Patent GB-292169-A (GB)
Title: Improvements in and relating to train dispatching systems
IPC: B61L7/08
Filed: 1928-06-15
Abstract: 292,169. General Railway Signal Co., (Assignees of Preston, N. de F.). June 16, 1927, [Convention date]. Selective distant control and signalling systems. -A continuously driven master selector co-operates with spring-driven wayside selectors with electromagnetic escapements producing synchronous movements of all selectors to control points and signals along a length of track from a central station. The wayside selectors are normally stationary but all are started in synchronism with the master selector when a selective code impulse is to be sent to any of said selectors or the one concerned only is started if an impulse is to be sent from a wayside selector to the central station for indicating the presence of a train at any particular section of the track. The wayside selectors are stopped in their zero position after sending or receiving any impulse. In the central cabin, the switchboard carries a diagram of the controlled track, with levers placed in geographical agreement with the points and signals controlled and lamps on the diagram indicate which sections are occupied by trains, being arranged to flash as a train enters the section until the operator actuates a switch to render the light steady until it is extinguished as the train clears the section. A permanent record of the occupation of each section of track is made on a moving paper strip by electrochemical or electromagnet means connected in shunt with the lamps.. A system of approach locking is described for a single track with sidings and by the use of directional stick relays in a system resembling that described in Specification 11804/14, [Class 105, Railway signals &c.], the occupation of the single line section by trains moving in different directions produces different results. Fig. 2 shows in skeleton form a modified system for control of the points and signals for a section O of single.track between two loops SD, SD', from a remote cabin in which there are arranged levers. LS, LS<2>, controlling through polarized relays SW, SW<2>, the switch point operating mechanisms (not shown) and a lever LZ, LZ<2> controlling the signals 5, 5d, 3, 1, 1<d> for one direction of traffic and signals 2, 2d, 4, 6, 6d for the other direction by means of polarized relays Z, Z<2> coacting with the armatures of relays SW, SW<2> and points detector contacts 14, 29. The cabin levers are situated on a diagram of the controlled track and points levers are arranged to be moved correspondingly to the required position of the points and the signal levers to right or left corresponding to the direction of traffic. The signal operating circuits are controlled by line relays 1H, 1<d>H, 2H, &c. energized under control of track relays (not shown), connected to insulated rail sections. In a similar system described and shown in detail in the Specification, separate levers, suitably interlocked, control the relays Z, Z<2>, and the line relay circuits are independent of the relays SW, SW<2>. The system includes directional stick relays in conjunction with the signals 3, 4, as disclosed in Specification 11804/14, [Class 105, Railway signals &c.], in which is described a typical absolute-permissive block system. By means of these relays, the line relay 2H is de-energized while the single track section is occupied by a westbound train but not by an eastbound train and a line relay is similarly deenergized by an eastbound train only. The preferred arrangement of control circuits for the switch machine and the approach locking for the switch points at one end of the loop SD is shown in Fig. 3. The switch-operating mechanism is electrically operated and of the kind described in Specification 169,795, [Class 105, Railway signals &c.], and includes contacts controlled by magnets RM, NM for operation, to reverse or normal respectively, these magnets being energized over contacts of relays RR, NR and the locking relay LR. The first two relays are alternatively energized by the polarized relay SW controlled from the cabin and relay LR is energized by a circuit including track relay contacts of sections g, d, and contacts on the signals 3, 1, 1<d>. 2<d>, 2, 6, 6<d>, so as to be energized only when a train approaches the relative signals at danger or caution or when no train is approaching. The switch machine may, if necessary, be reversed in mid-stroke by the operator reversing the polarity of relay SW. Relay LR may, when de-energized, cut off current from the switch machine or short circuit the motor as additional protection. Energization of either relay RR, NR breaks at the back contacts 99, 98, the circuit for signals 1, 1<d>, 2, 2d which then assume " stop " position. The stick relay SL provides for approach-locking protection for a train passing signal 3 at " clear." Stick relay SL<1> affords similar protection for trains in opposite direction on either the main track or the siding. To avoid difficulty due to locking of the switch machine when a switch movement is necessary under special conditions. a dual selector with a hand-throw mechanism as described in Specification 283,454, [Class 104 (i), Railway and tramway crossings &c.], may be provided. The synchronous selector system is shown in Figs. 4A, 4B of which Fig. 4A shows the circuits of a central station apparatus and Fig. 4B shows the circuits at a wayside selector controlling the points at one end of a loop and for transmitting indications of the operation of track relays related to that section of track to lamp indicators and a recording device in the central station. Each apparatus can be adapted for additional controls by the use of the spare contacts shown. The central transmitter and selector receiver comprises a motordriven continuously-running shaft 130 carrying two contact arms 140, 143 serving to connect rings 141, 146 to a number of spaced contact studs concentric therewith, and a disc 134 having an insulated annulus serving to make and break contact with fixed brushes 132 and a cam 136 serving to close switch 138 in the zero position of the shaft. Impulses of current are transmitted between the central and wayside apparatus by a stepping line PW, a common line CL and a control wire CW. The wayside selector comprises a, shaft 182 carrying a contact arm 200 which is rotated step by step by an electromagneticallywound spring 189 under control of an escapement controlled by an electromagnet 199 which is energized by impulses transmitted over the disc 134. The winding gear comprises a magnet 183 with a reciprocating armature 184 and make-andbreak contacts actuating a ratchet disc 188 to keep the spring 189 stressed. The spring acting on the armature 184 is so dimensioned as to break contact when the spring 189 is fully stressed. At each revolution of the shaft 130 the cam 136 in the zero position closes contact 138 and sends an impulse over the line PW from battery 220. If no tranmission from central station is to be made, this current is negative and serves to energize relay SR at each wayside selector, to move armature 230 to the contact 231 in preparation for a transmission to the central station if required. If a transmission from the central station is to be made, the appropriate lever LS is set and momentarily energizes stickrelay 153 and consequently, when arm 143 reaches zero, the stick-relay X picks up and reverses polarity of battery 220 to the stepping wire PW so that a positive current is sent over contact 138 and the relays SR at each wayside collector are energized to receive impulses to the stepping magnets 199 first over contacts 203, 228. 230 and then over another contact. The subsequent make-and-break of the circuit at disc 134 causes the shaft 182 to step synchronously with the shaft 130 and when arm 140 reaches contact 1st, the arm 200 meets contact 1st in the required wayside selector only and the relay SW is energized over a circuit from battery 180, lever LS, arm 140, bell-relay BR, control wire CW. arm 200 to polarized relay SW, common-line CL and relay BR. The relay SW moves its armature to a position dependent upon the polarity of battery 180 as determined by the lever LS being moved up or down and is stuck-up in either position by the local circuit from battery 208 and controls the points &c. as described in conjunction with Fig. 2 above. The two windings of relay BR are in opposition and this relay is not affected. On reaching stud 147, the arm 143 shunts relay 153 and relay X is de-energized. Transmission to the central station of an indication of the passage of trains over the sections is initiated by the picking-up or dropping-off of the armatures of the track relays, either singly or in combination and in conjunction with the directional stickrelays, as 2S, and line ralays, as 2H which momentarily energize the stick indicating-relay IR which completes a circuit over the armature 230 of relay SR, when the latter receives a negative impulse, to the stepping magnet 199 causing that wayside selector only to rotate synchronously with the central selector. When arm 200 reaches contact 204 the relay IR is de-energized. At contacts 2<nd>, 3<rd>, 4<th>, positive or negative currents are transmitted from B or N. over control wire CW, relay BR, arm 140, contacts 2nd, 3rd, 4th of central selector to relays 174, 178, 176 and common line CL. As only one coil of relay BR is energized, the single siroke bell BL is sounded to draw the operator's attention. Relays 174, 176, 178 control lamps on the track diagram. These lamps may each be provided with a flashing relay FR which can be put out of action by a hand switch 255 when the operator has observed the indication just received. The switch 255 is re-opened by subsequent de-energization of the relays 174 &c. due to reverse movement of the track relay armatures. The bell.relay BR is preferably polarized so as to sound the bell only when a train enters a track section and not as it leaves.