A paper machine processes rolls of paper having a density of 984 kg/m3. The paper roll is 1.50-m outside dia (OD) X 0.22-m inside dia (ID) X 3.23 m long and is on a simply supported, hollow, steel shaft with Sut = 400 MPa. Design a 2.5:1 reduction spur gearset to drive this roll shaft to obtain a minimum dynamic safety factor of 2 for a 10-year life if the shaft OD is 22 cm and the roll turns at 50 rpm with 1.2 hp absorbed.