| 摘要 |
<p>Door has a security system against forced opening with flame cutting equipment, whereby one or more spring-loaded bolts, mounted on the door are released when a cable is burned through, and are pressed by their springs into sockets in the door frame. The bolts are retained in the withdrawn position, against spring compression, by a cable. The cable passes over a series of pulleys and its end distant from the bolt is anchored to the door. The pulleys are so arranged that the cables form a grid covering the inside surface of the outer door plate.</p> |
