MEE 3090 HW Problem 13-9 To avoid the problem of interference in a pair of spur gears using a 25° pressure angle, specify the minimum number of teeth allowed on the pinion for each of the following gear ratios. (a) 2 to 1 (b) 3 to 1 (c) 4 to 1 (d) 5 to 1 Problem 13-10 For a spur gearset with ϕ = 20°, while avoiding interference, find: (a) The smallest pinion tooth count that will run with itself (b) The smallest pinion tooth count at a ratio mG = 2.5, and the largest gear tooth count possible with this pinion (c) The smallest pinion that will run with a rack Problem 13-17 Shaft a in the figure rotates at 600 rev/min in the direction shown. Find the speed and direction of rotation of shaft d. Problem 13-22 A compound reverted gear train is to be designed as a speed increaser to provide a total increase of speed of exactly 30 to 1. With a 20° pressure angle, specify appropriate numbers of teeth to minimize the gearbox size while avoiding the interference problem in the teeth. Assume all gears will have the same diametral pitch. Problem 13-24 A gearbox is to be designed with a compound reverted gear train that transmits 25 horsepower with an input speed of 2500 rev/min. The output should deliver the power at a rotational speed in the range of 280 to 300 rev/min. Spur gears with 20° pressure angle are to be used. Determine suitable numbers of teeth for each gear, to minimize the gearbox size while providing an output speed within the specified range. Be sure to avoid an interference problem in the teeth. Problem 13=29 A compound reverted gear train is to be designed to provide the appropriate ratio between the minute hand and the hour hand of a clock. The hour hand is attached to the shaft of gear 5, such that the rotational speed of the hour hand will equal the rotational speed of gear 5. The shaft of gear 2 passes through the center of the hollow shaft of gear 5, and has the minute hand attached to it. Use spur gears with a 20° pressure angle. Specify appropriate numbers of teeth, while minimizing the gearbox size and avoiding the interference problem in the teeth.
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