(under subclass 28) Systems in which an alternating or pulsating current used for actuating or controlling the traffic controlling devices and derived from a source not on the train uses both traction rails as conductors in series for the major portion of the block.
SEE OR SEARCH THIS CLASS, SUBCLASS:
26, 41+, 58+, 95, 98, 128+, and 130, for track-circuit systems.
176, and 253, for switch or signal actuated circuit-breakers in track-circuits.
449, 450 and 451, for tie-bars with insulated joints.
SEE OR SEARCH CLASS
238, Railways: Surface Track, 164, for the structure of rail bonds and subclass 152 for insulated rail joints.
