Patent GB-497118-A (GB)
Title: An improved traffic control system
IPC: G08G1/08
Filed: 1938-01-27
Abstract: 497,118. Road signals for controlling traffic. PAUL, J. N., and TOKHEIM OIL TANK & PUMP CO. Jan. 27, 1938, No. 2646. [Class 118 (ii)] In a control system, an electrical switching and timing unit having a normal position is driven by two members, one driving the unit towards the normal position to terminate a signal period and the other driving in the reverse direction, operated by traffic actuated means to prolong the period. Magnetically operated detectors D, Fig. 5, comprising coils 14 mounted on a permanent magnet bar 11 surrounded by iron wire 12 and contained in a waterproof casing 19 are arranged in the approaches to an intersection and connected to the coils of moving coil instruments A, A<1> so that upon the passage of a vehicle the coil A will oscillate, Fig. 2, causing the magnetic armature 24 to approach and be attracted to the contact 25, the relay C, Fig. 5, remaining energized after the cessation of the impulse. Upon contact c being closed, the coil B of an induction disc motor is energized, causing the motor to rotate the disc 28 having insulating parts 29. The disc also carries strikers 27 which engage the pointer 23 opening switch a and de-energizing C, coil B being energized over contacts 30, 31 until contact 31 passes on to an insulating part. A pedestrian may make a demand by closing switch p, a D.C. current flowing through coil A and resistance 43. Operation. The shaded parts of Fig. 6 show when a contact or coil is closed or energized. Upon a vehicle passing over a detector D in the NS lane, relay C pulls up and remains energized until a striker reaches switch a, during which time disc 32 is rotated, coil E being energized, contacts e, f<1> being respectively opened and closed, the closing of contact f<1> energizing coil K<1> to rotate the disc 36 and cam shaft, contact s<1> opening, de-energizing K<1> while the closing of t<1> energizes M causing the cam shaft to rotate to time the Change period, the signals being accordingly changed. Coil M is de-energized and coil K<1> energized due to contacts v<1> and r opening and closing at the commencement of the NS-GO period, coil K<1> timing the initial period. If a call is entered from the EW lane, disc 32<1> is rotated, the amount of rotation depending on the number of calls entered. At the end of this period contact r opens and contact q closes, the disc 36 now remaining stationary while coil F is energized to rotate the disc 32 until the rod 34 strikes the pin 35, contacts e and f<1> closing and opening respectively. As a call from the EW lane has been registered, contact f will be closed so that coil K is energized to rotate disc 36 to the commencement of the next Change period which is timed by the coil M. The WE-GO period is now timed in a corresponding manner to the NSGO period, the extension period being twice as long since two calls were registered causing the disc 321 to be rotated through twice the angle for one call. If no call is made from the NS lane the right of way remains with the EW lane during an idle period which is terminated by a call as described at the beginning of the cycle. If a call for extension is received during an extension period, the speed of rotation of disc 32 (or 32<1>) is reduced due to the energizing of coil E so that the extension period is increased by a period shorter than the period allotted to a waiting vehicle since the vehicle making this call will be moving. If switch g<1> is closed the right of way reverts to the EW lane after the NS-GO period whether a demand is entered or not, but no extension period of the EW initial period is allowed, this period being manually extended by the adjustment of the coil K<1>. If switch g is also closed, the system is not vehicle controlled, the GO periods having no extension or idle periods.