Abstract: A magnetically driven agitator which includes a member adapted to be mounted through a wall of a receptacle and which has a sleeve in which is housed a rotor which supports a first magnetic coupling structure. A propelling screw is disposed around the sleeve and supports a second magnetic coupling structure which cooperates with the first magnetic coupling structure in order to rotate the screw about an axis of rotation. The rotor is moveable parallel to the axis of rotation inside the sleeve between a first position where the first and second coupling structures are generally opposite to provide a maximum magnetic force therebetween to selected second positions where the magnetic force between the first and second coupling structures is varied such that the magnetic force may be reduced or substantially eliminated.

Abstract: A magnetically driven agitator for a mixture contained in a recipient which agitator is supported by a collar hermetically mounted in a wall of the recipient and which collar is provided with a blind sleeve inside which is housed a drive shaft provided with a first magnetic coupling. A propelling screw is disposed around the blind sleeve and is provided with a second magnetic coupling adapted to cooperative with the first magnetic coupling for driving the propelling screw about an axis of rotation. A third magnetic element carried by the propelling screw is disposed opposite a cell for detecting the movement of the third coupling element during rotation of the propelling screw about the axis of rotation.