Crop harvesting header with angle adjustment of the knife guards

A method for changing the effective cutter bar angle on a crop harvesting header comprising:

• providing a crop harvesting header including:
• a header frame structure arranged for movement in a direction of working movement across ground carrying a crop to be harvested;
• a cutter arranged across a forward edge of the header frame structure for cutting the crop;
• a cut crop transport arrangement mounted on the header frame structure for receiving and transporting the cut crop for further processing;
• the cutter including a cutter bar defining a flange projecting forwardly from the header frame structure and extending across the header frame structure;
• a plurality of knife guards mounted on the cutter bar at spaced positions thereon so as to project forwardly therefrom;
• a sickle knife having a knife drive bar extending across the knife guards for reciprocating movement thereon and a plurality of knife blades carried on the knife bar for co-operation with the knife guards in a sickle cutting action;
• each knife guard having at least one guard carrier lug for attachment to the flange by a bolt passing through a hole in the lug and a corresponding hole in the flange with a head on one end of the bolt and a nut on the other end of the bolt for clamping the lug to the flange;
• the method comprising adjusting an angle of forward projection of the knife guards relative to the flange so as to change an angle of the knife guards relative to the ground by:
• providing a first spacer element located between the lug and the flange and a second spacer element located on the bolt;
• the first spacer element being shaped such that it is tapered at a set angle so that the first spacer element is thicker on the front side of the bolt and thinner on the rear side of the bolt;
• the second spacer element being shaped such that it is tapered at the same set angle so that the second spacer element is thicker on the rear side of the bolt and thinner on the front side of the bolt;
• the spacer elements being clamped on the bolt with the flange and the lug to hold the lug at a first angle relative to the flange determined by the set angle;
• and reversing in position the first and second elements relative to the flange and the bolt so that the first spacer element is thicker on the rear side of the bolt and thinner on the front side of the bolt and the second spacer element is thicker on the front side of the bolt and thinner on the rear side of the bolt to hold the lug at a second angle relative to the flange determined by the set angle and different from the first angle by an angle twice the set angle.