Train horns are audible warning devices utilized by diesel and electric locomotives.

Powered by high-pressure air, typically 130-145 psi, and fed from a locomotive main air Reservoir. On locomotives built prior to the early 1990s, they are actuated by a manual lever/pull-cord, modern locomotives make use of pushbutton controls.

Many early train horns (1950s-era) were designed to play basic musical chords.

Operation

The basic operation of a train horn, or most any horn for that matter, is that the air flow throughout the horn causes oscillation, producing sound waves. The way the air oscillates in a train horn in particular is via a diaphragm. When air is applied to the horn, the diaphragm begins to vibrate. Since the position of the diaphragm at any given moment during the vibration will allow more or less air through the horn, the constant oscillation of the diaphragm causes "waves" of air which in turn produce audible sound.

Manufacturers

There have been four major manufacturers of train horns for use in North America:

Westinghouse

• Westinghouse (under their WABCO subsidiary) was the first to offer airhorns for railroad equipment, going as far back as the 1910s. Their E2 model was known by many for the deep, commanding tone it produced. Overshadowed early on by their competitors, WABCO no longer produces horns for the North American market.

The Leslie Co.

• The Leslie Co. originally began horn production by obtaining the rights to manufacture Kockum Sonic's line of Tyfon brand airhorns, marketing these for railroad use in the early 1930s. Their model A200 series graced the rooftops of countless locomotives, such as the legendary Pennsylvania Railroad GG1, as well as thousands of EMD E and F-units. Leslie would later develop their own line of multi-note airhorns, known as the SuperTyfon series, in direct competition with Nathan-AirChime. Until recently, SuperTyfon horns were the mainstay of almost all railroad motive power in the United States.

Nathan-AirChime, Ltd.

• Nathan-AirChime, Ltd. got its start in train horn production through the work of Robert Swanson in 1949. Prior to the early 1950s, locomotives were equipped with airhorns that sounded but a single note. Swanson set out to change this by developing a horn which could almost mimic the sound of a classic steam whistle. Using ancient Chinese musical theory, Swanson produced the six-note model H6. However pleasant the horn may have sounded, this was impractical for railroad use due to its immense size (over two feet tall), and weight (almost 100 pounds in the initial cast iron version). Since railroad equipment operates in areas restricted by physical clearance, the difference of only a few inches may prohibit that equipment from operating on the line in question. Swanson would later refine the design into the H5. As the model number indicates, this horn sounded a five-note, adjustable chord. Nathan-AirChime has since gone on to perfect their horn design with the M (1950), P (1953), and K (1954) series, respectively.

Prime Manufacturing, Inc.

• Prime Manufacturing, Inc. had produced locomotive appliances for many years prior to their entry into the horn market in the early 1970s. Basically a derivative of the Leslie SuperTyfon design (due to a Leslie patent expiration), though the Prime versions employed heavier castings and sounded a somewhat richer tone as a result. Sales were brisk (Union Pacific was a notable customer), and unable to keep up with offerings from Leslie and Nathan-AirChime, as well as ever-stringent FRA regulation, Prime left the horn market in 1999.

Audio Samples

All samples are in .WAV format unless noted.

• Leslie S3L (454kB)

• Leslie S5T (424kB)

• Prime PM920 (442kB)

• Nathan M5 (247kB)

• Nathan P5 (157kB)

• Nathan K5HL (312kB)

Train Horns and Popular Culture

Fitting a train horn to trucks or an SUV has become the current fad of many vehicle customizers. One should be reminded though, that train horns are extremely powerful devices, and use of one while in motor vehicle traffic can cause an accident. They may also violate local noise ordinances. Recent years have seen an increase of horn theft from railroad property, it is believed that the great majority of these crimes are perpetuated for the benefit of vehicle customizers and truckers.

On the other hand, there are those who collect train horns for their rarity and/or nostalgic value. Such items can command high prices among collectors. One rule of thumb could be that if the horn(s) are mounted prominently on the vehicle, the owner is a responsible collector. Whilst those of the faddish vehicle customizer are generally hidden from view (such as mounted within the hood or trunk) on the vehicle in question.

Due to the encroachment of development (particularly of the residential type), some suburban dwellers (known derisively as NIMBYs and CAVE People) have opposed the railroad use of the air horn as a trackside warning device. This despite the fact that in most locations, the railroad had been established long before the development sprang up. Residents in some communities have established quiet zones, in which train crews are instructed not to sound their horns, except in case of emergency. Given the speed at which many trains travel, as well as the disparity in mass between railroad equipment and an automobile or truck, such emergencies often occur without warning. The effects of a train colliding with an errant automobile have been likened to that same automobile striking an empty soda can.

External Links

• Five Chime Consultants - The original online spotters guide to diesel locomotive horns as used throughout the United States and Canada. Fully illustrated, with audio samples and background information on each horn.

• Trainhorns.net - Collectors guide to locomotive horns. Includes information on identifying rare makes and models, restoration, and maintenance.

• Leslie Controls, Inc. - Makers of SuperTyfon brand air horns for rail, marine, and industrial use.

• AirChime Manufacturing Co. Ltd. - Offers air horns and whistles for both heavy and light rail applications.

Sound production | Safety equipment