Patent GB-191318801-A (GB)
Title: Improvements in and relating to Railway Signals.
Inventor: TAYLOR JOHN DANIELS
Filed: 1913-08-19
Granted: 1914-04-02
Abstract: 18,801. Taylor, J. D. Aug. 28, 1912, [Convention date]. Electrical systems, automatic; slots, reversers and like apparatus; visual outdoor signals. - A semaphore signal, biased to one position, is held in other positions by an electro-magnetic transformer device comprising a primary and a secondary member, one of which members is fixed and the other movable. The signal is described for use as a two-position signal or a three-position signal in track relay systems using single-phase alternating current from line wires, resistance and reactance being inserted to give two-phase currents for driving the semaphore arms. The connexion is changed when the signal is released to return to danger, so that the currents in the two windings are substantially in phase, and the motor acts as a brake. The motor armature drives the semaphore spindle through a ratchet gear which is disengaged while the motor continues running backwards after the arm is arrested in the ' danger ' position. The operating-mechanism is shown in Fig. 1, and a section through the holding - device in Fig. 4, and a signalling system involving threeposition signals is shown in Fig. 8. The semaphore arm is mounted on the spindle 10 and is geared by toothed gear to the pinion 17 which has a conical seating on the spindle 15 against which it is spring-pressed. The motor armature M is a squirrel-cage rotor carried by a spider and connected to the spindle by a ratchet gear similar to that shown in Fig. 4. The stator has a double winding as shown. The holding-device comprises an armature H of squirrel-cage form having the same number of conductors 52 as there are poles of the stator member 29 which has a single winding. The rotor 48 is supported on a spider 12 which is loose on the spindle 15. The ratchet-wheel 32 is fast on the spindle 15 and a plate 14 is spring-pressed axially into contact with the wheel 32. Pawls 33 pivoted on the plate 14 are rocked by pins 34 on the spider so as to disengage the ratchet if the spindle tends to rotate in the direction of the arrow, as occurs when the signal is driven to the ' caution ' or ' clear ' positions. When the signal arm is released and is returned by gravity, it moves the spindle in the reverse direction and the armature H is rotated. The armature H is held in a given position if the stator is energized, each conductor occupying a position centrally under a pole-piece. In the system shown in Fig. 8, each section of track has a track-relay R, R<1>, R<2> supplied with current through reversing-switches on the signal arms. Other contacts in the signal - control circuits are operated by the signal mechanism. A train W, on entering section A from section B, de-energizes the relay R, which opens the circuits, and the signal S goes to ' danger ' under gravity. The relay R<1> then receives current through the switch 109 of signal S, which causes it to close the circuit from the secondary 107 of transformer T<1> over wires 79, 80, contacts 65, 66, and wire 86 to the windings 54, 55 of the motor M, one of which is in series with a resistance 57, the other with a reactance 58. The motor M thus energized drives the signal S<1> to the ' caution ' position as shown, and contacts 65, 66 are opened and contacts 63, 62 closed to energize the stator 31 of the holding-device H. The reversal of the switch 109 of signal S<1> causes the relay R<2> to reverse its armature to close a circuit from the secondary 107 of the transformer T<2> over wires 79, 81 and contacts 67, 68 to the motor M which drives the signal S<2> to ' clear,' in which position it is held by the device H which is energized over contacts 60, 61. The switch 109 of the signal S<2> does not change the connexion of the track-relay circuit of the next section during its movement from ' caution ' to ' clear,' so that the next signal is not affected. Should a train enter section B from a siding while the signal S<2> is clear, the relay S' will return to ' danger ' and reverse the relay circuit of signal S<2>. The signal S<2> moves towards ' caution ' under gravity, and as it approaches this position, the circuit from wire 84, over contact 41 controlled by the holding- device H, wire 85, and contacts 70, 71 to the winding 55 in parallel with the reactance 58, resistance 57, and winding 54 is closed. The currents in two windings 54, 55 are then substantially of the same phase and the armature serves as a brake for the signal arm. The contact 41 is carried by a pivoted armature 46 which bridges a gap in the magnetic circuit of the stator, Fig. 4, and in order to cause the magnetic flux to pass through the pivoted member, short-circuited conductors 53 with plates 49 are arranged on the adjacent polepieces. A system in which two position signals are used is also described. No switches are used in the track circuit, the track relays controlling one contact only which opens the circuit of the stator of the holding-device, and thus indirectly controls the circuit of the motor M.