Patent GB-190419875-A (GB)
Title: Automatic Block Signalling System for Railways.
Inventor: RICHARDSON ERNEST ARDISANA
Filed: 1904-09-15
Granted: 1905-01-12
Abstract: 19,875. Richardson, E. A. Oct. 26, A.D. 1903, [date applied for under Patents Act, A.D. 1901]. Automatic systems; signalling approach of trains. - In an automatic electric block system, either for a line normally clear or for a line normally blocked, track circuits are employed dispensing with aerial wires entirely in the case of a double track, but also employing short aerial wires at intervals on a single track. Polarized relays are not employed, and the system does not depend upon differences of resistance, or upon direction of current, or upon relays in series. In the application to a double track for "line normally clear," signal stations e, f, g, Fig. 1, are provided in one block, with a station h in the next block. The track rails a, b are provided with insulating-joints c at each station. Relaysj, j<1>, j<2>, j<3> at each station are energized from batteries k, k<1>, k<2>, from the station in advance, through the track rails a, b, and normally retain the signals at safety when excited, but the relay j' at the station g employs a third rail d in its circuit. A relay l is also provided at the station g in circuit with the battery k at the station h through the track rails a, b. When the relays j, j<1>, j<2>, j<3> are de-energized, the batteries o, o<1>, o<2>, o<3> are cut out of circuit with the several motors actuating the signals, returning each to danger. A train entering the block, and passing the station e from the left-hand side in the Figure, short-circuits the battery k<2>, and neutralizes the relay j<3>, breaking the circuit of the battery o<3>, and placing the signals at danger behind the train. Similarly, the train passing the station f short-circuits the battery k<1>, and places the signals at the station f at danger behind it. The circuit of the battery k<2> is still broken by the contact q<2>, to retain the signals at the station e at danger as well. The train passing the station g similarly sets the signals there at danger behind it, and here also cuts out a relay l, to maintain the circuit of the battery k<1> broken at the contact q<1>. When the train passes into the next block section past the station h, the relay j is neutralized, and the circuit of the battery k is completed by the contact q, whereupon the relays l, j<2>, ,j<3> are energized, and the signals restored to safety at the stations e, f, while the relay j<1> is still neutral, keeping the signals at danger at the station g. An intermediate station may be inserted between the stations g, h, with relays similar to the relays l, j<1> at the station g, with connections arranged, so that the train, on passing the intermediate station, blocks the signals there, and also retains them blocked at the station g. Fig. 5 shows the application to a double track normally blocked. The circuits of the relays j, j<1> j<2>, j<3> pass through contacts v, v<1>, v<2>, v<3> of extra relays m, m<1>, m<2>, m<3>, which are normally excited by local batteries, and retains the relays j, j<1>, j<2>, j<3> inert. A train entering a block section successively cuts out each relay m at the station in advance, and then the system acts in the manner described with reference to Fig. 1. The relays m, m<1>, m<2>, m<3> are energized as the train passes, and restore the signals to danger. In this case also, an intermediate station may similarly be inserted between the stations g, h, and it may be provided with an extra relay to obtain the "normally blocked" principle. The relays m, m<1>, m<2>, m<3> are cut out successively before an approaching train, and may thus be employed in conjunction with an annunciator to give warning of the approach of the train.