Patent GB-191411804-A (GB)
Title: Improvements in Automatic Block Signals for Railways for Absolute or Permissive Working.
Inventor: WIGHT SEDGWICK NORTH
IPC: B61L23/22
Filed: 1914-05-13
Granted: 1915-04-22
Abstract: 11,804. Wight, S. N. May 13. Electrical systems, automatic. - On singletrack railways, each train is protected in front and rear by a danger signal and a caution signal by the use of track relays across the rails of each subsection into which the section of track between signals is divided, and which relays control circuits to polarized control relays, which in turn control both the circuits to adjacent polarized control relays and also the signaloperating circuits. The signal-operating circuits are so arranged that, according to the direction of current through the polarized relay, different circuits are completed, by which the signal is set at 'caution' or 'clear,' and when the relay is de-energized, the signal returns to 'danger.' The circuit of the polechanging relays includes the armatures of stick relays, which are energized by the de-energizing of a track relay, but remain energized after the train clears the subsection. The polarity of the batteries supplying the polarized relays is dependent upon reversing-switches on the signals, or upon electro-magnetic reversing-switches. Figs. 2 and 3 show a length of single track comprising subsections D' ... D' with loops A A' and B B' provided with signals 3, 4, 5, 6 controlling traffic from left to right, and signals 11, 12, 13, 14 controlling traffic from right to left. Each signal 3, 4, 5, 11, 12, 13 is fitted with a reversing-switch 3', 4<1>, 5<1>, 11<1>, 12<1>, 13<1> which reverses when the arm moves between danger and caution positions, and reversing- switches controlled by neutral relays 87, 86 are provided at signals 14, 11, controlling the entrance to the loops A A', B B<1>. The apparatus is shown in the position occupied when all sections are clear of traffic and the signals are clear. A train on section D' de-energizes relay 26. Armature 270 opens the circuit of relay 62 from a battery 111 at signal 4. The armature 271 of this relay opens the circuit to the signal 3, which moves to danger and reverses the switch 3<1> to the position shown in dotted lines. The armature 316 of relay 26 closes a circuit to the stick relay 76, but this circuit is immediately broken by the contact 43 on the signal 3; the relay, however, remains energized by current passing in the holding-circuit through contacts 324, 271, until broken at the latter, when the relay 62 again becomes energized as the train passes on to section D'. The stick relay 77 is not energized because the relay 27 remains energized. Armature 326 of relay 76 closes the circuit from battery 109 through the reversing-switch 3<1>, contact 234, to the control relay of the signal for the section A', and, the switch 3<1> being in reversed position, the signal is set to caution position. Armature 325 closes a circuit from battery 109, through wire 265 and a switch on the signal for section A<1>, to a reversing-magnet at that signal corresponding to magnet 86 of signal 14, which reverses the battery supplying energy to a polarized control relay of the next signal in the rear, which is thereby set to clear, thus restoring the section to normal, since the stick relay becomes de-energized when the control relay is energized. When the armature 350 of relay 26 falls, it breaks the circuit of the control relay 63, the armature 351 of which opens the circuit of signal 13, which goes to danger and reverses the switch 13'. Armature 354 of relay 63 opens the circuit of control relay 65, thus causing the signal 12 to go to danger. Armature 358 of relay 65 opens the circuit of relay 67, and signal 11 goes to danger. The consequent reversal of switch 11<1> reverses the current through the control relay of the next signal controlling traffic from right to left, which thereupon goes to caution position and remains so until the train enters subsection D<6> and de-energizes the relay 31. The armature 399 of de-energized control relay 67 opens the circuit from battery 114 over wire 403 to a reversing-relay similar to 87, controlling the circuit to the control relay of the next signal for the traffic from right to left. The train on subsection D<1> is thus protected in front and rear by danger and caution signals. No change in the signals is made when the train passes on to section D<2>. When it is on section D', the relay 28 is deenergized, and signal 4 put to danger, thus reversing switch 4<1> and supplying current from battery 111 over contacts 294, 291, 274, 270 to control relay 62, which closes the circuit by which the signal 3 is moved to caution, and the signal next in the rear is subsequently moved to clear. In order to prevent de-energization of control relays at the entrance to a section, additional contacts 44, 49 are fitted at the signals in parallel with the contacts of the control relay which govern the next control relay so as to maintain the circuit during the temporary opening of the relay armature while reversal of current through the relay takes place. The Specification describes the action of the system when a train moves back and forth over the track.