A screed for road pavers, comprising a compaction unit, particularly a tamper with a tamper bar, that is drivable at cyclical work cycles with selectable stroke and selectable frequency for pre-compacting a pavement made from paving material, wherein the tamper comprises a rotatable eccentric shaft with respect to a connecting rod which drives the tamper bar at substantially vertical working cycles, wherein the compaction unit comprises an adjusting mechanism for the remote-controlled adjustment of the stroke of the compaction unit, wherein the adjusting mechanism can be operated hydraulically and/or electrically and/or mechanically during the ongoing paving work, wherein an automatic control system is provided which is operatively connected to the adjusting mechanism, and into which paving parameters, such as the paving speed and/or the pavement thickness as well as a target precompaction degree producible by the compaction unit, can be entered or in which said parameters can be stored, characterized in that A. the adjusting mechanism is arranged between the rotatingly drivable eccentric shaft in the screed and an eccentric bush which is rotatable on the eccentric shaft in a connecting rod driving the tamper bar at substantially vertical work cycles, in such a manner that the stroke of the tamper bar is adjustable by a relative rotational adjustment between the eccentric bush and the eccentric shaft, wherein in the eccentric shaft a driver which is axially adjustable, preferably electrically and/or hydraulically and/or mechanically adjustable, is supported in a rotationally fixed manner, the driver engaging into a thread-like guide path of the eccentric bush which is rotatably supported on the eccentric shaft, or B. the adjusting mechanism is arranged between the rotatingly drivable eccentric shaft in the screed and an eccentric bush which is arranged on the eccentric shaft in a rotationally fixed manner and is displaceable in a direction transverse to the axis of the eccentric shaft and is rotatable in a connecting rod driving the tamper bar, in such a manner that the stroke is adjustable by a transverse displacement of the eccentric bush relative to the eccentric shaft, or C. the adjusting mechanism is arranged between a bearing block supporting the rotatingly driven eccentric shaft and an adjusting lever which is articulated to a connecting rod driving the tamper bar and is adjustable in the bearing block, the adjusting lever and the one push rod drivable by the eccentric shaft being coupled with the connecting rod in a joint articulation axis, and wherein the bearing block has a straight or arcuate guide path which is engaged by an adjusting-lever pivot abutment which is movable by means of the adjusting mechanism along the guide path, and that the direction of extension of the guide path oriented in a direction transverse to the eccentric shaft is at least approximately oriented towards the axis of the eccentric shaft. A. the adjusting mechanism is arranged between the rotatingly drivable eccentric shaft in the screed and an eccentric bush which is rotatable on the eccentric shaft in a connecting rod driving the tamper bar at substantially vertical work cycles, in such a manner that the stroke of the tamper bar is adjustable by a relative rotational adjustment between the eccentric bush and the eccentric shaft, wherein in the eccentric shaft a driver which is axially adjustable, preferably electrically and/or hydraulically and/or mechanically adjustable, is supported in a rotationally fixed manner, the driver engaging into a thread-like guide path of the eccentric bush which is rotatably supported on the eccentric shaft, or B. the adjusting mechanism is arranged between the rotatingly drivable eccentric shaft in the screed and an eccentric bush which is arranged on the eccentric shaft in a rotationally fixed manner and is displaceable in a direction transverse to the axis of the eccentric shaft and is rotatable in a connecting rod driving the tamper bar, in such a manner that the stroke is adjustable by a transverse displacement of the eccentric bush relative to the eccentric shaft, or C. the adjusting mechanism is arranged between a bearing block supporting the rotatingly driven eccentric shaft and an adjusting lever which is articulated to a connecting rod driving the tamper bar and is adjustable in the bearing block, the adjusting lever and the one push rod drivable by the eccentric shaft being coupled with the connecting rod in a joint articulation axis, and wherein the bearing block has a straight or arcuate guide path which is engaged by an adjusting-lever pivot abutment which is movable by means of the adjusting mechanism along the guide path, and that the direction of extension of the guide path oriented in a direction transverse to the eccentric shaft is at least approximately oriented towards the axis of the eccentric shaft.