GB1529228A - Locks - Google Patents

Abstract

1529228 Locks CISA COSTRUZIONI ITALIANE SERRATURE AFFINI SpA 26 Nov 1975 [3 Dec 1974] 48507/75 Heading E2A A lock is formed from a casing 1 through an aperture 9 of which projects a spring latch 10 mounted rotatably on a sliding element 4 so that its axis of rotation is perpendicular to the direction of sliding i.e. of withdrawal of the latch. In ordinary opening of the door &c to which the lock is attached pressure in the direction of arrow A (Fig. 3) would cause the latch to rotate so that face 16 is at an angle to the edge 74 of keeper 72 thus providing a camming surface to force the element 14 into the casing 1 against spring 43 and permit the door to be opened. When the lock is in the locking position however pawl 68 engages recess 71 in the latch and so prevents the rotation and door opening. The pawl is maintained in this blocking position by means of flag 46, the edge 51 of which holds pawl 68 in place. Electrical and mechanical means are provided to remove the blocking and permit the door to open. The electrical means comprises an electromagnet 57 possessing two plungers 60, 61 biased outwards by springs 62, 63 (Fig. 5). When the current is applied the electromagnet attracts plate 54 which in turn attracts flag 46 partly by magnetic force and partly by hooking it by means of hook 55 on its lower edge. This removes flag 46 from the pawl 68 and so permits the door to open. The flag 46 is held in this position, even when the current is switched off, by means of tooth 64 which springs into retaining engagement under the action of spring 65. When the door is opened, however, element 14 slides, carrying flag 46 with it and so bringing the notch 50 on the lower edge of the flag into alignment with the tooth and so freeing the flag so that it can resume, under the urging of plungers 60. 61 the blocking position on later closure of the door. The mechanical means comprises a cylinder lock 42, actuation of which with a key moves element 41 against a side 36 of an angle element 33 (see Fig. 2). This pushes nose 37 against the flag and forces it out of the path of pawl 68 into the same position as before. Means to prevent picking are also provided. This comprises a rotatable plate 77 and a spring loaded rod 82 bearing a cross-pin 81. When the door is closed spring 86 urges plate 77 to a position in which tooth 87 blocks attempted withdrawal of sliding element 14 by picking. When the door is unlocked and opened, pawl 68 engages cam surface 92 and pushes the plate into a position in which the tooth 87 is free of element 14. Spring 85 urges the rod 82 out to the furthest extent, forcing pin 81 against the cam surface 80 to push the nose 91 of the plate out of the path of the pawl which can then return, on closure of the door. without hindrance.