QUESTION $2$: Since the wheel is in the middle, determine what happens to the vaks. For a lifespan of Lh $12500$ working hours, choose one of the rolling bearings $($single row deep rib$)$ of the rotating shaft. Take the shaft diameter as $25$ mm$.(35$ P$)$ Note: For those who cannot solve the gear question, the rolling circle diameter of the rotating wheel will be taken as $35$ mm$.$