Patent GB-373444-A (GB)
Title: Traffic signalling system and method of operating and resynchronising the motors thereof
IPC: G08G1/082
Filed: 1931-06-12
Abstract: 373,444. Road signals for controlling traffic; electric motor control systems. CROUSE-HINDS CO., Wolf Street, Syracuse, New York, U.S.A.-(Assignees of Bissell, C. H. ; 756, Comstock Avenue, Syracuse, New York, U.S.A.) June 12, 1931, No. 17150. Convention date, June 12, 1930. [Class 118 (ii).] Relates to synchronous control systems for operating street-traffic signals and for other purposes. In a road-traffic signalling system for a number of crossings, wherein the phase at successive crossings may be adjusted to permit continuous flow of traffic on the main street, the signals at each crossing are controlled by an electric motor driven timing mechanism which is arranged to stall its driving motor at the end of a predetermined cycle of operations, and the motors driving the timing mechanisms for the different crossings have their speeds regulated by a common control and are restarted simultaneously at intervals regulated by a common control. The synchronizing or re-synchronizing means includes braking coils for the motors, which may be of the induction disc type. Fig. 2 shows the master motor 21 with braking coils 31 at the central station and a secondary motor 22 with braking coils 32 at a crossing which drives timing cams for the red, green and amber signals at that crossing. The speed of the motors is varied by adjusting the handle 46 of a voltage reducer 33, which acts thus as a period control regulator. During the rotation of each timer shaft 98 a switchoperating arm 51 cuts out the braking coils of the companion motor and then cuts the braking coils in the main circuit so that the motor is stalled, and all the motors are stalled during some period of their operation at the same time and remain stalled until a cam 61 or 61c driven by the master motor 21 opens the shunt circuit controlled thereby, thus momentarily relieving all the motors of all retarding effect of the braking coils, so that the motors can start instantly, and once more cut in the braking coils simultaneously in the circuit controlled by the regulator 33. The braking coils of all motors connected in the shunt circuit controlled by cam 61 start a little earlier than those controlled by cam 61a. The adjustable arms 51 of the various motors are set to maintain a predetermined offset or phase relation of the signals, and if the arm 51 of any one timer would operate its switch arm 50 and hence stall the companion motor at a time when the amber light was displayed, then in order to avoid an extension of the amber light period, the braking coils of that motor are connected in the other shunt circuit by shifting a plug 67. The split-up of the traffic cycle into subdivisions at any crossing is regulated by cams controlled by a handle 85, and the extent of the amber period at any crossing is determined by cams controlled by handles 87, 88, the adjustable cams being arranged on nested shafts 115, 119, 127. The handle 85 engages an arm 141 and thus rotates a hollow shaft 115 to adjust the sections 102b, 102c of a cam, thereby, for example, shortening the period of contact of contacts 112, 113 to display the green light longer on the main street. The contact arm 111 is controlled by spring-related followers 109, 110 actuated by the adjustable cams 102b, 102c, 102a. A contact interrupter 140 is provided to produce flashing amber signal when required.