This equation indicates that the stiffness of the combined shaft-bearing system will be less than the stiffness of the sin-gle most flexible element. In this example, the shaft is the sin-gle most flexible element (kshaft = 8756.5 N/mm or 50,000 lbf/in.). According to Equation 1-8, the effective stiffness of the combined shaft-bearing spring system is only 7297.7 N/mm (41,670 lbf/in.).