Seal to protect the bearings of powder magnetic clutches or of similar devices against the ferromagnetic powder

Claim 1

A MAGNETIC CLUTCH COMPRISING A DRIVEN SHAFT, BEARINGS FOR THE SHAFT, A MAGNETIC PART CARRIED BY THE SHAFT, AN ANNULAR PERMANENT MAGNET ARRANGED IN SPACED COAXIAL RELATIONSHIP TO THE SHAFT AND HAVING OPPOSITE END FACES, ONE OF SAID END FACES BEING SPACED FROM THE MAGNETIC PART TO PROVIDE THEREBETWEEN A GAP, FINELY DIVIDED MAGNETIC MATERIAL LOCATED IN THE GAP, AND SEAL MEANS FOR PREVENTING THE MAGNETIC MATERIAL FROM ENTERING SAID SHAFT BEARINGS, SAID SEAL MEANS INCLUDING AN ANNULAR ELEMENT LOCATED BETWEEN THE SHAFT AND THE ANNULAR MAGNET, INWARDLY DIRECTED SPACED TEETH ON SAID ANNULAR MAGNET, INWARDLY DIRECTED FLANGE ON THE ANNULAR ELEMENT EXTENDING OVER THE OUTER PERIPHERY OF THE PERMANENT MAGNET FOR APPROXIMATELY ONEHALF OF THE HEIGHT OF THE PERMANENT MAGNET, A SECOND ANNULAR ELEMENT ON THE MAGNETIC PART, INWARDLY DIRECTED SPACED TEETH ON SAID SECOND ANNULAR ELEMENT EXTENDING INTO THE SPACES BETWEEN THE TEETH ON SAID FIRST ANNULAR ELEMENT FOR PROVIDING A LABYRINTH BETWEEN THE GAP AND THE BEARINGS, AND A RING OF NON-MAGNETIC MATERIAL SURROUNDING THE REMAINDER OF THE HEIGHT OF SAID PERMANENT MAGNET THEREBY PREVENTING SHUNTING OF THE MAGNETIC FLUX FOR BYPASSING THE GAP WITH THE SUCH FLUX MAGNETIZING THE PARTICLES IN THE GAP AND WITH ANY PARTICLES PASSING THROUGH THE GAP BEING RETAINED IN THE SPACES BETWEEN THE TEETH DUE TO THE MAGNETIC FIELD PRIOR TO ENTRY INTO THE BEARINGS.