Abstract: The invention concerns a rhythmic or indexing drive for transfer lines with a timed-bar driver making a reciprocating movement on a frame and couplable to at least one timed bar, wherein a longitudinally displaceable drive element driven by a drive source substantially parallel to the plane of movement of the timed bar, is coupled to the timed bar. Such an indexing drive is characterized by its simple construction, and permits a smooth starting and braking of the timed bar at high transfer speeds during the time of the indexing stroke. The invention senses loosening of the coupling by a pressure drop.