Hot Water posted:Too add to what Nick just posted, above; a lot depends on the steam supplied to the whistle. Many railroads chose to have the whistle supplied with superheated steam as compared to saturated (cooler) steam.
Also, many railroads had an air operated control cylinder to open and close the whistle steam supply, thus all the Engineer had to do was press down on a small brass lever, which controlled the air supply to the whistle operating cylinder (SP cab forwards and GS class 4-8-4s had such arrangements).
Jack, the N&W J Class were equipped with the Viloco whistle actuators, however they also had pull ropes on both sides of the cab. It appears from the bulk of N&W audio from the '50s that the crewmen eschewed the valve and preferred to "play" the whistles manually. New York Central was a big time user of the Viloco valve and in virtually all the recordings in my collection the whistle is either fully on or fully off (no quilling or feathering possible). Recordings of the Niagaras feature mostly the air horn, although the whistle is blown once or twice. K-11 Pacifics used in the New York and the West Shore commuter zones and on the Adirondack Branch were equipped with Hancock 3-Chimes and were manually operated. From what I've read, the mellow Hancocks created less of a disturbance than the more shrill NYC 6-chimes to residents in the bedroom communities where the commuter trains operated.
