Patent GB-231852-A (GB)
Title: Continuous inductive train control
IPC: B61L3/22
Filed: 1925-03-23
Abstract: 231,852. General Railway Signal Co., (Assignees of Wenholz, W. W.). April 7, 1924, [Convention date]. Electrical systems, automatic; track apparatus actuating signals on and for stopping trains.-In an automatic train control system in which alternating current is fed to insulated rail sections 1 except when the section in advance is occupied, the current normally being of opposite instantaneous polarity in the opposite rails, and the train carries inductively influenced coils R, R<1>, arrangements are made whereby false indication is avoided in the event of stray current in either rail, or of the same simultaneous polarity in both rails, the particular arrangements also providing for running of the train into uncontrolled territory such as branch lines, sidings &c. Each rail section is provided with a battery 4<0>, 4, 4<1> and direct current track relay 3, 3<1>, 3<2>, and alternating current is supplied from transmission lines T through transformers 6<0>. 6, 6<1> the secondaries of which are in series with the batteries. The primary circuits are controlled by contacts 7, 7<1>, 7<2> of the track relays of sections in advance. Sections B, C represent controlled, and sections D, E uncontrolled territory. Coils R. R<1> are tuned by condensers, and are respectively connected to the input terminals of amplifiers A, A<1>, the output circuits of which include the field coils 10, 11 of a three-position relay MR. The necessary phasedisplacement is obtained by suitable means such as a resistance 12 and inductance 13 in the respective coil circuits. The relay contact 9 normally occupies the full-line position shown, and maintains energized a green-lamp g and train control device K, which mav be of the kind described in Specification 27475/13, b, c representing connections to opposite poles of a local source of current. When the train enters a caution or danger section, relay MR is de-energized, and contact 9 moves to central position, breaking the circuits of lamp g and device K, and energizing a warning lamp r. A stray current in a single rail does not affect the relay, and stray currents of the same instantaneous polarity in both rails move contact 9 to the extreme left or reversed position, breaking the circuit of lamp r. This movement of the relay (when produced by prearranged conditions, is used to enable the driver to proceed into uncontrolled territory, the contact 9 closing a circuit through a push-button P (operated by driver) and a " no-signal" relay NS arranged to provide the necessary controls. A " no-signal " indicator NS<a> is also energized. When, in uncontrolled territory, contact 9 returns to mid-position, a hold-up circuit for relay NS is closed through contact 9, conductor 18, raised contact 19 of relay NS, and conductors 20, 16. A second contact of relay NS closes a circuit maintaining the device K energized. Section D at the entrance to uncontrolled territory may be. supplied with current through transformers 6<1> permanently connected to the lines T, and a loop L in series with the primary, (one side of the loop being mounted near the rail and the other side sufficiently remote to leave coil R unaffected), produces, in coils R, R<1> and relay MR, the effect of current of the same instantaneous polarity in both rails. Alternatively, such current may be supplied to the rails of section D in parallel. Section D is of sufficient length to effect operation of relay MR in a train moving at speed, and the combined lengths of section D, E cover a suitable braking distance. The primary circuit of transformer 6 supplying current to section C is controlled by the contact of a line relay LR, the circuit of which is controlled by contacts, in series, of the track relays 3<1>, 3<2> of sections. D, E. The signal S at the entrance to section C is also preferably controlled by the relay LR.