the forage harvester chosen for the purposes of the present disclosure is of the self - propelled type such as shown in u . s . pat . no . 3 , 701 , 239 . the invention is , nevertheless , equally adaptable to tractor - drawn machines . in the self - propelled machine , a fore - and - aft main frame or chassis 10 is carried by front and rear wheels 12 and 14 respectively and powered by a drive source such as an internal - combustion engine 16 . in the present case , both front and rear wheels are driven by hydraulic drive means indicated at 18 , 20 and 22 , and a change - speed transmission 24 is provided for the front wheels . these are elements that have many variables and , forming no part of the invention , will not be described in further detail . in a tractor - drawn harvester , the power source will include a suitable gear box on the harvester frame deriving its input from the tractor power take - off , again not specifically a part of the invention . the chassis 10 includes a transverse front axle 26 , and structure associated therewith at the fore part of the chassis or frame carries a gathering means or head 28 which may be of any known or other construction . this head gathers standing corn from the field in the usual manner and , by means of feed rolls 30 , for example , the gathered crop , including stalks , ears , leaves , etc . is moved rearwardly to a high - speed rotary cutterhead 32 which cooperates typically with a fixed knife 34 to chop the crop into relatively small fragments , all as is conventional . the cutterhead is here shown simply as a cylinder , the conventional knives being omitted in the interests of clarity and brevity . chopped crops are thrown forcibly downwardly and rearwardly as the cutterhead rotates in the direction of the arrow . in a known forage harvester design , the crops would normally be carried by a rearwardly running conveyor to discharge means , such as a blower 36 , located at an aft part of the machine . in a tractor - drawn machine , the conveyor would extend normally crosswise of the direction of travel and the blower would be at one side of the machine . these are details not specifically significant to the present disclosure . also , in a typical machine , a recutter screen could be employed directly behind and at a lower part of the cutter , usually in the quadrant between &# 34 ; three &# 34 ; and &# 34 ; six o &# 39 ; clock &# 34 ;. a recutter screen may be used in the present invention , and the arcuate slide for receiving such screen is shown at 38 ( fig3 ). as will appear subsequently herein , the elements combined in the invention may be removed and replaced by conventional means and the recutter screen slipped into place if desired . a substructure 40 of generally box - like nature is removably carried by the frame or chassis and extends from just behind and below the cutterhead to the area in the vicinity of the discharge blower 36 . this substructure and the components contained therein replaces the usual conveyor that extends from the cutterhead to the blower . part of the contents of this substructure are upper and lower compressor rolls 42 , rotating in opposite directions ( see arrows ) on transverse parallel axes parallel to the axis of rotation of the cutterhead . these rolls are of the externally corrugated or fluted type used in roller mills , and they run in close proximity to each other so as to further reduce crops coming from the cutterhead and are especially adapted to crack kernels . the rolls are located so that the upper roll is behind and at a level below the cutterhead axis and the lower roll is offset forwardly and substantially below the upper roll , the position being chosen as that in which the rolls can most efficiently receive crops from the cutterhead without intervening conveying means . the cutterhead throws the crops tangentially thereof in a downward and rearward direction directly into the bite of the rolls . the rolls in turn throw the further reduced crops mainly rearwardly but also downwardly into the fore part of fore - and - aft conveyor means , here a pair of augers 44 ( fig4 ), which move the reduced crops rearwardly to the blower 36 , the conveyor shafts having thereon a plurality of paddles 46 for throwing the crops laterally into a receiving or inlet opening 48 in the near side of the blower housing . the disposition of the rolls in the manner described , with the lower roll offset ahead of and below the upper roll enables the fore part of the conveyor means to nest closely to the rolls , in which area the fronts of the conveyors are suitably journalled at 50 in a cross wall 52 of the substructure . the conveyors or augers are shorter than the replaced augers by the amount necessary to house the compressor rolls , which adds to the interchangeability of the substructure and conventional conveyor . the mounting of the box - like substructure 40 may be accomplished as shown best if fig1 and 4 . each member of the chassis 10 has depending therefrom front and rear hangers 60 , each of which extends alongside the respective side of the substructure and each is attached to the associated side walls of the substructure by means such as removable pins 62 . the openings in the walls at the left - hand side of the substructure are seen at 64 in fig5 . in a preferred arrangement , the diameters of the rolls 42 are on the order of about one - third that of the cutterhead ; these , in the example shown , being respectively eight and twenty - four inches . the speed of rotation of the lower roll 42 is greater than that of the upper roll so as to avoid accumulation of processed crop , especially kernels . further , it is found that good results are obtained if the surface velocity of the slower roll is approximately that of cutterhead tangential velocity . by way of example , the cutterhead speed of rotation in r . p . m . may be 850 , that of the slower roll being 2250 and that of the lower roll about 2750 . exemplary drive means for achieving these results will be seen best in fig2 and 5 . as seen in fig2 the drive source or engine 16 has a drive shaft 70 which , by means of bevel gearing 72 , drives a cross shaft 74 on which the fan of the blower 36 is mounted . a belt drive 76 connects this shaft to the cutterhead shaft and a flat , or multi - v - belt drive 78 drives the upper compressor roll 42 . at the opposite side of the machine , a differential drive drives the lower roll and a cross shaft 80 for the augers . this drive comprises a sheave 82 on the shaft of the upper roll , a sheave 84 on the shaft for the lower roll , a sheave 86 on the cross shaft 80 , an idler sheave 88 and a multiple v - belt 90 trained about the sheaves in such manner that the lower and upper rolls rotate in opposite directions . bevel gearing 92 completes the drive to the augers 44 . the gathering mechanism and the feed rolls 30 may be driven in any suitable manner , the details of which are omitted since they form no part of the invention . the lower roll may have means for adjusting its position relative to the upper roll and they may preferably include resilient means to enable the rolls to move apart to accommodate foreign objects , all expedients known in roller mills and hence not disclosed in detail . the advantages of roller mills per se are also well known and need not be detailed here . one advantage , however , is that the roller mill installation in a forage harvester eliminates the disadvantages of using recutter screens . the rolls are more power efficient than recutter screens , because the screen reduces all the material to small particles . another is that the rolls result in fewer fines which can cause digestive problems and reduced feed utilization . cob particles are reduced to edible size and the silage as a whole is more uniform in length and thus will pack better in a silo or pit . the rolls are especially advantageous in reducing later corn harvest where harder kernels escape cracking by prior systems , besides producing good feed for older cows with worn teeth . many features and advantages in addition to those enumerated here will be recognized by those versed in the art , as will modifications in the preferred embodiment , all without departure from the spirit and scope of the invention .
a forage harvester , otherwise of generally typical construction , is modified to include kernel - processing means in the form of a pair of cooperative compressor rolls situated in close proximity to the cutterhead and adapted to receive from the cutterhead fragmented crops and to further reduce the crops and especially to crack the kernels . the compressor rolls are of the type usually employed in a roller mill and have corrugated cylindrical outer surfaces particularly adapted to crack the kernels .