there is disclosed herein a mechanical motion control mechanism which in one form may comprise an input shaft drivingly connected to an output shaft in such a manner that continuous rotation of the input shaft produces varying rotational movement of the output shaft characterized by an initial dwell period , an acceleration period , a constant velocity period , a deceleration period and another dwell period . the input and output shafts may be drivingly connected by means of a gear secured to the input shaft which is in meshing engagement with a second gear supported at one end of a pivot arm , the other end of which is secured to the output shaft . rotational and revolving movement of this second gear is controlled by the interaction of a plurality of cam followers engaging a cam surface so as to allow rotational , revolving , and various desired combinations of such movements in response to rotational movement of the first gear . alternatively , the input and output shafts may be drivingly connected by sprockets in place of the first and second gears with an interconnecting drive chain , belt or other similar devices . also , if desired , the first and second gears may be replaced with wheels having circumferential frictional surfaces in mutual driving engagement . in yet another embodiment the input and / or output may be in the form of linear motion in which case the first gear may be replaced with a rack engaging the second gear in such a manner as to produce the above movement period sequence .