Abstract: In a conveyor system, a retarder device (1) with a braking gap (40) for the passage of sheet stacks (4) collated with an overlap and regulated by a controller (35) via an actuator (33), the width of the braking gap (40) being positively adjusted, with the slight undersize necessary to generate the braking load, to the current stack height of the section of the stack stream (6) passing the braking gap (40). In this way the braking pressure acting on the stack sheets (4) can be kept substantially constant independently of the stack height. The braking pressure may also be adapted to the sensitivity of the sheet stacks (4) by a braking pressure relief unit in the form of a load relief element (42).