14-11 The steel pinion of Problem 14-4 is to mesh with a steel gear with a gear ratio of 4:1. The Brinell hardness of the teeth is 200, and the tangential load transmitted by the gears is 6 kN. If the contact fatigue strength of the steel can be estimated from the AGMA formula of Sc = 2.22 HB+200 MPa, estimate the factor of safety of the drive based on a surface fatigue failure. 14-4 A steel spur pinion has 16 teeth cut on the 20° full-depth system with a module of 8 mm and a face width of 90 mm. The pinion rotates at 150 rev/min and transmits 6 kW to the mating steel gear. What is the bending stress?