Example 1.10. Determine The Power Required To Run A 300 Mm Dia Shaft At 400 Rpm In Journals With Uniform Oil Thickness Of 1 Mm. Two Bearings Of 300 Mm Width Are Used To Support The Shaft. The Dynamic Viscosity Of Oil Is 0.03 Pas. (Pas = (N/M²) X S). Shear Stress On The Shaft Surface = T = U (Duldy) = U(U/Y) U = DN/60 = 7 X 0.3 X 400/60 = 6.28 M/S T = 0.03

 

 

Example 1.10. Determine the power required to run a 300 mm dia shaft at 400 rpm in journals with uniform oil thickness of 1 mm. Two bearings of 300 mm width are used to support the shaft. The dynamic viscosity of oil is 0.03 Pas. (Pas = (N/m) x s). == Shear stress on the shaft surface = tu (du/dy) = u(u/y) u = DN/60=x 0.3 x 400/60 = 6.28 m/s T=0.03 ((6.28-0) 0.001) = 188.4 N/m Surface area of the two bearings, A = 2 x DL Force on shaft surface = tx A = 188.4 x (2 x x x 0.3 x 0.3)= 106.6 N Torque Power required =106.6 x 0.15 = 15.995 Nm =2 NT/60=2xxx 400 x 15.995/60 = 670 W. (check using eqn. 1.9.2, P = 3 N2LR3/450 h = 669.74 W)