Patent GB-229826-A (GB)
Title: Improvements in or relating to electric alarm systems for the protection of safes orthe like
IPC: E05G1/10
Filed: 1924-01-17
Abstract: 229,826. Becaouri, W. Jan. 17, 1924. A larms operated by fusible devices; electric alarm systems.-An electric alarm system for protecting safes &c. against burglary e m p lo y s synchronous mechanisms in the safe, and at the alarm station respectively which interact to operate an alarm when attempts are made to melt the walls of the safe. Alarms are also given when the batteries or other mechanisms of the system are out of order. As shown in Fig. 1, axles 30, 1, in the safe and at an alarm station respectively, are rotated slowly at equal speeds by magnets 33, 13 connected in parallel and controlled by a, clockwork-driven commutator 10<1> connected in circuit with a batterv A. The axle 1 carries discs 2, 3 having teeth 4, 5 of equal or different lengths, and the axle 30 carries a disc 34 having teeth 31 arranged in a definite manner with respect to the disposition of the teeth 4, 5 on the discs 2, 3. An armature 6, 8, co-operating with the discs 2, 3 is operated by a magnet 7 in a circuit containing a battery C, line 27, finger 36, disc 34, pawl 35, inner protecting covering 38 of the safe, and line 28. Under normal conditions, this circuit is intermittently closed at the teeth 31 by the pawl 35 and the armature 6, 8 is operated so that it is kept from contact with the teeth 4. 5. The inner surface of the safe is provided with a protective packing formed by two or more slender strips 38, 50 of tin foil &c. arranged in zig-zag formation and insulated from each other. When the continuity of the strip 38 is destroyed by fire, the armature 6, 8 is not attracted at the proper moment and contact is made with the disc 3 to close an alarm circuit from the battery B, through the line 15, armature 6, 8, disc 3, finger 9, line 24, magnet 21, line 33 to contact 19 and batterv B. The armature 22 of the magnet 21 is thus attracted, and the heavier end of a lever 18 falls and breaks the circuit of the magnet 21 at the contact 19 and establishes the circuit of a bell 14 over the contacts 19<1>, 20. When the clockwork 10 stops, a bell 77 fed from a battery E is rung by the closure of contacts 61, 63. The contact 63 is mounted on a rack 62. Fig. 3, which is raised periodically bv a cam 51 on an axle 10‹ of the clockwork. When the cam ceases to act on the rack, due to continued rotation, the rack drops slowly under the control of a fan 53. When the clockwork is running, the cam 51 prevents the closure of the contacts 61, 63, but when it stops the rack falls sufficiently to establish the circuit of the bell 77. To ensure operation of the alarm even should the cam 51 stop in the position shown in Fig. 3, two or more racks operated by associated cams may be employed in such a manner that at least one of them closes the alarm circuit. The bell 77 is also rung by a contact 74 which completes the circuit at the contact 76 when the lever 18 is released. If the battery E and the clockwork 10 stop working simultaneously, a pin 98 operates a lever 99 to release mechanism which pushes the armature 22 from under the lever 18, which in falling operates the bell 14. The bell 14 is also rung if the battery A fails while the clockwork 10 continues to run. Cams are mounted on the clockwork axle 10‹ and the axle 1, in such a manner that during normal operation the cams cannot contact with each other, but if the axle 1 stops due to failure of the battery A contact is established and a circuit is completed from the. battery B, through the magnet 21, line 24, axle 1, axle 10‹, and line 81 to cause the operation of the bell 14. The lever 18 may operate a spring bell 58. An alarm may also be given when the bell 14 is out of order due to oxidation of the bell contacts. These contacts are inserted in circuit with the line 11 so that, if the contact between the armature 83 and the contact 84 is bad, the system operates in the same manner as if it were damaged and an alarm is given by the bells 58, 77. In order to prevent permanent attractions of the armature 83. a pivoted lever 85 falls and breaks the line 11 at the contacts 86 upon the first attraction of the armature 83. The batteries B, C are switched alternately into the circuit 27, 28 in order that an alarm may be given if the battery B is out of order. The bell 77 may be run over the lines 71, 72 by a second lever operating in the same manner as the lever 6, 8.