Position indicating system

Claim 1

IN A SYSTEM FOR CONTROLLING MATERIAL MOVEMENT FROM A SOURCE TO A MEASURING STATION HAVING A SELECTOR WITH AN ADJUSTABLE D.-C. SIGNAL OUTPUT CORRESPONDING TO A PREDETERMINED QUANTITY OF MATERIAL MOVEMENT, THE COMBINATION COMPRISING, A COMPARATOR FOR RECEIVING AND COMPARING THE SELECTED D.-C. SIGNAL WITH A VARIABLE D.-C. SIGNAL, A CONTROLLER RESPONSIVE TO SADI COMPARATOR ROR REGULATING MOVEMENT OF THE MATERIAL, A SENSING ELEMENT CONTINUOUSLY VARYING FROM A REFERENCE POSITION IN RESPONSE TO CONTINUOUS MOVEMENT OF MATERIAL TO THE MEASURING STATION, AN A.-C. SIGNAL SOURCE, AND INDUCTIVE TRANSDUCER ENERGIZED BY SAID A.-C. SIGNAL AND COUPLED TO SAID SENSING ELEMENT FOR EFFECTUATING SAID D.-C. SIGNAL AT SAID COMPARATOR WHICH VARIES SUBSTANTIALLY LINEARLY WITH DISPLACEMENT OF SAID SENSING ELEMENT FROM ITS REFERENCE POSITION SAID INDUCTIVE TRANSDUCER INCLUDING, A PRIMARY WINDING ENERGIZED BY SAID A.-C. SOURCE TO PRODUCE A LEAKAGE FLUX FIELD, AND A SECONDARY WINDING, MEANS FOR COUPLING ONE OF SAID WINDINGS FOR MOVEMENT WITH SAID SENSING ELEMENT AND THE OTHER OF SAID WINDINGS BEING MAINTAINED STATIONARY, SAID SECONDARY WINDING HAVING A NULL POSITION WHEN SAID MOVABLE ELEMENT IS AT SAID REFERENCE POSITION AND A LINEARLY PROPORTIONAL OUTPUT SIGNAL AS SAID SECONDARY WINDING IS RELATIVELY MOVE FROM SAID NULL POSITION, AND MEANS FOR RECTIFYING SAID SECONDARY WINDING OUTPUT SIGNAL, SAID CONTROLLER TERMINATING MATERIAL MOVEMENT IN RESPONSE TO SAID COMPARATOR SENSING THAT THE SELECTOR SIGNAL AND THE TRANSDUCER SIGNALS ARE SUBSTANTIALLY EQUAL.