GB855549A - Improvements in railway track-circuits signalling systems - Google Patents

Abstract

855,549. Railway track circuit signalling systems. COMPTEURS ET MOTEURS ASTER. May 27, 1957, No. 16736/57. Class 105. In a railway signalling system employing the track rails for the transmission of signalling current, the ends of a track circuit are connected respectively to a generating device and a receiving device tuned to the same frequency and to respective resonant circuits of the parallel or " wave-trap " type tuned to said frequency and each comprising at least one capacitor and an inductance comprised by a portion of the track. Thus a track-circuit section A without insulated joints, Fig. 10, is supplied by a generator 31 feeding an oscillatng circuit 2 comprised by a short portion 5 of track and a condenser 4 forming a " wave-trap " type circuit short-circuiting the rails at the operating frequency and isolating it from the adjacent track section C. In a similar manner the circuit 3 of capacitor 8 and portion 9 of the track isolates the track section A from section B. A receiver 32 is connected across the circuit 3. Short-circuiting cross-conductors 7 and 10 are connected across the rails 5 and 9, respectively. Entry of a train axle detunes the oscillating circuit and de-excites the receiver. The shortcircuiting cross-conductor instead of being perpendicular to the rails 1 (when so disposed the presence of an axle aligned therewith is without effect) may be disposed obliquely, Fig. 3, or in effect obliquely, Figs. 6-8 (not shown), and Fig. 5, which shows a disposition permitting tamping of the ballast without interfering with the short-circuiting conductor. For track circuit sections of considerable length the section is divided into a plurality of track circuits as in Fig. 10 with inter-circuit relay amplifier stages (Fig. 11, not shown).