I have a few questions about locomotive bells. First question, why do some bells start ringing very fast in cold weather but ring normally otherwise? I've noticed this mainly with EMD steel bells on locomotives. Second question, why do some mechanical bells, when turned on, make two quick rings at first, but then ring normally after those two rings? Third question, why do some bells ring at an inconsistent rate (I have noticed the bell on Milwaukee Road F7A 118-C at Illinois Railway Musuem is inconsistent, it sometimes rings quickly, sometimes rings slowly.) Thank you.
~FanOfTheRail
The clapper in a Diesel locomotive bell is powered by compressed air. The clapper has a device that regulates compressed air to the clapper to get it to swing into the sides of the bell. I am no mechanical engineer myself but my guess is the device regulating the compressed air like any compressed air valve gets worn over time or partially clogged with grime or grease or whatever. Probably impacts it's strike timing...........thats my guess.
Okay, thanks for the answer. Also, if I had to make a guess at the second question, the two quick rings are probably caused because the air line going to the bell is not fully pressurized because the air is just beginning to flow into it. Because there isn't much air, it might not be able to lift the hammer back far enough, and it will ring faster because there is less distance to travel before striking the bell? This is just a theory.
To answer your question regarding "an inconsistent rate," mechnical diesel locomotive bells (versus newer recorded electric bell sounds) sometimes get "gummed up" with dirt and debris causing the bell to slow down, be off cadence, click instead of ring or just not function at all. To eliviate this problem usually a spray of a solvent like WD40 on the mechanism that rings the bell is all that is needed to bring a locomotive bell back to life.
As was said they are air powered. The unit that drives it is called and air motor even though it doesn't turn but is a piston that travels back and forth. you can get everything you described depending on the wear on three different places, one is the motor itself, the pivot for the clapper and the other is the little arm on the clapper that the motor pushes on.
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