TABLE 1.

Definition of the stiffness values.

Symbol	Definition	Approximate range acc. Tmax
c1	Stiffness at low torque	∼0–10% of max. Torque
c2	Stiffness at middle torque	∼10–30% of max. Torque
c3	Stiffness at high torque	∼30–100% of max. Torque