Correct Answer : Option (D) : All of the above
Explanation : In some cases, portion of tooth below base circle is not involute due to large dedendum. This leads to overlapping of involute portion of teeth with the non-involute portion of the teeth.
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.