An actuating mechanism for the functional elements in a round baler for agricultural crops includes a tensioning arm which is provided with guide rollers and a pivotal arm and which is pivoted on the frame of the baler via a hydraulic cylinder. The hydraulic cylinder is arranged between the pivotal arm and a first arm of a bell crank, which is pivotally mounted on the tailgate. A second arm of the bell crank is selectively engageable with the front part of the housing.