Railroad Trains for the Soul: Locomotive Air Horns
An air horn is the locomotive’s primary safety device that provides an audible warning in addition to the lights, which are already covered in the previous blog post. When you stop at a railroad crossing, you can’t just look for the train. You should also try to listen carefully to its horn. That’s why everyone must “STOP, LOOK, and LISTEN,” no matter what they’re doing. Air horns are an effective replacement to whistles that are used on virtually all steam locomotives. As diesels and electrics became commercially available, it was decided that horns can be powered by air pressure and require no steam, enough to make a loud noise for the safety of all people. Since then, they come in a wide variety of shapes and sounds, some of which can produce a very musical chord.
Going back as far as the 1930’s, the first production air horns could produce a single note or “chime” and the most notable example is the Leslie A-200. However, single-chime horns became a safety problem, due to the confusion of sounds between trains and trucks. As a result, multi-chime horns were engineered to increase safety and to make a locomotive sound more distinguishable from any other transportation machine. One of the videos provided in this blog post is by Mike Armstrong (known as CoasterFan2105). Because he did a fabulous job with his research on train horns, it’s a little bit challenging for me to paraphrase this video, but there is some information that isn’t exactly covered.
When it comes to cab controls, early diesels typically had a steam-whistle rope that controls the valve of the horn. Later diesels have a lever-type device on the control stand for the same purpose. On many of the 1990’s-era comfort-cab locomotives, there’s a pushbutton built on the desktop console to blow the horn. The engineer can give a full volume of the horn by pulling the lever or pushing the button all the way to maximum. A partial blow causes the horn to sound at a softer volume and also causes some but not all of its notes to produce a sound. Model railroaders refer to this activity as “quilling” for multi-chime horns. More recent locomotives nowadays have the revived lever design because some railroad experts say it has better volume control of the horn and is easier to quill than the pushbutton. Additionally, some modern locomotives have a horn sequencer button that can be pressed to automatically play the standard crossing signal pattern (two long blasts, one short, and one long). The sequencer repeats the same exact pattern until its button is pressed again to silence the horn.
For many years, a lot of railroads have requested specific horn models as a standard feature in most of their locomotives. For example, one of the most talked about horns in the trainspotter community is the five-note Nathan/AirChime K5LA, which is extremely useful for Amtrak and many commuter railroads in North America. It is also common on two Class I freight carriers, including CSX and Norfolk Southern, in the eastern United States. A fan favorite, the K5LA is so popular that it’s been subdivided into three variants called “generations”: 1st, 2nd, and 3rd. On the west coast, Union Pacific and BNSF used to prefer a three-note version called the K3LA for many of their diesels. Canadian National, Canadian Pacific, and VIA Rail locomotives are typically fitted with the K3L and K3H horns that are marketed for the namesake country.
Beginning in the early 2000’s, the two largest locomotive builders, Electro-Motive and General Electric, began to standardize a single horn model for most if not all of their recent North American freight products. EMD uses the K5LLA (no typo) for its SD70ACe and SD70M-2 models; yes, this particular type does have two L’s. On the other hand, GE uses the K5HL (the successor to the relatively common K5H) for virtually all of the Evolution Series diesels. Like the original K5LA, which is still in production for newer passenger locomotives, both the K5LLA and the K5HL are both five-note horns manufactured by Nathan/AirChime and have also been subdivided into early and late generations.
Air horns are generally easy to spot on most diesels. They may be located on the cab roof or on top of the long hood. Sometimes, there are even two separate horns (one on the front end and another on the rear) used for not only switchers but even some mainline locomotives. Numerous vintage cab units typically had a pair of single-chime horns mounted on the cab portion, each facing the opposite direction. Only one of them can be activated depending on the direction of the unit. GE’s Tier 4 Evolution demonstrator locomotives contain a three-chime horn at or near the front and a two-chime at the rear. A lot of the EMD SD70ACe-T4 units also have a similar double-horn arrangement, except that the front one has five chimes.
To learn more about the types of railroad air horns, I highly recommend what in my opinion is by far the best source about these safety devices. Organized by a group called Five Chime Consultants, this website preserves the history of not just the common and rare horn models designed by Nathan/AirChime and Leslie but also some others from less known brands, including Prime Manufacturing Corporation and the Westinghouse Air Brake Company. Of course, the latter is best known for its train braking systems, but it did sell its horn products fairly well. As a special treat, you can even listen to the audio files of most horn types within the Five Chime Consultants website, so that you’ll get the idea of how they exactly sound. Here are some additional videos and sources featured in this blog post. While irritating to some residents but attractive to many railroad fans, air horns produce a nearly unmistakable sound of a train in order to adequately maintain safety of all communities that are near the tracks.
Train Horns: Train Talk Ep. 5 (CoasterFan2105)
Honk Honk - Why Trains Have Horns (Amtrak)
Milwaukee Road 4-8-4 steam locomotive No. 261 with Leslie A-125 air horn
Nathan K5H horn for CSX
GECX Tier 4 demonstrator in long hood forward operation
CSX ST70AH in long hood forward operation
A Nathan emergency horn for Canadian passenger locomotives
Train horns on a synthesizer