Sources
Help build the largest human-edited directory on the web.
Submit a site - Become an editor
Wikipedia. Licensed under the GNU Free Documentation License.
Are you an expert in this subject? Join the discussion and share your knowledge at Wikipedia.org.
Train horns in North America
From Wikipedia, the free encyclopedia
Train horns are audible warning devices found on diesel and electric locomotives.
(Note that this article deals with locomotive air horns as used throughout North America. For those used elsewhere, please refer to the Train horn article.)
Contents |
As diesel locomotives began to replace steam on North American railroads, it was realized that the new locomotives were unable to utilize the steam whistles then in use.
Early internal-combustion locomotives were initially fitted with truck horns, but these were found to be unsuitable, and so the air horn design was modified for railroad use.
Train horns are operated by compressed air, typically 130-145 psi (9-10 bar), and fed from a locomotive main air reservoir. On locomotives built prior to the early 1990s, they are actuated by a manual lever or pull-cord. Locomotives built today make use of pushbutton controls.
The basic operation of a train horn, or most any air horn for that matter, is that the air flow throughout the horn causes oscillation, producing sound waves. Oscillation in a train horn is accomplished 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.
The configuration and dimensions of the bell ("bell" being the correct term for the trumpet assembly) determine the frequency produced (measured in hertz), and hence, the fundamental.
Many early three and five-note train horns were designed to play basic musical chords.
There have been six major manufacturers of air horns for railroad use in North America. Of these, only Nathan Manufacturing, Inc. and Leslie Controls, Inc. remain today:
The Gustin Bacon Mfg. Co. of Kansas City, MO offered airhorns for use on railroad equipment prior to the Second World War.
The American Strombos Co. of Philadelphia, PA (later to become known as Buell) sold modified truck horns for rail use. They were often installed on small locomotives and railcars (for example the Doodlebugs).
Westinghouse (under their WABCO subsidiary) was the first to offer airhorns specifically for railroad equipment, going as far back as the 1910s. Their model E2 was known by many for the deep, commanding tone it produced. Overshadowed later on by their post-WWII competitors, WABCO no longer produces horns for the North American market.
The Leslie Company originally began horn production by obtaining the rights to manufacture the Kockums Mekaniska Verkstad line of Tyfon brand airhorns, marketing these for railroad use in the early 1930s. Their model A200 series would later grace the rooftops of countless locomotives, such as the legendary Pennsylvania Railroad GG1, as well as thousands of EMD E and F-units. Leslie eventually introduced their own line of multi-note airhorns, known as the Chime-Tone series, in direct competition with Nathan-AirChime.
Poor sales of the Chime-Tones (due to the added weight of the assembled horn, as well as requiring an ample air supply) led the Leslie Co. to develop the SuperTyfon line of horns utilizing interchangeable parts. Horns were offered in single, dual, triple, quad (in the case of Amtrak's SDP40F locomotives), and five note variants. Until recently, SuperTyfon products were the mainstay of almost all railroad motive power in the United States.
Today, the company is known as Leslie Controls, Inc., and continues to manufacture SuperTyfon air horns for the railroad industry.
AirChime, Ltd. got their 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 relatively large size and weight. It should be noted that 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.
Over the years, AirChime had continued to perfect their horn design with the M (1950), P (1953), and K (1954) series, respectively. With the exception of the K series, most of the AirChime horns have been labelled as Nathan-AirChime - indicating their US licensee.
As of 2006, AirChime no longer markets locomotive horns, having sold this division of their business to Nathan 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 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 compete with offerings from Leslie and AirChime, as well as ever-stringent government regulation, Prime left the horn market in 1999.
As many people do with their personal vehicles, railroads order locomotives with many different options in order to suit their operating and maintenance practices.
Horns are no exception, and railroad mechanical forces mount these on locomotives where they are deemed most effective at projecting sound. Below are a few images depicting the most common mounting locations:
 Leslie model S3L air horn mounted atop the cab roof of a Santa Fe locomotive in the classic location. |
 On many locomotives with high short hoods, such as this Norfolk Southern GP38-2 -- the air horn can be located away from the operating cab. |
 AirChime model K5H mounted on a custom bracket. Not only is the horn located here, but the air-operated bell as well. |
 On newer locomotives, the horn is mounted atop the engine compartment due to complaints from train crews. Unfortunately, acoustic performance suffers, and the sound is often muffled. |
Railroads are required by a variety of state and federal laws to sound horns in advance of all crossings. Horns are sounded for safety reasons, namely, to warn of approaching trains. (See also Train whistle (Whistle code) for traditional horn and whistle signals.)
The following are the required horn signals listed in the operating rules of most North American railroads, along with their meanings. Signals are illustrated by an "o" for short sounds, and "-" for longer sounds. (Note that these signals and their indications are updated to reflect modern practice.)
| Rule | Sequence | Indication |
|---|---|---|
| 14 (a) | o | Applying air brakes while standing. |
| 14 (b) | - - | *1. Proceeding. 2. releasing air brakes. |
| 14 (g) | o o | Acknowledging any signal not otherwise provided for. |
| 14 (h) | o o o | *Backing up. |
| 14 (j) | o o o o | Calling for signals. |
| 14 (l) | - - o - | 1. Approaching public crossings at grade. Trains or engines approaching public highway grade crossings shall sound the horn for at least 15 seconds, but no more than 20 seconds before the lead engine enters the crossing. Trains or engines travelling at speeds greater than 45 mph shall begin sounding the horn at or about, but not more than, one-quarter mile (1,320 feet) in advance of the nearest public crossing. Even if the advance warning provided by the horn will be less than 15 seconds in duration. This signal is to be prolonged or repeated until the engine or train occupies the crossing; or, where multiple crossing are involved, until the last crossing is occupied. 2. Approaching tunnels, yards, or other points where railroad workers may be at work. 3. Passing standing trains. |
| 14 (o) | o - | Inspect train for a leak in brake pipe system or for brakes sticking. |
| 14 (p) | Succession of sounds | Warning to people and/or animals. |
| 14 (q) | - o | When running against the current of traffic: 1. Approaching stations, curves, or other points where view may be obscured: and 2. Approaching passenger or freight trains and when passing freight trains. |
Exception: Engine horn signals required by rules 14 (b) and 14 (h) do not apply after momentary stops in continuous switching movements.
The following audio files are in .WAV format:
- Leslie A200 duo (256kB)
- Leslie S3L (340kB)
- Leslie SL4T (197kB)
- Leslie S5T (209kB)
- Prime PM920 (174kB)
- Nathan M5 (194kB)
- Nathan P5 (255kB)
- Nathan K5H (221kB)
(Audio files courtesy of Chris Moyer and Trainhorns.net)
On April 27, 2005, the Federal Railroad Administration (FRA), which enforces rail safety regulations, published the final rule on the use of locomotive horns at highway-rail grade crossings. Effective June 24, 2005, the rule requires that locomotive horns be sounded at all public grade crossings at least 15 seconds, but not more than 20 seconds before entering a crossing. This rule applies when the train speed is below 45 mph (70 km/h). At 45 mph or above, trains are still required to sound their horn at the designated location (usually marked with a whistle post).
The pattern for blowing the horn remains two long, one short, and one long. This is to be repeated as necessary until the lead locomotive fully occupies the crossing. Locomotive engineers retain the authority to vary this pattern as necessary for crossings in close proximity, and will be allowed to sound the horn in emergency situations no matter where the location.
A ban on sounding locomotive horns in Florida was ordered removed by the FRA after it was shown that the accident rate doubled during the ban. The new ruling preempts any state or local laws regarding the use of the train horn at public crossings. This also provides public authorities the option to maintain and/or establish quiet zones provided certain supplemental or alternative safety measures are in place, and the crossing accident rate meets government standards.
Fitting a train horn to trucks or an SUV has become the current fad of many vehicle customizers[1]. One should keep in mind 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 nostalgic value[2]. Such items can command high prices among collectors. One rule of thumb may 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 on the vehicle in question.
Due to the encroachment of development, some suburban dwellers (known derisively as NIMBYs and CAVE People) have opposed railroad use of the air horn as a trackside warning device.[3] This despite the fact that in most locations, the railroad had been established long before the development sprang up.
Residents in some communities have attempted to establish 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, incidents 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 [4].
- ^ Hornblasters. Retrieved on 2007-02-05.
- ^ Horns Inc.. Retrieved on 2007-02-05.
- ^ Noise Abatement Society. Retrieved on 2007-03-28.
- ^ Front Of Yonge Fire Department. Retrieved on 2007-02-06.
- CSXT Operating Rules (Effective October 1, 2004)
- CSX Transportation System Reissue Bulletin 001 (Effective January 1, 2007)
- Federal Railroad Administration - Complete text on the ruling concerning the use of locomotive horns at highway-rail grade crossings.
- 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.
- Nathan Manufacturing, Inc. - Offers air horns for both heavy and light rail applications.