Patent Publication Number: US-2007113532-A1

Title: Crop processor bearing protection

Description:
FIELD OF THE INVENTION  
      This invention relates to forage harvesters.  
     BACKGROUND OF THE INVENTION  
      Forage harvesters are machines which chop crop gathered from a field into small pieces to produce animal feed. In the case of crops such as grass or alfalfa, these will have been pre-cut and left to dry in the sun, so that the crop need only be gathered by the harvester. With other crops, such as maize, the forage harvester may also be required to cut the crop. Thus, the harvesters may be fitted with different headers to suit the crop being harvested.  
      The crop, whether cut maize or gathered grass, is fed into a rotating knife drum or cutter which comminutes the product. With grass crops, this alone is sufficient to produce the desired forage. However, when harvesting maize for silage purposes, the cutting alone does not suffice due to the presence of kernels in the crop. The kernels need to be cracked in order to release the nutrient, as uncracked kernels are hard for animals to digest. As cutting alone is insufficient to crack all the kernels, the crop is additionally passed through a crop processor which comprises two closely adjacent rollers, typically having serrated surfaces, which rotate such that there is slippage between the adjacent surfaces. The gap between the rollers is set to suit the size of grain passing through and the speed, rotational energy of the rollers, relative movement and serration of the surfaces together ensure cracking of any kernels that are still intact after chopping by the cutter.  
      The momentum of the maize from the crop processor or the grass from the cutter, as the case may be, carries the crop into an accelerator or blower which then propels it up a tower to a discharge spout through which it is discharged into a wagon or a trailer drawn by a separate vehicle driven alongside the harvester.  
      When chopping kernel-free crops, such as grass or alfalfa, the crop processor is not required and leaving it in place in the crop flow path results in its rollers being unnecessarily subjected to wear.  
      To avoid such wear, it has previously been proposed to remove the crop processor from the vehicle, but the size and weight of the crop processor make this a difficult and cumbersome task.  
      Another solution, disclosed in EP 1 229 778 and GB 2 414 373, is to pivot the crop processor away from its operative position in the crop path but to leave it on the vehicle in an inoperative position.  
      In such a forage harvester, when the crop processor is moved to the inoperative position, it may remain accessible to personnel. Because of the high speed of rotation of the rolls of the crop processor, this present a safety hazard. For this reason, safety regulations advise that the belt driving the rolls of the crop processor be removed.  
      If the forage harvester is operated with the crop processor rendered inoperative in this manner, vibration can cause damage to the bearings of the crop processor as the rolling elements of the bearings tend to make indentations in the surface of the raceways.  
      With a view to mitigating the foregoing disadvantage, means are provided in a forage harvester with a movable crop processor for slowly rotating the rolls of the crop processor when it is in the inoperative position.  
      Preferably the means for rotating the rolls of the crop processor in the inoperative position comprise an electric motor. Alternatively power for rotating the crop processor may be derived from the engine of the forage harvester through a suitable gearbox or from the blower, using a slipping clutch.  
      As previously mentioned, to avoid the danger presented by a fast moving belt, safety requirements call for the drive belt of the crop processor to be removed when the crop processor when it is in the inoperative position. Having removed the belt from around the pulley driven by the blower of the forage harvester, it is possible to use the same belt to couple drive to the crop processor from the electric motor or auxiliary gear box. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The invention will now be described further by way of example with reference to the accompanying drawings in which:  
       FIGS. 1 and 2  correspond to  FIGS. 6 and 7  of GB 2 414 373 which illustrate the problem underlying the invention, and  
       FIG. 3  is a partial view of an embodiment of the invention showing the drive of the crop processor when it is in the inoperative position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       FIGS. 1 and 2  are described in GB 2 414 373 in detail and its disclosure is imported herein by reference to avoid lengthy repetition. These figures are described below only to the extent necessary to allow an understanding of the present invention.  
      Crop cut from a field by a suitable cutter advances along a chute  10  to an accelerator  12  also termed a blower. The accelerator propels the cut crop up a discharge spout  14  from which it is delivered to a vehicle driven alongside the forage harvester. The crop may or may not be of a type that contains hard kernels that need to be crushed to render them digestible.  
      A crop processor  16  having a pair of closely spaced and usually serrated rollers is used to crush the kernels if they are present. When harvesting crops such as maize, which contain hard kernels, the crop processor is moved into the operative position shown in  FIG. 1  in which it lies in the path of the crop between the entry chute  10  and the discharge spout  14 . When harvesting crops such as grass and alfalfa that do not contain hard kernels, the crop processor is moved to an inoperative position outside the crop flow path, as shown in  FIG. 2 . In the arrangement shown in  FIGS. 1 and 2 , the crop processor  16  and the accelerator  12  are mounted on a common pivot frame  18  so that the accelerator is lowered towards the entry chute  10  when the crop processor  16  is moved to the inoperative position, this being done to reduce the risk blockages. It is not however essential in the present invention for the accelerator  12  nor indeed any other component to be movable, other than the crop processor  16  itself.  
      The crop processor  16  is driven from the accelerator  12  by means of a belt  20 . A separate belt is provided on the opposite side of the accelerator to drive the accelerator  12  from the main engine of the forage harvester which also powers the cutters.  
      As can be seen from the  FIG. 2 , it is possible to leave the belt  20  driving the rolls of the crop processor in place when it is in the inoperative position. However, this would result in the rolls of the crop processor rotating at high speed even though they are not in use and this can present a safety hazard. It is therefore advisable to remove the belt  20  when the crop processor  16  is not in use.  
      If the belt  20  is removed and the rolls of the crop processor are allowed to remain stationary when in the inoperative position of  FIG. 2 , the constant vibration of the crop processor caused damage to its bearings. Persistent hammering of the rolling elements of the bearing against the same spot on their raceways creates dents in the raceways which shortens the life of the bearings.  
      To mitigate this problem, the present invention proposed driving the crop processor slowly when it is in the inoperative position so that the bearing are not damaged. The rolls of the processor are rotated slowly, just for the purpose of keeping the point of contact between the rolling elements and the raceways constantly moving, thereby avoiding local denting of the bearing raceways.  
      The means for slowly driving the crop processor in its inoperative position is shown in  FIG. 3  as being an electric motor  22 . Furthermore, the same belt  20  is repositioned from the accelerator  12  onto the electric motor so that the same pulleys and belt tensioning system are used to drive the crop processor rolls when in the inoperative position.  
      It is not essential to use a separate electric motor as drive can be taken from-the main engine of the forage harvester or the crop accelerator through a reduction gearbox or a slipping clutch to allow the crop processor to turn much more slowly than it would in the operative position.