Abstract:
A forged sickle bar hold-down formed with a reduced transverse cross-sectional area and a first hole therethrough positioned toward the rear end of the hold-down is disclosed. The hold-down includes a second hole therethrough positioned between the reduced cross-sectional area and the first hole. In use, an attachment bolt is positioned through the first hole and a support bar and rigidly affixed thereto. A threaded adjustment bolt is inserted through the second hole and the support bar to selectively draw down on that portion of the hold-down forward of the reduced transverse cross-sectional area and thereby flex the forward portion of the hold-down which includes an elongated finger-like body portion with a knife section facing area.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The invention is this application is related to those disclosed and claimed in U.S. application Ser. Nos. 10/319,291, 10/319,353 and 10/319,355 entitled,respectively, “Mechanism for Preventing Misalignment of Hold-Downs”, “Sickle Cutterbar Assembly”, and “Stud Plate for Sickle Bar Hold-Down”. All of these applications were filed on the same date as the instant application, and all have the same inventors. 
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to a mowing apparatus of the reciprocating sickle type and more particularly to a hold-down with improved adjustment characteristics. 
     The general mode of operation of reciprocating sickle bar mowing apparatus is well known, as is the importance of keeping the sickle bar knife sections substantially parallel to the ledger surface on the guards, and maintaining the proper clearance between them for good shearing action. Some form of hold-down clip or plate extending over the knife sections is generally used for this purpose. 
     Heretofore known hold-down mechanisms, such as those shown in U.S. Pat. Nos. 3,490,215, 3,577,716, 4,012,891, 4,894,979 and 6,305,154 are widely used, but have not been entirely satisfactory. The difficulty of adjusting such mechanisms often results in mowers being operated with improper knife clearance. Too much clearance allows crop material to force the knife section away from the cutting edges of the guards, greatly reducing cutting efficiency. Too small a clearance results in drag on the sickle bar assembly and a resultant increase in wear rate and power requirements. For the older clip-type hold-downs, adjustment is generally accomplished by bending the forward portion of the hold-down clip up or down as required, by using a hammer. This method is time consuming and inconvenient, and usually requires removal of the sickle bar so that the adjustment must be checked by means of a gauge rather than by direct measurement with the knives in place. Some attempts at improvement of this type of hold-down clip have involved pivoting the clip in a cradle mounted on the frame member and providing screw-type adjusting means so that the clearance between the forward part of the clip and the sickle section can be varied. 
     Both the conventional hold-down clip and the screw adjusted versions are typically placed between guards where they suffer additional dual disadvantages—first, of being located so as to snag crop material divided and deflected into this area by the guards, and second, of having only an indirect effect in controlling knife clearances in that they are not directly above the guard ledger surfaces. 
     Other attempts at improvement have included a variety of less conventional designs including some in which the hold-down plate itself is a form of leaf spring or is spring loaded so that there is always hold-down pressure on the knife sections although, typically, means are provided for adjusting this pressure. This type of hold-down clip is in constant contact with the knife sections and the drag between them increases wear rate and the power required to operate the mowing apparatus. 
     In another design, the hold-down clip is centered on the guard and clamped in position with the same screw fastener that retains the guard. Typically, screw adjustment is provided to raise or lower the forward part of the clip, but before the screw adjustment can be made, the screw fastener must be loosened to permit pivoting of the hold-down clip, consequently loosening the guards and upsetting adjustment of the wear plates between the sickle bar assembly and the frame member. 
     It would be quite advantageous to have an adjustment mechanism that does not require removal of components, hammering, or the loosening of hardware to accomplish appropriate adjustments. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention is to provide a sickle bar hold-down with a novel mechanism for adjusting the spatial relationship between the hold-down and the sickle knife sections. 
     Another object of the present invention is to provide a sickle bar hold-down that is more easily and reliably adjusted relative to the sickle knife sections than similar mechanisms heretofore known. 
     It is another object of the instant invention to provide a forged sickle bar hold-down that has an elongated finger-like body portion with a knife section facing surface and a reduced transverse cross-sectional area at a strategic location that allows selective flexing of the finger-like body portion adequate to adjust the spatial relationship between the knife section facing surface and the sickle knife sections. 
     Yet another object of the present invention is to provide a sickle bar hold-down that is infinitely adjustable independently of the mechanism by which the hold-down is affixed to a support structure. 
     It is yet another object of this invention to provide an improved sickle bar hold-down that is durable in construction, inexpensive to manufacture, carefree of maintenance, facile in assemblage, and simple and effective in use. 
     These and other objectives are attained by providing a forged sickle bar hold-down formed with a reduced transverse cross-sectional area and a first hole therethrough positioned toward the rear end of the hold-down. The hold-down includes a second hole therethrough positioned between the reduced cross-sectional area and the first hole. In use, an attachment bolt is positioned through the first hole and a support bar and rigidly affixed thereto. A threaded adjustment bolt is inserted through the second hole and the support bar to selectively draw down on that portion of the hold-down forward of the reduced transverse cross-sectional area and thereby flex the forward portion of the hold-down which includes an elongated finger-like body portion with a knife section facing area. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a top plan view of a fragmentary part of a cutterbar assembly showing a complete assembly of the elements of the instant invention; 
         FIG. 2  is an enlarged vertical section taken along the line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a further enlarged sectional view of parts shown in  FIG. 2  to better illustrate the operation of key parts; 
         FIG. 4  is a top view of one hold-down forging, alone; 
         FIG. 5  is a side elevation of the forging of  FIG. 4 ; 
         FIG. 6  is a bottom plan view of the forging of  FIGS. 4 and 5 ; 
         FIG. 7  is a top plan view of the stud plate element; 
         FIG. 8  is a front elevational view of the stud plate of  FIG. 7 ; 
         FIG. 9  is an end, or side elevation of the stud plate of  FIGS. 7 and 8 ; and 
         FIG. 10  is an end elevational view of the hold-down forging in place on the stud plate with a single optional shim interposed. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The harvester or other machine with which the hold-down of the present invention is utilized has a crop cutting mechanism, most commonly referred to as a reciprocating sickle-type “cutterbar”  10  that normally extends horizontally across the path of forward travel of the harvester. The cutterbar  10  is typically affixed to the forward lower portion of a frame structure or a fairly rigid metallic floor member  11  so as to present the cutterbar at the initial crop-engaging portion of the machine. A plurality of sickle guards  12 , shown in phantom in  FIG. 1 , are positioned regularly across the bottom of the cutterbar. An elongate knife-back  14  also extends across the cutterbar and has removably affixed thereto by bolts  16 , a plurality of knife sections  18 . The knife sections  18  are reciprocated lengthwise (by means, not shown, at one or both ends depending upon whether it is a single or double sickle bar cutterhead) so that the cutting edges on the knives register with the generally matching edges of the guards  12  to create a scissoring action to sever the crop material. In order to ensure that the knife sections and guards maintain the proper relationship for cutting, a plurality, one above each sickle guard, of hold-downs  20  are attached. This “sandwich” of components, along with appropriate shims  22 , is held together and attached to the member  11  by fastener means in the nature of carriage bolts  15 . 
     In all such mechanisms, the relationship between the hold-down and the knife section is critical to efficient and effective operation, and the objective in performing such adjustment is to minimize the gap  24 , yet allow adequate space for the free movement of the knife sections. The hold-down of the instant invention is intended to promote easy and effective adjustment of this relationship. 
     Referring initially and broadly to  FIGS. 1 and 3 , the hold-down  20  is an elongate forging with a forward (in relation to the direction of travel of the harvester) finger-like portion  26  and a rear generally rectangular box-like portion  28 . Referring to  FIG. 3 , the overall objective is to adjust the position of the lower surface  30  of front portion  26  of hold-down  20  between the fixed-line location and the dotted-line location, i.e., adjust the size of gap  24 . 
     As best seen in  FIGS. 7-10  a generally rectangular stud plate  40 , comprising a flat portion of suitably rigid material such as, for example,  10 B- 38  steel, hardened, and two spaced-apart stainless steel studs  42  and  44  (also hardened) stud-welded thereto and two holes  46  and  48  therethrough and adjacent to the studs. The stud plate is compressed by carriage bolt  15  into the “sandwich” of components making up the cutterbar  10 . The material characteristics, particularly of the flat portion, are important because of the wear to which the components are subjected. In this case, the knife sections  18  reciprocate closely adjacent the bottom of the stud plate  40 , subjecting the two components to significant abrasion due to materials such as dirt and crop that move between the two. The preferred stainless steel studs do not corrode or “stick”to the nuts, and thus promote ease of adjustment. 
     The stud plate  40  mounts two hold-downs to the cutterbar structure  10  as shown generally in  FIG. 1 . Two is a convenient number of hold-downs making up this grouping, though any reasonable number could be used. Two provides what has been found to be the most expedient number for assembly and repair operations. Sometimes, however, because of the length of the cutterbar or for other reasons, single hold-downs may be used on part of the cutterhead assembly. Each hold-down  20  has a pair of holes  50  and  52  vertically therethrough similar in size and spacing to the studs and holes  42 ,  46  and  44 ,  48  of stud plate  40   50  that, as shown clearly in  FIG. 10  the holes  50  fit over studs  44  and the two holes  48 ,  52  are in alignment for the insertion of carriage bolts  15 . The lower area of the rear portion  28  of each hold-down  20  has a horizontal slot-like variably formed area raised relative to the lower surface  30  of the forward portion of hold-down  20  into which the stud plate  40  is fitted. The opposing upper surface, opposite the area into which the stud plate is fitted, is lowered and variably formed to receive a nut  60  on stud  42 . 
     In cross-section, as seen best in  FIGS. 2 ,  3 ,  5 , and  10 , rear portion  28  of hold-down  20  includes a narrowed section  62  (specially cross-hatched for illustration purposes in  FIG. 3 ). Narrowed section  62  is of such size and thickness as to permit a small amount of flexing of the forward portion  26  of the hold-down, in spite of the fact that the hold-down  20  is preferably a forging. With the cutterbar assembled as in  FIG. 2 , tightening of the nut  60  on stud  42  will cause flexure at section  62  and resultant pivoting of the forward portion  26  of hold-down  20  about that section, moving the lower surface  30  toward knife section  18 . 
     This adjustment is simple to accomplish in that it merely requires the insertion of a feeler gauge into the gap and the manipulation of nut  60 . There is no need to adjust or loosen other nuts and bolts, disassemble the cutterhead, or otherwise engage in complex multi-step mechanical manipulations. 
     The rearmost segment of the rear portion  28  includes a protruding ridge, or lip  70  extending across the rear end thereof. Lip  70  is generally perpendicular to the longitudinal axis of hold-down  20 , i.e., the axis running from the point of finger-like front portion  26  through the middle of rectangular rear portion  28 . Thus, in the assembled “sandwich”, when lip  70  is in registry with the rear edge of stud plate  40 , the front portion  26  of hold-down  20  is in proper position over the knife section  18 . Lip  70  also prevents the “wiggling”of front portion  26  of hold-down  20 , even if the hardware somehow becomes slightly loosened. The lip structure could be used on substantially any hold-down with or without the stud plate  40 —so long as a similarly appropriate edge is provided on the underlying components. 
     Appropriate shims  22  should be inserted in the assembly to assure that the hold-down is initially installed in a horizontal position. It is from this horizontal position that adjustments are made to respective gaps  24  in the various assemblies. 
     The shape of the hold-downs shown herein are what may be referred to as a “big foot”. Specifically, the “big foot” design can be identified in any of the cross-sectional views of the hold-down. Notice that there is only a very small cutout on the underside of the finger-like forward portion  26 . The smaller this cutout, the less opportunity there is for crop materials to become entangled, forming what is sometimes referred to as a “mustache”. These mustaches can become surprisingly long and even interfere with the cutting operation of adjacent knife sections and the flow of cut crop material to the processing components of the harvester. Other designs may be required by the hardware used to hold the knife sections and knife backs together. If the rivet heads or nuts protrude above the surface of the knife section, the hold-down will have to have a cutout of sufficient clearance to allow passage of the knife sections. 
     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the inventions. Accordingly, the following claims are intended to protect the invention broadly as well as in the specific form shown.