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.
Johnson bar (vehicle)
Many steam locomotives have valve gear controls which are set using a Johnson bar as referenced in Fred Eaglesmith's "Back There": "Hey Porter, tell that engineer, tell him this train's too slow. Tell him to let go that Johnson bar. I got places I got to go."