Abstract: A single drive motor is connected by a speed reducer directly to the shaft of one roll of the two aggressive surfaced rolls which form a chip destructuring nip. One roll is dynamically positionable perpendicular to its axis of rotation to open and close the nip. Each roll turns on a shaft positioned along the axis of the roll which is mounted to a frame by bearings. Only the non-positionable roll is driven directly by the drive motor. The roll which is dynamically positionable is driven by a tire arrangement mounted about the axes of the rolls. Opposed tires mounted on the spaced apart parallel shafts form a clutch-like means for driving the dynamically positionable roll.