Abstract: Each gripper chain assembly is driven by its own headshaft. The headshafts rotate in opposite senses and are powered from a motor/reducer combination. A sheave on the output shaft of the reducer is coupled by one endless belt with a sheave on one of the headshafts, and it is also coupled with a sheave on the other of the headshafts by another endless belt. The one belt is in a non-twisted configuration so that the sheave on the one headshaft rotates in the same sense as the reducer output shaft. The other belt is twisted into a figure eight configuration so that the sheave on the other headshaft rotates in the opposite sense. The two headshafts therefore provide the desired counter-rotation of the two gripper chain assemblies. The motor reducer is mounted on a base plate which is adjustably positionable on the conveyor's frame so as to enable the drive to be adjusted whenever the spacing distance between the two gripper chain assemblies is adjusted for conveying a different sized article.