| 摘要 |
In order to normally permit the unlocking of the door from its inside by means of a knob, while occasionally making an un-authorized opening impossible, the knob (19) is mounted upon a driver (20), which may be axially displaced into and out of engagement, respectively, with a rotatable member (14) in the lock. When the driver is retracted from the rotatable member, a radially directed peg (25) will be introduced into a groove (26) in a washer (24), in which the driver is journalled, which prevents rotation of the driver and the knob. The driver is provided with peripheral grooves (21, 22), which in co-operation with a spring loaded ball (23) form end portion stops for the driver. One (22) of these grooves is deeper than the other, and defines a breaking indication. An un-authorized activity at the knob will destroy the driver, but leaves the lock unharmed. |
