Described is an adjustable roll drive including a fixed drive cylinder having a fixed drive gear, a fixed intermediate gear rotated by the fixed drive gear, a movable intermediate gear rotated by the fixed intermediate gear, and a movable driven cylinder having a movable driven gear wherein the movable driven gear is rotated by the movable intermediate gear. A linkage system is employed to maintain a substantially constant distance between axes of successive gears and an adjustment mechanism to vary a distance between the fixed drive cylinder and the movable driven cylinder. The continuously adjustable roll drive may be adapted further for use in grain grinding operations.