Steam Locomotive Horns

SP 4462 with horn circled

Steam locomotives used whistles and diesels use horns, right? Not entirely. As diesels began to replace steam locomotives, it became obvious that the steam-powered whistles that had been popular would have to be replaced with an air-powered horn. During this transition, there were some cases of horns being employed on steam locomotives.

The Southern Pacific used horns (in addition to whistles) on both the GS series 4-8-4s and the Cab-Forwards. The Cab-Forward had electric horns installed on the rear of their tenders. When Cab-Forwards were making a reverse move, it was difficult for the cab crew to see all the way to the rear of the tender. It was also difficult for a person standing near the rear of a Cab-Forward to hear the locomotive moving because they were so far away from the "noisy" part of the locomotive. A horn was used to alert anyone passing to the rear of the locomotive during these movements.