| 摘要 |
Adjacent stations along a single track railroad without continuous train detection, are coupled by a communication channel over which distinctive signals requesting, acknowledging, accepting, and confirming completion of, train movements are transmitted. The operator at the departure station manually initiates the transmission of a first signal requesting a train movement to the adjacent station. The other station operator acknowledges the movement request by manually actuating the transmission of a second distinct signal accepting the move. The two signals jointly establish the requested traffic direction through the single track and clear the departure signal for the train. Occupancy of the single track by the train locks the channel to inhibit other movement requests, thus protecting the train while moving through the non-detection stretch. Arrival of the train at the far station is registered and confirmed by the operator who manually actuates the transmission of a train complete third signal. This actuates the reset of that station apparatus and reception of this third signal at the departure station actuates a system reset to restore at-rest conditions to enable preparation for the next train. In a first specific arrangement, the communication channel comprises two normally energized DC line circuits, one in each direction. Signals are transmitted by reversing the line polarity and the system locked by deenergizing both line circuits. The channel in a second form is a normally deenergized reversible DC line circuit. Signals are transmitted by applying energy of predetermined polarity from one or the other staton. The line circuit is held deenergized to lock the system during train movement.
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