Patent GB-439052-A (GB)
Title: Improvements in or relating to traffic control signals
IPC: G08G1/082
Filed: 1934-05-28
Abstract: 439,052. Road signals for controlling traffic. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, Liverpool, and PREIST, T. P., 104, Deveraux Drive, Poulton, Wallasey, Cheshire. May 28, 1934, No. 15905. [Class 118 (ii)] In a road traffic control system in which a number of signal units is controlled by a master controller, the master controller can work independently or can be controlled so far as phase and cycle time are concerned from the master controller of an adjacent group of signal units. As shown in Figs. 1 and 2, the master controller, which may control signal units in the manner described in Specification 403,732, comprises a switch with wipers MT which is stepped by magnet DM under control of relay A in the neontube timing circuit FA, A, QA. When an adjacent group is not functioning the timer steps at a fairly fast rate under control of the manually adjustable control MSW. When the adjacent group is working relays OSG and OSR operate in parallel with the red and green signal light and energize thermal relay TH which is sufficiently slow to release to hold during the amber period should neither red nor green lamps be then illuminated. As shown the phase agreement is made when the relay OSR operates. If, when the controlling group is switched on, the relay RSF is operated over wiper MT1 before relay OSR pulls up, as relay TH is energized, resistance X is cut into the timing circuit to slow down the next pulse of the timer and when relay A energizes, relays N and R are operated in series and lock. Relay N opens the timing circuit and relay R energizes relay S which cuts resistance W into the circuit. When relay OSR energizes, relay N releases and the master timer is restarted. If at the end of this cycle the master timer is again ahead relay RSF again energizes to increase the time of a single pulse and if relay OSR has not then operated when relay A pulls up, relays N and U are energized again to hold up the timer and to cut further resistance into the timing circuit. Additional relay groups such as R, S, T ; U, V, W ; are provided to insert additional resistances to the timing circuit as required. When the two timers are in step. The long pulse provided by the relay RSF and the resistance X is sufficient to maintain synchronism and when relays RSF and OSR energize together a quick step circuit for the timer is provided through low resistance Y to start the two timers on a new cycle in synchronism. If however relay OSR energizes before relay RSF, relay OSF is operated to energize relay 1R which steps magnet DM by self interruption until relay CO is operated to open the stepping circuit and to energize a relay, such as relay W, which releases relay V and cuts a resistance unit out of the timing circuit. If the "master" master-controller ceases to function relay TH falls away and as relay A is pulsed, the relays W, T &c. are operated in turn to cut out the resistance units so that the timer reverts to its faster independently controlled cycle. The contact y is controlled by the relay such as V in the next relay group and the dotted connection is made to the relays of the last group. Instead of relay groups the resistance units may be controlled by a switch operated in reverse directions by two magnets as disclosed in Specification 346,294 or the arrangement shown in Fig. 3, with two unidirectional switches may be used. The switch B is operated to increase the resistance and the switch A decreases it. When however switch B reaches its first contact, relay D is energized over wiper B2 and locks. Relay C energizes and magnets ADM, BDM are operated together and interact with relay C until wiper A2 reaches its first contact when relay E energizes to release relays D and E to stop movement of the switches. This ensures that the relative positions of wipers A1 and B1 are unchanged and the correct amount of resistance is included in the charging circuit when wiper B1 moves from one end to the other of its bank. When the master control terminates relay TH (Fig. 1) releases and pulses are received over the decrease lead to restore the switches to normal. When wipers A3 and B3 are in line, stop relay STP is energized to open the drive circuit of magnet ADM. This relay is also operated to open the increase drive circuit when the maximum resistance has been inserted in the timing circuit.