Patent GB-404949-A (GB)
Title: Improvements in or relating to traffic control signals
IPC: G08G1/08
Filed: 1932-07-23
Abstract: 404,949. Road signals for controlling traffic. AUTOMATIC ELECTRIC CO., Ltd., Strowger Works, and RENSHAW, P. B., Brookwood, Alder Road, West Derby, both in Liverpool. July 23, 1932, No. 20855. [Class 118 (ii).] A traffic-operated signalling system for use at road junctions and crossings is provided with means whereby it presents the same indication on all traffic lanes, in the absence of traffic but accords different treatment to the various routes as regards the time which elapses before right of way is given to the route on which traffic first approaches, the traffic operated devices bringing the signals into action in accordance with the traffic on the different routes. The signal may display a stop light on all approaches during the non- discriminating period or a fixed or flashing amber signal may be displayed. The signal is operated by a controller of the type described in Specification 356,102. As shown, the apparatus comprises road pads NSD, EWD, Fig. 1, operating relays E, D which close the charging circuit of a condenser QA through cam-operated contacts ; a set of cams mounted on a common shaft and rotated step-by-step into one of six positions by a solenoid under the control of a timing device to close certain of the contacts C1-C22 controlling the signal lamps ; and a timing device of the neon lamp type. Operation. Suppose the system to be working on a one colour plan and the cam shaft to be in the sixth position corresponding to a red light on the EW road only. The condenser QA is charging from the valve rectifier, HV, Fig. 2, through a circuit including the cam contact C4 and the switch VNS. If no traffic approaches on either road the condenser will charge up to the striking potential of the neon lamp FA, but this will not flash as the circuit is broken at d2 owing to the absence of traffic on the EW road. The condenser will continue to charge till it reaches the striking potential of the lamp FC which will flash, operating the relay C. Relay F operates and locks, opens the circuit of the relay C and connects the red lamp RNS on the NS road in parallel with the lamp REW. If now, a vehicle operates the road pad NSD, relay E will operate to release relay F at armature e3, thus extinguishing the lamps RNS and shunting the condenser QA at armature e2. After a period determined by the switch VNS lamp FC will again strike, restoring the red light RNS on the NS road. If the road pad EWD is operated the circuit of the neon lamp FA will be closed, so that this lamp strikes, operating relay A to advance the shaft of the controller to the first position, and to provide a charging circuit for the condenser QA over the switch ARN. After a short period the lamp FA strikes again, stepping the cam shaft to second position wherein the lamps REW are extinguished and the charging circuit of the condenser is completed by the switch IEW. The lamp FA will then strike again, moving the cam shaft to third position. In this position, if the road pad EWD is intermittently operated by the passage of traffic, the condenser QA will be shunted so that the lamp FC cannot strike. If a vehicle operates the road pad NSD during this period, the circuit of condenser QB is completed through the maximum period switch MXN causing the lamp FB to flash, operating relay B which opens the shunt path of condenser QA and causes the warning bell ALB to ring. The lamp FA now flashes, stepping the cam shaft to fourth position, lighting red lamps on all roads and closing the charging circuit of condenser QA through the switch ARE. Further operation of the lamp FA brings the cam shaft to fifth and sixth positions and the cycle is repeated. The switches INS, VNS, IEW, VEW, ARN, ARE, MXW and MXE are in circuit with a variable resistance X1-X17 by which the charging interval of the condenser QA may be controlled. The system can be operated on a 3-colour plan, the connections for which are shown dotted in Fig. 2. In a modification, Fig. 3, a flashing amber signal replaces the " red lamp on all roads " signal.