Patent GB-327438-A (GB)
Title: Improvements in automatic railway signals
IPC: B61L3/18
Filed: 1928-12-05
Abstract: 327,438. Balls, S. T. Dec. 5, 1928. Electrical systems, automatic; track apparatus actuating signals on trains and for stopping trains. -Relates to an automatic railway signalling system in which an electric generator or storage battery on the locomotive supplies the energy for actuating a miniature semaphore signal, a lamp and bell warning, and means for cutting off the steam supply and causing the actuation of the brakes on the locomotive and for actuating electric switches connected with track wires at the entrance and exit of line sections. A cab signal is given corresponding with the track semaphore signal and, if the latter is at danger, lamp and bell warnings are given, the steam supply is cut off and the brakes are applied. Should the line section be occupied then independently of the position of the track semaphore signals similar warnings are given. In normal operation the track electric switches are reset when the locomotive leaves the section but should a second locomotive enter they are not reset until the second locomotive leaves the section. The switch, Fig. 1, connected with the entrance wire of a line section comprises three double strips 4, 4a, 4b over which move brushes 6<a>, 6b carried by an arm 6 actuated by a solenoid 1, the rod 2 of which alternately rests on the teeth 13 and in the depressions 14 of a cam wheel actuated by a pawl 11 on the brush arm 6, so that alternately the double strips 4a and then 4 and 4<b> are connected by the brushes. The switch, Fig. 4, connected with the exit wire of the section comprises an arm 30 actuated by two solenoids 17, 18 and pawls 20, 25 so as to connect contact segments 34 or 35 with a segment 33. The wiring arrangement between the switches is shown in Fig. 6, and the locomotive wiring arrangement in Fig. 7. This latter comprises the electric storage battery AM and two solenoids 37, 38 connected with contact bows AB<1>, AB<2>, the first of which engages a wire BJ associated with a track semaphore signal and having a resistance BN<1> which is short circuited by a switch BN when the semaphore is at danger, so that the pull on the rod 39 of solenoid 37 depends on the position of such signal and, by acting against a spring 37<a>, correspondingly sets a miniature signal AF in the locomotive cab; if the signal is at danger the solenoid rod 39 closes a switch CB to give warning by a lamp AH and bell AJ and to cut off steam and apply the brakes. The other contact bow AB<2> engages the entrance or exit wires of the line section. When the locomotive enters a section, current flows through the solenoid 38, bow contact AB<2> to the track entrance wire BB and, as the segments 4a of the track electric switch are bridged, to the solenoid 1 which, on the bow AB<2> leaving the wire BB, moves the brushes on to segments 4 and 4b. The locomotive solenoid 38 is not sufficiently energized being in series with track solenoid 1. When the locomotive leaves the section, current flows through the exit wire BC to its switch and, as the arm of the latter is on segment 34, passes to the segments 4b of the first switch, which are bridged by the brush 6b, to the solenoid 1 and so resets the first switch. Should a locomotive enter an occupied section then as the first switch arm is in position to bridge the contact segments 4 the solenoid 18 is energized to move the arm of the second switch on to contact segment 35, so that when the first locomotive leaves the section it does not reset the first switch by energizing solenoid 1 but energizes the solenoid 17 to move the arm 30 on to contact segment 34 in readiness for the second locomotive to reset the first switch by energizing solenoid 1 on leaving the section. The solenoids 18 and 38 are of such resistance that when these are in series, that is, when a locomotive enters an occupied section, the solenoid 38 is sufficiently energized to close a switch on the locomotive to actuate the lamp and bell warning and to cut off steam and apply the brakes. The wires are arranged overhead. Two wires may be provided for the semaphore signal one adjacent and the other at some distance preceding it. Scrapers may be fitted to the contact bows.