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.
Fairlie locomotive
A Fairlie is a type of articulated steam locomotive that has the driving wheels on bogies. The locomotive may be double-ended (a double Fairlie) or single ended (a single Fairlie). Fairlies are most associated with the Ffestiniog Railway in Wales.