Shelter air lock chamber door bolting systems - have remote control activated blocking, locking and security bolts and contact slides

Two doors in the air-lock chamber, esp. for security installations of the bunker type, are fitted with bolting rod systems with blocking and securing bolts, controlled for alternate opening and closing from a central monitoring point. In each system one blocking bolt, at least, works in conjunction with a contact slide. The slides are connected by flexible constant-length remotely activated members to locking bolts fitting on grooved security bolts. The latter are hinged, dependent on opposite-way movement, to a switch lever in the monitoring point, by other flexible constant-length remotely activated members. This is simple to provide, and reliable even after long periods of inactivity, without servicing.