Abstract: This invention relates to a device for monitoring the temperature of the wheels of passing railroad cars. More particularly, this device includes a self-calibration function wherein a predetermined heat source is attached to the device, a fixed amplifier amplifies the resulting electric signal so as to generate a signal comparable in magnitude to that generated by a passing train, a variable gain amplifier further amplifies the signal, and the resulting signal is converted to a digital signal. The digital signal is used as a signal to the feedback input of a variable gain amplifier. In response to the digital signal, the variable gain amplifier adjusts its gain until the feedback signal reaches a predetermined value.

Abstract: A speed independent system is used for obtaining a preselected number of samples from an object moving along a fixed path, such as a railroad train passing through a sensing zone along the section of track. The sensing zone is defined by a pair of wheel sensors. Upstream of the sensing zone a third sensor is positioned. The distance between the third sensor and the closer of the pair of sensors comprises a reference distance which is the length of the sensing zone multiplied by a known multiple. The time for the train to pass through the reference distance is obtained and then divided by a divisor comprising the product of the known multiple and the desired number of samples to obtain a single interval. During the time the train passes through the sensing zone consecutive intervals are counted off to obtain the desired number of samples.

Abstract: A method is provided for determining whether an output signal from a magnetic railway wheel detector is produced by the actual passage of a wheel over the transducer. The output signal is compared with an amplitude threshold value and the time period between the zero crossing point and the time at which the signal attains amplitude threshold is compared with a time threshold level. The thresholds are set as a function of the speed of the train. Unless the thresholds are exceeded the output signal is disregarded.

Abstract: A railroad car hot box detector system is provided which includes a variable circuit means for processing the heat signal generated by an infra-red detector viewing a sensing zone along a section of track. The system includes a conditioning circuit which determines one or more conditions of the train (such as the wheel speed or temperature of the car bottom) and uses that information to vary the processing circuit to enable the heat signal to be processed optimally for the detected condition.

Abstract: An improved method and circuit is provided for processing waveforms from a railway car heat signal to eliminate spurious signals and to differentiate between roller bearings and friction bearings in a railroad hot box detector system. The waveforms generated by passing bearings are discretely sampled and spurious signals are eliminated by considering only those signals that fall within the crossing points of a threshold value. Discrimination between roller bearings and friction bearings is obtained by determining the ratio of the sum of the discrete values of the amplitude of the waveform within a first set of samples between the crossing points to the sum of the discrete values of the amplitude of the waveform within a second set of samples between the crossing points.

Abstract: A system is provided for determining whether a railway car passing a sensing station is a freight car. The system utilizes wheel trips along the track at the sensing station to determine the spacing between axles of the car. If the spacing between axles is determined to fall between slightly more than 4' - 5" to slightly less than 6' - 1" the car is presumed to be a freight car.