GB716504A - Improvements in or relating to impact-operable electric alarm switch devices - Google Patents

Abstract

716,504. Impact-operable switches; switch cases. CATHODEON, Ltd. Oct. 24, 1952, [Oct. 25, 1951], No. 24977/51. Class 38(5) An impact-operated switch intended for use with fire-preventing means on an aircraft, comprises a frangible casing 1 enclosing a coiled electrode 9 and a rod electrode 5. one end of the rod 5 being located in an insulating block 8 so that undesirable lateral movement of the rod is prevented. The upper end of the rod 5 is sealed through a glass bead 7 to a metal mounting 4 soldered to a flange 3 sealed to the casing 1. The coiled electrode 9 is under compression and acts between an apertured metal cup 10 on the block 8 and an apertured metal cup 14 accommodated in a further metal cup 17 slidable relatively to the mounting 4 in a direction along the rod axis, a spring 19 thus being held under compression by the electrode 9 between the mounting 4 and a shoulder 20 on the cup 17. On fracture of the casing 1 such that its lower part is removed, the electrode 9 removes its pressure on the spring 19 which thereupon moves the cup 17 so that a shoulder 21 thereon engages a contact 22 on the rod 5 and an external circuit is completed. Should the blow strike the casing 1 end on, the electrode 9 is further compressed and the cup 10 engages a contact 23 on the rod to complete the circuit. If the blow is sideways the circuit may also be completed by the direct engagement between the electrodes 1. 5. The switch may be mounted in a separate socket, Figs. 1, 3, and to this end an externally threaded metal sleeve 24 is secured to the mounting 4. The socket comprises a spring 32 non-rotatably mounted in a body 26. the sleeve 24 being screwed into the spring. One end 35 of the spring is connected to a terminal 36 situated in an insulating block 38 fixed by screws 46, 47 to the body 26, and a termination 25 on the rod 5 abuts a stud contact 42 on the block 38 connected to a further terminal 40. The external leads pass to the terminals 36, 40 through rubber seals 51, 52 and channels 49. 50 in the block 38, a cover 54 being screwed to the latter. A further cover 56 is screwed over the body 26 and rubber seals 48, 55. 59 are provided between the several parts of the socket. In another construction, Fig. 4, an insulating block 66 is moulded around the end of the switch, the block having a terminal 65 connected by a lead 64 to the rod 5. the other terminal comprising a flange 61 soldered to the mounting 4. To facilitate testing, a connection 69 from the rod 5 is sealed through the casing 1 to a terminal 70. Specification 574,947 is referred to