Patent GB-939184-A (GB)
Title: Improvements in means for inhibiting the storage of signals generated in dependence upon rolling resistance of railway cars
IPC: B61L17/00
Filed: 1960-04-21
Abstract: 939,184. Hump-yard retarder control systems. WESTINGHOUSE AIR BRAKE CO. April 21, 1960 [April 27, 1959], No. 13951/60. Class 105.  In a railway hump yard classification system, means are provided to inhibit the storage of a measured value of rolling resistance when this value is outside a predetermined range or if the rate of change of the measured value is outside predetermined limits. The arrangement is for use in a hump yard system and includes a radar velocity meter 5 which, when a cut of vehicles traverses its measuring section, pro-  duces at its output terminal a voltage between 0-100V. which is a function of the rolling resistance of the cut. Storage means 18 is also provided to store an acceptable signal. The measured value is applied to the input terminal a of storage device 18 via two resistors R1 and R3, forming part of a signal clamping device 10. This device produces a bias voltage of 100 volts across resistor R7 which is connected via resistor R2 to the junction of resistors R1 and R3. Since the ratio of resistor R1 to resistor R2 is 1 : 4, the signal produced at the junction when input signal is supplied to terminal a, is equal to the value of the signal plus 20% of the difference between the signal value and the 100V. supplied across resistor R7. In addition, the output end of resistor R3 is connected by diode D2 to a second source of voltage developed across R4, this voltage is 26 volts and the arrangement prevents an output voltage from the clamp device of less than 26 volts (corresponding to an input voltage at terminal a of less than 6 volts) being applied to the storage devcie 18. Storage is effected by operation of relay H which is controlled via track relay 2TR and relay VR which forms part of a two valve switching arrangement 20 and is energized when the voltage supplied to a time delay circuit 19, which is connected to the input of the switching device, is 150 volts and de-energized when this voltage is 300 volts. The voltage at the input terminal a of the time delay device is controlled by five units 9, 13, 14, 16 and 17. Time delay unit 9 normally supplies at its output terminal b a voltage of 300 volts, but when a cut of vehicles enters track section IT, relay ITR releases and disconnects at its contact b the negative bias supplied to the unit from battery B3 and after a time delay of approximately three seconds valve V1 conducts and supplies an output voltage of 150V. The measured value of rolling resistance is applied to lower limit detector 13 and if this value is above 6 volts this detector produces an output of 150 volts and if below 6 volts the detector output rises to 300 volts. In addition, the measured value is connected to an upper limit detector 14 which supplies an output of 150 volts if its input voltage is below 100 volts and an output of 300 volts if its input signal rises above 100 volts. The measured value is also supplied to a differentiator circuit 15 which measures the rate of change of this value and applies a voltage which is a function of this rate of change to two further limit detectors 16 and 17 which supply an output of 150 volts if the rate of change is within present limits and an output of 300 volts if the preset limits are exceeded in a positive (17 or negative (16) direction. Thus approximately three seconds after the cut enters track section IT and before it enters section 2T, a value of rolling resistance may be stored if all the limit detectors supply an output voltage of 150 volts indicating that the value falls within present limits and that its rate of change is within preset limits.