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.
Swiss locomotive and railcar classification
Steam powered tank locomotives were always given an "E", and the maximum speed of the locomotive was designated with a lower case letter. Thus, an Ea 3/6 was a tank locomotive with v > , three coupled drive axles, and three unpowered axles. With steam locomotives, separate driving mechanisms were displayed. So, for example, a Mallet locomotive was named G 2x2/2 or G 2/3+2/2, and not G 4/4 or G 4/5.