Is there a specific reason why train horns consist of two different tones instead of just one?
I'm not sure of this but I once heard that the single tones were often confused as truck horns. I'm sure that some of the posters on this forum have more details on that.
Not specific, but:
When diesels were new, they mostly? all? had single-note horns. Eventually people noticed how much nicer the chords from three-chime and five-chime horns sounded. Guess three is usual now?
I suspect that three-chime horns are a cost compromise between a single note "honker" and a five chime, so you'll see a lot of three-chimes in use.
There are complete sites dedicated to the various and sundry horns available. Purists can tell you a make and model by just listening.
I believe that at one time, Canadian horns had a prescribed tuning.
Amtrak's five-chimes are nominally tuned to D#, F#, G#, B, D#. That can vary due to age, fouling, etc.
Watching the various rail cams can expose you to some gawdawful noises, again, due to age, fouling, etc.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
I understood the single note honkers would arouse moose during rutting season up in the northern parts of the continent. The chords solved that problem, and also made it more identifiable to motorists that it was a train (if they were listening, of course).
I believe that a lot of the five-chime horns had two of the chimes reversed to help carry the sound in the opposite direction.
The comments about maintenance ring true. I can remember NKP chime horns with sticky valves that sounded horrendous.
CSSHEGEWISCHThe comments about maintenance ring true. I can remember NKP chime horns with sticky valves that sounded horrendous.
Now most of the the horns have an all on or all off valve. Our newer engines came equipped - the older engines were retrofitted because of PTC.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.
zugmannNow most of the the horns have an all on or all off valve. Our newer engines came equipped - the older engines were retrofitted because of PTC.
Our "legacy" engines can be played with a bit. Partly depends on how long the run is between the valve on the control stand and the actual horn.
I recall once reading that some locos had a horn that automatically sounded the prescribed crossing signal.
As for types of horns, the New Haven once favored the Hancock "AirChime," which sounds like a steam whistle. That speaker looking thing on the FL9's is the whistle.
For a while some engines were equipped with a horn sequencer that sounded the crossing horn signal. It would repeat until turned back off. Some still out there. Ours were activated by a big foot button.
The horn mag valves sometimes will freeze up in extreme cold. For GE types, the valve is under the cab and you can thaw it out to where it will work by putting the main heater and both sidewall heaters on high.
PTC will now blow the crossing sequence. At first it would just blow the horn in one long sound until the horn button is pushed.
Jeff
cx500 I understood the single note honkers would arouse moose during rutting season up in the northern parts of the continent. The chords solved that problem, and also made it more identifiable to motorists that it was a train (if they were listening, of course).
The ONR (Ontario Northland) had a really unique three chime horn IIRC for just that reason. It was really distinct (almost like a wavering tone) and really sounded quite unique and a bit eerie on a quiet night at a distance as it whistled crossings North and South of Temagami station.
All the Amtrak P42s had a horn sequencer, which also actuated the bell 'for thirty seconds' when triggered. They had foot controls, but these would only engage blowing at full power -- you needed to use the manual button to get the reduced intensity.
I could not understand why the PTC developers didn't arrange for the horn to blow an emergency pattern when auto-actuated.
As Rich mentioned, my understanding is that Canada mandated a three-note horn because there were accidents where people who were used to the steam whistle sound mistook the single note "blat" horn as being a truck horn.
I know the DMIR didn't like the single-chime horns on their first diesels. They tried Hancock air whistles, but found the sound didn't carry far enough. Eventually they settled on a five-chime horn set-up that they felt more closely approximated the sound of the Missabe's steam engine whistles.
I grew up across the street from a railroad (MN&S) that used Hancock air whistles. After hearing them for 20+ years, suddenly having that sound replaced in the early 80's with the Soo Line's very loud "BLAT" airhorns took some getting used to.
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