TRAIN SPEED CONTROL SYSTEM

摘要

High frequency detector track circuits are coupled to the rails at crossbonds which divide the track stretch into sections without insulated joints. The HF transmitters supply track energy both directions from alternate bonds into each track section of the adjoining pair. Correspondingly tuned receivers at the other end of each section control track relays which indicate the track occupancy condition. Successive pairs of track sections have different frequencies selected on a random basis from a predetermined plurality. Train control energy of a different, single frequency is supplied to the rails at the exit end of each section and is modulated by one of a plurality of low frequency code rates selected in accordance with the track occupancy condition of advance sections as determined by the track circuits. Each train is equipped with train control apparatus including at least cab signals and overspeed protection. Receivers inductively coupled to the rails pick up and supply the speed signals through a demodulator and active filters to register an allowed speed indication in accordance with the detected code rate. Train speed sensing apparatus registers the actual train speed. Overspeed detection apparatus then compares allowable and actual speeds, detects an overspeed condition, and actuates an automatic braking action if the train operator does not initiate a speed reduction within a preset time limit.