Question

2. A shaft carrying a 10KN load is supported by two identical plain journal bearings. The shaft, which normally rotates at 3000 rev/min has, at the bearing region, a nominal diameter of 50 mm and a length of 16 mm. Starting with a radial clearance ratio of 0.0015 and neglecting thermal effects a) Calculate the temperature of the lubricant which will produce an eccentricity ratio of 0.7 if the oil used is SAE10 b) Comment of the necessity to supply lubricant to the bearing and calculate the minimum oil supply rate, assuming that the bearing acts as a 360° bearing. c) What is the lowest speed at which the shaft can rotate and still maintain a minimum film thickness above an acceptable limit of 3 m, at a temperature of 55°C? Figure Q2 Temperature F 80 00 20 140 10 180 200 220 240 260 280 10 10 10 0.7 0.6 0.5 20 50 60 70 120 130 140 90 100 Temperature (°C) iscosity versus temperature for typical SAE grade

Answer 1

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