Harvester header with belt length adapting mechanism

An agricultural header comprising

• a frame adapted to be connected to an agricultural harvester, the frame comprising a floor surface substantially defining the width of the header, wherein an auger is mounted to the frame above the floor surface, the auger being provided to laterally transport crop material towards a central crop-receiving aperture;
• a cutter bar forming the leading edge of the header, the cutter bar being mounted to the frame via a slide so that the cutter bar is moveable between a retracted and an extended position;
• and
• a belt conveyor for transporting crop material from the cutter bar towards the auger, the belt conveyor extending between a first shaft that is mounted to the frame at a predetermined distance from the auger and a second shaft that is mounted to the slide at a predetermined distance from the cutter bar, and wherein the belt conveyor is provided with a belt-length-adapting mechanism so that the length of the belt between the first shaft and the second shaft is changeable between a short track corresponding to the retracted position and a long track corresponding to the extended position of the cutter bar, wherein the belt conveyor comprises at least a third shaft and a fourth shaft respectively connected to the slide and the frame, wherein the third and fourth shafts, together with the first and second shafts, form the length-adapting mechanism.