The Collaborative International Dictionary of English v.0.48:

Switching \Switch"ing\,
   a. & n. from Switch, v.
   [1913 Webster]

   Switching engine, a locomotive for switching cars from one
      track to another, and making up trains; -- called also
      switch engine. [U.S.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

switch engine
    n 1: a locomotive for switching rolling stock in a railroad yard
         [syn: switch engine, donkey engine]