Source : Webster's Revised Unabridged Dictionary (1913)

Handwheel \Hand"wheel`\, n. (Mach.)
   Any wheel worked by hand; esp., one the rim of which serves
   as the handle by which a valve, car brake, or other part is
   adjusted.

Source : WordNet®

handwheel
     n 1: a wheel worked by hand
     2: control consisting of a wheel whose rim serves as the handle
        by which a part is operated