Patent GB-190501321-A (GB)
Title: Improvements in and relating to Railway Electric Signals.
Inventor: HUFF SLAUGHTER WILLIAM
Filed: 1905-01-23
Granted: 1906-01-23
Abstract: 1321. Huff, S. W. Jan. 23. Signalling systems; contacts, mechanical.-Automatic electrical normal-danger systems are described for either single tracks or double tracks, and employing either 'home' and 'distant' or merely 'home' signals at each station. One track rail is divided into insulated sections, for use in track circuits, and no lead wires between stations are required. In one form, a mechanical treadle operated by the train wheels is employed to actuate the semaphore and an electric switch included in the signalling-circuits. Fig. 1 shows a system employing 'home' signals only on a double track. The semaphore 6 is lowered to 'safety' when an electro-magnet 10 included in a local circuit with a battery 14 and the armatures of relays 13, 16 is energized. The armature 9 is then withdrawn from the supporting-catch 8<x> on the signal rod 8, so that the semaphore 6 falls to 'safety' and is restored to 'danger' by any suitable automatic arrangement. Any operative mechanism for the semaphore 6 may be employed which is dependent on the closing of the local circuit of the electro-magnet 10. One track rail 1 is continuous, the other 2 being divided into long insulated sections 3 between stations and short insulated sections 4, 4<a> on either side of the semaphore 6. Track batteries 20<B>, 20<c> at the stations normally oppose one another. If the block ahead is clear and a train arrives upon the section 4 at the station B from the left, the relay 13 is energized from the battery 20<c> at the next station through the wires 21, 17, rail 3, wire 17<a>, relay 13, wires 21, 18, relay 16, wire 19, section 4, train wheels, and the rail 1 back to the battery 20<c>. Simultaneously, the relay 16 is energized by the battery 20<B> through the wires 21, 18, relay 16, wires 19, section 4, train wheels, and the rail 1 back to the battery 20B. The energized relays 13, 16 attract their armatures, close the local circuit of the magnet 10, and so lower the semaphore 6 to 'safety,' and the train proceeds. A train in the section between the stations B, C short-circuits the battery 20<c> and deenergizes the relay 13, which prevents the lowering of the semaphore 6. Such a train, however, closes a circuit between the battery 20<B>, the relay 13, and the rails 3, 1, but the following train on the section 4 at station B has already short-circuited the battery 20<B> through the relay 16 and, since the relay 13 is of high resistance compared with the relay 16, the current from the battery 20<B> through the relay 13 at station B is not sufficient to cause attraction of the armature of this relay 13. Hence the semaphore 6 remains at 'danger' ; or polarized relays 13, 16 may be adopted with the same effects. The lead 21 is connected to the section 4<a> so that the battery 20<B> is short-circuited when the train passes upon the section 4<a>, de-energizing the relay 16 and restoring the semaphore 6 to 'danger.' Also back flow from the battery 20<B> to the station A is prevented until the train has passed off the section 4<a>. A resistance 23 may be inserted in the lead 21 to ensure effective short-circuit of the batteries 20 at each station when the train is upon the section 4<a>; this resistance 23 may be dispensed with if the batteries 20 are of high internal resistance. In a modified form for use on single tracks, the relays 13, 16 are duplicated at each station, one pair of relays governing the semaphore for trains approaching in one direction and the other pair for oppositely-moving trains. The armatures of the relay 16 and its duplicate are each provided with two contacts and leads, and close circuits in either the energized or the de-energized conditions of the relays. Thus, for safety' conditions, an approaching train must not only find its appropriate pair of relays energized but also the other pair of relays de-energized. In this case the lead 21 is not connected to the section 4<a>, but a resistance connects the sections 4, 4<a> to allow a train entering on the section 4 to energize only its relay 16 and not the adjacent duplicate relay owing to the high resistance, although this duplicate relay is energized when the train passes on to the section 4<a> to restore the semaphore to 'danger,' and the relay 16 remains energized because the high resistance allows sufficient current to pass to retain the already attracted armature. Hence the semaphore is retained in the danger' position when the train passes upon the section 4<a>. This resistance connecting the sections 4, 4<a> may be replaced by a make-and-break switch arrangement, Fig. 3<a>. As the train enters upon section 4, the semaphore falls to 'safety' and the descending signal rod 8 engages by means of a projection 25<c> with a lever 25<a> pivoted at 25<b>, thereby raising the switch rod 25<d> and closing the contacts 25<e>, 251. The relays 16, 16<a> are thus both connected through the contact 25<f> with the battery 20<B> and are both energized to retain the signal at danger' when the train passes upon the section 4<a>. The actual movement of the semaphore to 'danger' is obtained by the passage of the train over a mechanical treadle 8<c> connected to the rod 8, but this does not allow the switch rod 25<d> to fall because the attached armature 25<g> of the make- and-break switch magnet 25 is attracted, the magnet 25 being included in the circuit of the battery 20<B> through the wires 21, 21<b>, 25<h>, contact 25<e>, wire 19, section 4, and the train wheels, or through the wires 21, 21<b>, 25<h>, contact 25<e>, wire 19<a>, section 4<a>, and the train wheels. In fact, the make-and-break switch only resumes its normal position when the train has passed beyond the section 4<a> on to the section 3. In another modified form employing both 'home' and distant' semaphores on a double track, the magnet 29, Fig. 4, controlling the distant semaphore 26 is included in a local circuit with the usual battery 14 and relay 16, and an additional relay 32 energized, together with the usual relay 13, from the battery 20<C> at the station ahead. If no train is in either block BC or CD, both relays 13, 32 are energized, together with the relay 16 when a train arrives on the section 4 at station B. Hence both semaphores 6, 26 fall to 'safety,' the circuit of the magnet 29 being the wire 30, armature 31, wire 30<r>, battery 14, wire 11
, armature 15, and the wire 30<t> back to the magnet 29. Another train now in the section BC short-circuits the battery 20<c> and de-energizes both relays 13, 32, so that both semaphores 6, 26 remain at 'danger.' A train in the second section CD ahead short-circuits the battery 20<c>, but still allows sufficient current to flow therefrom back to the 'home' relay 13 to energize it, but the distant relay 32 requires a stronger current and remains de-energized. Hence in this case the home semaphore 6 drops to 'safety,' but the distant semaphore 26 remains at 'danger.' In a further modification, using 'home' and distant' signals on a single track, the system shown in Fig. 4 is modified in a similar manner to that employed for a single track using ' home ' signals only. The home' and 'distant' relays, Fig. 4, are duplicated and provided with polarized armatures, each to be responsive to trains coming in one direction only.