Geared steam locomotive
A geared steam locomotive is a type of steam locomotive which uses gearing, usually reduction gearing, in the drivetrain, as opposed to the common directly driven design.
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."