GB1484249A - Key operated lock mechanisms and keys therefor - Google Patents

Abstract

1484249 Magnetic locks LOWE & FLETCHER Ltd 10 Sept 1974 [13 June 1973] 28075/73 Heading E2A A magnetic lock has tumblers 10a, 11a made of a non-magnetic material and provided with a plurality of formations for receiving a magnet 31, at least one of these formations actually containing one. The key 33 has a shank 35 provided with a number of blind bores 39 corresponding in position to the formations 28, 29, 30 in the tumblers with the bore corresponding to the one in the tumbler which contains a magnet also containing one 42. The poles of these magnets are so arranged that the tumblers are retracted to the position shown in Fig. 2, that is out of engagement with the outer cylinder 16 of the lock by mutual attraction on insertion of the key. In this position the key-receiving member 12 may be rotated to actuate the unlocking mechanism. The tumblers are raised to the engaged position by a weaker repulsion between like poles of the magnets 26 in the key-receiving member 12 and 25 in the tumbler. The key 33 is provided with shoulders 42 which engage with the key plate 43 to prevent the key being withdrawn when the tumblers have been rotated out of the position in which they are aligned with the corresponding recesses 20 in the outer cylinder 16. In an alternative arrangement the polarity of the magnets is altered so that the tumblers are biased to the disengaged position. Insertion of the correct key causes them to engage so that rotation of the key rotates the outer cylinder 16 to which the lock drive is linked.