32 b in the usual way. The timing sheave  176  is entrained by a timing belt  178 , which in turn entrains a timing sheave  180  on an upright shaft  182  associated with the cutter  32 a. The shaft  182  projects into a right angle gearbox  184  which operably connects with the cutter  32 a in the usual manner. 
     The cutters  32 b- 32 i are drivingly interconnected with one another through the gear case  34  by spur gears in the same manner as disclosed with respect to  FIGS. 1-8 . Similarly, the endmost cutters  32 a and  32 j are carried on hollow support extensions  40  which are devoid of spur gears and other drive mechanism in the same manner as disclosed in  FIGS. 1-8 . Consequently, it will be seen that driving power for the cutter  32 a is obtained exteriorly of the gear case  34  via mechanism broadly denoted by the numeral  186  and including the timing sheave  176 , the timing belt  178  and the timing sheave  180 . Hydraulic motor  166  thus provides driving power for both the cutter  32 a and the cutter  32 b. 
     At the opposite end of the machine, the hydraulic motor  168  is supported on its own C-shaped bracket  188  high above the top wall  110  of the header by a platform  190  and struts  192 . An output shaft  194  from the hydraulic motor  168  carries a timing sheave  196  and passes on down through the bracket  188  for operable connection with the cutter  32 i in the usual manner. A timing belt  198  is entrained around the timing sheave  196  and also a timing sheave  200  on the upper end of an upright shaft  202  associated with the cutter  32 j. Shaft  202  passes downwardly through and is supported by a C-shaped bracket  204  attached on the front wall  62  of the header and connects with the cutter  32 j as its lower end in the usual manner. Thus, it will be seen that the timing sheave  196 , the timing belt  198  and the second timing sheave  200  comprise mechanism  206  for transferring driving power from the shaft  194  of cutter  32 i to the shaft  202  of cutter  32 j. The motor  168  thus drives both the cutter  32 i and the cutter  32 j. 
     Moreover, it will be seen that the two hydraulic motors  166 ,  168  cooperatively drive and share the load of all of the cutters  32 a- 32 j associated with the cutter bed  30 . Since the intermediate cutters  32 b- 32 i are all interconnected via the gear train within the gear case  34 , and the cutters  32 a and  32 j are connected to the input drive shafts  174  and  194  of the hydraulic motors  166 ,  168 , all cutters of the cutter bed  30  simultaneously receive driving input power from the hydraulic motors  166  and  168 . With the motors  166  and  168  connected in a parallel hydraulic fluid flow relationship, any additional loading experienced by one of the motors  166  or  168  is immediately shared by the other hydraulic motor, thus maintaining equal loads on the two motors. This also means, for example, that the spur gear associated with the cutter  32 b does not need to bear all of the loading from the other spur gears in the gear case since approximately one half that loading is directed to the spur gear associated with the cutter  32 i at the opposite end of the gear case  34 . Consequently, bearings, gears and other components of the system will have significantly increased wear life. 
     Load Compensating Circuit 
       FIG. 10  shows a hydraulic drive and control circuit which is especially suited for a self-propelled machine in which the tractor portion is provided with an engine  208  and an onboard pump  210  that is mechanically driven by the engine  208 . The pump  210  is preferably a pressure-compensated, load-sensitive pump, a suitable one of which is available from Vickers, Inc. of Omaha, Nebr. A swash plate of the pump  210  may be adjustably stroked or destroked to change its angular position so as to correspondingly adjust the output flow rate of oil therefrom as measured, for example, in gallons per minute. 
     A high pressure line  212  leads from the pump  210  to a tee connections  214 , where one branch line  216  leads to the motor  166  and another branch line  218  leads to the motor  168 . A return line  220  leads from the motor  166  back to another tee connection  222 , while a return line  224  leads from the motor  168  to the tee connection  222 . From the connection  222  a single low pressure line  226  leads to the backside of the pump  210 . A case drain line  227  leads from the backside of the pump  210  to the tank  240  to remove any oversupply of oil to the pump  210  and to provide cooling for the pump. In the preferred embodiment, the compensating pump  210  is provided with a fixed displacement, vane-type charge pump (not shown) of well known construction to supply oil to the pump  210 . Broadly speaking, the lines and connections  212 - 226  comprise an operating circuit for the motors  166  and  168 . 
     The operating circuit  228  is illustrated in solid lines in  FIG. 10 , while a control circuit for the operating circuit  228  is illustrated for purposes of clarity primarily in dashed lines and is denoted broadly by the numeral  230 . One component of the control circuit  230  is a pilot operated, two-position poppet valve  232  which can either be open or closed. The poppet valve  232  is located in the line  212  upstream from the tee  214  and is normally closed as illustrated in FIG.  10 . Two conditions must be met before it can be shifted to its open condition to allow flow there past to the motors  166  and  168 . First, there must be pressure in the line  212  sufficient to shift the spring-loaded poppet via a pilot line  234 . Second, an electrically operated control valve  236  must be energized and shifted out of its closed position of  FIG. 10  to an open position leftward of that illustrated in  FIG. 10  so as to communicate a return line  238  from the poppet valve  232  to tank  240  via a tank line  242 . Normally, with the electrically operated valve  236  in its closed position of  FIG. 10 , the return line  238  communicates with a high pressure line  244  connected to the main high pressure line  212 . An orifice  246  in high pressure line  244  reduces the pressure therein somewhat on the downstream side of the orifice  246  such that the resulting pressure within line  238  plus the resistance of a spring  248  of the poppet valve  232  keeps the poppet  232  normally closed. When the electric valve  236  is opened, the high pressure line  244  simply comes into communication with a line  250  having a check valve  252  that prevents further flow through the line  250 . When the electric valve  236  is in its closed  FIG. 10  position the line  250  communicates with tank  240  via the tank line  242  and the check valve  252  can open, but there is no operating pressure in the operating circuit  228  on the downstream side of the poppet valve  232  so there is no meaningful flow through the line  250  to the tank  240  at this time. It is contemplated that the electric valve  236  will be controlled from the cab of the tractor in an easily accessible position to the operator. 
     The poppet valve  232  is operable to serve as a restrictive orifice when in its open position. Thus, when poppet valve  232  is open and pressurized fluid is flowing through the line  212 , there is a pressure drop as the fluid passes through the poppet valve  232 . In other words, the pressure at a tee connection  254  on the upstream side of the poppet valve  232  is higher at such time than the pressure at a tee connection  256  on the downstream side of the poppet  232 . This pressure differential, more specifically the magnitude thereof, is utilized to control an adjusting circuit  258 , comprising a portion of the control circuit  230 , for adjusting the volume output of the pump  210  whose swash plate may be denoted schematically for purpose of illustration by the arrow  260  associated with the pump  210 . 
     The adjusting circuit portion  258  of the control circuit  230  includes a high pressure line  262  that joins with the high pressure line  212  at the tee connection  254  and leads to the left end of a pressure differential operated load compensating valve  264 . On the other hand, the opposite, right end of the load compensating valve  264  viewing  FIG. 10  communicates with the lower pressure tee connection  256  via a low pressure line  266 . The load compensating valve  264  is biased toward its closed position of  FIG. 10  by an adjustable spring  268  such that the compensating valve  264  only shifts rightwardly to its open position when the pressure differential between the tee intersections  254  and  256  is sufficiently high as to overcome the resistance of the spring  268 . When in such open, rightwardly shifted position, the load compensating valve  264  communicates a short line  270  from the high pressure line  262  with a destroking piston  272  via a pressure limiting valve  274  and flow lines  276 ,  278  on opposite upstream and downstream sides of the limiting valve  274 . The destroking piston  272  is operable to shift the swash plate  260  in a direction to reduce the volume output at such time. On the other hand, when the load compensating valve  264  is in its unactuated position of  FIG. 10 , the destroking piston  272  is communicated with the tank  240  via a drain line  280  leading from the valve  264  such that the destroking piston  272  receives no operating pressure at that time. Conversely, the stroking piston  282  of the pump  210  is communicated with the high pressure line  262  via flow line  284  at all times such that the stroking piston  282  continuously seeks to move and hold the swash plate  260  in its maximum flow position. Moreover, the stroking piston  282  has a spring associated therewith that biases the piston  282  toward a full stroke position even when there is no pressure in the high pressure line  212 . 
     When the load compensating valve  264  is rightwardly shifted out of its position in  FIG. 10  to an operated position so as to communicate the destroking piston  272  with the high pressure line  262  via short line  270 , line  276  and line  278 , both the destroking piston  272  and the stroking piston  282  simultaneously receive the same operating pressure from high pressure line  262 . However, the surface area of the destroking piston  272  is larger than that of the stroking piston  282 , causing the destroking piston  272  to dominate and force the swash plate back toward a neutral position in which no oil is pumped by the pump  210 . 
     The limiting valve  274  is normally held in its closed position of  FIG. 10  by the adjustable spring  286  at the left end of the valve viewing FIG.  10 . Thus, the amount of pressure required to open the limiting valve  274  can be adjusted by varying the force of the spring  286 . When in its closed position of  FIG. 10 , the limiting valve  274  simply communicates the flow line  278  of the destroking piston  272  with the reservoir  240  via lines  276  and  280 , assuming the load compensating valve  264  is in its unactuated position of FIG.  10 . When the fluid pressure within the main operating line  212  reaches the limit established by the limiting valve  274 , the valve is caused to shift leftwardly from its  FIG. 10  position by pressure in a short line  288  which is connected to the high pressure line  262  to bring pressure to bear against the right end of the valve  274 . This will cause the destroking piston line  278  to be communicated with a flow line  290  leading to the valve  274  from the high pressure line  262  so as to admit high pressure oil to the destroking piston  272 . Although both the destroking piston  272  and the stroking piston  282  will be exposed to the high pressure simultaneously, because of the greater surface area of the destroking piston  272 , the destroking piston will immediately shift the swash plate  260  back to neutral to stop the pump from pumping oil. 
     When the engine  208  is first started and the pump  210  begins operation, the swash plate  260  becomes stroked to its maximum volume position since the stroking piston  282  is spring biased to its maximum stroke. Pressure begins to rise in the main operating line  212 , but no oil can flow to the motors  166  and  168  at this time because the poppet valve  232  is closed. Consequently, inasmuch as there is essentially no oil pressure at the tee connection  214  at this time as long as the poppet valve  232  remains closed, the pressure differential seen by the loading valve  264  climbs to its operating level, at which time the loading valve  264  is caused to shift rightwardly from its  FIG. 10  position to align the flow line  270  with the flow line  276 . This operates the destroking piston  272  to return the swash plate  260  to its neutral position so that no additional oil is supplied by the pump  210  at this time. 
     When the operator is ready to start cutting, he operates a switch (not shown) in the tractor cab to energize the electric valve  236 . This shifts the valve  236  leftwardly from its position in  FIG. 10  to communicate the return line  238  with the tank line  242 , which lowers the pressure within line  238  sufficiently that the pressure in pilot line  234  can shift the poppet valve  232  to its open position. Once the poppet valve  232  is open, the operating circuit  228  becomes fully pressurized and the motors  166  and  168  commence rotating. 
     As pressurized oil passes through the poppet valve  232 , the valve  232  functions as a restrictive orifice, causing a pressure drop on the downstream side of the valve  232 . Thus, the pressure at tee connection  254  is normally higher than the pressure at tee connection  256 . The control circuit  230  takes advantage of this differential to communicate the higher pressure at tee connection  254  to the left end of load control valve  264  via line  262 , and the lower pressure at tee connection  256  to the right end of the load control valve  264  via line  266 . When this differential exceeds the preset limit, the load control valve  264  shifts rightwardly, communicating the destroking piston  272  with high pressure fluid via lines  262 ,  270 ,  276  and  278 . This destrokes the pump  210  to prevent the volume flow rate from exceeding a preset amount as determined by the adjustment of the control spring  268 . 
     During cutting operations the harvester sometimes encounters heavy cutting conditions which put load on the operating circuit  228  and tend to lug down the engine  208 . If this tendency to reduce the engine speed were not counteracted in some way, the pump  210  would slow down, the rate of flow of oil from the pump  210  would be reduced, and the cutting speed of the motors  166  and  168  would correspondingly decrease. Accordingly, the adjusting circuit  258  of the control circuit  230 , in particularly the load compensating valve  264 , is operable to responsively stroke the swash plate  260  when increased loading in the operating circuit  228  tends to lug down the engine  208 , thus maintaining the cutting speed of the cutter bed  30  essentially constant at all times. 
     It will be seen in this respect that when the motors  166  and  168  become more difficult to rotate due to increased resistance at the cutter bed  30 , such additional loading is immediately experienced in the high pressure operating line  212 . This additional loading tends to make the engine  208  slow down so as to lower the volume flow rate from the pump  210 . This volume decrease, however, results in a decrease in the pressure differential across the poppet valve  232  such that the compensating valve  264  stays in its leftmost position of  FIG. 10  to cause the stroking piston  282  to shift the swash plate  260  in a direction to increase the volume flow rate of oil from the pump  210 . The increased volume flow rate from the pump  210  compensates for the reduction in engine speed. Consequently, the cutters  32  remain turning at the desired cutting speed even when heavy conditions tend to lug down the engine  208 . Once the heavy conditions are handled, the engine  208  speeds back up and tend to increase the volume rate of oil leaving the pump  210 . However, any such volumes increase merely increases the pressure on the upstream side of the poppet valve  232  so as to increase the pressure differential seen by the compensating valve  264 . When such differential reaches the preset limit, the valve  264  shifts rightwardly viewing  FIG. 10  to expose the destroking piston  272  to high pressure oil and thus shift the swash plate  260  in a direction to bring the rate of flow back down to its normal level. Of course, if the cutter becomes plugged, the limiting valve  274  will kick in and shut down the flow from the pump  210  to avoid damage to the system. 
     One suitable operating and control system, including the pump  210  with its destroking piston  272  and stroking piston  282 , poppet valve  232 , electric control valve  236 , compensating valve  264  and limiting valve  274 , is available from Vickers, Inc. of Omaha, Nebr. as system No. PVH98-MCD-V1OR-02306232, assembly No. 02-306232. The poppet valve  232  and the electric control valve  236  may be obtained separately from the other valves of the system, combined within a valve block or unitary body, from Modular Controls Division of Vickers, Inc., Carrol Stream, Ill., as Part No. MCD-4326. 
     Non-Auger Conveying Means 
       FIGS. 11-18  relate to alternative arrangements for conveying the crop materials severed by cutters  32 a and  32 b as well as  32 i and  32 j inwardly toward the discharge opening  102 . For the sake of space, only the left end of the header has been illustrated in connection with the alternative arrangements, but it will be understood that a similar construction is also utilized at the opposite end of the header. Furthermore, some of the embodiments utilize hydraulic drive and others utilize mechanical drive, and such two different power types are considered interchangeable insofar as the conveying principles disclosed by the alternative embodiments of  FIG. 11-18  are concerned. 
       FIGS. 11 and 12  show a conveying means  292  in the form of a wide, upright, flat endless belt  294  that is entrained around the impeller cages  46  and  100 . Because the impeller cages  46  and  100  are driven in clockwise directions viewing  FIG. 12 , the forwardly facing front surface of the conveyor belt  294  moves from right to left, or inwardly toward the discharge opening  102 . 
     It will also be noted that the front surface of the belt  294  is spaced rearwardly from the forwardmost extremity of the cutters  32 . Thus, there is presented a certain accumulation space between the forward extremities of the cutters and the vertical face of the belt  294  within which the crop material can flow as it is severed and directed laterally inwardly. 
       FIGS. 13 ,  14  and  15  show an alterative conveying means  296  comprising an upright, rotary drum  298  and the impeller cages  100  and  46 . The drum  298  is located between the impeller cages  46  and  100  with its front periphery in line with the corresponding front peripheries of the cages  46  and  100 , thus effectively presenting a forwardly facing crop conveying surface somewhat similar to the front conveying surface of the belt  294  in  FIGS. 11 and 12 . An overhead belt and pulley drive  300  for the drum  298  receives driving power from the shaft  80  associated with the cutter  32 b so as to rotate in a clockwise direction viewing  FIG. 14 , like the impeller cages  46  and  100 . The drum  298  is suspended from the top wall  54  of the header by an upright shaft  302  of the drive and by a suitable bracket (only fragmentarily shown)  304  secured to the upright front wall  62  of the header. It will be noted in  FIG. 13  that the bottom of the drum  298  is spaced above the upper surface of the gear case  34  such that there is no support or drive structure directly beneath the drum  298 . Moreover, it will be noted that the periphery of the drum  298  is vertically ribbed to enhance its crop conveying capabilities. 
     The conveyor means  306  in  FIGS. 16 ,  17  and  18  comprises a third impeller cage  308  in combination with the other two impeller cages  46  and  100 . As with the drum  298  of  FIGS. 13-15 , the cage  308  is located between the other cages  46  and  100  and has its forward extremity in line with the corresponding forward extremities of the other cages. Thus, all three of the cages  46 ,  308  and  100  cooperatively present an effective front conveying surface that is set back from the forward most cutting circles of the cutters  32 a and  32 b to provide space in which the crop can flow laterally inwardly. The cage  308  is driven in a clockwise direction viewing  FIG. 17 , corresponding to the direction of rotation of the cutters  32 a and  32 b. 
     The cage  308  is constructed in an identical manner to the cages  46  and  100  and therefore will not be explained in detail. Unlike the cages  46  and  100 , however, the cage  308  is suspended in place with an absence of drive structure or cutter structure beneath the bottom thereof and the top of the gear case  34 . An upright drive shaft  310  extends upwardly through the center of the cage  308 , through the top wall  54 , and into a flat horizontal gear case  312 . Within the gear case  312 , a gear train is contained for transferring power between the shaft  80  of cutter  32 b, the shaft  310  of the cage  308  and the shaft  50  of the cutter  32 a. Such gear train includes a spur gear  314  on the shaft  80 , a spur gear  316  on the shaft  310 , a spur gear  318  on the shaft  50 , an idler gear  320  rotatably supported in meshing engagement with the spur gear  314  and  316 , and a second idler gear  322  in meshing engagement with the spur gears  316  and  318 . It will be seen that the gear case  312  can be as long as necessary to accommodate the length of gear train that is appropriate for the number of cutters and conveyor cages utilized outboard of the discharge opening  102 . Thus, although the present invention has been illustrated with only two outboard cutters  32 a and  32 b, it will be appreciated that a greater number of outboard cutters may be utilized. A similar gear train and case could be used as one form of overhead power transmitting mechanism in lieu of the mechanisms  83  and  134 ,  136  and  148 ,  150  and  158 , and  186 ,  206 . 
     The power for driving the cutter bed  30  in the embodiment of  FIGS. 16-18  is hydraulic power, one of the hydraulic motors  66  being illustrated as drivingly coupled with the shaft  80  of the cutter  32 b. Mechanical power could be used instead. 
     Furthermore, although the embodiments of  FIGS. 16-18  illustrate a single, relatively large diameter rotary member between the cages of the two outermost cutters, it will be appreciated that the single member could be replaced by two or more smaller diameter rotary members without departing from the principles of the present invention. If the smaller diameter members are utilized, it would be important to shift their axes of rotation far enough forwardly to assure that their forward extremities are generally transversely aligned with the front extremities of the cages  46  and  100 , for example, so as to effectively provide a moving conveying surface. 
     Although preferred forms of the invention have been described above, it is to be recognized that such disclosure is by way of illustration only, and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventors hereby state their intent to rely on the Doctrine of Equivalvents to determine and assess the reasonably fair scope of their invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention as set out in the following claims.