A header for an agricultural harvester comprising: a frame; a knife drive assembly including a housing that houses a first epicyclical drive and mounts the first epicyclical drive to the frame, the first epicyclical drive including: a first rotatable wheel having a first central rotational axis, and a first planetary flange having: a first eccentric axis, the first planetary flange rotatable about the first eccentric axis and revolvable about the first central rotational axis, and a first output shaft, carried by the first planetary flange and spaced from the first eccentric axis, wherein operation of the epicyclical drive results in oscillating motion of the first output shaft in a direction transverse to the first central rotational axis; and a first cutter bar directly connected to the first output shaft, the first cutter bar extending in a direction transverse to the first central rotational axis; and characterized in that the housing further houses a second epicyclical drive and mounts the second epicyclical drive to the frame, the second epicyclical drive including: a second rotatable wheel having a second central rotational axis; and a second planetary flange having: a second eccentric axis, the second planetary flange being rotatable about the second eccentric axis and revolvable about the second central rotational axis, and a second output shaft, carried by the second planetary flange and spaced from the second eccentric axis, wherein operation of the epicyclical drive results in oscillating motion of the second output shaft in a direction transverse to the second central rotational axis; and in that the header further comprises a second cutter bar directly connected to the second output shaft, the second cutter bar extending in a direction transverse to the second central rotational axis. a frame; a knife drive assembly including a housing that houses a first epicyclical drive and mounts the first epicyclical drive to the frame, the first epicyclical drive including: a first rotatable wheel having a first central rotational axis, and a first planetary flange having: a first eccentric axis, the first planetary flange rotatable about the first eccentric axis and revolvable about the first central rotational axis, and a first output shaft, carried by the first planetary flange and spaced from the first eccentric axis, wherein operation of the epicyclical drive results in oscillating motion of the first output shaft in a direction transverse to the first central rotational axis; and a first rotatable wheel having a first central rotational axis, and a first planetary flange having: a first eccentric axis, the first planetary flange rotatable about the first eccentric axis and revolvable about the first central rotational axis, and a first output shaft, carried by the first planetary flange and spaced from the first eccentric axis, a first eccentric axis, the first planetary flange rotatable about the first eccentric axis and revolvable about the first central rotational axis, and a first output shaft, carried by the first planetary flange and spaced from the first eccentric axis, wherein operation of the epicyclical drive results in oscillating motion of the first output shaft in a direction transverse to the first central rotational axis; and a first cutter bar directly connected to the first output shaft, the first cutter bar extending in a direction transverse to the first central rotational axis; and characterized in that the housing further houses a second epicyclical drive and mounts the second epicyclical drive to the frame, the second epicyclical drive including: a second rotatable wheel having a second central rotational axis; and a second planetary flange having: a second eccentric axis, the second planetary flange being rotatable about the second eccentric axis and revolvable about the second central rotational axis, and a second output shaft, carried by the second planetary flange and spaced from the second eccentric axis, wherein operation of the epicyclical drive results in oscillating motion of the second output shaft in a direction transverse to the second central rotational axis; and in that the header further comprises a second rotatable wheel having a second central rotational axis; and a second planetary flange having: a second eccentric axis, the second planetary flange being rotatable about the second eccentric axis and revolvable about the second central rotational axis, and a second output shaft, carried by the second planetary flange and spaced from the second eccentric axis, a second eccentric axis, the second planetary flange being rotatable about the second eccentric axis and revolvable about the second central rotational axis, and a second output shaft, carried by the second planetary flange and spaced from the second eccentric axis, wherein operation of the epicyclical drive results in oscillating motion of the second output shaft in a direction transverse to the second central rotational axis; and in that the header further comprises a second cutter bar directly connected to the second output shaft, the second cutter bar extending in a direction transverse to the second central rotational axis.