The Collaborative International Dictionary of English v.0.48:

Yerk \Yerk\, v. t. [imp. & p. p. Yerked; p. pr. & vb. n.
   Yerking.] [See Yerk.]
   [1913 Webster]
   1. To throw or thrust with a sudden, smart movement; to kick
      or strike suddenly; to jerk.
      [1913 Webster]

            Their wounded steeds . . .
            Yerk out their armed heels at their dead masters.
                                                  --Shak.
      [1913 Webster]

   2. To strike or lash with a whip. [Obs. or Scot.]
      [1913 Webster]