Patent GB-190207689-A (GB)
Title: Improvements in Electric Signalling on Railways.
Inventor: SIRUBLE JACOB BAKER
IPC: B61L23/16
Filed: 1902-04-01
Granted: 1902-06-19
Abstract: 7689. Struble, J. B. April 1. Electric railways and tramways, signalling on ; semaphore &c. signals ; signalling &c, between trains; contacts, electric.-Relates to railway signalling, more especially for electric railways. In order to prevent the improper operation of the signals by leakage of the power current from the rails, the signals are arranged to be actuated by alternating currents only. One of the rails, Fig. 1, is divided into insulated sections 1, 2, 3, the other rail 4 serving as the return for both motor and signal circuits. One pole of an alternating-current generator 5 is connected to the rail 4, and the other pole is connected to the sections of the other rail, preferably through transformers 6, the secondary coils of which are connected to the rails. The track circuit of each block section includes any suitable translating-mechanism 8, whereby the alternating current in the track circuit is caused to induce another current in a second circuit 9, which, as shown, includes a relay 10 adapted to close, between its armature 11 and contact 12, the operating-circuit 13 of the signal 14. The signal circuit 13 may be energized through a converter 15 from the generator 5, the circuit being closed so long as an alternating current passes through the track circuit. When a vehicle enters the section, the track circuit is short-circuited, the armature 11 is released, and the signal goes to danger.' When the translator 8 is in the form of a converter, it is preferably made of low resistance and protected from excessive direct currents by a non-inductive resistance 16. The heating of the primary coil may be further prevented by connecting a reactance coil 17 across the track circuit. In another arrangement, the relay 10 is omitted, the mechanism for operating the circuit being connected directly to the secondary coil of the translator 8. In a further modification, the signal-operating motor forms the translator, and is included in the track circuit. Fig. 5 shows another arrangement, in which the armature 19 of the electromagnet 9<a> completes the signal-operating circuit 13 between its arm 22 and the contact 23, so long as an alternating current is passing through the coils 18 of the magnet. The armature 19 is cut to form tongues 20, which carry closed coils 21. The alternating current in the coils 18 produces an alternation in the magnetic field, and so induces currents in the coils 21, the neutralizing effect of the currents so induced causing an angular displacement of the magnetic axis, so that the armature is held in the position shown. When the alternating current ceases through the short-circuiting of the track circuit, the spring 24 draws the armature into horizontal position, so breaking the signal circuit. Any direct current through the coils 18 acts only to reinforce the spring 24 to break the circuit. In a modification, the tongues 20 and coils 21 are on the poles of the magnet 9<a>, the neutralizing- currents being induced directly in the coils 21 from the coils 18. In another arrangement, the armature 19 is provided with a coil connected to the motor 5 &c. In this case, the alternating currents through the coils of the magnet 9<a> and the armature coil produce like polarity in the adjacent poles of the magnet and armature, so holding the armature in position to close the signal circuit. When the alternating current ceases, or when it is overpowered by the action of a direct current through the magnet coils reinforcing the spring 24, the signal circuit is broken, and the signal goes to danger.'