The spur gear train given in HW5.4 is to be designed (4 gears in total) for a factor of safety of 2 for bending and 2.5 for surface stresses. Material to be used is Grade 2 through-hardened steel. Assume quality standard of 5, uncrowned tooth, enclosed and accurately mounted. All gears in the system must be designed to survive 10^8 cycles with a reliability of 0.99. Find the required surface hardness for individual gears. Make any additional assumptions as your see fit.