Page:Popular Science Monthly Volume 90.djvu/934

 Dispatching Cars on One-Track Lines

��A new signaling system by which one man controls any number of cars

���ANEW signaling system for control- ling interurban cars on one-track trolley lines consists of an indicating instrument at the dispatcher's office which constantly records the progressive positions of every car in service. This record is made electrically by a number of third rails which are strung along the tracks and at the sidings.

When the cars pass over one of the third rails, a shoe makes contact with the rail, and two electric circuits are controlled. One cir- cuit is in the car itself and another leads from the rail to the dispatcher's in- strument. The closing of the latter circuit operates an

���When the cars pass over the third rails two electrical circuits are closed by a shoe, one to the car and one to the dispatch office

��The indicating instrument in the dispatcher's office records on a revolving sheet of paper the progressive positions of each car in service

At left : The signal lights in the motorman's box of the car. A red light means to side- track and a green light means "Proceed"

��electric pen and records the arrival of the car on the paper of the instrument. The dispatcher immediately moves a lever which controls a return circuit to the third rail. It is this which operates the signal- circuit in the car. If the lever is moved one way, a relay in the car circuit connects in a green light placed above the motorman's head, and the motorman proceeds on his way. If the lever is moved the opposite way, a red light is shown, which light warns the motorman to turn from his course into the next siding. Arriving at the third rail at this siding, the motorman waits for the "all clear" signal before going ahead once more.

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