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.
South African Class 14E
Unlike the later dual voltage Classes 19E, 20E and 21E which were equipped to automatically transition between AC and DC mode on the run, the Class 14E had to be stopped and then restarted under the different voltage. Upon their introduction in 1990, these were some of the most powerful electric locomotives on the Spoornet roster. They featured three-phase AC motors (induction motors) made by Siemens. In addition, they incorporated Siemens' sophisticated train communication network system.
All earlier South African electric locomotives, with the exception of the Orex Line's Class 9Es, ran on spoked wheels using spur gears. Amongst South African electric locomotives, the Class 14E was the first to have solid wheels with double helical or herringbone gears and with a traction motor to wheel gear ratio of 20:103. This gear ratio had the result that, while the three prototypes were very fast, they struggled to pick up a load. The locally built Class 14E1, on the other hand, ran on spoked wheels with helical gears and had a more conservative traction motor to wheel gear ratio of 18:67..