Patent GB-434732-A (GB)
Title: Improvements in or relating to traffic control systems
IPC: G08G1/082
Filed: 1934-03-08
Abstract: 434,732. Road signals for controlling traffic. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, Liverpool, and PREIST, T. P., 104, Deveraux Drive, Poulton, Wallasey, Cheshire. March 8, 1934, No. 7425. [Class 118 (ii)] In a road-traffic signalling system in which a number of signal units are controlled from a main station, the signal units are stepped in accordance with the sum of the lengths of pulses from the main station through individual neon-tube timing equipment so that the individual stations can have different cycle distribution. The cycle time is the same for all units, being fixed by syncluonizing pulses transmitted from the main station. A spare master timer takes over automatically if the master timer fails whilst if the signalling equipment is not functioning, apparatus is brought into operation which can either cut out the lamps and give an alarm or arrange the equipment to work on a non-synchronous basis under local control. Operation of main equipment. When the apparatus is functioning switches SEC, TNT, Fig. 2 are set to adjust the time between impulses and conductors 10 and 11 are joined so that condenser 1QA charges over switches TNT, SEC, and conductor 12, and lamp IFA strikes allowing relay 1A to operate. Relay U pulls up and relay V energizes and locks. At contact v2 condenser 1QA is shorted so that relay 1A releases and U falls away allowing relay W to pull up. Relay W completes the pulsing circuit PL at w1 and at w4 completes a charging circuit for 1QA over resistance 1YC, which is adjusted to allow 1QA to charge in 1 second. Relay 1A is then again energized and, as relay W is operated, relay X pulls up over contact w2 followed by relay Y. Condenser 1QA is discharged over y2, relays 1A and X release, relay Z energizes and W falls away removing the pulse from the line PL. When relay W releases, relays Y and Z fall away and the cycle is repeated sending pulses to line of one second duration and at a predetermined frequency. Whenever relay W is operated a charging circuit is completed for condenser 1QB so that after a predetermined number of impulses have been transmitted, condenser 1QB becomes fully charged and relay 1B is operated. Relay 1S energizes and locks, discharging 1QB and connecting a synchronizing pulse to wire SY for the inter pulse period. In addition when relay Z operates it closes at z2 a circuit across conductors 13, 14 associated with the spare timer so that the timer discharges. These conductors correspond to 17, 18, Fig. 1, but the spare timer has a resistance similar to 1YD in the charging circuit, so that its charging rate is slow. If relay Z does not operate however the relay corresponding to 1A in the spare equipment energizes to remove the short across 10, 11, Fig. 2, and short its own resistance corresponding to 1YD, to give an alarm and to take over the timing operations. Operation at sub-stations. The substation shewn in Figs. 3, 4 and 5 is arranged to be synchronized with the cam shaft in position 5. Assuming the camshaft is in position 3, giving Green to " B " street then whilst the pulse current is on conductor PL relay P is energized and condenser 2QA is charged, its charging time being controlled by switches GB. When 2QA has charged relay 2A operates and magnet 2S energizes to step the cam shaft. Position 4 is the amber position and condenser 2QA is charged over AB independently of relay P and the transmitted pulses and the shaft is stepped to position 5 giving Green to A street, This is the synchronizing position and the shaft remains until relay C is operated by the synchronizing pulse moving the shaft to position 6, but not altering the display. Relay P now again becomes effective and 2QA is charged under the joint control of switch GA and the pulses. When 2QA is charged, relay 2A again operates and the shaft is stepped to position 1, where condenser 2QA is controlled over AA. In position 2 the shaft is controlled over resistance 2YD and cam C3 and the shaft is moved into position 3 when the cycle above described is repeated. If the apparatus is to be synchronized in position 2 instead of position 5 contacts Z8, Z5 and Z11 are connected to Z9, Z6 and Z12 respectively instead of to Z7, Z4, and Z10. Condenser 2QB is always charging at a slow rate in series with resistance 2YC, but when the apparatus is functioning correctly, the cam shaft stepping magnet 2S is energized and its contacts 2s2 operate to discharge QB before it is fully charged. If however operation of magnet S is delayed relay B is energized to cut out the apparatus and give an alarm or to cut the apparatus away from the pulsing control and allow it to operate as an isolated unit. This latter is effected by joining Z1 and Z2 and Z7, Z8, and Z9 and disconnecting Z5 and Z11. In this case the dial readings of switches GA, GB, &c., read in seconds. Specification 403,720 is referred to.