Abstract: A round baler for forming crop material into cylindrical bales. The baler has a main frame, a pair of side walls, a crop pickup mounted on the main frame, and a tailgate pivotally connected to the main frame. The tailgate is operative between a closed position during which a bale is being formed in an expandable chamber, and an open position during which a formed bale is being discharged from the chamber. A sledge assembly, pivotally mounted on the main frame for movement between a bale starting position and a full bale position, has crop engaging transverse rollers for urging the crop material along a spiral path in the chamber for starting and forming a bale. An apron is supported along a continuous path on the main frame and tailgate by a plurality of rotatable guide members. The path has an inner course that cooperates with the sledge rolls on the sledge assembly to define moveable walls of the chamber. A drive roll moves the apron along the continuous path.