Patent GB-784636-A (GB)
Title: Improvements relating to electrical equipment for signalling between railway tracks and moving railway vehicles
IPC: B61L3/12
Filed: 1954-06-16
Abstract: 784,636. Track apparatus actuating signals on trains and stopping trains. CONSTANTINI, A. June 16, 1954 [June 18, 1953], No. 17637/54. Class 105. Equipment for signalling to a railway train cab, e.g. the condition of the track signals or to initiate a train braking or stopping operation comprises on the train a dipole or similar transmitter of very high frequency and one or more receivers, each in the form of a normally unenergized conductor located on the track which when a signal is to be given are set tuned to the transmitter frequency so that when the transmitter passes in close proximity to a tuned receiver a disturbance is produced in the highfrequency oscillator energizing the transmitter which disturbance is detected and used to provide visual or aural indications in the cab or to initiate a desired operation. The transmitter and receivers may be dipole antennµ disposed with their axes parallel to the direction of the track and a receiver may be rendered resonant or non-resonant by an electrical contact adapted to be operated to connect the two dipole parts together for resonance at the transmitting frequency in accordance with the stop or proceed condition of the associated track signal. As shown, a push-pull oscillation generator 18, 19 feeds a dipole antenna 4 through a transformer 20. As the dipole 4 passes a tuned receiver 15 e.g. to give a warning signal or cautionary alarm, the electromagnetic coupling between the two antennµ creates an increased output in the generator 18, 19, which is detected by a rectifier 22 and parallel-connected capacitor 23 tightly coupled through transformer 21 to the oscillator, the increased positive potential produced across the capacitor 23 being applied by conductor 24 to trigger off a thyratron 26 to provide a discharge path for a capacitor 29 through a relay winding 31, the relay picking up to close its front contact 32 to pick up relay 33. The relay 33 is held over its front contact 34 and by this time the disturbance in the oscillator 18, 19 is over and the thyratron is back to its non- conducting condition. The discharge path for the capacitor 29 is also opened at back contact 35 of relay 33 and at front contact 35 a discharge circuit is prepared for a second capacitor 39 for a subsequent signal, e.g. an immediate warning signal or prompt alarm as the train transmitter passes a subsequent receiver. At front contact 36 of relay 33 a warning indicator 37 is operated. As the subsequent receiver is passed by the transmitter, the thyratron 26 is triggered to provide the discharge path for capacitor 39 to pick-up relay 40 followed by relay 42 which holds over front contact 43, opens the discharge circuit at back contact 44 and provides at front contact 45 an immediate warning signal 46 or prompt alarm. The apparatus is returned to its normal condition by opening momentarily a contact 27 in the hightension supply conductor 17 to release the relays. The relay 42 may control the application of brakes. A supervisory device 9 may be provided to give an indication if the potential on conductor 24 fails due to failure of the oscillator 18, 19 or detecting device 22, 23. This device 9 consists of a thyratron 48 arranged by condenser 55 to operate intermittently in the event of any failure on the lead 24 and so to actuate a supervisory indicator 51 through a relay 50.