Nathan Manufacturing, Inc. is the exclusive manufacturer of the AirChime models. Some BNSF freight trains use the Nathan P-5, which is a five-chime horn assembly made of sand-cast aluminum with frequencies that range from 220 Hz to 554 Hz. Nathan also makes the K series of die-cast aluminum. Since BNSF railroad travels throughout the US, AirChimes may be ordered with conical snow shields.
Leslie Controls has been the manufacturer of many locomotive products for over 100 years. Its Air Whistles were produced with the intention of using less air, for more efficient, yet louder, train horns. The Leslie model RS3K with echoes was used by Burlington Northern before the company merged with Santa Fe.
The Prime Mfg. Model 990 is a three-chime air horn that whose major purchaser was BNSF. Although the Prime Manufacturing Co. no longer exists, its air horns can still be heard on locomotives today. Prime's heavy ribbed bell horns give a richer sound than many other air horns. Another characteristic is that Prime's horn's can be sounded at either full or half blast.
Although the Westinghouse AirBreak Company is not a major competitor in the train horn market, under the trade name WABCO it is credited with possibly having manufactured the first chime air horn. Its Pneuphonic horns were available in single, double and triple configurations, with the larger ones, called "honkers," tuned to a chord. Not very many exist today on BNSF or any other rail locomotives.
