Anyone know how these are activated?
That's someting I've wondered about for a long time.
Just what activates the signals..starts the bells ringing, lights flashing, and drops the gates?
I wasn't just overly sure so my bad. I agree with you q2bman its alot of electronics for fourteen flashing lights, two bells, and two gates on a standard crossing.q2bman wrote:Not exactly t-bolt. The sensor is an electric current in the rail sent out from the signal shanty in each direction for a long distance. At the end of the "distance" they place a canaster containing some electronic componants that "filter" the AC signal sent by the shanty. When an approaching "shunt" such as a train shorts the rail past the canister the computer in the shanty reads the speed at which the ac signal is being shunted towards the shanty. The computer calculates the speed the train is traveling and sends an activation signal to the relays that activate the crossing signal. The signal is set for a 30 second advance warning to the train entering the crossing. At the crossing the system has a "island" that activates the signals no matter what speed. The island is uaualy close to the crossing. Something like 15' either side. If an approaching train stopped prior to entering the island, the computer will sense the movement has stopped and allow the corssing system to turn off. Very complicated and awsome! The newer shanties house a computer with a fax line that will report false activations, malfunctions, and lots of other stuff. The older versions are just voltage goig to the canister that activates as soo as the train passes it. Neat system though. You realy should take a peek inside if you get a chance. Very complicated for some red flashy lights!!
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