GB219639A - Improvements relating to railway traffic controlling apparatus - Google Patents

Abstract

219,639. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Lewis, L. V.). July 26, 1923, [Convention date]. Electrical systems, automatic; lamp signals.- Electrically operated railway signal devices are supplied with current directly from electron tube devices without the intervention of relays having moving parts. The relative phases and magnitudes of the voltages impressed upon the plate and grid of each tube are adjusted to give the required indications and are made dependent upon the traffic conditions. Generally the lamps are arranged in the plate circuits of the electron tubes and the grid voltage is controlled and may be either reversed or cut off entirely. Several systems are shown and described in detail, some of which include three indication lamps; in some cases lamps are energized during both parts of the alternating current cycle. An arrangement of transformers is described for reversing the phase of the track current without a relay having moving parts.. Fig. 2 shows the entrance end of a section with a relay transformer H supplied with alternating current from the far end of the section. With the section clear, the potential on the grid of the electron tube D<1> is such the current passes from transformer 16, through green lamp G, wire 10 and transformer winding 17, the inductive action of which is counterbalanced by that of the winding 17<a> in circuit with rectifying tube K. No current is therefore supplied to the red lamp. When the track is occupied, the transformer H, lamp G and winding 17 are de-energized and the red lamp R is illuminated. Fig. 4 shows a system in whicn the circuit of the green lamp G includes a transformer L which determines the potential of the grid of the second electron tube D<2> controlling the red lamp R. Fig. 6 shows an arrangement ior supplying current during both halves of the alternating current cycle to the lamp G by the use of two electron tube devices D<1>, D<2>, the grids of which are of opposite potential, the plate circuits being in parallel through the lamp. Systems giving " clear," " caution," and "danger " signals are described dependent upon reversal of phase of the track-rail circuit of the next section when the red lamp circuit is energized, this circuit including a reversed secondary winding ot the track supply transformer.