Patent GB-361685-A (GB)
Title: Improvements in and relating to road traffic signalling systems and apparatus therefor
IPC: G08G1/081
Filed: 1931-01-06
Abstract: 361,685. Road signals for controlling traffic. BRITISH THOMSONHOUSTON CO., Ltd., Crown House, Aldwych, London.- (Assignees of Leonard, V. W. ; 3315, Taylor Street, Fort Wayne, Indiana, U.S.A.) Jan. 6, 1931, No. 518. Convention date, Jan. 6, 1930. [Class 118 (ii).] In an electric signalling system in which a central station M synchronously steps a plurality of auxiliary controllers A, B .. at consecutive road intersections, means are provided at the central station for varying the operation of the signals so that they may be given either simultaneously or progressively. At the central station an induction motor 2 drives through change-speed gearing cams for operating contacts 7, 8 in conjunction with contacts 9, 10 for transmitting impulses to the controllers A. B ... The speed of the motor is regulated by adjusting the position of shading coils- Each controller A, B . . comprises a ratchet stepby-step mechanism 42, 46 operated by the alternate energization of electromagnets 40, 41 so as to move a perforated disc 47 having a pair of pins 49, 50 adapted to be placed in any of the perforations 48. These pins engage periodically stems 58, 57 operating springs 51, 52 controlling contacts 53 .. 56. A relay 59 at each controller controls a contact spring 60 and contacts 61, 62 so that when the relay is de-energized, the solenoid 40 is under the control of the pin 50, and when the relay is energized, the solenoid 40 is under the control of the pin 49. A set of cams 68, 69, 70 is provided for operating by means of an arm 73 the contact springs 74 .. 77 in turn, for the operation of the red, amber and green signals R, AM, AC, G, while another set of cams 71, 72 serves to restore the arm 73 to its initial position, in the manner described in Specification 346,094, these cams being relatively adjustable by means of external lever arms provided with interlocking mechanism. A cam 13 driven by the motor 2 first holds contact springs 15, 16 in engagement, then engages springs 15, 14, and finally restores the original relation. When the controllers A, B .. are all in synchronism the springs 51, 52 are in engagement with their corresponding contacts 54, 56 at each controller at the same time that the spring 15 is in engagement with the spring 16. If any controller falls out of synchronism with the transmitter, the disc 47 of such controller will be brought to a stop until the transmitter catches up. Re-synchronizing may be effected manually or automatically. As long as switches 112, 114 are both closed, the discs 47 continue to advance indefinitely, whatever the relation of the controllers, but by opening the switch 114 for an interval of time longer than the time it takes a disc 47 to make a complete rotation, all the controllers are again brought into synchronism. For the automatic maintenance of synchronization, the cam 13 operates in place of the switches 114, 112, by automatically closing and opening the circuits periodically. This is effected by opening switches 114, 112, and closing a switch 115. For the " progressive " operation of the signals, the pins 50 are suitably displaced, and in order to enable the signals to be brought back into a condition of non-progression, the pins 49 are all set along the same radius in the controllers A, B ... Moreover, by opening a switch 116, thereby de-energizing the relays 59 and switching the reset control to the pins 50, the latter are automatically re-aligned and " progression " is restored. When the switch 116 is closed, the pins 49 determine non-progression.