Patent GB-191324658-A (GB)
Title: Improvements in or relating to Railway Signalling.
Inventor: DOWNES ALLAN JOHN
IPC: B61L23/12
Filed: 1913-10-30
Granted: 1914-10-29
Abstract: 24,658. Downes, A. J. Oct. 30. [Cognate Application, 10,435/14.J Electrical systems, non - automatic; combined electrical and mechanical systems, non- automatic; track apparatus actuating signals on trains and other than on trains; miniature signals. - A manuallyoperated signalling-key for a section is held on so as to be operative by a luck automatically controlled by the conditions in one or more adjacent sections. The lock may be rendered operative by means of. the semaphore lever. In one construction, an electric circuit is operated under the joint control of the signalling- key and anything that occupies the track section, this circuit being arranged to s u p p l y currents of different strengths according to the position of the key and to give signals. The signals may be given simultaneously in the engine and in the cabin. The engine E and cabin C, Fig. 6, are connected as shown with the track rail A and a sectionalized conductor B. When the signalling-key K in the cabin is moved into the safety position shown, it will not remain there unless the core M<1> is magnetized. This core is provided with four windings, namely the winding m<1> and three other windings (not shown) which are, relatively to the winding m<1>, demagnetizing - windings. The winding m<1> is energized when, subject to the usual interlocking arrangements permitting, the semaphore lever has been pulled off and the contact F thereby closed. Of the three demagnetizing-windings, two are energized from the instruments for the track sections to the left and right respectively of the section controlled by the instrument shown. Each instrument includes a safety signalling-device S<2> in the form of a relay, the armature r<2> of which closes circuit from a local battery C<3> through three circuits in series indicated partially at m<2>, m<3>, m<4>. The circuits m<2>, m' include demagnetizing-windings on the cores M<1> in the instruments for the sectiors to the left and right respectively of the section represented by the instrument shown, while the circuit m<3> includes a demagnetizing-winding on the core M<1> shown. Each such demagnetizing- winding is alone insufficient to release the key K from the pull of the winding m<1>, but any two on the same core can release it. Supposing the key K to remain down under the pull of the coil m<1>, the battery C' is in readiness to deliver current through S<2>, a change-over switch X and an indicator I as soon as a train enters the section, whereupon current from the battery C<1> closes the relay armature r<2> and the double armature of the relay R<2> on the engine, where a safety signal is thus given by a suitable device S', the relay R' being short-circuited. In the cabin, the core M<1> is partially demagnetized by the winding m<3>, and should either of the adjacent sections be occupied, and either have its key depressed or its switch X in the dotted position, one or other of the demagnetizing-coils m<2>, m<4> is also energized and the key of Fig. 6 does not remain in the safety position. The contact K<1> is thereupon closed and current flows through the relay D<2>, and through X, I to the engine. As the resistance of D<2> is high compared with S<2>, a relatively weak current flows, sufficient to energize R<1> but not R<2> on the engine; visual and audible danger signals S<5>, D' are therefore operated. At the same time, the relay armature r<1> is closed in the cabin and the danger signal D<3> is operated. The armature r<2> is connected to the armature r<1> so as to close when this closes but so as to be free to be closed independently by its own coil S<2>. By pressing the buttons S<3>, S<4>, the circuit can be broken; these push-buttons afford a means of communication by the dot-and-dash code between the engine-driver and the signalman. In a modification, the relay D<2> is replaced by a plain resistance coil in series with a danger signal. In other modifications, in place of the device D<2> the currents of different strengths are obtained by using another battery, suitably arranged in the cabin or engine circuit. In a suitable construction, Fig. 4, the key K is held by a spring K<7> with its contacts K' closed. When the key is depressed, the contacts K<2> are closed, and a catch K<6> engages a projection K<4> of an armature K<3> carried by a spring K<8>. When the magnet M is energized by a train entering the section, the armature K<3> is attracted so that the projection K<4> clears the catch K<6> and a second projection K<5> engages the projecting core. On the train leaving the section, the current ceases and the projection K<5>, under the influence of the spring K<8>, clears the core and the key returns to the position shown. An alternative construction for utilizing two currents of different strength to operate safety and danger signals comprises two magnetic devices D<1>, S', Fig. 5, so proportioned that, when a weak current flows through both, the device S<1> is sufficiently energized to pull down a miniature semaphore arm S<6> to the safety position, but is magnetically saturated, while the device D<1> is so slightly magnetised that when a sufficiently stronger current flows, the device D' overpowers the pull of S<1> and reverses the signal. A suitable relay for use with the invention comprises a core made of two strips of iron J, Figs. 11 and 12, bent as shown and threaded into a magnetizing-bobbin L, the core and bobbin being supported on screws N. The armature is a flat iron bar O having two holes enabling it to move freely up and down the screws N, the upward travel being limited by the ends J<1> of the core. The armature carries a contact P co-operating with an adjustable contact P<1>, and two relays may be arranged as shown on a single base.