3-68 to 3-71* A countershaft carrying two V-belt pulleys is shown in the figure. Pulley A receives power from a motor through a belt with the belt tensions shown. The power is transmitted through the shaft and delivered to the belt on pulley B. Assume the belt tension on the loose side at B is 15 per- cent of the tension on the tight side. (a) Determine the tensions in the belt on pulley B, assuming the shaft is running at a constant speed. (b) Find the magnitudes of the bearing reaction forces, assuming the bearings act as simple supports. (c) Draw shear-force and bending-moment diagrams for the shaft. If needed, make one set for the horizontal plane and another set for the vertical plane. (d) At the point of maximum bending moment, determine the bending stress and the torsional shear stress. (e) At the point of maximum bending moment, determine the principal stresses and the max- imum shear stress. 0 250 mm 450 mm 300 mm T₂ 250-mm dia. 100 2 kN 0.3 kN 200-mm dia. 30-mm dia. B 250-mm dia. Problem 3-68* 230 mm T₁ 280 mm 30-mm dia. 300 mm 400-mm dia. 1800 N Problem 3-69* 270 N