AirChime entered into the commercial horn business in 1949 with the H5, the world's first 5-chime horn. Prior to this, Robert Swanson, founder of AirChime, had produced 4 Hexatone H6 horns. These six-chime horns never saw long service lives, but three survive. They were essentially what was needed to get AirChime up and going. Over the past 50 years, AirChime has become the dominant name in railroad-application air horns, refining their horns into what some may call perfection: the K5LA. It should be noted that Nathan is only the US licensee of AirChime.
Bob Swanson's goal was to create a horn that as closely resembled a steam whistle as possible.
The K series was supposedly the closest, though I personally don't think there is any comparison between a horn and whistle.
It was hoped that with the K series, the pitch would rise with more air applied to the horn.
Though this wasn't achieved, the pitch drop present with other air horns was virtually eliminated.
Coupled with the D# minor 6th chord of the K5H, the original 5-chime K horn, the K horn is thought by many to be the closest sound to "a whistle in the night".
I think Brent Lee did a great job putting the Airchime history as concise as possible. Thanks, Brent!
I have been discussing the history of the early Airchimes recently with some people and here is the info for H's and N models.
The H6's were made in 1949. There were 4 of these. The original, serial #1 was cast iron. This horn was scrapped and destroyed. Swanson then made 3 aluminum H6's, serial #'s 1-3. (all 3 aluminum H6's exist today) Aluminum #1 replaced cast iron #1. Shortly after this, Swanson began making the five chime H5's, starting with serial #4... There were a total of 88 H5's made. ([9] of them exist today) What gets confusing is when the N3's were introduced. There were 20 N3's made. They started at serial #88... (#88 and 95 exist) When the N3's were being made they entered into the same numbering system and the H5's were not in sequence anymore. Swanson had started on a refined version of the H5, which was to be the N5, but was soon turned into the new model, the M5. In 1950, the M5 was introduced, and the very early M5's had serial #'s like the H6's, H5's, and N3's. The M5's were also in this same numbering system, which put everything out of sequence even more. The highest known H5 is serial #125 which is youngest of the [9] that exists today...
Here's a simple production timeline for Swanson's horns:
1949: H6, H5, & N3 Models introduced
1950: The last of the H5's were put into service, Model M (roundbase prototype) introduced
1951: Continued production of round base Model M.
1952: Round base Model M dropped, introduction of scallop base Model M. The same model is still offered today by Nathan. Swanson worked on his new model, the T5.
1953: Airchime introduced the Model J3 for Canadian snowplows. Swanson introduces his new Model P, which is the result of his work on the T5.
1954: Swanson introduces the Model K.
1956: Swanson introduces the Model MK, which has an M like back cap, which allows adjustment for variable operating pressure. ... It took an 1 1/2" socket to turn the adjustable MK back cap!
1957: Swanson drops the Model MK for the new K adjustable back cap which requires a 3/4" wrench.
1969: Adjustable K back cap dropped from production.
1976: Nathan adds the P #4A bell per D. H. Ellsworth for Amtraks first order of F40's which had P5A's. Swanson designs the L manifold. Swanson adds the #3A and 4A bells to the catalog for the new American tuned K5LA, changes his K5 designation to the now specific K5H, K5HA, K5L, and K5LA. Swanson decides to die-cast the Model K, purchases a die-cast machine for $80,000 The die-cast machine ends 22 years of sand cast Model K production.
1977: January 25, 1977, Swanson sends Deane H. Ellsworth the first production die-cast K5LA. Nathan changes the castings on Nathan P's.last updated 02.17.2004