The Collaborative International Dictionary of English v.0.48:

Rock shaft \Rock" shaft`\ [Cf. Rock, v. i.] (Mach.)
   A shaft that oscillates on its journals, instead of
   revolving, -- usually carrying levers by means of which it
   receives and communicates reciprocating motion, as in the
   valve gear of some steam engines; -- called also rocker,
   rocking shaft, and way shaft.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Way shaft \Way" shaft`\
   1. (Mach.) A rock shaft.
      [1913 Webster]

   2. (Mining) An interior shaft, usually one connecting two
      levels. --Raymond.
      [1913 Webster]