Geared steam locomotive
This gearing is part of the machinery within the locomotive and should not be confused with the pinion that propels a rack locomotive along the rack between the rails. The geared steam locomotives that have been built have been for conventional track, relying on the adhesion between wheels and rail.
Steam whistle
Locomotive steam trumpets were soon replaced by steam whistles. Air whistles were used on some Diesel and electric locomotives, but these mostly employ air horns.