Fig. 2.
Idealized motor behavior. (Left) The motor torque–speed curve is nearly constant up to a knee speed, whereupon it decreases nearly linearly. Here, torque is normalized to the maximum torque at stall (ω = 0). The curve is self-similar for increasing pmf. For a given viscous load (characterized by its frictional drag coefficient, ζii = 1, 2, 3), the speed of the motor is determined by the intersection of the “load line” with the motor torque curve. (Right) The motor speed is nearly constant with pmf for different viscous drag loads. The experimental data supporting these idealized curves are given in Fig. 3.