Patent GB-371737-A (GB)
Title: Improvements in and relating to control apparatus for traffic signal installations
IPC: G08G1/081
Filed: 1931-09-03
Abstract: 371,737. Road signals for controlling traffic. SIEMENS & HALSKE AKT.- GES., Siemensstadt, Berlin. Sept. 3, 1931, No. 24775. Convention date, Sept. 4, 1930. [Class 118 (ii).] In a signalling installation for traffic control, controlling operations of different character (for example transmission by seconds and synchronization every minute) are transmitted between a central station, Fig. 1, and one or more signal stations, Fig. 2, by current closings and interruptions lasting for different lengths of time. Each signal station may act as a transmitting station for another more distant traffic signal station. The switching devices at the central station comprises a number of relays A, B, C mutually influencing each other, which according to the length of the current closings or interruptions become operative altogether or partially. A longer interruption produced by a line break acts in such a manner on the switch device of the signal station that its motor gearing is automatically switched in to rotate at a slower speed, and to control the signal stations connected in cascade to this signal station. The switch devices R, r<2>, r<1>, provided for the reception of the control currents are utilized both for the production of the desired switching processes in the signal station as well as for the forwarding on of the control processes. A continuously running motor Mo rotates a " seconds " disc Ss and a " minute " disc Sm actuating contacts ks, kl, k<2>. The relay A has a working and a reversing contact, the latter effecting the switching forward every second of the signal device, Fig. 2, by a short current interruption. The relay B has a very slow action so that the contact b<3>, controlled thereby and operated once every minute, may, if necessary, produce a current interruption considerably longer than the line interruption produced by the contact a<2>. The third relay C is switched in by a contact of relay B, which itself is energized by the first relay A. The relay C holds itself through its own contact c<2>, and at the same time breaks through its contact c<1> the current circuit for the relay A. A line break'relay D is also provided in order to switch in a fault indicator lamp L. Other line break relays D<1>, N are provided at the signal station, Fig. 2. Before the release of the current interruption in the connecting line, the strongly retarded dropping relay cl is switched in by the contact r<2>, the relay R controlling this contact being cut off by the contact a<2> every second. The relay E is switched in by the reversed contact r<2> and holds itself by its contact e<2>, preparing through the contact e<1> the current circuit for the motor switch relay M, which operates on reversal of the contact a<2> and holds itself through contact m<1>. The motor M<1> is thus connected to a source W of alternating current and moves forward at high speed the " seconds " and " minute " discs S<1>s, S<1>m, whereby first a relay S is energized and by its contact s<2> interrupts the holding circuit for the relay E. The relay M by contact s<1> holds itself until the " seconds " disc S<1>s releases the contact ks<1> and the relay S is demagnetized. By opening contact s<1> the motor switch relay M is now released and interrupts by contact m<2> the circuit of the motor M<1>. This switching forward every second of the motor M<1> is utilized to give the traffic colour signals in a definite sequence. The " seconds " current interruption is, by means of contact r<1> of the relay R, transmitted to the next succeeding signal station for operating its motor, this signal station being similarly connected to the next, and so on. For synchronizing every minute the motor gearing of the signal station, a considerably longer current interruption is transmitted to the signal station, the relay R being consequently demagnetized for such a length of time that the reversal of the contact r<2> is sufficient for the drop of the slow-acting relay C<1>. A relay T adapted to be energized by the " minute " disc S<1>m is included in the switching arrangement for making, in the event of irregularity, the motor gearing independent of the further switching current interruptions taking place every second. Only when the " minute " impulse is released from the central station can the motor gear at the signal station be further moved.