| 摘要 |
A door latch mechanism 10 comprises a retractable latch 1, first and second connection mechanisms 14, 16 which receive door handles to retract the latch 12, wherein the first connection mechanism 14 can be used to disable the second connection mechanism 16 preferably by means of a blocking member 42 having arcuate edge 61 which engages with a slave follower of the second connection mechanism. A key operated lock arrangement 34 is also operable to disable the drive mechanism 16 be means of rotating the blocking member via movement of pin 70. The inside door handle remains available to retract the latch arrangement 12, even after the lock arrangement 34 has been operated. Accordingly, a user leaving the premises can lock the external handle 24 but another user still inside the premises can leave in an emergency, despite the mechanism being locked to an outside user. Preferably the blocking member is moved by the first connection mechanism through a lost motion connection in the form of a slot 57. The latch may also be deadlocked via spring biased plunger 84.
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