| 摘要 |
A keyless combination lock is protected against manipulation by the inclusion of a rotary member turned by rotation of the dial of the lock and which, after excessive rotation from a datum position, such as is likely to occur under conditions of manipulation, serves to move a protective member into an operative position such that operation of the lock is impossible, e.g. by isolating the probe of the lock from the combination wheels. The rotary member is also connected to mechanism for returning it to its datum position after a time delay and arrival at the datum position serves to return the protective member back to an inoperative position if it has previously been moved to its operative position. The return mechanism may start to operate as soon as the rotary member is turned from its datum position and may include a spring which is progressively stressed as the rotary member is turned. The stress in the spring then serves to return the rotary member to its datum position at a rate determined by an escapement mechanism. |
