The gears or other components make the three shafts rotate in such a way that <math>\scriptstyle a=pb+qc</math>, where <math>\scriptstyle a</math>, <math>\scriptstyle b</math>, and <math>\scriptstyle c</math> are the angular velocities of the three shafts, and <math>\scriptstyle p</math> and <math>\scriptstyle q</math> are constants.