An oscillatory drive arrangement comprises a camshaft which is rotatable about its axis. Two lay-shafts are carried by a carrier for rotation about respective axes parallel to the axis of rotation of the camshaft, each lay-shaft carrying a cam which is engaged with a drive lever fixed to the camshaft. A sprocket wheel drives a sun gear which is engaged with planet gears and mounted freely upon the lay-shafts and the two planet gears being engaged with an internally toothed annular gear, whereupon rotation of the sun gear causes the two planet gears and to progress around the annular gear, taking the lay-shafts and with them together with the carrier. A second planet gear is mounted for rotation with each of the lay-shafts and each of these second planets being engaged with an internally toothed second annular gear which is rotated as a result of the motion of the lay-shaft so as to rotate the cams and and apply pulses to the motion of the drive lever. |