A conveyor system for unloading crop material from an agricultural harvester, the conveyor system comprising: an adjustable-length discharge tube (126, 1260) for discharging crop material from the agricultural harvester to a location for receiving crop material, the discharge tube (126, 1260) having a length, the discharge tube (126, 1260) comprises an intake end for receiving crop material into the discharge tube and a discharge end (132, 2040) for discharging crop material from the discharge tube (126, 1260), the discharge tube comprising at least a first tube section (142, 1260) and a second tube section (152, 2020), the first tube section movably attached to the second tube section in an adjustable arrangement, the first tube section (142, 1260) and the second tube section (152, 2020) each being hollow and collectively defining a passage for conveying crop material through the discharge tube (126, 1260), with one of the first tube section (142, 1260) and the second tube section (152, 2020) being movable relative to the other of the first tube section and the second tube section to adjust the length of the discharge tube (126, 1260); and an endless conveyor belt extending through and movably displaceable within at least a portion of the discharge tube (126, 1260); the conveyor system further comprising a constant force take up system attached to one of the first tube section and the second tube section, the constant force take up system maintaining a substantially constant tension in the conveyor belt during axial displacement of one of the first tube section and the second tube section relative to the other of the first tube section and the second tube section; characterized in that the constant force take-up system is a hydraulic cylinder mounted to one of the first tube section and the second tube section. an adjustable-length discharge tube (126, 1260) for discharging crop material from the agricultural harvester to a location for receiving crop material, the discharge tube (126, 1260) having a length, the discharge tube (126, 1260) comprises an intake end for receiving crop material into the discharge tube and a discharge end (132, 2040) for discharging crop material from the discharge tube (126, 1260), the discharge tube comprising at least a first tube section (142, 1260) and a second tube section (152, 2020), the first tube section movably attached to the second tube section in an adjustable arrangement, the first tube section (142, 1260) and the second tube section (152, 2020) each being hollow and collectively defining a passage for conveying crop material through the discharge tube (126, 1260), with one of the first tube section (142, 1260) and the second tube section (152, 2020) being movable relative to the other of the first tube section and the second tube section to adjust the length of the discharge tube (126, 1260); and an endless conveyor belt extending through and movably displaceable within at least a portion of the discharge tube (126, 1260); the conveyor system further comprising a constant force take up system attached to one of the first tube section and the second tube section, the constant force take up system maintaining a substantially constant tension in the conveyor belt during axial displacement of one of the first tube section and the second tube section relative to the other of the first tube section and the second tube section; characterized in that the constant force take-up system is a hydraulic cylinder mounted to one of the first tube section and the second tube section.