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.
GWR steam rail motors
The steam rail motors (SRM) were self-propelled carriages operated by the Great Western Railway in England and Wales from 1903 to 1935. They incorporated a steam locomotive within the body of the carriage.