Adjustable hold-down for sickle guards

A method of adjusting an agricultural sickle bar cutting mechanism, including a sickle bar assembly, wherein the sickle bar cutting mechanism is affixed to and supported by the forward end, as determined by the operational direction of travel, of the frame of a crop mowing machine, said sickle bar assembly having a plurality of sickle guards attached to said forward end of said frame in side-by-side relationship generally horizontally along said forward end, each said sickle guard with at least one elongated portion extending forwardly and having a first generally planar upwardly facing surface;

• an elongate knife back;
• a plurality of knife sections each with angled forwardly converging cutting edges affixed to said knife back generally uniformly along the length thereof, each said cutting edge intersecting with a cutting edge on the adjacent knife section at a rear vertex, said knife back adapted to reciprocate along the length of said plurality of sickle guards such that the rearward vertices of said knife sections register with said first surfaces to cut crop material;
• a plurality of elongate hold-downs, one of said hold-downs associated with each said portion and having a second generally planar downwardly facing surface, said first and second surfaces forming a slot between each sickle guard and respective hold-down in which said knife sections reciprocate;
• each said hold-down comprising an elongate one-piece body having a tapered front portion, and an opposing generally rectangular rear portion with a width, a top surface and an opposing bottom surface, said front portion including said second planar surface and corresponding to part of said bottom surface and adapted to align with a sickle guard and knife section, said rear portion further including a generally planar first rear surface generally perpendicular to the planes of said top and bottom surfaces;
• each said second generally planar downwardly facing surface does not have protrusions of any kind extending therefrom;
• at least one hole through said rear portion and rigidly affixed to and bearing on said forward end of said frame by a first nut and bolt;
• said bottom surface of said rear portion of said elongate body positioned to intimately contact said sickle bar assembly and including a ridge across the said width of said rear portion and protruding perpendicularly away from said lower surface of said elongate body, said ridge having a rear surface corresponding to said first rear surface of said rear portion and a generally parallel registration surface closely spaced from said rear surface toward said tapered front portion, whereby said ridge registration surface may register with a portion of the said sickle bar assembly and thus properly align and maintain the spatial relationship between the front portion of the hold-down and the sickle guard;
• each said hold-down further having a reduced transverse cross-sectional area adjacent and forwardly of said point at which said hold-down is rigidly affixed to and bearing on said frame and having a second generally vertical hold therethrough adjacent to and forward of said reduced transverse cross-sectional area;
• a second bolt through said second hole, with a second nut thereof, said second nut tightened on said second bolt to the point that said hold-down is flexed about said reduced transverse cross-sectional area, modifying the spacing between said second surface and said knife section, though not completely eliminating said spacing, the method comprising the steps of:
• (a) aligning said ridge registration surface with a portion of the sickle bar assembly;
• (b) tightening or loosening said second bolt to flex said hold-down about said reduced transverse cross-sectional area to reduce or increase, respectively, the spacing between said second surface and said knife section;
• and
• (c) always maintaining some space between said second surface and said knife section.