15.27 An 18-tooth pinion with a diametral pitch of 6 rotates 1800 rpm and drives a 36-tooth gear at 900 rpm in a gear speed reducer. The pinion and gear with 20 ° full-depth involute teeth are keyed to shafts that are simply supported by bearings. The bearings on each shaft are 2.0 in. from the gear center. If the gears transmit 0.5 hp, what are the forces on the pinion, gear, and shafts?