Western Railroad Discussion > whistle-horn

Whatis the difference between a whistle and a horn? This is a serious question.

A whistle makes noise by air (or steam) passing across an opening in a tuned chamber, like blowing across the top of a soft drink bottle.

A horn makes noise by the vibration of a diaphragm inside the housing.

The meanings are obscured, since railroad rule books refer to whistle signals, when pretty well all locomotives nowadays are equipped with horns.

Simplified, an air horn is a device where pressurized air is forced through one or more (metal) reeds, the sound then amplified and directed by the horn shaped bell, as in a megaphone.
A whistle is air or, in the case of a steam locomotive, steam is released from pressure into a pipe like device with a sort of window cut in it at the proper location and of the proper size to make a tone, such as blowing across a beer bottle. The tone will change with the length of the pipe and the shape, size, and location of the opening. Normally, a whistle will require much more volume or gas, whether air or steam, to operate it than a horn.

A horn can also be electric, such as on an automobile where power is applied to a coil causing electromagnetism to draw a reed like device against a solid object. When this happens, the circuit is also momentarily interrupted and the coil releases the reed. This happens rapidly, causing a sound vibration. This vibration, again, is amplified and directed through the "bell" of the horn.
Mark D.

Also, whistles are much more pleasing to the ear.

And....."whistle freely for men and equipment..."

Thanks for the information

> MarkD wrote:

> Also, whistles are much more pleasing to the ear.

I'll mostly agree with you on that, except for K5LAs- beautiful sound!

Actually, many of the manufacturers of locomotive air horns refer to them as "whistles," or "air whistles." For example, in the Leslie catalog I have, their offerings for commonly used railroad horns are termed: "Leslie Supertyfon Air Whistles," but we would commonly refer to them as air horns.

The true difference is that an air horn uses air to cause vibrations in a material diaphragm, usually made of a sturdy metal, phenolic, or plastic material whereas in a whistle, the medium itself (steam or air) is the vibrating element.

Mike

All I can say is that I consider it a "whistle". The rule books call it "whistle signals" and not "horn signals" however, the newer locomotives have a button that says "horn" on it. My father is an old head engineer and he still calls it a whistle. Whistle is proper as far is I am concerned.

Michael_SD40-2
BNSF Southwest Division
US NAVY (active)

Yes yes, I go around on this with a friend who demands that all train horns be called "whistle," when they are, by any technical and dictionary (oh, that!) definition HORNS. "Whistle" is both a traditional railroad term (and we all know how tradition-bound railroaders are) and a generic term for air and steam-operated signals. No, we don't "mouth" a happy tune, either, but that don't mean the mouth is a whistle, does it? Ergo, one can perfectly legitimately whistle with a horn. I'm whistling off for now. Kurt.

Do you know why cows wear bells? Because their horns don't work. HAHA upkpfan