(under subclass 131) Systems, mostly electric, wherein upon the approach of a train to the switch or signal the switches, signals, or other movable elements are automatically locked in position.
(1) Note. The systems in this subclass are sometimes referred to in the art under the term "electric detectors".
SEE OR SEARCH THIS CLASS, SUBCLASS:
25+, for semi-automatic electro manual lock-and-block signal systems.
106, for manually controlled electrically actuated lock-and-block signaling systems.
