Conveyor belt tensioner for an agricultural harvesting header

An agricultural harvesting header (102) comprising a conveyor belt tensioning arrangement, said agricultural harvesting header (102) comprising:

• a frame (105);
• a plurality of arms (202) pivotally coupled to the frame (105) at the rear ends to pivot up and down at their forward ends with regard to said frame (105) and extending forward from said frame (105);
• a conveyor belt (108, 112) disposed on said plurality of arms (202) to carry cut crop material;
• a first roller (210) supporting a first end loop of the conveyor belt (108, 112) for reversing the direction of said conveyor belt (108, 112), said first roller (210) being supported on a first one of said plurality of arms (202);
• and
• the tensioning arrangement further comprising:
• a second roller (208) comprising a front end and a rear end and a central axis, wherein the conveyor belt (108, 112) is wrapped around the second roller (208) for approximately 180 degrees to form a second end loop of the conveyor belt (108, 112);
• an elongate roller carriage (228) comprising a front end and a rear end, said elongate roller carriage (228) being configured to support the second roller (208) for rotation about the central axis, wherein the elongate roller carriage (228) has front carriage guide (410) at the front end and a rear carriage guide (412) at the rear end;
• front and rear guide members (224, 226) fixed with respect to an endmost pivoting arm (202A) of said plurality of arms (202), wherein the front guide member (224) supports the front carriage guide (410) and the rear guide member (226) supports the rear carriage guide (412), wherein the front and rear guide members (224, 226) constrain the elongate roller carriage (228) to translate with respect to the frame (105) in a direction generally parallel to a direction of travel of the belt (108, 112);
• an elongate tensioning beam (230), the tensioning beam (230) comprising a front end and a rear end, wherein a central portion of the tensioning beam (230) is coupled to a central portion of the elongate roller carriage (228) to apply pressure to the elongate roller carriage (228);
• and
• a spring assembly (232) fixed to the endmost pivoting arm (202A), said spring assembly (232) comprising a spring (240) disposed to apply pressure to the rear end of the tensioning beam (230);
• wherein the elongate roller carriage (228) defines an aperture (402), and further wherein a pin coupled to the elongate tensioning beam (230) is disposed in the aperture (402) to apply pressure to a surface of the aperture (402).