an adjustment device for adjusting seats includes a rotatable drive element , a rotatable output element , a first clamping element freewheel that blocks the output element continuously in different positions in both adjustment directions and that is released by a release element and a second clamping element freewheel that is coupled via the release element to the first clamping element freewheel , blocks the output element continuously in different positions in both adjustment directions and is released by an actuating element . the drive element is pre - tensioned in a middle position via two springs acting in different directions and the two springs pre - tension the actuating element in a middle position .