50 FARM MACHINERY 



Problem : Find the safe load on an oak doubletree 4 

 feet long, 4 inches wide, 2 inches thick. Factor of 

 safety = 6. 



Let L = length in inches, W = load in pounds, b thickness, 

 d = width in inches. 



Bending moment = YA WL = Y 4 W& = 12W. 



Section modulus = ~ = 2 ^ (4) ' - = 5-333- 



Modulus of rupture for oak =13,000. 



Sect. Mod. X Mod. of Rupt. 

 Bending moment = Factor of Safety 



5-333X13,000 



" = 063 pounds. (Ans.) 



