A round baler (10) is provided with a single set of baling means (22) like belts, which are trained over a serious of fixed and mobile rolls (18 and 20). In order to form a bale (38) of a large diameter several loops are formed in said baling means (22), which loops are controlled by two pivot arms (14, 16). The position of these pivot arms (14, 16) is controlled by a common actuator (58).