A header for an agricultural harvester comprising a frame, an epicyclical drive (224, 226) supported by the frame, the epicyclical drive (224, 226) including: a first rotatable wheel having a first substantially vertical rotational axis, a first disk having a first eccentric axis rotatable about the first substantially vertical rotational axis, the first substantially vertical rotational axis being parallel to the first eccentric axis, wherein operation of the epicyclical drive (224, 226) results in oscillating motion of the first disk in a direction transverse to the first substantially vertical rotational axis; a first cutter bar directly connected to the first disk, a second rotatable wheel having a second substantially vertical rotational axis, a second disk having a second eccentric axis rotatable about the second substantially vertical rotational axis, the second substantially vertical rotational axis being parallel to the second eccentric axis, wherein operation of the epicyclical drive (224, 226) results in oscillating motion of the second disk in a direction transverse to the second substantially vertical rotational axis; a second cutter bar directly connected to the second disk wherein the first cutter bar extends in a direction substantially transverse to the first substantially vertical rotational axis and the second cutter bar extends in a direction substantially transverse to the second substantially vertical rotational axis, characterized in that the oscillating motion of the first disk is in line with a longitudinal axis of the first cutter bar, and and that the oscillating motion of the second disk is in line with a longitudinal axis of the second cutter bar. a first rotatable wheel having a first substantially vertical rotational axis, a first disk having a first eccentric axis rotatable about the first substantially vertical rotational axis, the first substantially vertical rotational axis being parallel to the first eccentric axis, wherein operation of the epicyclical drive (224, 226) results in oscillating motion of the first disk in a direction transverse to the first substantially vertical rotational axis; a first cutter bar directly connected to the first disk, a second rotatable wheel having a second substantially vertical rotational axis, a second disk having a second eccentric axis rotatable about the second substantially vertical rotational axis, the second substantially vertical rotational axis being parallel to the second eccentric axis, wherein operation of the epicyclical drive (224, 226) results in oscillating motion of the second disk in a direction transverse to the second substantially vertical rotational axis; a second cutter bar directly connected to the second disk wherein the first cutter bar extends in a direction substantially transverse to the first substantially vertical rotational axis and the second cutter bar extends in a direction substantially transverse to the second substantially vertical rotational axis, characterized in that the oscillating motion of the first disk is in line with a longitudinal axis of the first cutter bar, and and that the oscillating motion of the second disk is in line with a longitudinal axis of the second cutter bar.