A FLUID PRESSURE PROBE SYSTEM FOR GENERATING A SIGNAL IN RESPONSE TO THE LOCATION OF AN ARTICLE AT A SELECTED POSITION AT A WORK STATION. THE SYSTEM INCLUDES A PLURALITY OF INDIVIDUAL DIFFERENTIAL RESPONSIVE TRANSDUCERS CONNECTED IN PARALLEL TO A COMMON PRESSURE MANIFOLD SO THAT MANIFOLD PRESSURE IS NORMALLY APPLIED TO BOTH SIDES OF EACH TRANSDUCER TO NORMALLY MAINTAIN A ZERO DIFFERENTIAL PRESSURE. A PROBE HAVING A VENT PASSAGE IS CONNECTED TO EACH TRANSDUCER BETWEEN ONE SIDE OF THE TRANSDUCER AND THE POINT OF CONNECTION TO THE MANIFOLD. THE OUTLET OF THE VENT PASSAGE IS NORMALLY CLOSED BY A SIMPLE BALL VALVE SEATED IN THE END OF THE PASSAGE AND MAINTAINED IN ITS CLOSED POSITION BY THE PRESSURE WITHIN THE PASSAGE. THE

PROBE IS MOUNTED IN THE WORK STATION AT A LOCATION SUCH THAT THE BALL IS UNSEATED BY THE ARTICLE WHEN THE ARTICLE IS IN THE DESIRED LOCATION, THUS CREATING A DIFFERENTIAL PRESSURE AT THE TRANSDUCER. A RESTRICTED ORIFICE IS LOCATED BETWEEN THE POINT OF CONNECTION OF THE VENT PASSAGE TO THE TRANSDUCER AND THE POINT OF CONNECTION OF THE TRANSDUCER TO ONE SIDE OF THE MANIFOLD TO PREVENT THE PRESSURE DROP PRODUCED BY THE VENTING FROM TRIGGERING ANY TRANSDUCERS OTHER THAN THE ONE TOW WHICH THE ACTIVATED PROBE IS CONNECTED.