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.
Track gauge conversion
Few steam locomotives are constructed to allow for gauge change. Those that are include some in East African Railways, Garratts, and the Victorian Railways R class R766. Construction of steam locomotives in this way is difficult due to the position of the boilers and the fireboxes. The gauge change is only to a wider gauge.