GB1223142A - Cylinder lock - Google Patents

Abstract

1,223,142. Cylinder locks. R. C. SPAIN. 23 Jan., 1968 [1 March, 1967], No. 3425/68. Heading E2A. ' A cylinder lock according to one aspect of the invention comprises a cylinder shell 23 rotatably containing a key plug 29 with a keyway extending longitudinally therein, a fence 45 slidably engaged in a slot extending laterally of the keyway in the key plug to prevent rotation of the key plug in the shell, a set of tumblers 61a to 61e located in a row of holes in the plug transverse to the keyway, each of said tumblers having a tip such that when an appropriately cut key 24 is inserted into the keyway the tumblers are moved longitudinally to bring their outward ends into alignment with the shear surfaces between the plug and the shell and selected tumblers are also rotated by the key, local parts of all the tumbler sides then being in alignment with adjacent complementary parts of the fence such as to allow inward retraction of the fence to an unlocking position permitting rotation of the key plug relative to the shell, and means 55 for inwardly retracting the fence. A side bar cylinder lock according to a second aspect of the invention comprises a cylinder shell 87 rotatably containing a key plug 85 with a keyway therein, a fence 81 constituting a side bar and slidably engaged in a slot extending laterally of the keyway in the key plug to prevent rotation of the key plug in the shell, a set of tumblers 105 located in a row of holes in the plug transverse to the keyway, each of said tumblers having a tip such that when an appropriately cut key is inserted into the keyway the tumblers are moved longitudinally and selected said tumblers are also rotated by the key, all the tumblers then being disposed so that local annular and longitudinally extending true gate notches in the sides of the tumblers become aligned with adjacent projecting parts of the fence, and means 91 for inwardly retracting the fence. In the first aspect Figs. 6 to 9 the shell also has a plurality of bores 57a, 57e for receiving a plurality of drivers 60a, 60e one for each tumbler, the drivers being biassed by springs 63a, 63e so that the drivers urge the tumblers into the keyhole. Entry of the key into the keyhole moves the tumblers and drivers so that their abutting surfaces are on the shear surfaces between the key plug and the shell so that rotation of the key plug is not prevented by any of the tumblers or drivers being positioned across the shear surfaces. In the construction shown there are five tumblers and five drivers and the key has its notches which are engaged by the tumblers, so made that three of the five notches are angularly disposed relative to the axis of the key the tumblers each having a chisel-shaped end portion which is engaged by the key so that when each tumbler is in its correct notch of the key, the disposition of the notch positions the tumbler about its axis to a position in which a true gate (such as 111, Fig. 9) is aligned with a corresponding fence projection (such as 103a, Fig. , 9); the rotation of the key plug can then take place since the abutting ends of the tumblers and drivers are at the shear surfaces and the movement of the fence is not impeded. Three of the tumblers have false notches 107 so that an incorrect key will position the tumblers to allow the fence projections to enter the false notches which are not deep enough to enable the key plug to be turned. Rotation of each of the tumblers is limited by a stop lug 39a to 39e (Fig. 6) these are provided on a stop plate 37 which is inserted in a laterally opening slot in the key plug 29 which slot also receives the fence 45. Each stop engages a notch in the corresponding tumbler the length of the notch being such that movement of the tumbler is limited. In the second aspect, Fig. 11, the drivers are omitted and the tumblers 105 and their biassing springs 121 are contained wholly in the key plug. The means 91 is is a cam so constructed that it will bend if torque is applied to the key plug and the fence cannot be moved into the proper position. The fence is biassed into engagement with the cam by a plurality of springs 99. Each tumbler has a chisel shaped end portion so that it is rotated by angularly disposed notches of the key as previously described and it has a true gate (not shown) which extends axially of the tumbler as previously described and also the notch which cooperates with the stop to limit the rotation of the tumbler. In addition the tumbler has three annular notches 115, 117, 119 one of which 115 constitutes a true gate and the others false gates, the notch forming the true gate being deeper than the others; the fence has projections for engaging both the annular true gate and the axial true gate of each tumbler and for both gates to receive their projections the tumbler must be aligned with the projections both by rotational movement and axial movement caused by the key. When all the tumblers are so aligned with the fence the key plug can be rotated by the key so that the cam 91 cams the fence into the true gates after which the plug can be rotated to the unlocking position. (For Figures see next page)