driving wheel

driving wheel (plural driving wheels)

1. (rail transport) On a steam locomotive, a powered wheel driven by the locomotive's pistons or turbine.
   • 1951 March, David R. Webb, “British 4-4-2 Tank Locomotives”, in Railway Magazine, page 152:

     While not, perhaps, the handsomest of 4-4-2 tanks, as they had a rather large proportion of their driving wheels exposed, they proved very useful locomotives, doing yeoman work on suburban trains around London and Birmingham, and later on numerous rural routes.

• driver (sense 15)

• driving axle