Adjustable hold-down for sickle guards

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.

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 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”10that normally extends horizontally across the path of forward travel of the harvester. The cutterbar10is typically affixed to the forward lower portion of a frame structure or a fairly rigid metallic floor member11so as to present the cutterbar at the initial crop-engaging portion of the machine. A plurality of sickle guards12, shown in phantom inFIG. 1, are positioned regularly across the bottom of the cutterbar. An elongate knife-back14also extends across the cutterbar and has removably affixed thereto by bolts16, a plurality of knife sections18. The knife sections18are 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 guards12to 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-downs20are attached. This “sandwich” of components, along with appropriate shims22, is held together and attached to the member11by fastener means in the nature of carriage bolts15.

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 gap24, 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 toFIGS. 1 and 3, the hold-down20is an elongate forging with a forward (in relation to the direction of travel of the harvester) finger-like portion26and a rear generally rectangular box-like portion28. Referring toFIG. 3, the overall objective is to adjust the position of the lower surface30of front portion26of hold-down20between the fixed-line location and the dotted-line location, i.e., adjust the size of gap24.

As best seen inFIGS. 7-10a generally rectangular stud plate40, comprising a flat portion of suitably rigid material such as, for example,10B-38steel, hardened, and two spaced-apart stainless steel studs42and44(also hardened) stud-welded thereto and two holes46and48therethrough and adjacent to the studs. The stud plate is compressed by carriage bolt15into the “sandwich” of components making up the cutterbar10. 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 sections18reciprocate closely adjacent the bottom of the stud plate40, 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 plate40mounts two hold-downs to the cutterbar structure10as shown generally inFIG. 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-down20has a pair of holes50and52vertically therethrough similar in size and spacing to the studs and holes42,46and44,48of stud plate4050that, as shown clearly inFIG. 10the holes50fit over studs44and the two holes48,52are in alignment for the insertion of carriage bolts15. The lower area of the rear portion28of each hold-down20has a horizontal slot-like variably formed area raised relative to the lower surface30of the forward portion of hold-down20into which the stud plate40is fitted. The opposing upper surface, opposite the area into which the stud plate is fitted, is lowered and variably formed to receive a nut60on stud42.

In cross-section, as seen best inFIGS. 2,3,5, and10, rear portion28of hold-down20includes a narrowed section62(specially cross-hatched for illustration purposes inFIG. 3). Narrowed section62is of such size and thickness as to permit a small amount of flexing of the forward portion26of the hold-down, in spite of the fact that the hold-down20is preferably a forging. With the cutterbar assembled as inFIG. 2, tightening of the nut60on stud42will cause flexure at section62and resultant pivoting of the forward portion26of hold-down20about that section, moving the lower surface30toward knife section18.

This adjustment is simple to accomplish in that it merely requires the insertion of a feeler gauge into the gap and the manipulation of nut60. 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 portion28includes a protruding ridge, or lip70extending across the rear end thereof. Lip70is generally perpendicular to the longitudinal axis of hold-down20, i.e., the axis running from the point of finger-like front portion26through the middle of rectangular rear portion28. Thus, in the assembled “sandwich”, when lip70is in registry with the rear edge of stud plate40, the front portion26of hold-down20is in proper position over the knife section18. Lip70also prevents the “wiggling”of front portion26of hold-down20, even if the hardware somehow becomes slightly loosened. The lip structure could be used on substantially any hold-down with or without the stud plate40—so long as a similarly appropriate edge is provided on the underlying components.

Appropriate shims22should 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 gaps24in 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 portion26. 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.