379,326. Road-traffic signals. SIEMENS & HALSKE AKT.-GES., Siemensstadt, Berlin. May 12, 1931, No. 14090. Convention date, May 12, 1930. [Class 118 (ii).] In a traffic control system wherein cyclically operated signals at a plurality of points are controlled from a central station, the duration of the individual signals of a cycle may be varied without altering the duration of the cycle by means located at the central station. Two methods are described, one in which all traffic points after a selected one have the individual signal duration similarly varied, and a second in which the signals of any single traffic point only are varied. The central station apparatus comprises a motor-driven shaft W, Fig. 1, carrying fixed seconds and minute discs S1, S2 respectively and cam discs Sgr, Sge, Sro, corresponding to green, yellow, and red signals, frictionally attached thereto, the disc Sge having two independently adjustable cams corresponding to the two yellow signals in a cycle. The seconds disc S1 operates contact K1 each second, the minute disc S2 opens contact K2 once per minute, and a contact K3 is operable by the cams Ngr, Nge1, Nge2, Nro on the adjustable discs Sgr, Sge, Sro. The normal line current to the first traffic point, Fig. 2, is fed from a transformer T, over lines l1, l2, a second transformer Tl being provided for the " frequency " control of individual traffic points. Individual traffic points. The various traffic points are connected in cascade. Each traffic point, Fig. 2, has motor-driven cam mechanism corresponding to that at the central station and includes relays SR, UR, and VR susceptible respectively to diminution, interruption, and increase of the current in lines l1, l2. When contacts K1 open, inserting resistance W1 in the line l1, l2 circuit, the decreased current causes relay SR to release. A motor M<1> energizes over circuit s, contact sr, contact 1 of minute disc S<1>2, and W4, its circuit being maintained between the actuations of relay SR over contact 1 of the seconds disc S\ while the respective seconds discs S1, S<1>1 make 60 steps. The relay SR<1>, Fig. 3, of the next traffic point is similarly operated by contact 2 of S<1>1 inserting resistance W<1>1 in line l<1>1, l<1>2 fed from transformer T3 and so on for all the remaining traffic points. Assuming the yellow lamp Lge to have been just lighted (lamps Lgr, green, and Lro, red, being.shorted by their respective relays Rgr, Rro) cam disc Sgr<1> will after five seconds close contacts Kgr. Relay Rgr energizes over r, contact Kgr to s, and locks up over its own contact 2 and Kge. The yellow lamp Lge is shorted and Lgr, green, lighted over r, contact 1 of a relay HR which is governed by a thermo contact TK and which is permanently excited when the system is working, 1 of Rro, W5, 1 of Rgr, W6, Lgr, contact 2 of HR to s, the red lamp of the opposing street being lighted in parallel therewith. After 25 seconds the appropriate cam on disc Sge<1> breaks contact Kge when the yellow lamp is inserted, Lgr being again shorted. After a further 5 seconds, cam Sro<1> closes contact Kro to energize relay Rro which locks up over its contact 2 and Kge, inserts the red lamp Lro, and shorts Lge. After a further 25 seconds the motor M<1> circuit is interrupted at contact 1 of the minute disc S<1>2, but if the traffic point is in phase with the central station the minute disc S2 thereof simultaneously interrupts line l1 at contact K2. Relays SR and UR relapse and contacts sr, ur thereof close the circuit of motor M<1> which therefor continues to rotate, the cycle of signals above described being repeated. When, due to the rectification of a disturbance, for example replacement of a blown fuse, a motor M<1> is restarted and in consequence the traffic points are out of phase they come to rest together with their subsequent traffic points with their minute disc operative to open their motor circuit and are again advanced when in phase by this synchronizing signal over relay UR, UR<1>, .. Individual signals control, first method. At each traffic point is an arm SP bearing a projection normally lying in the paths of the cams Sgr<1>, Srol, Sge<1>. A magnet EM is energized from transformer T2 over contact vr, and contact 1 of a relay HR1 to retract this arm when relay VR is energized by shorting circuit of resistance W2, Fig. 1. This is effected by the cams Ngr, Nge1, Nge2, Nro just prior to arm Sp engaging the corresponding cams at Sgrl, .., Fig. 2, these cams therefore remaining fixed relative to shaft motor M<1>. To alter the duration of individual signals of the cycle, the cams Ngr, Nge1, Nge2, Nro are manually rotated with respect to the shaft of motor M to an appropriate position. The motor M<1> rotates as before but arm Sp holds the cams Sge<1>, Sgrl, Sro<1> against rotation until they are in positions similar to those of the corresponding cams in Fig. 1, when the new cycle signals are given. Contact K13 operated by discs Sge<1>, Sro<1>, Sgr<1>, Fig. 2, functions similarly to K3, Fig. 1, to effect the signal alteration in the next traffic point through relay VR<1>, Fig. 3, and so on. At each traffic point is a relay FR susceptible only to currents at a predetermined frequency. A transformer T1, Fig. 1, is excited at this frequency, relay FR operates and de-energizes at contact fr a holding relay HR1, the armature of which has a retarded fall-off but a quick return, thus opening its contact 2 and transferring the control of the magnet EM and pawl Sp from relay VR to relays FR and HR1. In the momentary opening of contact 2 and before contact HR1, 1 is made, pawl Sp locks and holds the cams as required by the impulses from transformer T1. When required a pulse from T1 is sent of sufficient length to operate both HR1 contacts 1 and 2 and so excite EM to remove pawl Sp to free the cams. As such controlling operations need precise duration automatic controlling means is preferably employed to effect them. To stop the signals resistance W2 is permanently short-circuited, relay VR operating a sufficient time for the thermo-contact TK to close the circuit of a relay HR which opens the lamp circuits. Individual signals control, second method. When the lamps of a single selected station are to be released from the automatic normal control described above for special control at the appropriate frequency an arrangement of circuits shown in Fig. 4 is employed. The normal automatic operating means is shown diagrammatically at S, k, R, R<1> at stations VA1, VA2 ; R representing the relays Ryr, Rro, the circuits for which are now arranged as shown in Fig. 5, with the contacts g3, g4 of a slow relay G, Fig. 4, and contacts b5, d5 of relays B, D in position for normal automatic working by alternate action of relays Rgr, Rro. When the central station key T is depressed a frequency responsive relay F at a traffic point VA1 is energized from a generator FM, over BA, T, FM, l2, Ko, F. Contact f1 opens and a normally energized relay E de-energizes when a yellow signal following a green signal is shown by operation of cam Sge<1>. The slow relay G now operates over e2 causing the automatic control of the lamps by relays Rgr, Rro, Fig. 5, to be removed at contacts g3, g4, and the signal sequence to be given through contact g1 by the relays A .. D by temporarily releasing key T for each signal change, which causes the relays A .. D to energize cyclically, relays B, D energizing the red, Lro, and green, Lgr, lamps respectively, the yellow signal Lge being normally shown. At each operation of key T relay E energizes. The operations of relay E are indicated on a lamp L at the central station Z lit by operation of a direct current relay H. Instead of projections on the cam discs Sgr, Sge, &c. as described above, indentations or recesses may obviously be employed.