A turning bar is used to turn a web of material. The turning bar includes an outer jacket that is provided with holes on at least one section of its circumference. An inner chamber of the turning bar is provided with compressed air. A piston is arranged in the inner chamber and is movable to block selected ones of the holes. A motor is used to move the piston via a control signal provided by a control circuit. The turning bar can be pivoted by 90.degree. on a frame around a pivot axis that is perpendicular to a longitudinal axis of the turning bar. A transmission couples a rotational movement of the piston around the longitudinal axis to a pivoting motion of the turning bar.