Correct Answer : Option (D) : 251.7mm
Explanation : d(t)=m[z+4cosϒ-2] where ϒ=9.46â° is the lead angle. tanϒ=2/12, z=40 and m=6mm
Correct Answer : Drums with helical grooves
Explanation : They have more bearing surface of the drum and prevent friction between adjacent turns of the rope.
Correct Answer : Increasingly centrifugal force in large sheaves
Explanation : Larger sheaves have higher centrifugal forces and higher cost because more material is used in their construction.
Correct Answer : Both bending and tensile stress
Explanation : There is direct tensile stress due to load being raised as well as bending stress.