Pneumatic measuring circuit

Claim 1

IN A PNEUMATIC CIRCUIT FOR MEASURING A WORKPIECE, (A) A SENSING LINE CONNECTED TO A SOURCE OF AIR UNDER PRESSURE AND TERMINATING AT A GAP WHICH VARIES WHEN THE SIZE OF THE WORKPIECE TO BE MEASURED VARIES, (B) MEANS DEFINING A RESTRICTED PASSAGE HAVING ONE END CONNECTED TO SAID SENSING LINE, (C) A SIGNAL LINE CONNECTED TO THE OTHER END OF SAID RESTRICTED PASSAGE, (D) A SIZE INDICATING DEVICE CONNECTED TO SAID SIGNAL LINE, (E) AND A PNEUMATIC VALVE HAVING A PASSAGE CONNECTING SAID SIGNAL LINE TO SAID SENSING LINE AROUND SAID RESTRICTED PASSAGE WHEN THE VALVE PASSAGE IS UNOBSTRUCTED, SAID VALVE HAVING A FLEXIBLE DIAPHRAGM THEREIN HAVING ONE SIDE EXPOSED TO PRESSURE IN SAID SENSING LINE AND THE OTHER SIDE EXPOSED TO PRESSURE IN SAID SIGNAL LINE, SAID DIAPHRAGM MOVABLE IN RESPONSE TO A CHANGING PRESSURE DIFFERENTIAL THERON TO CONTROL SAID VALVE PASSAGE AS THE PRESSURE CHANGES IN THE SENSING LINE.