Security device for door raised and lowered between lateral rails - is based on spring-biased rotary plate which holds bolt in retracted position only while lifting cable is taut

摘要

The door (1) comprising a number of jointed horizontal metallic slats is operated by a cable (3) running around two skew rollers (4) and along a vertical rail on each side of the doorway. Each cable is terminated at a peg (5) in a polygonal plate (6) coupled by a straight lever (11) to a locking bolt (16). Slackening of the cable causes a coil spring (not depicted) to rotate (8) the plate about a horizontal axis (7), driving the bolt into a hole (18) through the rail, and closing an alarm switch (21). USE/ADVANTAGE - For sliding door, lifting gate, sliding grating, etc. Effective security even against forced entry by leverage from beneath door.