Patent GB-190617272-A (GB)
Title: Improvements in Apparatus applicable to Electric Signalling and especially applicable for use in Fire Alarm Installations.
Inventor: WALKER CHARLES LESLIE
Filed: 1906-07-31
Granted: 1907-07-25
Abstract: 17,272. Walker, C. L. July 31. Order or alarm apparatus.- In electric signalling-apparatus, particularly applicable to firealarm installations, means are provided for signalling to the central station the number or name of the station from which the alarm was transmitted. Fig. 1 is a plan of the indicator mechanism at the central station. The armature 2 of the electromagnet 1 is pivoted at 3 and carries detents 5, 6, which engage the teeth 7 of a wheel 8. When the electro-magnet 1 is energized, the armature 2 overcomes the spring 4, freeing the detent 5 from the recess 9 and closing a second circuit, by which current can pass to the electro-magnet 1 after the first circuit is broken. The wheel teeth project downwards beyond the rim, and the lower portion of each of the detents has its front so formed that, when it engages a tooth of the wheel, this is set in motion. The fronts of the upper portions of the detents are formed at right-angles to their direction of motion, and, striking on the rim of the wheel between the teeth, completely bring it to rest, thus preventing the possibility of the mechanism leaping or missing a tooth. One pair of pointers is carried by the spindle 13 and the other pair by a sleeve 14, and bevel-wheels 15, 16 on the spindle and sleeve gear with a bevel-wheel 17 attached to the wheel 8. A quarter segment of a dial is marked so as to indicate the different stations, and over this one of the pointers will always be travelling. An apparatus similar to that described, with the exception that the indicator mechanism is omitted and the wheels have two notches, is provided at each station, but the recesses 9, 10 are placed in different positions at the different stations. In some cases the wheels may be provided with two or more pairs of deep notches. Fig. 6 illustrates a tilting circuit-breaker comprising circular tubes 20, 21, preferably evacuated of air and containing mercury, carried by a block 22 mounted loosely on a bent spindle 23 which is rotatable about a vertical axis. Spring blades 22<1> keep the block from rotating, and, as shown in Fig. 8, contacts 24, 25, 28, 29 pass through the outer tube, and contacts 26, 27, 30, 31 through the inner tube. In the outer tube 20 is a construction 20<1> which prevents the free flow of mercury. The spindle 23 has attached to it a plate 32 carrying a tooth 33 which normally engages a projection 34 on the armature 35, which is free to turn about the electro-magnet 37. When a current passes through the magnet 37, the armature 35 turns and frees the tooth 33 from the projection 34, and a spring causes the spindle to make half a turn, a thumb-screw 39 being provided for turning the spindle to its original position. The spindle may have a continuous motion, and in some cases may be used to make and break the circuit to produce the step-by-step motion. In Fig. 8, 40 is a station provided with a contact-maker which may be of the type described in Specification No. 6899A, A.D. 1903, [Abridgment Class Fire, Extinction &c. of]. Taking the case of a fire-alarm, when the mercury rises to the contact 43, a circuit is closed from the battery 44, through the coil 37 of the mercury contact-breaker, contacts 27,26, 25, 24 to another battery 46, and coils 47, 48 of the instruments at the central and calling stations respectively. The armature at station 40 closes a contact 49, completing a circuit from battery 46, contacts 24, 25,49, magnet coils 48, 47, and back to the lattery, the mercury in the inner tube of the contact-breaker shifting to the position shown in dotted lines, thus closing the circuit between contacts 30, 31. The circuit of a contact-breaker is thus completed through a local battery 50, and it commences to make and break the circuit of battery 46, thus causing the wheels of the instruments at the central and calling stations to revolve until one of the detents enters a deep notch in the escapement wheel, thereby breaking contact at 49. The instrument at the central station then indicates the number of the calling station and gives an audible signal. The mercury in the outer tube, which has been retarded by the constriction 20', has by this time reached the contacts 28, 29, and, if the mercury at the calling station 46 has risen to the contact 51, the circuit of a continuously-ringing alarm gong 52 is completed, but, if the mercury does not reach contact 51, the attendant can restore the instrument at the central station to its normal position by the push-button 53. In a modification of the apparatus shown in Fig. 3, two toothed wheels and a polarized armature are used, one wheel being turned by positive impulses, the other by negative impulses.