Patent GB-232551-A (GB)
Title: Improvements relating to railway traffic controlling apparatus
IPC: B61L23/16
Filed: 1924-12-31
Abstract: 232,551. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Grondahl, L. 0.). April 15, 1924, [Convention date]. Electrical systems, automatic; slots, reversers, and like apparatus; visual outdoor signals.-An automatic electric traffic-controlling system has direct current electromagnetic devices (relays, signal operating mechanism &c.) operated from sources of alternating current through the medium of rectifiers. A signal-operating mechanism is also described. Figs. 1<A>, 1<B> and 1<C>, when placed end to end, represent a length of line divided into insulated sections AB, BC, - - GH. Each section has a direct-current track relav R<A>, R<B> &c. and signal S<A>, S<B> &c. at the entrance end, and current is supplied to the track rails at the exit ends through pole-changers P<B>, P<C> &c. controlled by the signal of the next section in advance. The signals are of three-position semaphore type normally indicating " proceed," but indicating " stop " and " caution " at the entrance of an occupied section and the next section to the rear, respectively. A generator J connected to transmission lines M supplies track current through transformers T<2>, T<4> &c., rectifiers K<2>, K<4> &c., and the pole-changers and signal-operating current through transformers T<1>, T<3>, T<5> &c., rectifiers K<1>, K<3> &c., and circuits controlled by the track relay contacts, as described below. Each rectifier comprises four elements which may be of the kind described in Specification 194.653, [Class 38 (ii), Electric currents, Converting &c.], having copper in contact with cuprous oxide, and arranged so that, referring to K<2>, current from one halfwave passes through element 4 to pole-changer P<B> and back through element 7, whilst from the other halfwave it passes through element 6 and returns through element 5. Unidirectional impulses capable of operating D.C. devices are thus supplied to the track relays and signals. Each polechanger supplies current of " normal " polarity when the co-operating signal indicates "proceed" or " caution " and " reversed " polarity when the signal indicates " stop." Each track-relay has neutral contacts 10, 14, 30 and a polarized contact 69. Switch points are shown at L, and operate a contact device 28 to shunt the track circuit when the points are open. An indicator I, which may be of two-position miniature semaphore type, shows whether the points may be opened, and is energized from transformer T<1> through contacts 30, 32, 34 (in series) of relays R<A>, R<B>, R<C> so that presence of a train between points A, L is indicated. Section DE is subdivided into portions DX, XE each with its own track circuit. Relay R<X> controls the polarity of current supplied to portion DX in accordance with the position of signal S<E> and, when de-energized by a train in portion XE, bridges the rails of portion DX to de-energize relay R<D>. A crossing bell N is provided at X, its circuit from transformer T<9> being closed when either of two contacts 47, 51 is released by the corresponding winding 45, 27 of a relay Q. Circuit of winding 45 includes a contact 43 of relay R<D> and circuit of winding 27 includes a contact 26 of relay R<X> so that the bell rings when a. train is in either portion DX, XE. Section GH is the last block of the system, track current being supplied from transformer T<15> without pole-changer. Signal S<G> has only two positions indicating " stop " and " caution." Signal SF in section FG is a two-position manually controlled train order signal, indicating " stop " or " proceed." Track current to section EF is supplied from transformer T<12> through pole-changer P<F> operated by signal SF, the polarity being " reversed " when signal SF indicates " stop " so that signal S<E> indicates " caution." When section FG is occupied, relay R<F> bridges rails of section EF through contact 57 and wires 58, 59 and signal S<E> indicates " stop." When section GH is occupied, " reversed " current is supplied to section FG, and polarized contacts 55, 60 connect rectifier K<12> direct to section EF (eliminating pole-changer PF), supplying " reversed " current so that signal S<E> indicates " caution " irrespective of the position of signal S<F>. An application of the invention to a non- polarized track circuit system is described in which the polarized contact of the track relay described above is replaced bv a contact of a line relay controlled by the signal of the next section in advance. Fig. 3 shows signal-operating arrangements, relay RA being de-energized and the parts in " stop " position. An arm 90 pivoted at 90<a> effects movement of the signal arm 87, of a contact 106, and of a contact operating cam 111. Arm 90 has a forked pivoted nose 99 held rigid by toggle mechanism 101 when a magnet 100 carried by the arm is energized, but released when the magnet is de-energized. A motor 89 when energized drives two chains 92. 93 running over sprocket wheels, each chain having rollers 98 adapted to engage nose 99 and raise arm 90. As shown, the circuits of magnet 100 and motor 89 are broken at contact 14. When relay R<A> is energized by " reversed " current, the magnet circuit is closed from rectifier K<1> over contacts 10, 105, 106, conductors 107, 108, 13 and contact 14, and motor circuit is closed over contacts 10, 120, 110, conductors 112, 113, 13 and contact 14. The chains are thus driven, rollers 98 on chain 92 engaging nose 99 and raising the arm to caution position, where it is held bv a catch 102, rollers 98 then leaving the nose 99. The motor circuit is also broken at contact 120 by cam 111, which closes contact 119. When relay R<A> receives " normal " current, the motor circuit is again closed over contact 10, polarized contact 69, conductor 116, contacts 117, 119, 110, conductors 112, 113, 13 and contact 14. Magnet 100 is maintained energized over con,tacts 10. 69, 115, 106 and conductor 107. The rollers 98 on chain 93 raise arm 90 to " proceed " position, where it is retained by a catch 103, the motor circuit being broken at 117 by a proection 121. When the magnet circuit is broken at contact 14, nose 99 is released, and the parts return to the " stop " position.