A round baler includes a forming belt defining a baling chamber having an inlet through which crop material enters. A belt tensioning system includes a tension arm and a plurality of moveable rollers that move for maintaining tension in a forming belt while allowing a diametric size of the bale to increase during formation. A starter roll is positioned immediately upstream of the inlet relative to a rotational direction of the bale within the baling chamber during formation. The starter roll is moveable during bale formation in a direction at least partially directed toward a central transverse axis of the baling chamber to maintain a constant inward deformation distance into an exterior circumferential surface of the bale as the diametric size of the bale increases during formation.

A take-up or serpentine arm assembly for an agricultural baler, which arm assembly is moveable between a first position corresponding to an empty bale chamber of the baler and a second position corresponding to an at least partially filled bale chamber of the baler. The arm assembly includes a primary arm having a first rotatable roll mounted thereto and a secondary arm having a second rotatable roll mounted thereto. The secondary arm is moveably connected to the primary arm, or vice versa, such that in the first position of the arm assembly, the second rotatable roll is positioned a first distance away from the first rotatable roll, and in the second position of the arm assembly, the second rotatable roll is positioned a second distance away from the first rotatable roll that is less than the first distance.

A baler for forming round bales of crops, includes: a frame providing an internal volume; a feeding unit; a plurality of belts placed side by side in the internal volume; a tensioning system having tensioning arms for applying a tension to the belts so to generate a corresponding pressure on the crops; a control unit; wherein the control unit is connected to the tensioning system and is programmed for automatically setting the tensioning of the belts to a start value, at the bale starting point, and for automatically increasing the tensioning of the belts to reach the tensioning set point responsive to a predetermined swivel angle of the tensioning arms around an articulation point as the arms move upwards.

A round baler and a method for operating a round baler are disclosed. The round baler has a variable diameter and is bounded by an endlessly rotating pressing means. The pressing means is guided by a plurality of rollers, wherein a loop of the pressing means is guided by a first clamping arm mounted on the housing side and by a second clamping arm mounted on the housing side. The first and second clamping arms are adjusted by actuators so that at least one compaction pressure is generated with which the pressing means acts to form a round bale. A control unit automatically controls the actuators depending on a compaction power curve, accounting for operating parameters and/or environmental parameters of the round baler, thereby maintaining a substantially stable operating point during the shaping process, in which the required compaction power and the available drive power are substantially equal.