by carajul
I was watching trains at Bound Brook the other day and got to thinking about block signals. Can anyone tell me, in plain English, how they function? I'm assuming one rail is a + and the other acts as - but can't figure it out.
One theory is that the left rail is + with a current and when the metal wheels/axels touch the - rail it completes the circuit and power flows thru the red light bulb. The problem is the current loop is before the bulb.
So theory #2 is that one rail is + and one is -, when the metal wheels/aels touch the - rail it becomes +, you then have two + lines causing a short circuit. But how does a short cause a red light to illuminate?
One theory is that the left rail is + with a current and when the metal wheels/axels touch the - rail it completes the circuit and power flows thru the red light bulb. The problem is the current loop is before the bulb.
So theory #2 is that one rail is + and one is -, when the metal wheels/aels touch the - rail it becomes +, you then have two + lines causing a short circuit. But how does a short cause a red light to illuminate?