Patent GB-1008908-A (GB)
Title: Improvements relating to locking mechanism
IPC: E05B29/00
Filed: 1963-11-14
Abstract: 1,008,908. Key locks. J. F. WELLEKENS. Nov. 14, 1963, No. 44941/63. Heading E2A. A locking mechanism comprises a housing 1, a latch-bolt actuating plug 3 mounted for rotative movement in the housing, a plurality of buttresses 13 encircling the plug and adjustable in a direction transversely of the housing, apertured tumblers 12, engaged by the buttresses and movable through the plug, releasable means 27 for holding the buttresses together against movement relatively to one another after they have been set to permit the acceptance of a specific key by the tumblers, the buttresses when released being free to move in relation to one another to permit the tumblers to adapt themselves to the contour of a different key inserted through the tumblers. In the construction shown in Figs. 1 and 17 each tumbler is of the wafer type and in addition to the tumblers associated with the buttresses, of which there are five, there is an additional tumbler 12c which is a key holding tumbler and grooves are provided in the housing 1 to permit sliding movement of this tumbler. Each of the buttresses has a base portion with a substantially ovate opening 15 through which the plug 3 extends and within which it rotates and each buttress has two flat parallel sides 16, 17 by which it is guided for transverse movement in the housing, the flat sides preventing rotation. Each buttress has a peripheral wall defining an ovate recess with opposite curved wall sections 20 and 21 which are engaged by lugs 12b of the tumblers when it is required to shift the buttresses transversely to accommodate a new key. Oppositely positioned recesses 23 are provided in the wall sections 20 and 21 with which the lugs 12b of the tumblers are engageable to lock the plug against rotation. Opposite faces of the buttress are serrated as indicated at 24, 25 and 26 the buttresses being interengaged by these serrations to prevent relative shifting movement of the buttresses with respect to one another after they have been positioned by a new key. The buttresses are held in the adjusted position by a curved clamping spring 27. This spring has a pair of laterally projecting lugs which are normally disposed in a pair of longitudinal grooves 30a and 31 in the inner surface of the housing 1. The spring is confined between a closure plate 32 near one end of the housing and a flat pressure plate 33. The pressure plate has two laterally extending lugs 34 and 35 which engage the grooves 30a and 31, a central opening 36 which encircles the plug and a release lug 37 disposed in the opening and which engage a groove 9, Fig. 5, in the plug. Between the pressure plate 33 and one end of the group of buttresses is an annulus 38 to which is spot welded a spring 39 which presses the butresses lightly together during the relief of prsssure on them by the spring 27. When it is desired to change a key, a tool 46, Fig. 23, having two prongs is used. The lock mechanism is first locked by the key which is in use and such key is then withdrawn from the mechanism; the tool 46 is then engaged with the lugs 34 and 35 of the pressure plate by inserting its prongs through openings into the grooves 30a and 31. The key in use is then reinserted into the mechanism and turned counterclockwise through 90 degrees to the unlocking position. This rotation causes shoulders 54 of the key to engage cam surfaces 48 of the tool so moving the tool axially and causing the pressure plate 33 to bear on the spring 27 and relieve the pressure on the buttresses. During the last 5 degrees of movement of the key the engagement of the lug 37 with the groove 9 causes the lugs 34 and 35 to move behind abutments 66, Fig. 13 of the housing, this causing the plate 33 to hold the spring 27 in a compressed condition in which pressure on the various buttresses is relieved. The key is then removed from the plug and a new key is inserted; turning this key back to the locked position causes the tumblers to bear by their lugs 12b on the inner surfaces of the curved wall sections 20 and 21 and this moves the buttresses transversely to a required position in which they co-operate with the tumblers in their new positions as determined by the key. Towards the end of the movement of the key the groove 9 in the plug engages the lug 37 on the pressure plate and moves it so that its lugs 34 and 35 are again aligned with the grooves 30a and 31 thus allowing the spring 27 to apply pressure once again to the buttresses to clamp them in their new positions. The key and tool are then removed from the mechanism. In a modification the pressure plate and spring are omitted and the buttresses have plane faces; they are held in their adjusted positions by a rod which is insertable from either the front or the rear of the lock mechanism through a longitudinal passage. The rod engages in aligned grooves of the buttresses to hold them against shifting and when it is required to use a different key the rod is withdrawn and the new key is used, substantially as described above, to position the buttresses, after which the rod is reinserted. In a modification of this construction the rod instead of being removable is provided with a plurality of groups of serrations one group for each buttress and each buttress is provided with a corresponding group of serrations on one edge, the rod being movable between two positions, in one of which the serrations of the rod engage with the serrations of the buttresses and in the other position of which the serrations are disengaged. In this latter position the buttresses can be moved transversely as previously described to enable a new key to be used. In each construction the tumblers differ among themselves as regards the position of the key slot in relation to the lugs 12b.