Patent GB-276631-A (GB)
Title: Improvements in or relating to automatic traffic signal timing switches
IPC: G08G1/085
Filed: 1927-07-04
Abstract: 276,631. Crouse-Hinds Co., (Assignees of Bissell, C. H.). Aug. 25, 1926, [Convention date]. Make-and-break switches, mechanical. - Comprises cam-operated timing switches for road traffic signals in which the ratio of the traffic cycle i.e. the times of the " go '' and " stop " signals can be varied. Green, red, and amber signal lights are presented in opposite directions on streets running North and South and in opposite directions on an intersecting East and West street, the green signals being shown North and South while the red signals are presented East and West and vice versa. An amber signal is presented to denote that the signals are about to change from green to red or red to green. The switch mechanism is mounted as a unit in a box closed by a cover through which the spindles for regulating the mechanism protrude. The motor 4 is of the well-known disc type, the margin of the disc 5 moving between the poles of a magnet 8. The speed is regulated by a magnetic brake comprising a permanent swinging magnet 9 more or less overlapping the disc according to the adjustment of a lever 12 provided with a pointer 16 moving over a scale 17 on the cover 2. The cam shaft 20 is driven from the motor shaft 50 by crank 51 and link 57. lever 52, quadrant 54, and pinion 55. The quadrant lever 52 is pivotally carried on a part 53 which is adjustable about a pivot 58 by a pinion 61 and teeth 62 on the part 53 so that the angular relation between links 52, 57 may be adjusted and hence the time of oscillation of the cam shaft. The shaft 59 of the pinion protrudes through the casing and is provided with a lever 63 carrying a gauge plate 66 moving over a scale of time intervals. The shaft 20 carries three cams 22, 23, 24, the first cam 22 controlling the green lights presented N., S. and the red lights presented E. and W., the second cam 23 controlling red lights N. and S. and green E. and W., while the third cam 24 controls the amber light which denotes that a change of signal on the other lights is about to be made. The cam 24 is formed in sections adjustably mounted on the shaft 20 to regulate the time the light is on. Each cam has coacting with it a follower on one of the switch members 26, 27, 28. These members are pivoted on a rod 29 and each includes a glass tube 35 mounted in terminal pieces carried by a block 36 of insulation. A contact at each end of the tube is connected to binding devices on a terminal support 42, the terminals on which are connected to the signal light circuits by wires which are connected to terminals on a binding device 45 on the front of the box. During the tilting of the members 26, 27. 28 the mercury breaks contact between the tube terminals. The cams 22, 23 are mounted on sleeves 73 connected by a yoke 74 having projections 75, 76 extending crosswise of the shaft 20. A collar 79 keyed to the shaft is provided with projections 77, 78 through which pass set screws 80. The space between the ends of the screws and the arms 75, 76 determines the amount of lost motion between the shaft 20 and cams 22, 23 and hence determine the overlap of the amber lamp in the red and green light intervals.