Locks – Operating mechanism – Key
Patent
1990-08-22
1991-09-10
Wolfe, Robert L.
Locks
Operating mechanism
Key
E05B 3508
Patent
active
050463420
DESCRIPTION:
BRIEF SUMMARY
FIELD OF INVENTION
The present invention relates to a cylinder lock of the kind which comprises a plug or cylinder which is mounted for rotation in a cylinder housing and which has a keyway provided therein and a row of pin-channels having pins disposed therein and being intended for coaction with at least two rows of pin-channels disposed in the cylinder housing and having spring-actuated pins located therein, namely a first row of pin-channels which correspond to a standard lock mode in which a standard key can be inserted into the lock and the cylinder or plug turned, and a second row of pin-channels which is inclined to the first row and and which corresponds to a service position, and in which lock one or more of which pin-channels of said row accommodate intermediate pins in addition to upper pins, wherein when the lock is in its service mode, a service key can be inserted into the lock and the plug turned and a standard key can also be inserted into and removed from the plug, but wherein the service key is latched against withdrawal when the lock is in a standard lock mode.
Such locks have the advantage that a person with access to a service key, for example a janitor or like attendant with respect to a block of apartments, can obtain access to an apartment with the aid of the key, but only if the occupier of the apartment so permits. When the occupier of an apartment is willing for the janitor or like person to enter the apartment during his/her absence, he/she turns the lock to the service lock mode when leaving the apartment, so that the janitor can enter with the aid the service key.
When leaving the apartment, however, the janitor cannot turn the plug to its standard mode or position, since he/she will be unable to remove the key from the lock, with the plug in said standard mode.
When the occupier of the apartment leaves the lock in its standard mode, it is not possible to enter the apartment with the aid of the service key. Although it is possible in some instances to insert the key into the keyway, one or more pins in the pin channels will prevent rotation of the lock plug. The plug can be turned, however, irrespective of whether the lock is in its standard mode or its service mode.
BACKGROUND PRIOR ART
SE-B-8307139-9 (GKN-Stenman) describes a lock of this kind in which one of the intermediate pins has a larger diameter than a corresponding upper pin in the first row of pin-channels and a corresponding pin-channel in the plug has a widened part capable of accommodating said intermediate pin of larger diameter. In this case, the intermediate pin can be accommodated in the widened part of the plug pin-channel, but is unable to enter plug pin-channels of smaller diameter, and hence the service key is latched. This solution is simple from the aspect of manufacture and affords several advantages. However, if an attempt is made to remove a service key with the lock in its normal or standard mode, there is a risk that the intermediate pin will wedge between a widened and a narrower channel part, therewith making it impossible to return the plug to the service mode of the lock. This means that the service key cannot be removed under any circumstance and that the lock must be broken into, in order to open the lock.
NO-A-793880 (Elkem-Spigerverket) describes another lock arrangement in which the number of pin-channels in the standard mode of the lock differs from the number of pin channels in the service mode thereof. In this case, withdrawal of the service key when the lock is in its standard mode is prevented, because of the inability of a corresponding lower pin to move upwards in the service mode of the lock. It is comparatively simple, however, to file down the part of the key concerned, so as to negate the intended latching effect.
Lock constructions are also known to the art in which the plug is intended to move axially in relation to the plug housing, when the plug is turned to lock or unlock the lock mechanism. These lock constructions, however, do not have the aforesaid special function
REFERENCES:
patent: 3264852 (1966-08-01), Gysin
patent: 4099395 (1978-11-01), Garza
patent: 4376381 (1983-03-01), Muus
Assa AB
Wolfe Robert L.
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