Lock for safe and strong room door - has second bolt which is actuated by breaking of wire on attempt to forced opening

摘要

The door is is locked by a mechanism which consists of a number of sliding bolts (4). Each bolt is in the form of a cylinder which is closed at the outer end by a wall (6). The bolt houses a second hollow cylinder (11) which forms a guide for a second bolt (17). The latter is spring-loaded and is normally held in its retracted position by a wire (15). In the event of an attempt to open the door by burning a hole in it, the wire (15) is burnt through so that the second bolt (17) is pushed outwards by the spring (19) and is held in its outer position by a spring-loaded catch (21). ADVANTAGE - Increased security against burglary.