Speed indicating dynamoelectric machine and tachometer generator structure therefor

Claim 1

A SPEED INDICATING DYNAMOELECTRIC MACHINE COMPRISNG A FRAME, A MAIN STATOR SUPPORTED BY SAID FRAME, A MAIN ROTOR MOUNTED WITHIN SAID STATOR ON A SHAFT, A PAIR OF END PLATES SUPPORTING SAID SHAFT AND FIXEDLY SECURED IN RELATION TO SAID FRAME, A TACHOMETER, ROTOR SUPPORTED ON SAID SHAFT AXIALLY BETWEEN ONE OF SAID END PLATES AND SAID MAIN ROTOR AND STATOR AND HAVING A RELATIVELY SMALL THICKNESS IN THE AXIAL DIRECTION OF SAID SHAFT, SAID TACHOMETER ROTOR HAVING A PLURALITY OF CIRCUMFERENTIALLY DISPOSED TEETH SEPARATED BY RESPECTIVE SLOTS, TACHOMETER STATOR CORE MEANS SUITABLY SUPPORTED BETWEEN AND SUBSTANTIALLY MAGNETICALLY ISOLATED FROM SAID ONE END PLATE AND SAID MAIN ROTOR AND STATOR, SAID TACHOMETER STATOR CORE MEANS ALSO HAVING A RELATIVELY SMALL THICKNESS IN THE AXIAL DIRECTION OF SAID SHAFT AND HAVING AT LEAST A PAIR OF OPPOSED POLE FACES BETWEEN WHICH SAID ROTOR IS DISPOSED FOR ROTATION WITH SAID ROTOR TEETH FORMING A ROTOR GAP THEREWITH AND SAID ROTOR SLOTS FORMING AN EFFECTIVE SLOT GAP THEREWITH, A PERMANENT MAGNET PHYSICALLY DISPOSED FORT MAGNETIC CONNECTION WITHIN SAID TACHOMETER STATOR CORE MEANS IN A FLUX LOOP PATH IN CLUDING SAID ROTOR THROUGH SAID POLE FACES, A COIL LEG HAVING OUTPUT COIL MEANS DISPOSED THEREON MAGNETICALLY CONNECTED IN ANOTHER FLUX LOOP PATH INCLUDING SAID PERMANENT MAGNET, GAP MEANS DISPOSED IN SAID OTHER LOOP PATH BETWEEN SAID COIL LEG AND SAID MAGNET AND OUTSIDE SAID ROTOR FLUX LOOP PATH, SAID COIL LEG GAP MEANS HAVING A MAGNETIC RELUCTANCE GREATER THAN THAT OF SAID ROTOR GAP AND LESS THAN THAT OF SAID EFFECTIVE SLOT GAP.