Air driven dental handpieces

Claim 1

IN DENTAL HANDPIECE, AN AIR-DRIVEN TURBINE COMPRISING A GENERALLY CYLINDRICAL HOUSING HAVING AN AXIALLY-EXTENDING SHAFT ROTATABLY MOUNTED THEREIN, AN IMPELLER ON SAID SHAFT IN SAID HOUSING, SAID IMPELLER BEING CYLINDRICAL IN SHAPE AND HAVING A MULTIPLICITY OF PERIPHERAL PARALLELWALLED SLOTS FORMING RADIALLY-EXTENDING TEETH, SUPPORTING ARM EXTENDING RADIALLY FROM SAID HOUSING AND HAVING A DRIVE AIR CONDUIT EXTEND THERETHROUGH SAID HOUSING HAVING A DRIVE AIR CONDUIT EXTEND THERETHROUGH, SAID HOUSING HAVINGS DUIT AND BEING POSITIONED AND ARRANGED TO DIRECT DRIVE AIR TANGENTIALLY AGAINST THE TEETH OF SAID IMPELLER, SAID TEETH BEING BEVELED AT THEIR LEADING EDGES RELATIVE TO THE DIRECTION OF IMPELLER ROTATION TO REDUCE INTERFERENCE BETWEEN SUCH LEADING EDGES AND THE AIR DISCHARGED INTO SAID HOUSING AND TO THEREBY INCREASE THE TORQUE OF SAID IMPELLER, AND EXHAUST MEANS PROVIDED BY SAID HOUSING AND ARM FOR CONVEYING EXHAUST AIR FROM SAID IMPELLER, SAID EXHAUST MEANS INCLUDING A SLOT EXTENDING THROUGH A SIDE WALL OF SAID HOUSING AND HAVING A RADIAL EXTENSION IN AN END WALL THEREOF COMMUNICATING WITH THE INTERIOR OF SAID HOUSING TO EXHAUST AIR FROM ONE END OF SAID IMPELLER AS WELL AS FROM THE OUTER PERIPHERY THEREOF, SAID EXHAUST MEANS INCLUDING AN EXHAUST CONDUIT EXTENDING THROUGH SAID ARM AND COMMUNICATING WITH SAID SLOT, SAID EXHAUST CONDUIT TERMINATING IN AN EXHAUST PORT IN A PERIPHERAL GROOVE EXTENDING ABOUT SAID ARM, A PERFORATED RING MOUNTED FOR ROTATIONAL AND AXIAL MOVEMENT UPON SAID ARM AND NORMALLY EXTENDING OVER SAID GROOVE, AND AN ANNULAR REPLACEABLE FILTER ELEMENT DISPOSED WITHIN SAID RING FOR ABSORBING OIL FROM AIR DISCHARGED THROUGH SAID PORT, AND COOPERATING MEANS PROVIDED BY SAID ARM AND RING TO PREVENT AXIAL DISPLACEMENT OF SAID RING UNLESS SAID RING IS FIRST ROTATED INTO A SELECTED POSITION OF ADJUSTMENT.