31. See Figure P12-31 . The shaft is rotating at 650 rpm, and it receives 7.5 hp through a flexible coupling. The power is delivered to an adjacent shaft through a single helical gear B having a normal pressure angle of 20 and a helix angle of 15. The pitch diameter for the gear is 4.141 in. Review the discussion of forces on helical gears in Chapter 10, and use Equations 12-1 (), (122). (12-4), and (12-5) in this chapter to verify the values for the forces given in the figure. Draw the complete free-body diagrams for the shaft in both the vertical plane and the horizontal plane. Then draw the complete shearing force and bending moment diagrams for the shaft in both planes. WXB VrB Spacer Flexible coupling A Mating worm not shown WB B W.B C DB = 4.141 in WIB = 351 lb W-B-132 lb WXB = 94 lb Helical gear FIGURE P12-31 B