Abstract: A method and apparatus for detecting an impact sound, such as a sound caused by a railroad vehicle approaching a construction location. The apparatus comprises an arrangement for detecting impact sound or vibrations with a receiver mounted at the rail, for example, and, further, an evaluation circuit for processing the vibrations and triggering a warning signal when the intensity of the receiver-output signal continuously increases, for example, when the intensity in a predetermined frequency range passes through predetermined threshold values during predetermined times. Thus, an approaching railroad vehicle can be positively detected by monitoring a continuously increasing sound or vibration which is propagated in the rails.

Abstract: The present invention relates to bearing defect detectors and in particular to an acoustic system for detecting defects in the bearings of moving railroad cars and identifying the location of these defects.

Abstract: An apparatus for the detection of impact frequencies in moving railway train bearings which are characteristic of bearing defects. The apparatus transduces acoustic vibrations of the bearings into an electrical signal and extracts an envelope modulated carrier frequency component from the electric signal. The envelope is extracted from the carrier frequency component and is analyzed by a bandpass filter. The bandpass filter includes a switch capacitor filter controlled by a master clock which, in turn, is controlled by train speed and/or direction sensors positioned along the track on which the train travels.

Abstract: This invention relates to apparatus for the detection of accustic impact frequencies, characteristic of bearing assembly failure during operation, which modulate an acoustic carrier frequency band. This apparatus allows for on-site or field application with high-level of ambient noise such as are present in railroad yards. This apparatus allows for early detection of such failures, so that a repair may be made before damaging heat build-up or catastrophic bearing failure occurs. Additionally, with sufficient early warning in railroad applications, a train may continue running to a railyard for convenient shop repair rather than expensive field repair.

Abstract: There is disclosed a system for detecting a flat portion of a peripheral surface of a vehicle wheel disposed in rolling engagement with a track rail. A detecting device is provided for detecting one of acceleration representative of vibration of the wheel, stress developing in a support member connected to the wheel, and a noise produced by the rolling of the wheel on the rail to produce a first detection signal in response to a predetermined angular movement of the wheel. A device is provided for determining whether the first detection signal is above a predetermined reference level to produce a second detection signal in synchronism with the rotation of the wheel and indicative of a wheel flat portion of above a predetermined length.

Abstract: Method and apparatus for detecting the presence of flat wheels on railroad cars, comprising an electro-acoustic transducer located on the track wayside so as to pick up the vibrations generated by a passing train. If a flat wheel is present it will generate a periodic clanging sound at a frequency proportional to train speed and wheel diameter. The invention capitalizes particularly on the measurement of train speed to control the response of an adaptive filter so as to enhance the periodic clanging frequency with respect to the background noise, thereby to improve the signal-to-noise ratio; the enhanced signal is further autocorrelated for ten wheel revolutions and if a periodic signal is present in the narrow frequency band of interest, a large periodic autocorrelation output will result and, as a consequence, any wheel flat will be readily detected and will act to trigger an alarm to alert the train crew of the condition.