Method of measuring the uniformity of gearings

Claim 1

IN AN ARRANGEMENT FOR MEASURING THE PRECISION OF A GEAR TRAIN, IN COMBINATION, A GEAR TRAIN HAVING INPUT SHAFT AND AN OUTPUT SHAFT; MEANS FOR ROTATING ONE OF SAID SHAFTS, A FIRST MAGNETIC RECORD OF A PERIODIC SIGNAL; MEANS FOR MOVING SAID RECORD; A STATIONARY FIRST MAGNETIC HEAD ARRANGED FOR READING SAID RECORD WHEN SAID RECORD IS MOVED; A SECOND MAGNETIC HEAD CONNECTED TO ONE OF SAID SHAFTS FOR READING MOVEMENT THEREWITH RELATIVE TO SAID RECORD; MIXER MEANS CONNECTED TO SAID MAGNETIC HEADS FOR PRODUCING A FIRST OUTPUT SIGNAL RESPONSIVE TO THE FREQUENCY DIFFERENCE OF THE READINGS OF SAID HEADS; A MAGNETIC RECORD CARRIER; MEANS FOR RELEASABLY CONNECTING SAID CARRIER TO THE OTHER ONE OF SAID SHAFTS FOR JOINT MOVEMENT THEREWITH; MEANS FOR PRODUCING A SECOND MAGNETIC RECORD ON SAID CARRIER RESPONSIVE TO SAID OUTPUT SIGNAL; RELEASABLE MOTOR MEANS FOR MOVING SAID CARRIER WHEN RELEASED FROM SAID OTHER SHAFT; A STATIONARY THIRD MAGNETIC HEAD ARRANGED FOR READING SAID SECOND MAGNETIC RECORD WHEN THE SAME IS MOVED BY SAID RELEASABLE MOTOR MEANS; A FOURTH MAGNETIC HEAD; MEANS FOR CONNECTING SAID FOURTH HEAD TO SAID OTHER SHAFT FOR READING MOVEMENT THEREWITH RELATIVE TO SAID SECOND RECORD; MIXER MEANS CONNECTED TO SAID THIRD AND FOURTH MAGNETIC HEADS FOR PRODUCING A SECOND OUTPUT SIGNAL RESPONSIVE TO THE FREQUENCY DIFFERENCE OF THE READINGS OF SAID THIRD AND FOURTH HEADS; AND MEANS FOR COMPARING SAID OUTPUT SIGNALS.