are warning bells created equal?

[cabforward]

bells seem to vary as horns.. i hear them at slow tempo (once per sec); and fast tempo (2-3 per sec).. steam locos. in old films seem to have slower-ringing bells; diesels often have faster-ringing bells, which carry a greater warning of danger.. but, i've listened to diesels with slow-ringing bells..
any comments, or does this sound too stupid to dignify?

[edblysard]

Not at all, the bells work off of a vacuum valve, sorta like your old automobile windshield wipers, which, by the way, is the same system used on locomotives, vacuum powered wipers. The reason is simplicity. All the thing really wears out are o rings, which are cheap, and its easy to chase down vacuum leaks, as opposed to electrical shorts. If you listen to the bell closely, you can hear the vacuum valve make a hiss and the valve opens. It pulles the clanger back and then the valve releases its vacuum, and gravity makes the clanger, or striker, fall down against the bell. The reason they have a different tempo is due to the age of the valve, and the idle speed of the diesel. Faster idle, slower bell, slow diesel speed, fast bell, due to more manifold vacuum at slow speed. As for the speed of bells in films, well, ever wonder what a Foley artist is? See the credits at the end of a movie. They should call them by their real name, sound effects people. With the exception of dialogue, almost all the sounds you hear in a movie, doors slamming, horns honking, bells ringing, even the sounds of a fist fight, are "dubbed" into the sound track by the foley artist. The reason they record the "live" sound is so the foley people have something to go by.
Watch railroad movies carefully, and you can hear the click/clack of wheels going over track joints, but look, and you see continuiously welded rail, no joints!
And depending on the type of steam loco, well, they use steam to drive the ringer in the bell, and the engineer can adjust the speed by opening or closing the valve to the bell.
Stay Frosty,
Ed

[cabforward]

this is too trivial, but i believe this forum is a form of therapy..

i remember in the '50s, when mp had light blue/cream colors, where the bell was on some locos.. and it made sense.. in sitting with the long-hood forward and engineer on the right side, the bell was at waist level on the LEFT side of the loco.. this is good, because the engineer couldn't see that side.. the bell was there to alert anyone thinking about crossing in front, and heard more easily as it was on the same side of the loco. as the persons at risk.. maybe its a crock, but it sounds good and for a 10-year old back then, pretty sharp thinking..

[edblysard]

Dont know if thats the reason or not, but we use MK1500d's, and the bell is on the firemans side, just under the sill,(frame) in front of the fuel tank. From working on the ground around a lot of locomotives, I can tell you it really dosnt matter where the bell is, they are loud, and can be heard no matter where you are standing. But that may be one of the reasons. I have seen them mounted on the top, and on the nose of other, older locos, but for the most part, on the newer ones, the bell is mounted on the frame, where it is easy to get to, for maintainance.
Ed