GB397584A - Improvements in, or relating to, automatic road traffic control signals - Google Patents

Abstract

397,584. Road signals for controlling traffic. WALKER, R. W., 26, Munro Road, Glasgow. March 29, 1932, No. 8918. [Class 118 (ii).] The interval ratio of automatic traffic control signals is automatically varied at fixed times to suit the known average traffic densities in the cross roads for the ensuing periods. A cam 3 having its radii R1, R2, R3 proportioned to represent the known variations in traffic ratio or traffic intensity is rotated at a speed in agreement with its graduation so as to determine, by means of a follower 6, lever 10, rack 8, and toothed wheel 1, the angular position of the shaft 2 controlling the interval ratio. An alternative construction is suggested by the lever 12 pivoted at 13 and having the connections shown by broken lines. Fig. II shows the cam 3 lifting a follower 6 so as to connect one of the contacts 14a .. 14k and energize the corresponding electromagnet 15a .. 15k, thus moving an arm 16 fitted on the control shaft 2 and carrying a magnet. Other forms of cam may be used, with lateral movement. Different cams, corresponding, for example, to the requirements of weekdays, Saturdays and Sundays, may be brought into. operation by a sliding movement relative to the follower 6. An extra cam surface may be provided at the end of the calculated period to suit normal requirements. Helical cams may be used, or a series of cams over which the follower 6 is made to travel in succession by being pressed through gaps in dividing plates. Cam devices operating over a considerable period, such as a week are described. Where the cam units and the controls are driven off the same motor, a conical variable friction drive may be so arranged that the act of altering the cycle also alters, in compensation, the speed of the cam units.