Diesel Airhorns

[Anonymous]

I am very interested in knowing if anyone can give me information (esp. an engineer!) on the quilling (?) or feathering of diesel airhorns. This has always fascinated me. I'm told that newer engines with recent technology only allow a blast to be "on" or "off" with no ability to vary the tone, such as i remember with earlier locos having the "pull-cord." However, i recently saw and heard an Amtrak engineer really "playing" with the horn, (P30) warning a motorist. Can anyone elaborate?

[Anonymous]

Well, its your luck day. I am a horn expert. Standard cab locomotives have an air valve directly in the airline that feeds the horn. It works like turning on your water faucet. But on the newer wide cab locos that same valve is located behind paneling and controled by a single electric relay, with one exception. Amtrak locomotives have a two-stage relay, or better yet, a "city" stage and a "country" stage all in the same button. So the engineer only has a half on or all the way on with those horns. Amtrak engineers need to be able to have that "city" or half stage for use in suburban or station areas. I hope this info helps.

[Anonymous]

Well, its your luck day. I am a horn expert. Standard cab locomotives have thier horn valve directly in the airline that feeds the horn. So it works like a water faucet. Wide cab locos have thier valve behind some paneling, and its controled by a single stage electric relay (the push button on the consol). On Amtrak locos, they have a two-stage relay to give them a "city" stage and a "country" stage all in the same button. So Amtrak engineers can pu***he horn button all the way down for the "country" stage of the relay, or half way down for the "city" stage. This is useful for when the train is in a station or a suburban area and cant disturb nearby residents.

[Anonymous]

Thanks so much for your response!But I'm wondering, why wouldn't freight locos need this ability as well as Amtrak locos, since they travel similar routes through rural as well as urban areas?

[Anonymous]

the trick is not to hit the horn button as hard... if you just feather it..it will sound..but not as loud as if you where to hold it down all the way....