In the early 1950s's, Robert E. Swanson (the founder of AirChime Manufacturing co, already partnered with Burnett Power Saws, and Holden Co of New York ) designed a revolutionary new type of airhorn - the K-series. Intended as a replacement for the popular P-series of airhorns, they featured two diaphragms per bell and operated efficiently on much less air pressure. They produce a superharmonic , of over twelve octaves , also stirring up "ghost harmonics" . Swanson also employed super-catenoid bell flares , balancing and perfecting this horn to an even higher degree than anything else on the railroad.
Today, K-series horns are the most popular horns in North America, with the "K5HL" ( an "evolution" new GEVO horn) ,K3H, K3LA and K5LLA making up the majority.
The United States Government mandated the decibel , or sound volume of the once popular Leslie RS3L and RS5T to be too high , and forever banished them . The new, deeper toned Nathan K5HL and K5LLA were designed as their compliant, modern day replacement, however , they are not quieter , they are actually louder.
The series began with two variants - the five-chime K5H, and the three-chime K3H.The K5H had five bells - numbers KS-1 through 5. It played a chord of D-sharp minor sixth (D#, F#, A#, C, D#), a very eerie and attention-grabbing chord.
The K3H, on the other hand, had three bells - numbers KS-1 through 3. It played a D-sharp minor triad (D#, F#, A#). Due to defects in manufacturing, some K3H's had an odd KS-2 bell that played a G, making a pleasant major triad.With the introduction of Amtrak in the United States, Swanson was approached to design a more pleasant-sounding horn than the eerie D# minor of the K5H. He agreed, and designed the K5LA, which played a very pleasant B-major 7th chord in the first inversion. The K5LA, again, had five bells, but two were modified for the major chord (KS-1, 2, 3A, 4A, and 5). The K5LA was also built on a new "low-profile manifold" mounting, as seen in the photograph. The K3H was also modified into the K3LA, which plays a major chord, with the KS-3 being swapped out for a KS-4A.
In 2004, the Federal Railroad Administration posted a law stating that all locomotive horns must not only have a minimum volume, but also a maximum. Seemingly in response to this new regulation, AirChime began production of two more five-chime horns for new locomotives.One is the K5HL, which is a standard K5H but with the KS-5 swapped out for a KS-1L, which plays a low C. The resulting chord is a rather unsettling C, D#, F#, A# and C. The other is the K5LLA, which is pretty much a standard K5LA but with the KS-5, again, swapped for a KS-1L. The resulting sound is a very dischordant C, D#, F#, G# and B.
There is a variation of the K5LLA, where the KS-1 bell is replaced with a different sounding one. This "Canadian" tuned K5LLA produces a sound resembling older Nathan horns. Only VIA Rail Canada and GO Transit uses this variation.
The K5HL is standard equipment on new GE locomotives, and the K5LLA is standard on new EMD's. Oddly, the K5HL is usually mounted backwards, with four of the bells facing the rear of the locomotive. Some K5HL's are assembled with a KS-3A bell instead of the standard KS-3, and are called K5HLL's.
The K-series horns are comprised of the following bells or chimes, ordered in pitch from lowest to highest:
All K-series models are listed below, along with their components and the year they were introduced.
|K5H||1, 2, 3, 4, 5||High||1954|
|K3H||1, 2, 3||High||1954|
|K5LA||1, 2, 3A, 4A, 5||Low||1975|
|K3LA||1, 2, 4A||Low||1975|
|K5HL||1L, 1, 2, 3, 4||High||2004|
|K5LLA||1L, 1, 2, 3A, 4A||Low||2004|
When a K5H is built with a low-profile manifold, it's known as a K5L. The same applies for a K5LA on a high-profile manifold - K5HA. Such a setup is very rare, however, since most railroads that use the K5LA have height restrictions that limit usage of high-profile horns.
Some K3H's have odd KS-2 bells that sound a G, making a pleasant major chord. This is due to an unintended error in manufacturing, but does not affect the volume or efficiency of the horn.
K-series bells can be reversed on the manifold, allowing the horn to be used for back-up movements.
Earlier in the series' production, K-horns were available with adjustable "MKS" bells, allowing the operator to change the pitch if desired. This option affected the reliability of the horns somewhat and was soon phased out. In fact, the K5H sound sample above is an example of such a horn, tuned perfectly to the chord of D#min6. It sounds no different from a standard K5H.
When the K-series started out, the horns were cast in sand molds, making a very smooth, almost clarinet-like, sound. Later on, the sand molds were phased out in favour of the more efficient die-cast method. This affected the sound greatly, making the horns louder and more aggressive-sounding. This did not change the pitches of the bells, however, unlike what happened to the P-series.
The K5LLA is also available as a K5LLB, which uses differently-tuned bells to sound like an older M-5.
Amtrak's Acela and HHP-8 electric locomotives are fitted with an odd variant of the K5LA. The horn has five bells spread across two manifolds - a standard K3LA with bells KS-1, 2, and 4A, but also an odd two-chime horn with bells KS-3 and 5. The two sets together cause a very unique, dischordant sound. The horn is known by railfans as the 'hybrid K5LA', and is only mounted to the Acela units.