Patent GB-387030-A (GB)
Title: An improved method of and apparatus for electrically operating or controlling road traffic signals automatically
IPC: G08G1/082
Filed: 1931-09-08
Abstract: 387,030. Road - traffic signalling- apparatus. SCOTT, W. H. and GLENDENNING, S. E., Gothic Works, Norwich. Sept. 8, 1931, Nos. 25246/31 and 11383/32. [Class 118 (ii).] In electrically operated road-traffic signalling- apparatus wherein two or more coupled signal equipments are employed, each equipment is provided with a check controller comprising a rotary contact drum having contact segments which establish the feed to the operating circuit of the equipment, and at a predetermined point in the rotation of the controller establish conditions effecting a retardation or interruption in the operation of the equipment, should the latter have advanced out of step, so that all the equipments resume their operations in correct relationship from the check point. In the embodiment shown in Fig. 1, each equipment has an isolating switch B, a selecting controller C for the lamp circuits, a check controller D, and a delay action relay E serving as an impulse transmitter for intermittently exciting a solenoid F, the plunger of which is adapted, through appropriate mechanism, to impact a step-by-step rotation to the controllers geared or otherwise arranged to rotate together. The lamp circuits include red, amber, and green lamps R., A, G and R<1>, A, G<1>, the circuits being made and broken in predetermined order by the operation of the selecting drums C and co-operating contacts bearing thereon. The impulse transmitter E, similar to that described in Specification 370,148, comprises two delay action electromagnets 1 co-operating with a rocking armature 2 adapted to make contacts at 3, 4 alternately, thus exciting the solenoid F intermittently. Current is fed from the mains M to each equipment by way of a contact 6 associated with the check controllers D, each of which carries a contact ring having a gap or dead section 5 therein. When all the gaps 5 are reached in the rotation, the interrupted feed is replaced by a temporary feed from the mains established through the medium of an electromagnetic selector 7 having an armature 8 adapted on release to bridge contacts 9. The operating coils of the selectors 7 are fed in parallel from the mains M by a common feeder 10 which is fed in parallel through the check controllers D by feeders 11. Thus should any of the equipments progress out of step, the gap 5 in its check controller D will be reached prematurely, and the feed to the mechanism EF will be interrupted until the gaps 5 in the controllers D of the other equipments are reached, when all the equipment will resume operation. If desired, an arrangement may be adopted in which two feeds and two gaps are provided, one for each alternate half-cycle. Instead of using selectors, each equipment may be pro vided with a pair of-contacts closing when the check point is reached, the contacts being connected in series so that when all the equipments reach the checkpoint, a circuit is established providing a temporary feed for all the equipments. Alternatively, a combination of contact segments and selectors may be employed to change the periodicity of the operating mechanisms EF, so as to slow down the mechanism, without stopping it..In the form shown in Fig. 2, feeds 12, 13 are provided for each mechanism EF, and the period of each feed is determined by selective excitation of feed governing circuits 14, 15 under the control of a master timing device 16; which may be driven by clockwork, or electromagnetic means such as EF, or other suitable mechanism. The master timing device 16, which may be in the form of a rotary controller, is included in circuit with a suitable source of supply alternately to excite the extraneous circuits 14, 15, each of which includes an electromagnetic selector 17, 18. The local operating circuits EF are complete in themselves, and can be isolated and operated independently if desired. The selectors 17, 18 are adapted alternately to bridge contacts 19, 20 and 21, 22, which are connected respectively to the mains M, and to contacts bearing on check controllers D which govern the mechanisms EF through contacts 6. The contact rings connected to the contact 20, 22 have gaps 5, 5<1> respectively arranged at positions corresponding to the end of half a signal cycle. Auxiliary speeding - up means are provided locally to advance automatically any equipment which lags. Where, as described in Specification 385,618, the controllers are driven step by step through pawl and ratchet gearing operable by the plunger 23 of a solenoid 24 intermittently excited by impulses from the mechanism EF, the stroke of the plunger being varied by a tappet 25 co-operating with stops 26 on a hinged arm 27 rocked by a cam 28, the auxiliary speeding-up means comprises a coil 29 adapted on excitation by the selectors 17, 18 to swing the arm 27 into such a position, over an additional stop 30, that the stroke of the plunger 23 is increased. The selectors 17, 18 are provided with auxiliary contacts 31, 32, and 33, 34, and the check controllers D with contact segments 35, 35<1> corresponding approximately in length to the overlaps between the check contact rings. The contacts 31, 33 are connected to the local mains for each equipment, and the contacts 32, 34 are connected to brushes 36, 37 respectively co-operating with the segments 35, 35<1>, a brush 38 feeding the coil 29 from a continuous contact ring 39 connected to these segments. When this arrangement is adopted, the speed-up mechanism may be utilized to increase the speed of the operating mechanism EF instead of or in conjunction with the variation in stroke of the drive transmitting mechanism. One of the check controllers D may be adapted to serve as the master controller. A further embodiment is also described, including check controllers having gapped contact rings and check selectors as in the first example, and speeding-up means for each equipment as described in the second example above. In each of the embodiments, the check controllers, and, where provided, the speeding-up segments, are rendered capable of independent rotation, so that it can be fixed in any predetermined relation to the selector drum for the lamp circuits.