Equation (17–7) is called the belting equation, but Eqs. (17–9), (17–10), and (17–11)
reveal how belting works. We plot Eqs. (17–10) and (17–11) as shown in Fig. 17–8
against Fi as abscissa. The initial tension needs to be sufficient so that the difference
between the F1 and F2 curve is 2T/D. With no torque transmitted, the least possible
belt tension is F1 = F2 = Fc .