FLEXIBLE MECHANICAL AUTOMATION ASSEMBLY MACHINE, NAMELY, A MACHINE USED IN AN AUTOMATED ASSEMBLY OPERATION IN WHICH THE MACHINE MAY GRASP A WORKPIECE AND MOVE THE WORKPIECE SELECTIVELY ON THREE AXES IN TIME RELATIONSHIP TO THE OPERATION TO BE PERFORMED ON THE WORKPIECE; AND MACHINE PARTS THEREFOR, NAMELY, GEARS, GRIPPERS, BELTS AND ELECTRIC MOTORS