. Electric railway journal . T. I. & E. SIGNALS—DOUBLE SIGNAL AND RELAY VIEW 894 ELECTRIC RAILWAY JOURNAL [Vol. 50, No. 20. car to run out onto the main line from the siding. Theindicator line winding is controlled through a contacton the time-element relay which completes this circuitwhen the relay finally picks up. This relay avoids theuse of a preliminary in such a case for the followingreasons: Assuming that a car was just about to ac-cept the clear signal at the entrance to a block whichhad no preliminary section and that the car was soclose to the signal that the motorma
. Electric railway journal . T. I. & E. SIGNALS—DOUBLE SIGNAL AND RELAY VIEW 894 ELECTRIC RAILWAY JOURNAL [Vol. 50, No. 20. car to run out onto the main line from the siding. Theindicator line winding is controlled through a contacton the time-element relay which completes this circuitwhen the relay finally picks up. This relay avoids theuse of a preliminary in such a case for the followingreasons: Assuming that a car was just about to ac-cept the clear signal at the entrance to a block whichhad no preliminary section and that the car was soclose to the signal that the motorman did not noticethe change in indication from clear to dangerwhen the switch was thrown, the switch indicatorwould not clear until the fifteen seconds time requiredby the relay to pick up had elapsed. Before this time,the approaching car would have entered the block andopened the line circuit, cutting energy off from theline wire which supplies energy to the switch indi-cator. The latter, therefore, would not clear and thecrew of the car in the siding would know that anothercar was approaching and would restore the switch toits normal
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