摘要 |
<p>A twisting tumbler lock with a side bar is provided with additional levels of security by a axially reciprocable slider which is normally positioned to block operation of the side bar but is moved by a specially configured key to free operation of the side bar. This provides a third level of locking security, it also allows master keying. The unique key has a portion of a rib formed to cooperate with the slider to further allow key control.</p> |