| 摘要 |
A lock for locking closed a housing for an alarm pull station includes a lock cam and a lock cylinder assembly. The lock cylinder assembly includes: a lock actuation cylinder having a keyhole exposed on a front side of the housing and a key actuation socket in registry with the keyhole, and a tumbler plate movable transversely through the lock actuation cylinder and interposed between the keyhole and the socket. The tumbler plate includes a bore which is out of registry with the keyhole and movable into registry with the keyhole by a key pushed into the keyhole. The lock actuation cylinder is rotatable by an Allen wrench key fit into the socket. The lock actuation cylinder is surrounded by a lock body which is fixed to the housing. The tumbler plate is biased to be engaged into a slot in the lock body and is moveable transversely by the key to disengage the lock body. The lock actuation cylinder rotates the lock cam for locking the base plate to the cover. The lock cylinder assembly allows opening of the housing using a commonly available Allen wrench but prevents visual inspection of the key socket, through the keyhole, to ascertain the correct size key.
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