Locks – Parts – attachments – accessories and adjuncts – For key-operated mechanism
Patent
1997-01-28
1998-07-14
Barrett, Suzanne Dino
Locks
Parts, attachments, accessories and adjuncts
For key-operated mechanism
70420, 70407, E05B 1508
Patent
active
057787123
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a cylinder lock/key combination of the kind defined in the preamble of claim 1. The invention also relates to a key and to a key blank.
Cylinder locks of the kind in which the key slot accommodates in the rotational centre of the lock plug an element which makes the insertion of a lock-picking tool difficult to achieve, and keys that are designed for use with such locks, are known for instance from DE-C-36 12 38 (Bergmann), DE-C 6 42 131 (Hermann Bode in Hannover), U.S. Pat. No. 877,930 (Katzenberger) and FR-A-2,525,267 (Toutain).
One common drawback with these constructions is that if the tumbler pins housed in the cylinder and the plug need to be changed, for instance when re-coding the lock or because one or more tumblers have been damaged, this change cannot be effected conventionally in the actual place where the lock is fitted.
A slot-carried element of the aforesaid kind fitted axially in the key slot of the plug affords the advantage of making the insertion of a lock-picking tool into the key slot difficult. However, because of the difficulty in carrying out on-site tumbler changes with the aid of a tool of the kind referred to, this type of lock has been unsuccessful commercially, despite being difficult to pick.
A tumbler change often requires the use of a tool which can be passed through the plug from beneath. The tool is used to force the tumblers out of their respective chambers, so as to enable a new set of tumblers and associated springs to be inserted and the tumbler chambers in the cylinder closed.
The cylinder and the fitted plug is then ready to be fitted in place for continued use, optionally together with a new key if it has been found necessary to re-code the lock as a result of changing tumbler pins.
DE-C-217 799 (Hartmann) describes a padlock whose key includes a bore or recess whose profile can vary in accordance with the profile shape of a pin element provided in the lock and onto which the key is inserted. This pin element is non-rotatable and forms a key turning centre.
U.S. Pat. No. 1,932,706 (Neer) describes a lock construction that includes a central key journalling centre having a round shape. The key code has the form of a screw-thread.
U.S. Pat. No. 1,477,318 (Crass) describes a type of lock which includes a slot-carried element wherein the coding shall face downwards in order for the key to be inserted into the key opening in the plug. The key is thus profiled only in the actual inlet to the plug. The key does not lift the tumbler pins as it is inserted into the lock, and the lock is therefore of the lever tumbler kind, i.e. a lock in which the tumbler pins are not activated until the key is turned. The slot-carried element forms a bearing, i.e. a centre for rotation of the key. The preamble of the following claim 1 includes features that are characteristic of this known lock.
In this lock, the slot-carried element referenced 16 in FIGS. 2 and 5 forms a stop surface which supports the tumbler pins in the absence of a key in the lock. That part of the key which embraces the slot-carried element is thick and has a regular shape. This means that the lock can be easily picked by inserting a lock-picking tool into the keyhole in the absence of a.
OBJECTS OF THE INVENTION
One object of the present invention is to provide a cylinder lock/key combination which includes a slot-carried element and which is an improvement on earlier known combinations, and with which the slot-carried element can be given a novel function, namely a function of enabling keys to be produced with very thin, curved and irregular profiled parts which make picking of the lock with a lock-picking tool difficult to accomplish.
Another object of the invention is to provide a cylinder lock/key combination which includes a slot-carried element which is able to coact with a tumbler pin replacement tool which can be used to remove all tumblers in the plug and the cylinder respectively after being inserted, despite the fact that the slot-carried element makes pi
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Assa AB
Barrett Suzanne Dino
LandOfFree
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