fig1 is a schematic view of a harvester 10 , which comprises a chassis 11 supported on wheels 12 , where the chassis 11 supports a corn head 13 for harvesting corn through a feeder house 14 with a corn head angle adjuster 15 connected between the corn head 13 and the feeder house 14 . fig2 is a cut away plan view of the corn head 13 . the corn head 13 , which is used to harvest multiple rows at a time , comprises ; a first pair of gathering belts 17 , a first pair of knife rolls 18 ; a first gathering belt drive system 19 mechanically connected to the first pair of gathering belts 17 ; a first knife roll drive system 20 mechanically connected to the first pair of knife rolls 18 ; a gathering belt speed switch 22 ( fig1 ) connected to a gathering belt speed controller 50 , and a knife roll speed switch 23 ( fig1 ) connected to a knife roll speed controller 52 . fig3 is a detailed view of the first gathering belt drive system 19 and the first knife roll drive system 20 . the first gathering belt drive system 19 , comprises first gathering belt input shafts 25 , which are connected to other gathering belt drive systems and first gathering belt output shafts 26 that are mechanically connected to the first pair of gathering belts 17 . the first knife roll drive system 20 , comprises first knife roll input shafts 28 mechanically connected to other knife roll drive systems and first knife roll output shafts 29 mechanically connected to the first pair of knife rolls 18 . the first gathering belt drive system 19 and the first knife roll drive system 20 may be housed in separate housings forming two gear boxes or the same housing forming a single gear box . a first motor 31 is mechanically connected to a the first gathering belt input shaft 25 . a second motor 32 mechanically connected to a first knife roll input shaft 28 , through a torque sensor 51 ( fig2 ). the torque sensor 51 and the first motor 31 are connected either electrically , mechanically , or hydraulically to a knife roll speed controller 52 . the gathering belt speed controller 50 controls the speed of the first motor 31 . the knife roll speed controller 52 controls the speed of the second motor 32 . a first pair of sprockets 33 are mounted on the first gathering belt output shafts 26 . the first pair of gathering belts 17 are mounted on and driven by the first pair of sprockets 33 . the first pair of knife rolls 18 are directly connected to the first knife roll output shafts 29 . in this embodiment , the corn head 13 , further comprises ; a second pair of gathering belts 37 , a second pair of knife rolls 38 ; a second gathering belt drive system 39 mechanically connected to the second pair of gathering belts 37 and the first gathering belt system 19 ; a second knife roll drive system 40 mechanically connected to the second pair of knife rolls 38 and the first knife roll drive system 20 . an input shaft of the second gathering belt drive system 39 is mechanically connected to a first gathering belt input shaft 25 . second gathering belt output shafts are mechanically connected to the second pair of gathering belts 37 . an input shaft of the second knife roll drive system 40 is mechanically connected to a first knife roll input shaft 28 . the output shafts of the second knife roll drive system 40 are mechanically connected to the second pair of knife rolls 38 . a third pair of gathering belts 44 , a third pair of knife rolls 45 , a third gathering belt drive system 46 , a third knife roll drive system 47 , are also shown in this embodiment . the input shaft of the third gathering belt drive system 46 is mechanically connected to the second gathering belt drive system 39 . the input shaft of the third knife roll drive system 47 is mechanically connected to the second knife roll drive system 40 . a fourth pair of gathering belts 54 , a fourth pair of knife rolls 55 , a fourth gathering belt drive system 56 , a fourth knife roll drive system 57 , are also shown in this embodiment . the input shaft of the fourth gathering belt drive system 56 is mechanically connected to the third gathering belt drive system 46 . the input shaft of the fourth knife roll drive system 57 is mechanically connected to the third knife roll drive system 47 . a separator covering 60 is shown to cover a right gathering belt of the fourth pair of gathering belts 54 and a left gathering belt of the third pair of gathering belts 44 . other separator coverings are also provided to similarly cover gathering belts of adjacent pairs of gathering belts . an auger 61 is located at the rear of the gathering belts . a ground speed sensor 49 , fig1 is mounted to the chassis and detects the ground speed of the harvester 10 . both the ground speed sensor 49 and the gathering belt speed switch 23 are connected either electrically or hydraulically to a gathering belt speed controller 50 , fig2 . fig4 is a detailed view of the corn head angle adjuster 15 . the corn head angle adjuster comprises a corn head bracket 65 for mounting to the corn head 13 , a feeder house bracket 66 for mounting to the feeder house 14 , and a first adjuster cylinder 67 and a second adjuster cylinder 68 mounted between the feeder house bracket 66 and the corn head bracket 65 . the feeder housing bracket 66 comprises a mounting frame 69 , a pair of devises 70 , and a pair of hydraulic cylinder mounts 71 . the corn head bracket 65 comprises a mounting frame 72 , a pair of clevis tubes 73 , and a pair of hydraulic cylinder mounts 74 . the clevis tubes 73 fit into the devises 70 to form a pivot about a horizontal axis . in other embodiments , other pivots may be used between the feeder house bracket 66 and the corn head bracket 75 . the pivot is preferably on the lower parts of the feeder house bracket 66 and the corn head bracket 75 as shown . a feeder house hydraulic cylinder 78 , fig1 extends from the chassis 11 to the feeder house 14 . an angle controller 79 , fig2 is connected between an angle switch 80 and the first and second adjusting cylinders 67 , 68 . in operation , the harvester 10 is propelled through a corn field by the wheels 12 . a row of corn passes between the first pair of gathering belts 17 and the first pair of knife rolls 18 . the first pair of gathering belts 17 gather in the corn stalks , and the first pair on knife rolls 18 engage the corn stalks . the gathering belt speed controller 50 receives input from the gathering belt speed switch and the ground speed sensor and controls the speed of the first motor 31 , which controls the speed of the first pair of gathering belts 17 and the second pair of gathering belts 37 . this allows the speed of the gathering belts to be set either by the operator or according to the ground speed , or by a combination of both . the knife roll speed controller 52 is used to control the second motor 32 , which controls the speed of the second motor , which controls the speed of the first pair of knife rolls 18 and the second pair of knife rolls 38 . this allows the speed of the knife rolls to be set by either the operator or according to the torque on the knife rolls or by a combination of the both . it is desirable to increase the speed of the knife rolls if the torque increases . this is because , an increase in torque indicates an increase in the corn stalks engaged with the knife rolls . it is desirable to increase the knife roll speed to properly process this increased volume . the independent drive system allows the speed of the gathering belts to be controlled independently of the speed of the knife rolls . the controllers use this independent speed to allow for a more efficient processing of the corn stalks . the angle switch 80 is set by the operator to specify the desired angle of the first pair of knife rolls 18 are to make with the horizontal , which in this embodiment is an angle between 20 ° and 30 °. the setting of the angle switch 80 is communicated to the angle controller 79 , which measures the present angle of the corn head 13 using a sensor such as a level measuring device . if the desired angle is greater than the present angle that the first pair of knife rolls 18 makes with the horizontal then angle controller 79 causes the feeder house hydraulic cylinder 78 to extend , lifting the corn head 13 from the ground , and the first and second adjusting cylinders 67 , 68 extend to increase the angle that the first pair of knife rolls 18 makes with the horizontal pivoting the corn head 13 around the devises 70 , until the desired angle is reached . if the desired angle is less than the present angle that the first pair of knife rolls 18 makes with the horizontal then the first and second adjusting cylinders 67 , 68 retract to decrease the angle that the first pair of knife rolls 18 makes with the horizontal , until the desired angle is reached and the feeder house hydraulic cylinder 78 retracts , lowering the corn head 13 . thus by activating the first and second adjusting cylinders 67 , 68 in combination with the feeder house hydraulic cylinder 78 , a harvester with a corn head is provided , which may harvest at various angles , thereby optimizing the harvesting function in changing field conditions . if the operator lowers the corn head 13 close to the ground , the movement of the feeder house 14 causes the angle of the corn head 13 to change . the angle controller 79 changes the angle of the corn head 13 , so that the desired angle of the corn head 13 is achieved near the ground . if the operator raises the corn head 13 , the movement of the feeder house 14 causes the angle of the corn head 13 to change . the angle controller 79 changes the angle of the corn head 13 , so that the desired angle of the corn head 13 is achieved at a distance above the ground . as used in the specification and claims means for mechanically connecting may be by screws , bolts , clutch mechanisms or drive shafts . other embodiments of the invention may provide other gearbox or controller configurations to provide the independent speed control between knife rolls and gathering belts . other embodiments may use other power means in place of the first and second adjusting cylinders , to rotate the corn head around the pivot provided by the clevises . other power means may also be used in place of the feeder house hydraulic cylinder for raising and lowering the feeder house . the invention may also be provided as a kit to existing harvesters . while preferred embodiments of the present invention have been shown and described herein , it will be appreciated that various changes and modifications may be made therein without departing from the spirit of the invention as defined by the scope of the appended claims .
a harvester for harvesting crops , such as rows of corn , includes a corn head having a knife assembly and a gathering belt assembly whose speeds are independently controllable with respect to each other . the independent control permits optimization of the harvester for operation under a wide variety of ground conditions . the harvester also includes a mechanism for adjusting the angular position of the corn head with respect to an associated feeder house .