| 摘要 |
<p>1496126 Axial pin-tumbler lock CHICAGO LOCK CO 29 Sept 1975 [11 Feb 1975] 39723/75 Heading E2A An axial split-pin tumbler lock is constructed for use with two keys, key 1 being the true unlocking key and key 2 a "prevent" key which is used to turn the lock to such a position that one or more tumblers are inaccesible for picking and from which keys 2 and 1 must be used in that order to unlock the lock. The lock comprises a cylinder 30 within which is located a three part plug comprising a rear sleeve part 50, fixed to the cylinder, a rotatable intermediate spindle part 54 including an axial lock shaft 60 extending through the sleeve 50 to the bolt 36 and a rotatable front drive part 56 mounted by shaft 68 in the spindle part and bearing an axial post 70 having a key-engaging groove 72 at the front. Each plug portion has a plurality (e.g. seven) axial bores which are so arranged that in a first position in which the lock is fastened, they are all aligned but that in a second position, obtained by rotating the drive portion 56 relative to the portions 50 and 54, some bores are continuous through all three portions but some are only aligned in the sleeve 50 and spindle 54. Each bore contains a pin-tumbler assembly 34, comprising a spring 82 and pins 84, 86 and 88. In the first locking position (Fig. 6 not shown) these pins lock drive portion 56 and spindle 54 to the fixed sleeve 50. Insertion of key 1 (Fig. 7) adjusts the tumbler pins so that spindle 54 is locked to drive portion 56 but free of sleeve 50 so that the key can rotate these two together and undo bolt 36. Key 1 cannot be removed in the unlocking position since lug 15 is held behind flange 41. Key 2 is cut so that its insertion (Fig. 8) depresse the tumbler pins to the extent required to free drive portion 56 from the spindle 54, so allowing it to rotate on its own to a position in which at least one bore is blocked by an undrilled portion 80 of drive portion 56 and is thus not accessible for picking whilst others are continuous through all three portions so that removal of the key 2 - with lug 25 passing through slot 43 - allows the tumblers to lock all plug portions together. Both keys are then needed to unlock the lock.</p> |
