CONTROL SYSTEM FOR SUPPRESSING WHEEL SQUEALING NOISES PRODUCED BY RAILROAD CAR RETARDERS

摘要

This disclosure relates to a control system for suppressing wheel squealing noises produced by an activated frictional type of fluid pressure operated railroad car retarder. A microphonic transducer is disposed in the immediate vicinity of the car retarder for picking up and converting the sound wave pressures into alternating current signals. A band-pass filter network is arranged to pass a select band of frequencies of the alternating current signals. A diode rectifier converts the passed alternating current signals into a d.c. voltage. An integrating circuit produces an output signal which is substantially the time integral of the d.c. input voltage. An operational amplifier compares the output signal of the integrating circuit with an input reference signal and produces an output signal when the output signal is greater than the input reference signal. The output signal drives a power amplifier for causing the energization of an electromagnetic exhaust valve which deactivates the car retarder.