advanced shaft mechanics

Fig. 14.10 shows a shaft carrying a pulley A and a gear B and supported in

two bearings C and D. The shaft transmits 20 kW at 150 r.p.m. The tangential force Ft on the gear B

acts vertically upwards as shown.

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The pulley delivers the power through a belt to another pulley of equal diameter vertically

below the pulley A. The ratio of tensions T1 / T2 is equal to 2.5. The gear and the pulley weigh 900 N

and 2700 N respectively. The permissible shear stress for the material of the shaft may be taken as

63 MPa. Assuming the weight of the shaft to be negligible in comparison with the other loads, determine

its diameter. Take shock and fatigue factors for bending and torsion as 2 and 1.5 respectively