CHARTS AND TABLES 



19 



WR^ OF SYMMETRICAL BODIES 



For computing WR'^ of rotating masses of weight per unit volume p, by resolving the body into 

 elemental shapes. See page 208 for effect of WR^ on electric motor selection. 



Note: p in pounds per cubic incli and dimensions in inches give WR'^ in Ib.-in. squared. 



1. Weights per Unit Volume of Materials. 



Weight, Lb. 

 Material per Cu. In. 



Cast iron . 260 



Cast-iron castings of heavy section i.e., flywheel rims . 250 



Steel 0.283 



Bronze 0.319 



Lead 0.410 



Copper 0.318 



2. Cylinder, about Axis Lengthwise through the Center of Gravity. 



\o\Mme = '^L{D\- D\) 



4 



(a) For any material: 



WR-' = ~ pL{D\ - DS) 



where p is the weight per unit volume. 

 (6) For cast iron: 



L{D\ - DS) 



WR'- = 



39.2 



(c) For cast iron (heavy sections) : 



_ LjDS - PS) 

 ^^ ~ 40.75 



(d) For steel : 



WR^ = 



LjDh - D\) 

 36.0 



3. Cylinder, about an Axis Parallel to the Axis through Center of Gravity. 



Volume = I L{D\ - D\) 



^■g 



(a) For any material: 



(6) For steel: 



*^""-"" 4.50 V 8 ^yj 



4. Solid Cylinder, Rotated about an Axis Paredlel to a Line that Passes through the Center of 

 Gravity and Is Perpendicular to the Center Line. 



If V 



11 r ^ 



Volume = ^ D'-L 

 4 



(a) For any material: 



(b) For steel: 



+• ' 



WR 



"'" 4.50 Vl2 ^ 16 ^ / 



