The power shaft shown in the figure 2 is subjected to torsion 350 in-lb between

Question

The power shaft shown in the figure 2 is subjected to torsion 350 in-lb between segment B and C at point C there is a concentrated load of 275 lb. The length of the shaft is L = 7.5 in. The distance between A and C is La = 2.25 in Ld=4.75 in. The diameter of the shaft d = 0.75 in. The material is 31400 OQT 700. Determine the design factor of based on Modified Goodman Theory or ASME Ecliptic theory. If the power shaft shown in Figure 2 rotates at 1850 rpm, specify the suitable bearings to support the shaft at A and B. Assume both bearings have a design life of 2450 hours

Explanation / Answer

Life L10=(10^6/(60n))*(Cr/Pr)^3*h

where n is no. of revolutions in rpm

L10 is the life for the bearings to sustain 10^6 revolutions (90% reliability, that is 90% of the bearings do not fail)

Use it to be 10^6.

Cr= Basic Dynamic load ratings, charts are available for it, through which you can choose which bearing is to be used.

Pr=X.Fr+Y.Fa

where Fr= radial load

Fa= axial load

here Fa=0 and X=1

hence Pr=Fr

h=2450 hrs..

substitute to get the answer, Cr choose it from tables,

sorry could not find the Cr values for you as the time is about to get over.

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