The layout of a transmission shaft carrying two pulleys B and C and supported on bearings A and D is shown in figure 1 below. Power is supplied to the shaft by means of a vertical flat belt on pulley B that is then transmitted to pulley C carrying a horizontal flat belt. The maximum tension in the belt on pulley B is 3 kN. The angle of wrap for the bigger pulley is 180° and 160° for the smaller pulley. The coefficient of friction between the belt and pulleys is 0.25. The shaft is made of mild steel with shear yield strength of 420 N/mm2 and the factor of safety is 3. Neglecting the mass of the belt and assuming that the loads are suddenly applied on the shaft, determine the shaft diameter on strength basis. Make reasonable assumptions where necessary including the weight of pulleys.