Abstract: A non-linear filter which reduces high signal-to-noise ratio due to sharp and erratic variations in an input signal by charging a storage capacitor through a long time constant charging circuit so that the stored signal level lags an increasing input. A parallel path with a much lower time constant rapidly discharges the capacitor upon input decreases, so that the stored signal matches the more accurate lower input signal level. A practical application is for car space measurements in railroad yard storage tracks to substantially reduce erratic distance measurements due to poor shunting under moving cars. The distance measurement signal is applied through an integrator network to a first of four FET operational amplifiers, whose input and feedback networks have selected time constants to substantially filter out background noise due to the track signal frequency.

Abstract: Two car retarders and an interposed means to push the cars are installed on a storage track. The upstream retarder slows the cars. The downstream retarder collects the cars released from the upstream retarder. The cars, coupled as a block, are pushed from the downstream retarder.

Abstract: A control algorithm developed for the master, intermediate, and group retarders of a classification yard enables control of the speed of car cuts in the switching area to achieve predetermined constant running times between the hump and the entrance into the assigned bowl track. Said another way, the retarders are controlled to maintain the same time spacing between cut centers, while moving through the switching area, as established by the humping rate. This reduces the number of misroutes due to catch-up with a preceding cut yet allows a constant humping speed. Various cut parameters, cut speeds, and curve and tangent track rolling resistances of each cut are measured and used as needed in determining the required exit for the cuts from the retarders. A different control algorithm for the tangent point regarders, one located in each bowl track, controls the speed of cuts assigned to that storage track, in accord with entry speed, cut parameters, track conditions, etc.