Practice Exam 2

# Practice Exam 2 - calculated in part(e if you desire a life...

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Problem 1 The 18 tooth pinion is driven 5000 rpm by a motor that delivers 20 lb in of torque. The gears provide a double reduction in speed, with the output taken from the 36 tooth gear. Both the 6-pitch and 9-pitch gears have a 25 o pressure angle. Neglecting the small friction loss in the gears and bearings determine: a) (5 pt) pitch diameters of each gear (including the pinon) b) (5pt) what are the tangential and normal forces applied by the pinion (gear 1) to gear 2 (the one it is driving) at contact c) (5pt) what are the tangential and normal forces applied by the output gear 4 to gear 3 that drives it d) (10 pt) what are the radial loads applied to the countershaft bearing A and B . (Hint: sketch the countershaft as a free body in equilibrium). e) (3 pt) How many rpm does bearing B rotate at? f) (5pt) Assuming a bearing load of 100 lbf at bearing B with the speed you

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