Abstract: A magnetic coupling assembly for driving a conveyor roll from a power drive while automatically disengaging the conveyor roll from the power drive when an accumulation occurs of the parts being transported by the conveyor. In one embodiment, a drive sprocket and conveyor roll are mounted on a fixed axle between a pair of spaced conveyor side rails. The conveyor roll includes a tube portion having a permanent magnet mounted therein and the drive sprocket includes a sprocket hub having a field face member secured to one of its ends in opposing relationship to the permanent magnet. By varying the air gap between the permanent magnet and field face member, the torque capacity is varied, thereby permitting slippage between the drive sprocket and conveyor roll at different torque levels.