Patent GB-460213-A (GB)
Title: Railway traffic controlling apparatus
IPC: B61L3/22
Filed: 1935-07-22
Abstract: 460,213. Railway signalling systems. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd. July 22, 1935, No. 20825. Convention date, Feb. 12. [Class 105] A railway signalling system with wayside and cab signals given by coded rail current has the rail current coded by means of a saturation relay which comprises an impedance winding inserted in an alternating current feed circuit to the rails, such impedance being rendered ineffective whenever current is supplied to a saturating winding and this saturating current being controlled by the traffic conditions in a block section thereby to control the feed of coded alternating current to a rear section. In the arrangement shown coded alternating track circuit current of different interruption rates is fed to the exit end of each track section under the control of an impedance winding 12 (in series with the alternating current supply) which is rendered non-effective during the " on periods of a saturating current in a winding 10 supplied over one or other of continuously operating interruption contacts 17, 13 which make 75 and 180 interruptions a minute. At the entrance end of each section this coded rail current, passes to a rectifier and winding 5 to saturate an impedance 6 which is thus rendered non-effective in a code-following manner and thereby permits the energization of a non-tuned relay and, with 180 code, of a tuned relay. The section 2-3 includes a level crossing, and is therefore made a " cut section " with the code normally repeated in the half-section 2-2<a> by the action of the saturating winding 5 at the " cut " point 2a on a feed impedance 7 for the half-section 2-2<a>. The level-crossing road signal XS is operated by an interlocking relay XR controlled by the relays F2, F<2a> of the half-sections which relays are energized so long as rail current is operating to permit the nullifying of feed impedance 24 for such relays F2, F2a. When a train at the left enters the section 2-3 the saturating winding 5 at the point 2 no longer receives current and therefore the impedances 24, 6 at such point 2 de-energize the relay F<2> and the relays H2, J2. The back contact 26 of relay F<2> de-energizes the interlocking relay XR to set the road signal XS in operation. Relay H<2> at its back contact 18 lights the danger signal R at the entrance to the section 2-3 and at its back contact 14 causes the caution code of 75 interruption rate to be applied to the rear section through the action of the saturating winding 10 on the feed impedance 12 for such rear section. When the train is past the crossing sustained alternating current is fed to the half section 2-2<a> over back contact 27 of relay F<2>a which dropped on entry of the train into the half-section 2<a>-3. This sustained rail current causes the relay F<2> to be re-energized thereby energizing the first winding of the interlocking relay XR and so cancelling the road signal XS. When the train enters section 3-4: the danger signal is given at the entrance to such section (in the manner already described for section 2-3) and the 75 code is supplied to the section 2-3 thereby energizing the relay H<2> but not the relay J<2> of section 2-3. Thus the relav H<2> at its front contact 18 causes the caution signal Y for section 2-3 to be lit (over back contact 19 of relay J<2>) and at its front contact 14 causes 180 code to be applied to the rear section. When the train enters the section at the right of the point 4 then 75 code is applied to section 3-4 and thereby the relay H<3> is energized and so causes 180 code to be applied in section 2-3 so that the relays H<2>, J<2> at the point 2 are both energized and at their front contacts 18, 19 light the clear signal G for the section 2-3. The coding contacts 17, 13 may be approach energized. The coded rail current may operate cab signals by effecting a codefollowing saturation in corresponding apparatus on the locomotive.