When Fixed At One End, And Loaded At The Other - Rule

Multiply the weight to be supported in pounds by the length of the cylinder in feet; divide the product by .6 of the value of the material, and the cube root of the quotient will give the diameter.

Note

When the cylinder is loaded uniformly throughout its length, the cube root of half the quotient will give the diameter.

Example

What should be the diameter of a cast-iron cylindrical beam, 8 ins. in length, to support 15000 lbs. without permanent injury?

3 ins.=.66 feet; 15000 x. 66 / .6X225 =74.07; and ³√74.07=4.2.