166 



HANDBOOK OF MECHANICAL DESIGN 



TWO -BEARING SHAFTS OF UNIFORM STRENGTH 



Values of "□" Q, 



0.2 



0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 



Load 



:H _ i- 



Di- 



I 



A 



-H 



Load 



^m. 



c 



-4 Di ^ 



-- A 



^ 



In designing a shaft with two bearings, the diameter at the point between the bearings where 

 the load or resrdtant of loads is applied is calculated from considerations of deflection or stress. From 

 the chart the minimum diameter at any other point a distance A from the center line of the bearing 

 can be found. In the case of a shaft extension, the diameter at the bearing is calculated and the 

 chart gives the minimum diameter at any other point a distance A from the load. These "minimum 

 diameters" are shown plotted on the shaft, the points forming a curve. It will be apparent that 

 the section of the shaft at the inside neck of the bearing or at the load must be sufficient to take care 

 of shear and twisting moment. Example: Shown by dotted line: A = ^4. in.: S = 15 in.: C = 4% 

 in.: D = 3.26 in. from the chart. 



