Apparatus for electrically measuring unbalance of rotating workpieces

Claim 1

APPARATUS FOR ELECTRICALLY MEASURING UNBALANCE OF ROTATING WORKPIECES, COMPRISING JOURNALLING STRUCTURE FOR ROTATIONALLY SUPPORTING THE WORKPIECE TO BE TESTED, PICKUP MEANS CONNECTED TO SAID STRUCTURE FOR PROVIDING AN ALTERNATING PICKUP VOLTAGE IN RESPONSE TO OSCILLATORY UNBALANCE EFFECTS DUE TO ROTATION OF THE WORKPIECE, AUXILIARY GENERATOR MEANS ADAPTED FOR CONNECTION WITH THE WORKPIECE AND HAVING TWO ALTERNATING OUTPUT VOLTAGES 90* PHASE DISPLACED FROM EACH OTHER, FIRST AND SECOND POTENTIOMETER RESISTORS CONNECTED TO SAID GENERATOR VOLTAGES RESPECTIVELY AND HAVING EACH A FIXED TAP AND A SLIDE CONTACT, FIRST AND SECOND REVERSIBLE TWO-PHASE MOTORS EACH HAVING A ROTOR AND TWO FIELD CIRCUITS FOR ROTATING SAID ROTOR IN RESPONSE TO SAID RESPECTIVE FIELD CIRCUITS BEING SIMULTANEOUSLY EXCITED BY PHASE-DIFFERENT RESPECTIVE VOLTAGES, SAID FIRST MOTOR HAVING ONE OF ITS TWO FIELD CIRCUITS CONNECTED TO THE