Patent GB-525270-A (GB)
Title: Improvements in self-regulating automatic traffic-control systems
IPC: G08G1/07
Filed: 1939-02-16
Abstract: 525,270. Road signals for controlling traffic. FOREST CITY ELECTRIC CO., Ltd. (Nachod & United States Signal Co., Inc.). Feb. 16, 1939, No. 5052. [Class 118 (ii)] [Also in Group XXXVII] In a control system in which each road has vehicle-operated means to give it the right-ofway and prevent another road obtaining it for a predetermined period after each actuation, a constantly operating timing device closes contacts at regular fixed intervals which contacts, if the transfer preventing means is continuously actuated by one road, close circuits for forcibly transferring the right of way to another road in response to a call therefrom. The system described comprises also the following features (1) a warning signal of varying duration used only for forced transfers (2) automatic return of right-of-way after a forced transfer (3) automatic return of right-of-way to an arterial road (4) manual control by trolley car drivers (5) automatic cyclic transfer in the absence of calls (6) road-pad construction. Road pad switches, Figs. 10 and 11. A trough shaped casing 22a contains a wiring cable conduit 22b and pairs of partitions 22c for the reception of vertically moving blocks 24 which on pivots 31 support sectional road plates 30 covered bv flexible material 30c. The switch proper comprises terminals 26 mounted in outlets 27 from the conduit and bridged, when vehicle actuation occurs, by contacts 25 mounted on the blocks 24 the upward movement of which under the action of springs 29 is limited by studs 24a. Construction of timing and control mechanism. Figs. 1 and 2. A constantly running motor 33 drives shaft 34 which carries (1) a cam disc 100 controlling cyclic operation of the signals and forced transfer from a continuous, traffic stream, (2) timing devices 94, 96 for.the forced transfers from the two streets, (3) a pair of timing devices 91, 90 respectively for ordinary transfer to E.W. traffic and automatic return thereto after forced transfer to N.S. traffic and (4) a pair of similar devices 93, 92 for N.S. traffic. The shaft also tensions a spring drum controlling an escapement operated commutator 53 for switching the signals. The disc 100 has a cam 100d, Fig. 9, which closes contacts 116 or 122 each half revolution for effecting cyclic transfer of right-of-way, and adjustable cams 104, 105 on opposite faces for controlling contacts 109, 110 and 113, 114 used in the arrangements providing for the forced transfer and prevention of automatic return of right-of-way. All the timers are of the same general construction which will be described with reference to timer 93, Fig. 2. The insulating body of the timer carries two conducting rings 93c, d connected to sliprings 93f, g engaged by brushes 93q, r. The body also carries a complete series of radial springs 93j each provided at its outer end with a spring controlled trigger 93k which, when a spring passes a cam hook 93o is drawn to the right so that a shoulder thereon engages a notch in the body and, when a spring passes the vertically movable operating member 89 are adapted to be released so that the conducting rings 93c, d are bridged until the spring again engages cam hook 93o. The timers 91, 93 are arranged to close their circuits for 10 seconds and timers 90, 92 for 15 seconds, and timers 94, 96 close their circuits for a period in excess of 10 seconds. The triggers of timers 94, 96 also have contacts 94s, 96s which close pairs of contacts 94T, 96T, at a point in the revolution of the timers. The spring 52 for the escapement controlled commutator 53 is maintained in tension by a drum 37 fixed on shaft 34 and carrying on its right-hand face spring controlled detents engaging projections on a sleeve 43 mounted inside the drum and fixed to shaft 34a carrying the escapement spring. The sleeve 43 has cam teeth 43a on its inner edge engaging similar teeth on a sleeve 42 which slides axially within the drum to operate a cone clutch against the action of spring 38. The arrangement is such that when the spring tension is sufficient to overcome the resistance of sleeve 42 and its associated parts, the detents disengage the projections and move along arcuate slots, the clutch being simultaneously disengaged, but when the spring tension is insufficient the reverse action occurs. The triggers of timers 90, 91 for timing the 15 and 10 second periods are released by members 76 operated by bell-cranks 73 by means of bar 63 moved to the left by magnet 68 which also opens contacts 72. The bar also moves bar 57 to the left to release escapement wheel 53f one step. Bar 77 controlled by relay 79 operates in a similar manner by moving bar 57 to the right. The timers 94, 96 are operated by magnets as shown. Operations under light traffic conditions. Assuming N.S. has the right-of-way, a call from E.W. operates the middle winding of relay 150, Fig. 14, which holds temporarily over its upper winding and energizes winding 128 of a threeposition relay whereupon magnet 68 of the E.W. timer pulls up. Bars 63, 57 are thereby moved to the left, a trigger on timer 91 is tripped to close contacts c, d for 10 seconds and escapement 53 is operated by bar 57 to change over the leads to the G and R signals. Bar 63 also opens at 72 the holding circuit of relay 150 which relapses followed by the three position relay and relay 68, but escapement bar 57 remains in the left hand position. The closure of contacts 91 c, d operates 134a for 10 seconds to prevent a call from N.S. from becoming effective. Another E.W. call within the 10 seconds simply operates another trigger on timer 91 to extend the period. After 10 seconds relay 134a relapses to permit a N.S. call already registered by relay 150a to become effective, but if no such call has been made E. W. retains the right-of-way. When the right-of-way is with E.W. (bar 57 to the left) and an E.W. call comes in simultaneously with a N.S. call both coils 127, 128 of the three position relay are operated in the E.W. direction and one coil 127a, thereof in the N.S. direction to give the relay preference to the call on the existing right-of-way. Forced transfer of right-of-way of an E.W. traffic stream by a N.S. call. As a result of the traffic stream, bar 57 has been moved to the left and relay'134a operated to prevent transfer on a N.S. call. As previously described,.cam contacts 109, 110 are connected every two minutes, and when this occurs, relay 134 (lower) and magnet 96 are operated. Magnet 96 operates a trigger on its timer to hold itself and relay 134 for more than 10 seconds and thereby prevents further calls from E.W. from becoming effective, so that contacts 91c, d open 10 seconds later to release 134a. The N.S. call has operated and held 150a, and the release of 134a permits winding 128a of the three position relay to operate its armature to the right to energize relay 79 which moves bars 77, 57 to the right. Bar 57 operates escapement 53 to change the signals while bar 77 opens contacts 83 to release relay 150a and the three position relay, and releases a trigger on timer 93 to close contacts 93c, d for 10 seconds for energization of relay 134 to prevent transfer back to the E.W. road. Shortly after the opening of 91c, d, 96c, d open to release 134 so that further operation of the system depends on subsequent traffic conditions. A forced transfer is accompanied by a warning signal. This is operated by contacts 96s closed by timer 96 at a time when relay 134a is operated and thereby operating relay 164 to connect up warning signal A which is extinguished when 134a relapses on transfer of right-of-way. The length of the warning signal will depend on the time elapsing before the last operation of timer 91 and the operation of timer 96 and when this is equal to the normal period, none will be displayed since the last E.W. vehicle will have had time to cross. Control by driver of trolley car. The trolley has a contact B6, Fig. 13, which the driver may ground over switch 172 on E.W. cars or 173 on N.S. cars and which engages in succession contact B3 located at about the same position as the road pad, contact B4 located between the pad and the intersection, and contact B5 located at the stopping place at the intersection. If the driver wishes to go straight across he operates the switch which energizes winding 156 or 156a as the case may be of a three position relay when B6 is engaging B3. The effect of this is to simulate a call by operating 150 or 150a and to bring in the forced transfer feature without delay by connecting the same circuits as contacts 113, 114 or 109, 110. Similar operations ensue if the switch is operated when the car has stopped to discharge passengers with contacts B6, B5 in engagement. When contacts B3, B4 are in engagement, and the driver wishes to stop, he may avoid delay to intersecting traffic by operating the switch which now simulates a call on the intersecting road. Automatic cyclic transfer independently of traffic. A cam projection on disc 100 closes contacts 116, 122 alternately each half revolution. Assuming that E.W. traffic has the rightof-way, and that no traffic has passed for some time, the closure of contacts 122 operates relay 150a and simulates a N.S. call to transfer the right-of-way as previously described, the rightof-way remaining at N.S. for one minute whereupon closure of contacts 116 simulates an E.W. call, and so on, assuming that no vehicular call occurs in the meantime. If, however an E.W. call occurs just before contacts 122 close, relay 134a is operated to prevent an ordinary transfer to N.S. and the right-of-way would normally be retained for a further 10 seconds. Under the present circumstances however, contacts 109, 110 are operated for an interval including the operation of contacts 122 and forced transfer occurs as previously described. Automatic return of right-of-way after forced transfer. If this is to be applied to the E.W. street, switch 170 is closed and if to the N.