Patent GB-190818670-A (GB)
Title: Improvements in or relating to Railway and like Signalling Systems.
Inventor: COLEMAN CLARENCE WILLIAM
Filed: 1908-09-05
Granted: 1909-12-06
Abstract: 18,670. Coleman, C. W. March 16, [date applied for under Section 91 of Patents &c. Act, 1907]. Automatic systems.-To increase the inductive effect between a current-carrying coil and a track rail carrying signal-controlling periodic current, the magnetic circuit surrounding the coil and including the track rail is completed by the use of plates C, D, E, Fig. 2, of magnetic material. The wires A of the coil lie closely against the web B of the track rail. The plates are secured in place by clamps F connected by bolts G and are discontinuous as shown in Fig. 1 so as to confine the induced currents to the rail. The apparatus is particularly applicable to the signalling system described in Specification No. 12,795, A.D. 1908. The Specification in the original form, as open to inspection under Section 91 (3) (a), comprises also the following signalling system which does not appear in the Complete Specification as accepted. The system comprises the use of track circuits and alternating current with continuous track rails, which are cross-bonded and supplied with signalling- current by induction from coils mounted at each end of a block in close proximity to the track rails. Home and distant signals are used, and are selectively controlled by reversing the phase of the current in the line relay. The two sets of track rails 1, 2, Fig. 1 (cancelled), are bonded at the stations A, B by bonds 3 of small impedance, and the block section so formed is supplied with signalling-current from transformers 6, 7 energized from the main supply-leads 4, 5. The moving- coils 13 of track relays 11, 12 are energized from track coils 9, 8 placed at each end of a block, and the fixed coils 15 are energized from feed wires 16,17, which are fed from transformers 20 connected to the mains 4, 5. The fixed coil of each line relay 25 is connected through line - wires 18, 22, contacts 28, controlled by the track relays 12, 11 and a pole-changing switch 29 with the feed wires 16, 17 at the station ahead. The moving-coil of each line relay 25 is connected directly to the feeders 16, 17 at the same station. Each line relay 25 has a contact finger 27 actuated by a neutral armature and responsive merely to presence of current in the fixed coil, as well as the finger 26 on the moving coil, which is responsive to changes of phase bet een the currents in the fixed and moving coils. In the operation of the system a train is assumed to be just outside the block A, B to the west of A. The current in the track rails is then shortcircuited through the wheels and axles, and the track coil 8 and moving-coil of relay 12 at A are de-energized. The home' semaphores 23 and ' distant' semaphores 24 at each station are'actuated by any electrical apparatus, and move to danger ' by gravity when the circuit is broken. When the moving-coil of relay 12 at A is de-energized, the circuit of the fixed coil of the relay 25 at A is broken at the contact 28, and the contacts 26, 27 of the relay 25 are consequently broken, which breaks the circuits of both home' and distant' semaphores at A to indicate danger.' The circuit of each 'distant' semaphore also passes through a contact 38 controlled mechanically by the movement of the adjacent 'home ' semaphore arm so that the distant semaphore circuit is broken when the home' semaphore is at 'danger.' This prevents the anomaly of a 'distant' signal indicating 'clear' when the home' signal indicates danger.' When the signals at A move to 'danger,' the 'home' semaphore arm 23 mechanically reverses the pole-changing switch 29, and reverses the phase of the current in the fixed coil of the line relay 25 at B. This breaks the contact 26 at this relay, and the distant' signal 24 at B moves to danger,' but the contact 27 is still made because the fixed coil of the relay 25 at B is still energized and the 'home' signal 23 at B indicates 'safety.' The line wire 22 is used in conjunction with another line wire 39 for the relays controlling the signals for the other track 2.