Hancock air whistle

Therefore, Hancock developed their line of air whistles in an attempt to romanticize the diesel locomotives.

Additionally, the NH's 40 Budd RDCs had two Hancock 4700 whistles, plus their Mack FCD-1 & FCD-2 railbuses, 30 GP9s, 15 RS-11s, 15 H-16-44s, 20 SW1200s & their fleet of Pullman-Westinghouse stainless steel MUs.

Other railroads occasionally used them, notably the New York Central on some RS-3s, the Seaboard Air Line on their SDP-35s, the Cambria & Indiana on its SW9s, and the Minneapolis, Northfield & Southern.

Class I railroads eventually replaced their Hancock whistles with horns, namely for safety reasons.

The most common was the 4700, which consisted of the whistle along with a large, rectangular bowl in the same plane as the languid plate.