I have a few questions regarding the buzzer mechanism used on the Long Island Railroad's older locomotive hauled coaches, the P72 and converted PT72 MU trailers.

What exactly was this device used for in train operations?

Where exactly would this device be located within the car itself?

Are there any pictures out there to show what such a device would look like?

What was the voltage needed to work the buzzers?

Any info is greatly appreciated.

I'm going to hazard a guess that the buzzer voltage probably came from the locomotive, via the MU cables, so it'd probably be 72 volt DC coming down B+ from the engine (memory says it's the #13 wire, but check, and returning via the Alarm wire (again memory says it is #2, but check). The voltage didn't originate in the car, but came from the locomotive. At least they did on the newer experimental Long Island cars built by Tokyu Car Company. Since it was probably a signal to the engineer, it's a logical but educated guess. Others who are more current, or have the schematics or wiring diagrams may correct me, and that's OK.

G.F.Payne
Baltimore

The buzzer is trainlined through the entire consist, used to signal the engineer or whoever is in the cab when testing the train. Basically the same signals for forward, reverse, stop, ect. as a whistle/horn. Where I work they are in the ceiling.