Hancock is perhaps best known for their steam whistles, such as the "steamboat" whistles on Union Pacific 844 and 3985, SP 4449, Frisco 1522, and N&W 611. The Hancock type 4700 was an air whistle intended for use on diesel locomotives that simulated, as much as possible, the sound of a steam whistle. The whistles were used extensively by New Haven, Seaboard, and Minneapolis Northfield & Southern, as well as a number of shortlines.
The whistle could be ordered with or without the bowl-shaped reflector. Without a reflector, the whistle was catalogued as a type 4710. Photo and whistle courtesy Ray Weart.
Original tuning was: A major triad (E, A, C#)
Though pleasant to hear, the 4700 was not as loud and commanding
as most airhorns. Difficult to hear at speed, the whistle eventually fell out of favor,
and production ceased about the middle of the 1960's. The last large user was the Minneapolis
Northfield & Southern, and with their merger into the Soo Line, the whistles were soon
removed. Some Hancock 4700's can still be heard on shortline and industrial locomotives.
Hancock 4700 sound samples:Courtesy Pacific Automotive,
Sample 1...204kB...9 seconds
Sample 2...182kB...8 seconds
Sample 3...61kB...3 seconds